/src/git/builtin/pack-objects.c

Source (jump to first uncovered line)
#include "builtin.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "repository.h"
#include "config.h"
#include "attr.h"
#include "object.h"
#include "commit.h"
#include "tag.h"
#include "delta.h"
#include "pack.h"
#include "pack-revindex.h"
#include "csum-file.h"
#include "tree-walk.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "list-objects-filter-options.h"
#include "pack-objects.h"
#include "progress.h"
#include "refs.h"
#include "streaming.h"
#include "thread-utils.h"
#include "pack-bitmap.h"
#include "delta-islands.h"
#include "reachable.h"
#include "oid-array.h"
#include "strvec.h"
#include "list.h"
#include "packfile.h"
#include "object-file.h"
#include "object-store-ll.h"
#include "replace-object.h"
#include "dir.h"
#include "midx.h"
#include "trace2.h"
#include "shallow.h"
#include "promisor-remote.h"
#include "pack-mtimes.h"
#include "parse-options.h"

/*
 * Objects we are going to pack are collected in the `to_pack` structure.
 * It contains an array (dynamically expanded) of the object data, and a map
 * that can resolve SHA1s to their position in the array.
 */
static struct packing_data to_pack;

static inline struct object_entry *oe_delta(
    const struct packing_data *pack,
    const struct object_entry *e)
{
  if (!e->delta_idx)
    return NULL;
  if (e->ext_base)
    return &pack->ext_bases[e->delta_idx - 1];
  else
    return &pack->objects[e->delta_idx - 1];
}

static inline unsigned long oe_delta_size(struct packing_data *pack,
            const struct object_entry *e)
{
  if (e->delta_size_valid)
    return e->delta_size_;

  /*
   * pack->delta_size[] can't be NULL because oe_set_delta_size()
   * must have been called when a new delta is saved with
   * oe_set_delta().
   * If oe_delta() returns NULL (i.e. default state, which means
   * delta_size_valid is also false), then the caller must never
   * call oe_delta_size().
   */
  return pack->delta_size[e - pack->objects];
}

unsigned long oe_get_size_slow(struct packing_data *pack,
             const struct object_entry *e);

static inline unsigned long oe_size(struct packing_data *pack,
            const struct object_entry *e)
{
  if (e->size_valid)
    return e->size_;

  return oe_get_size_slow(pack, e);
}

static inline void oe_set_delta(struct packing_data *pack,
        struct object_entry *e,
        struct object_entry *delta)
{
  if (delta)
    e->delta_idx = (delta - pack->objects) + 1;
  else
    e->delta_idx = 0;
}

static inline struct object_entry *oe_delta_sibling(
    const struct packing_data *pack,
    const struct object_entry *e)
{
  if (e->delta_sibling_idx)
    return &pack->objects[e->delta_sibling_idx - 1];
  return NULL;
}

static inline struct object_entry *oe_delta_child(
    const struct packing_data *pack,
    const struct object_entry *e)
{
  if (e->delta_child_idx)
    return &pack->objects[e->delta_child_idx - 1];
  return NULL;
}

static inline void oe_set_delta_child(struct packing_data *pack,
              struct object_entry *e,
              struct object_entry *delta)
{
  if (delta)
    e->delta_child_idx = (delta - pack->objects) + 1;
  else
    e->delta_child_idx = 0;
}

static inline void oe_set_delta_sibling(struct packing_data *pack,
          struct object_entry *e,
          struct object_entry *delta)
{
  if (delta)
    e->delta_sibling_idx = (delta - pack->objects) + 1;
  else
    e->delta_sibling_idx = 0;
}

static inline void oe_set_size(struct packing_data *pack,
             struct object_entry *e,
             unsigned long size)
{
  if (size < pack->oe_size_limit) {
    e->size_ = size;
    e->size_valid = 1;
  } else {
    e->size_valid = 0;
    if (oe_get_size_slow(pack, e) != size)
      BUG("'size' is supposed to be the object size!");
  }
}

static inline void oe_set_delta_size(struct packing_data *pack,
             struct object_entry *e,
             unsigned long size)
{
  if (size < pack->oe_delta_size_limit) {
    e->delta_size_ = size;
    e->delta_size_valid = 1;
  } else {
    packing_data_lock(pack);
    if (!pack->delta_size)
      ALLOC_ARRAY(pack->delta_size, pack->nr_alloc);
    packing_data_unlock(pack);

    pack->delta_size[e - pack->objects] = size;
    e->delta_size_valid = 0;
  }
}

#define IN_PACK(obj) oe_in_pack(&to_pack, obj)
#define SIZE(obj) oe_size(&to_pack, obj)
#define SET_SIZE(obj,size) oe_set_size(&to_pack, obj, size)
#define DELTA_SIZE(obj) oe_delta_size(&to_pack, obj)
#define DELTA(obj) oe_delta(&to_pack, obj)
#define DELTA_CHILD(obj) oe_delta_child(&to_pack, obj)
#define DELTA_SIBLING(obj) oe_delta_sibling(&to_pack, obj)
#define SET_DELTA(obj, val) oe_set_delta(&to_pack, obj, val)
#define SET_DELTA_EXT(obj, oid) oe_set_delta_ext(&to_pack, obj, oid)
#define SET_DELTA_SIZE(obj, val) oe_set_delta_size(&to_pack, obj, val)
#define SET_DELTA_CHILD(obj, val) oe_set_delta_child(&to_pack, obj, val)
#define SET_DELTA_SIBLING(obj, val) oe_set_delta_sibling(&to_pack, obj, val)

static const char *pack_usage[] = {
  N_("git pack-objects --stdout [<options>] [< <ref-list> | < <object-list>]"),
  N_("git pack-objects [<options>] <base-name> [< <ref-list> | < <object-list>]"),
  NULL
};

static struct pack_idx_entry **written_list;
static uint32_t nr_result, nr_written, nr_seen;
static struct bitmap_index *bitmap_git;
static uint32_t write_layer;

static int non_empty;
static int reuse_delta = 1, reuse_object = 1;
static int keep_unreachable, unpack_unreachable, include_tag;
static timestamp_t unpack_unreachable_expiration;
static int pack_loose_unreachable;
static int cruft;
static timestamp_t cruft_expiration;
static int local;
static int have_non_local_packs;
static int incremental;
static int ignore_packed_keep_on_disk;
static int ignore_packed_keep_in_core;
static int allow_ofs_delta;
static struct pack_idx_option pack_idx_opts;
static const char *base_name;
static int progress = 1;
static int window = 10;
static unsigned long pack_size_limit;
static int depth = 50;
static int delta_search_threads;
static int pack_to_stdout;
static int sparse;
static int thin;
static int num_preferred_base;
static struct progress *progress_state;

static struct bitmapped_pack *reuse_packfiles;
static size_t reuse_packfiles_nr;
static size_t reuse_packfiles_used_nr;
static uint32_t reuse_packfile_objects;
static struct bitmap *reuse_packfile_bitmap;

static int use_bitmap_index_default = 1;
static int use_bitmap_index = -1;
static enum {
  NO_PACK_REUSE = 0,
  SINGLE_PACK_REUSE,
  MULTI_PACK_REUSE,
} allow_pack_reuse = SINGLE_PACK_REUSE;
static enum {
  WRITE_BITMAP_FALSE = 0,
  WRITE_BITMAP_QUIET,
  WRITE_BITMAP_TRUE,
} write_bitmap_index;
static uint16_t write_bitmap_options = BITMAP_OPT_HASH_CACHE;

static int exclude_promisor_objects;

static int use_delta_islands;

static unsigned long delta_cache_size = 0;
static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
static unsigned long cache_max_small_delta_size = 1000;

static unsigned long window_memory_limit = 0;

static struct string_list uri_protocols = STRING_LIST_INIT_NODUP;

enum missing_action {
  MA_ERROR = 0,      /* fail if any missing objects are encountered */
  MA_ALLOW_ANY,      /* silently allow ALL missing objects */
  MA_ALLOW_PROMISOR, /* silently allow all missing PROMISOR objects */
};
static enum missing_action arg_missing_action;
static show_object_fn fn_show_object;

struct configured_exclusion {
  struct oidmap_entry e;
  char *pack_hash_hex;
  char *uri;
};
static struct oidmap configured_exclusions;

static struct oidset excluded_by_config;

/*
 * stats
 */
static uint32_t written, written_delta;
static uint32_t reused, reused_delta;

/*
 * Indexed commits
 */
static struct commit **indexed_commits;
static unsigned int indexed_commits_nr;
static unsigned int indexed_commits_alloc;

static void index_commit_for_bitmap(struct commit *commit)
{
  if (indexed_commits_nr >= indexed_commits_alloc) {
    indexed_commits_alloc = (indexed_commits_alloc + 32) * 2;
    REALLOC_ARRAY(indexed_commits, indexed_commits_alloc);
  }

  indexed_commits[indexed_commits_nr++] = commit;
}

static void *get_delta(struct object_entry *entry)
{
  unsigned long size, base_size, delta_size;
  void *buf, *base_buf, *delta_buf;
  enum object_type type;

  buf = repo_read_object_file(the_repository, &entry->idx.oid, &type,
            &size);
  if (!buf)
    die(_("unable to read %s"), oid_to_hex(&entry->idx.oid));
  base_buf = repo_read_object_file(the_repository,
           &DELTA(entry)->idx.oid, &type,
           &base_size);
  if (!base_buf)
    die("unable to read %s",
        oid_to_hex(&DELTA(entry)->idx.oid));
  delta_buf = diff_delta(base_buf, base_size,
             buf, size, &delta_size, 0);
  /*
   * We successfully computed this delta once but dropped it for
   * memory reasons. Something is very wrong if this time we
   * recompute and create a different delta.
   */
  if (!delta_buf || delta_size != DELTA_SIZE(entry))
    BUG("delta size changed");
  free(buf);
  free(base_buf);
  return delta_buf;
}

static unsigned long do_compress(void **pptr, unsigned long size)
{
  git_zstream stream;
  void *in, *out;
  unsigned long maxsize;

  git_deflate_init(&stream, pack_compression_level);
  maxsize = git_deflate_bound(&stream, size);

  in = *pptr;
  out = xmalloc(maxsize);
  *pptr = out;

  stream.next_in = in;
  stream.avail_in = size;
  stream.next_out = out;
  stream.avail_out = maxsize;
  while (git_deflate(&stream, Z_FINISH) == Z_OK)
    ; /* nothing */
  git_deflate_end(&stream);

  free(in);
  return stream.total_out;
}

static unsigned long write_large_blob_data(struct git_istream *st, struct hashfile *f,
             const struct object_id *oid)
{
  git_zstream stream;
  unsigned char ibuf[1024 * 16];
  unsigned char obuf[1024 * 16];
  unsigned long olen = 0;

  git_deflate_init(&stream, pack_compression_level);

  for (;;) {
    ssize_t readlen;
    int zret = Z_OK;
    readlen = read_istream(st, ibuf, sizeof(ibuf));
    if (readlen == -1)
      die(_("unable to read %s"), oid_to_hex(oid));

    stream.next_in = ibuf;
    stream.avail_in = readlen;
    while ((stream.avail_in || readlen == 0) &&
           (zret == Z_OK || zret == Z_BUF_ERROR)) {
      stream.next_out = obuf;
      stream.avail_out = sizeof(obuf);
      zret = git_deflate(&stream, readlen ? 0 : Z_FINISH);
      hashwrite(f, obuf, stream.next_out - obuf);
      olen += stream.next_out - obuf;
    }
    if (stream.avail_in)
      die(_("deflate error (%d)"), zret);
    if (readlen == 0) {
      if (zret != Z_STREAM_END)
        die(_("deflate error (%d)"), zret);
      break;
    }
  }
  git_deflate_end(&stream);
  return olen;
}

/*
 * we are going to reuse the existing object data as is.  make
 * sure it is not corrupt.
 */
static int check_pack_inflate(struct packed_git *p,
    struct pack_window **w_curs,
    off_t offset,
    off_t len,
    unsigned long expect)
{
  git_zstream stream;
  unsigned char fakebuf[4096], *in;
  int st;

  memset(&stream, 0, sizeof(stream));
  git_inflate_init(&stream);
  do {
    in = use_pack(p, w_curs, offset, &stream.avail_in);
    stream.next_in = in;
    stream.next_out = fakebuf;
    stream.avail_out = sizeof(fakebuf);
    st = git_inflate(&stream, Z_FINISH);
    offset += stream.next_in - in;
  } while (st == Z_OK || st == Z_BUF_ERROR);
  git_inflate_end(&stream);
  return (st == Z_STREAM_END &&
    stream.total_out == expect &&
    stream.total_in == len) ? 0 : -1;
}

static void copy_pack_data(struct hashfile *f,
    struct packed_git *p,
    struct pack_window **w_curs,
    off_t offset,
    off_t len)
{
  unsigned char *in;
  unsigned long avail;

  while (len) {
    in = use_pack(p, w_curs, offset, &avail);
    if (avail > len)
      avail = (unsigned long)len;
    hashwrite(f, in, avail);
    offset += avail;
    len -= avail;
  }
}

static inline int oe_size_greater_than(struct packing_data *pack,
               const struct object_entry *lhs,
               unsigned long rhs)
{
  if (lhs->size_valid)
    return lhs->size_ > rhs;
  if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
    return 1;
  return oe_get_size_slow(pack, lhs) > rhs;
}

/* Return 0 if we will bust the pack-size limit */
static unsigned long write_no_reuse_object(struct hashfile *f, struct object_entry *entry,
             unsigned long limit, int usable_delta)
{
  unsigned long size, datalen;
  unsigned char header[MAX_PACK_OBJECT_HEADER],
          dheader[MAX_PACK_OBJECT_HEADER];
  unsigned hdrlen;
  enum object_type type;
  void *buf;
  struct git_istream *st = NULL;
  const unsigned hashsz = the_hash_algo->rawsz;

  if (!usable_delta) {
    if (oe_type(entry) == OBJ_BLOB &&
        oe_size_greater_than(&to_pack, entry, big_file_threshold) &&
        (st = open_istream(the_repository, &entry->idx.oid, &type,
               &size, NULL)) != NULL)
      buf = NULL;
    else {
      buf = repo_read_object_file(the_repository,
                &entry->idx.oid, &type,
                &size);
      if (!buf)
        die(_("unable to read %s"),
            oid_to_hex(&entry->idx.oid));
    }
    /*
     * make sure no cached delta data remains from a
     * previous attempt before a pack split occurred.
     */
    FREE_AND_NULL(entry->delta_data);
    entry->z_delta_size = 0;
  } else if (entry->delta_data) {
    size = DELTA_SIZE(entry);
    buf = entry->delta_data;
    entry->delta_data = NULL;
    type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
      OBJ_OFS_DELTA : OBJ_REF_DELTA;
  } else {
    buf = get_delta(entry);
    size = DELTA_SIZE(entry);
    type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
      OBJ_OFS_DELTA : OBJ_REF_DELTA;
  }

  if (st) /* large blob case, just assume we don't compress well */
    datalen = size;
  else if (entry->z_delta_size)
    datalen = entry->z_delta_size;
  else
    datalen = do_compress(&buf, size);

  /*
   * The object header is a byte of 'type' followed by zero or
   * more bytes of length.
   */
  hdrlen = encode_in_pack_object_header(header, sizeof(header),
                type, size);

  if (type == OBJ_OFS_DELTA) {
    /*
     * Deltas with relative base contain an additional
     * encoding of the relative offset for the delta
     * base from this object's position in the pack.
     */
    off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
    unsigned pos = sizeof(dheader) - 1;
    dheader[pos] = ofs & 127;
    while (ofs >>= 7)
      dheader[--pos] = 128 | (--ofs & 127);
    if (limit && hdrlen + sizeof(dheader) - pos + datalen + hashsz >= limit) {
      if (st)
        close_istream(st);
      free(buf);
      return 0;
    }
    hashwrite(f, header, hdrlen);
    hashwrite(f, dheader + pos, sizeof(dheader) - pos);
    hdrlen += sizeof(dheader) - pos;
  } else if (type == OBJ_REF_DELTA) {
    /*
     * Deltas with a base reference contain
     * additional bytes for the base object ID.
     */
    if (limit && hdrlen + hashsz + datalen + hashsz >= limit) {
      if (st)
        close_istream(st);
      free(buf);
      return 0;
    }
    hashwrite(f, header, hdrlen);
    hashwrite(f, DELTA(entry)->idx.oid.hash, hashsz);
    hdrlen += hashsz;
  } else {
    if (limit && hdrlen + datalen + hashsz >= limit) {
      if (st)
        close_istream(st);
      free(buf);
      return 0;
    }
    hashwrite(f, header, hdrlen);
  }
  if (st) {
    datalen = write_large_blob_data(st, f, &entry->idx.oid);
    close_istream(st);
  } else {
    hashwrite(f, buf, datalen);
    free(buf);
  }

  return hdrlen + datalen;
}

/* Return 0 if we will bust the pack-size limit */
static off_t write_reuse_object(struct hashfile *f, struct object_entry *entry,
        unsigned long limit, int usable_delta)
{
  struct packed_git *p = IN_PACK(entry);
  struct pack_window *w_curs = NULL;
  uint32_t pos;
  off_t offset;
  enum object_type type = oe_type(entry);
  off_t datalen;
  unsigned char header[MAX_PACK_OBJECT_HEADER],
          dheader[MAX_PACK_OBJECT_HEADER];
  unsigned hdrlen;
  const unsigned hashsz = the_hash_algo->rawsz;
  unsigned long entry_size = SIZE(entry);

  if (DELTA(entry))
    type = (allow_ofs_delta && DELTA(entry)->idx.offset) ?
      OBJ_OFS_DELTA : OBJ_REF_DELTA;
  hdrlen = encode_in_pack_object_header(header, sizeof(header),
                type, entry_size);

  offset = entry->in_pack_offset;
  if (offset_to_pack_pos(p, offset, &pos) < 0)
    die(_("write_reuse_object: could not locate %s, expected at "
          "offset %"PRIuMAX" in pack %s"),
        oid_to_hex(&entry->idx.oid), (uintmax_t)offset,
        p->pack_name);
  datalen = pack_pos_to_offset(p, pos + 1) - offset;
  if (!pack_to_stdout && p->index_version > 1 &&
      check_pack_crc(p, &w_curs, offset, datalen,
         pack_pos_to_index(p, pos))) {
    error(_("bad packed object CRC for %s"),
          oid_to_hex(&entry->idx.oid));
    unuse_pack(&w_curs);
    return write_no_reuse_object(f, entry, limit, usable_delta);
  }

  offset += entry->in_pack_header_size;
  datalen -= entry->in_pack_header_size;

  if (!pack_to_stdout && p->index_version == 1 &&
      check_pack_inflate(p, &w_curs, offset, datalen, entry_size)) {
    error(_("corrupt packed object for %s"),
          oid_to_hex(&entry->idx.oid));
    unuse_pack(&w_curs);
    return write_no_reuse_object(f, entry, limit, usable_delta);
  }

  if (type == OBJ_OFS_DELTA) {
    off_t ofs = entry->idx.offset - DELTA(entry)->idx.offset;
    unsigned pos = sizeof(dheader) - 1;
    dheader[pos] = ofs & 127;
    while (ofs >>= 7)
      dheader[--pos] = 128 | (--ofs & 127);
    if (limit && hdrlen + sizeof(dheader) - pos + datalen + hashsz >= limit) {
      unuse_pack(&w_curs);
      return 0;
    }
    hashwrite(f, header, hdrlen);
    hashwrite(f, dheader + pos, sizeof(dheader) - pos);
    hdrlen += sizeof(dheader) - pos;
    reused_delta++;
  } else if (type == OBJ_REF_DELTA) {
    if (limit && hdrlen + hashsz + datalen + hashsz >= limit) {
      unuse_pack(&w_curs);
      return 0;
    }
    hashwrite(f, header, hdrlen);
    hashwrite(f, DELTA(entry)->idx.oid.hash, hashsz);
    hdrlen += hashsz;
    reused_delta++;
  } else {
    if (limit && hdrlen + datalen + hashsz >= limit) {
      unuse_pack(&w_curs);
      return 0;
    }
    hashwrite(f, header, hdrlen);
  }
  copy_pack_data(f, p, &w_curs, offset, datalen);
  unuse_pack(&w_curs);
  reused++;
  return hdrlen + datalen;
}

/* Return 0 if we will bust the pack-size limit */
static off_t write_object(struct hashfile *f,
        struct object_entry *entry,
        off_t write_offset)
{
  unsigned long limit;
  off_t len;
  int usable_delta, to_reuse;

  if (!pack_to_stdout)
    crc32_begin(f);

  /* apply size limit if limited packsize and not first object */
  if (!pack_size_limit || !nr_written)
    limit = 0;
  else if (pack_size_limit <= write_offset)
    /*
     * the earlier object did not fit the limit; avoid
     * mistaking this with unlimited (i.e. limit = 0).
     */
    limit = 1;
  else
    limit = pack_size_limit - write_offset;

  if (!DELTA(entry))
    usable_delta = 0; /* no delta */
  else if (!pack_size_limit)
         usable_delta = 1; /* unlimited packfile */
  else if (DELTA(entry)->idx.offset == (off_t)-1)
    usable_delta = 0; /* base was written to another pack */
  else if (DELTA(entry)->idx.offset)
    usable_delta = 1; /* base already exists in this pack */
  else
    usable_delta = 0; /* base could end up in another pack */

  if (!reuse_object)
    to_reuse = 0; /* explicit */
  else if (!IN_PACK(entry))
    to_reuse = 0; /* can't reuse what we don't have */
  else if (oe_type(entry) == OBJ_REF_DELTA ||
     oe_type(entry) == OBJ_OFS_DELTA)
        /* check_object() decided it for us ... */
    to_reuse = usable_delta;
        /* ... but pack split may override that */
  else if (oe_type(entry) != entry->in_pack_type)
    to_reuse = 0; /* pack has delta which is unusable */
  else if (DELTA(entry))
    to_reuse = 0; /* we want to pack afresh */
  else
    to_reuse = 1; /* we have it in-pack undeltified,
         * and we do not need to deltify it.
         */

  if (!to_reuse)
    len = write_no_reuse_object(f, entry, limit, usable_delta);
  else
    len = write_reuse_object(f, entry, limit, usable_delta);
  if (!len)
    return 0;

  if (usable_delta)
    written_delta++;
  written++;
  if (!pack_to_stdout)
    entry->idx.crc32 = crc32_end(f);
  return len;
}

enum write_one_status {
  WRITE_ONE_SKIP = -1, /* already written */
  WRITE_ONE_BREAK = 0, /* writing this will bust the limit; not written */
  WRITE_ONE_WRITTEN = 1, /* normal */
  WRITE_ONE_RECURSIVE = 2 /* already scheduled to be written */
};

static enum write_one_status write_one(struct hashfile *f,
               struct object_entry *e,
               off_t *offset)
{
  off_t size;
  int recursing;

  /*
   * we set offset to 1 (which is an impossible value) to mark
   * the fact that this object is involved in "write its base
   * first before writing a deltified object" recursion.
   */
  recursing = (e->idx.offset == 1);
  if (recursing) {
    warning(_("recursive delta detected for object %s"),
      oid_to_hex(&e->idx.oid));
    return WRITE_ONE_RECURSIVE;
  } else if (e->idx.offset || e->preferred_base) {
    /* offset is non zero if object is written already. */
    return WRITE_ONE_SKIP;
  }

  /* if we are deltified, write out base object first. */
  if (DELTA(e)) {
    e->idx.offset = 1; /* now recurse */
    switch (write_one(f, DELTA(e), offset)) {
    case WRITE_ONE_RECURSIVE:
      /* we cannot depend on this one */
      SET_DELTA(e, NULL);
      break;
    default:
      break;
    case WRITE_ONE_BREAK:
      e->idx.offset = recursing;
      return WRITE_ONE_BREAK;
    }
  }

  e->idx.offset = *offset;
  size = write_object(f, e, *offset);
  if (!size) {
    e->idx.offset = recursing;
    return WRITE_ONE_BREAK;
  }
  written_list[nr_written++] = &e->idx;

  /* make sure off_t is sufficiently large not to wrap */
  if (signed_add_overflows(*offset, size))
    die(_("pack too large for current definition of off_t"));
  *offset += size;
  return WRITE_ONE_WRITTEN;
}

static int mark_tagged(const char *path UNUSED, const char *referent UNUSED, const struct object_id *oid,
           int flag UNUSED, void *cb_data UNUSED)
{
  struct object_id peeled;
  struct object_entry *entry = packlist_find(&to_pack, oid);

  if (entry)
    entry->tagged = 1;
  if (!peel_iterated_oid(the_repository, oid, &peeled)) {
    entry = packlist_find(&to_pack, &peeled);
    if (entry)
      entry->tagged = 1;
  }
  return 0;
}

static inline unsigned char oe_layer(struct packing_data *pack,
             struct object_entry *e)
{
  if (!pack->layer)
    return 0;
  return pack->layer[e - pack->objects];
}

static inline void add_to_write_order(struct object_entry **wo,
             unsigned int *endp,
             struct object_entry *e)
{
  if (e->filled || oe_layer(&to_pack, e) != write_layer)
    return;
  wo[(*endp)++] = e;
  e->filled = 1;
}

static void add_descendants_to_write_order(struct object_entry **wo,
             unsigned int *endp,
             struct object_entry *e)
{
  int add_to_order = 1;
  while (e) {
    if (add_to_order) {
      struct object_entry *s;
      /* add this node... */
      add_to_write_order(wo, endp, e);
      /* all its siblings... */
      for (s = DELTA_SIBLING(e); s; s = DELTA_SIBLING(s)) {
        add_to_write_order(wo, endp, s);
      }
    }
    /* drop down a level to add left subtree nodes if possible */
    if (DELTA_CHILD(e)) {
      add_to_order = 1;
      e = DELTA_CHILD(e);
    } else {
      add_to_order = 0;
      /* our sibling might have some children, it is next */
      if (DELTA_SIBLING(e)) {
        e = DELTA_SIBLING(e);
        continue;
      }
      /* go back to our parent node */
      e = DELTA(e);
      while (e && !DELTA_SIBLING(e)) {
        /* we're on the right side of a subtree, keep
         * going up until we can go right again */
        e = DELTA(e);
      }
      if (!e) {
        /* done- we hit our original root node */
        return;
      }
      /* pass it off to sibling at this level */
      e = DELTA_SIBLING(e);
    }
  };
}

static void add_family_to_write_order(struct object_entry **wo,
              unsigned int *endp,
              struct object_entry *e)
{
  struct object_entry *root;

  for (root = e; DELTA(root); root = DELTA(root))
    ; /* nothing */
  add_descendants_to_write_order(wo, endp, root);
}

static void compute_layer_order(struct object_entry **wo, unsigned int *wo_end)
{
  unsigned int i, last_untagged;
  struct object_entry *objects = to_pack.objects;

  for (i = 0; i < to_pack.nr_objects; i++) {
    if (objects[i].tagged)
      break;
    add_to_write_order(wo, wo_end, &objects[i]);
  }
  last_untagged = i;

  /*
   * Then fill all the tagged tips.
   */
  for (; i < to_pack.nr_objects; i++) {
    if (objects[i].tagged)
      add_to_write_order(wo, wo_end, &objects[i]);
  }

  /*
   * And then all remaining commits and tags.
   */
  for (i = last_untagged; i < to_pack.nr_objects; i++) {
    if (oe_type(&objects[i]) != OBJ_COMMIT &&
        oe_type(&objects[i]) != OBJ_TAG)
      continue;
    add_to_write_order(wo, wo_end, &objects[i]);
  }

  /*
   * And then all the trees.
   */
  for (i = last_untagged; i < to_pack.nr_objects; i++) {
    if (oe_type(&objects[i]) != OBJ_TREE)
      continue;
    add_to_write_order(wo, wo_end, &objects[i]);
  }

  /*
   * Finally all the rest in really tight order
   */
  for (i = last_untagged; i < to_pack.nr_objects; i++) {
    if (!objects[i].filled && oe_layer(&to_pack, &objects[i]) == write_layer)
      add_family_to_write_order(wo, wo_end, &objects[i]);
  }
}

static struct object_entry **compute_write_order(void)
{
  uint32_t max_layers = 1;
  unsigned int i, wo_end;

  struct object_entry **wo;
  struct object_entry *objects = to_pack.objects;

  for (i = 0; i < to_pack.nr_objects; i++) {
    objects[i].tagged = 0;
    objects[i].filled = 0;
    SET_DELTA_CHILD(&objects[i], NULL);
    SET_DELTA_SIBLING(&objects[i], NULL);
  }

  /*
   * Fully connect delta_child/delta_sibling network.
   * Make sure delta_sibling is sorted in the original
   * recency order.
   */
  for (i = to_pack.nr_objects; i > 0;) {
    struct object_entry *e = &objects[--i];
    if (!DELTA(e))
      continue;
    /* Mark me as the first child */
    e->delta_sibling_idx = DELTA(e)->delta_child_idx;
    SET_DELTA_CHILD(DELTA(e), e);
  }

  /*
   * Mark objects that are at the tip of tags.
   */
  refs_for_each_tag_ref(get_main_ref_store(the_repository), mark_tagged,
            NULL);

  if (use_delta_islands) {
    max_layers = compute_pack_layers(&to_pack);
    free_island_marks();
  }

  ALLOC_ARRAY(wo, to_pack.nr_objects);
  wo_end = 0;

  for (; write_layer < max_layers; ++write_layer)
    compute_layer_order(wo, &wo_end);

  if (wo_end != to_pack.nr_objects)
    die(_("ordered %u objects, expected %"PRIu32),
        wo_end, to_pack.nr_objects);

  return wo;
}


/*
 * A reused set of objects. All objects in a chunk have the same
 * relative position in the original packfile and the generated
 * packfile.
 */

static struct reused_chunk {
  /* The offset of the first object of this chunk in the original
   * packfile. */
  off_t original;
  /* The difference for "original" minus the offset of the first object of
   * this chunk in the generated packfile. */
  off_t difference;
} *reused_chunks;
static int reused_chunks_nr;
static int reused_chunks_alloc;

static void record_reused_object(off_t where, off_t offset)
{
  if (reused_chunks_nr && reused_chunks[reused_chunks_nr-1].difference == offset)
    return;

  ALLOC_GROW(reused_chunks, reused_chunks_nr + 1,
       reused_chunks_alloc);
  reused_chunks[reused_chunks_nr].original = where;
  reused_chunks[reused_chunks_nr].difference = offset;
  reused_chunks_nr++;
}

/*
 * Binary search to find the chunk that "where" is in. Note
 * that we're not looking for an exact match, just the first
 * chunk that contains it (which implicitly ends at the start
 * of the next chunk.
 */
static off_t find_reused_offset(off_t where)
{
  int lo = 0, hi = reused_chunks_nr;
  while (lo < hi) {
    int mi = lo + ((hi - lo) / 2);
    if (where == reused_chunks[mi].original)
      return reused_chunks[mi].difference;
    if (where < reused_chunks[mi].original)
      hi = mi;
    else
      lo = mi + 1;
  }

  /*
   * The first chunk starts at zero, so we can't have gone below
   * there.
   */
  assert(lo);
  return reused_chunks[lo-1].difference;
}

static void write_reused_pack_one(struct packed_git *reuse_packfile,
          size_t pos, struct hashfile *out,
          off_t pack_start,
          struct pack_window **w_curs)
{
  off_t offset, next, cur;
  enum object_type type;
  unsigned long size;

  offset = pack_pos_to_offset(reuse_packfile, pos);
  next = pack_pos_to_offset(reuse_packfile, pos + 1);

  record_reused_object(offset,
           offset - (hashfile_total(out) - pack_start));

  cur = offset;
  type = unpack_object_header(reuse_packfile, w_curs, &cur, &size);
  assert(type >= 0);

  if (type == OBJ_OFS_DELTA) {
    off_t base_offset;
    off_t fixup;

    unsigned char header[MAX_PACK_OBJECT_HEADER];
    unsigned len;

    base_offset = get_delta_base(reuse_packfile, w_curs, &cur, type, offset);
    assert(base_offset != 0);

    /* Convert to REF_DELTA if we must... */
    if (!allow_ofs_delta) {
      uint32_t base_pos;
      struct object_id base_oid;

      if (offset_to_pack_pos(reuse_packfile, base_offset, &base_pos) < 0)
        die(_("expected object at offset %"PRIuMAX" "
              "in pack %s"),
            (uintmax_t)base_offset,
            reuse_packfile->pack_name);

      nth_packed_object_id(&base_oid, reuse_packfile,
               pack_pos_to_index(reuse_packfile, base_pos));

      len = encode_in_pack_object_header(header, sizeof(header),
                 OBJ_REF_DELTA, size);
      hashwrite(out, header, len);
      hashwrite(out, base_oid.hash, the_hash_algo->rawsz);
      copy_pack_data(out, reuse_packfile, w_curs, cur, next - cur);
      return;
    }

    /* Otherwise see if we need to rewrite the offset... */
    fixup = find_reused_offset(offset) -
      find_reused_offset(base_offset);
    if (fixup) {
      unsigned char ofs_header[MAX_PACK_OBJECT_HEADER];
      unsigned i, ofs_len;
      off_t ofs = offset - base_offset - fixup;

      len = encode_in_pack_object_header(header, sizeof(header),
                 OBJ_OFS_DELTA, size);

      i = sizeof(ofs_header) - 1;
      ofs_header[i] = ofs & 127;
      while (ofs >>= 7)
        ofs_header[--i] = 128 | (--ofs & 127);

      ofs_len = sizeof(ofs_header) - i;

      hashwrite(out, header, len);
      hashwrite(out, ofs_header + sizeof(ofs_header) - ofs_len, ofs_len);
      copy_pack_data(out, reuse_packfile, w_curs, cur, next - cur);
      return;
    }

    /* ...otherwise we have no fixup, and can write it verbatim */
  }

  copy_pack_data(out, reuse_packfile, w_curs, offset, next - offset);
}

static size_t write_reused_pack_verbatim(struct bitmapped_pack *reuse_packfile,
           struct hashfile *out,
           off_t pack_start,
           struct pack_window **w_curs)
{
  size_t pos = reuse_packfile->bitmap_pos;
  size_t end;

  if (pos % BITS_IN_EWORD) {
    size_t word_pos = (pos / BITS_IN_EWORD);
    size_t offset = pos % BITS_IN_EWORD;
    size_t last;
    eword_t word = reuse_packfile_bitmap->words[word_pos];

    if (offset + reuse_packfile->bitmap_nr < BITS_IN_EWORD)
      last = offset + reuse_packfile->bitmap_nr;
    else
      last = BITS_IN_EWORD;

    for (; offset < last; offset++) {
      if (word >> offset == 0)
        return word_pos;
      if (!bitmap_get(reuse_packfile_bitmap,
          word_pos * BITS_IN_EWORD + offset))
        return word_pos;
    }

    pos += BITS_IN_EWORD - (pos % BITS_IN_EWORD);
  }

  /*
   * Now we're going to copy as many whole eword_t's as possible.
   * "end" is the index of the last whole eword_t we copy, but
   * there may be additional bits to process. Those are handled
   * individually by write_reused_pack().
   *
   * Begin by advancing to the first word boundary in range of the
   * bit positions occupied by objects in "reuse_packfile". Then
   * pick the last word boundary in the same range. If we have at
   * least one word's worth of bits to process, continue on.
   */
  end = reuse_packfile->bitmap_pos + reuse_packfile->bitmap_nr;
  if (end % BITS_IN_EWORD)
    end -= end % BITS_IN_EWORD;
  if (pos >= end)
    return reuse_packfile->bitmap_pos / BITS_IN_EWORD;

  while (pos < end &&
         reuse_packfile_bitmap->words[pos / BITS_IN_EWORD] == (eword_t)~0)
    pos += BITS_IN_EWORD;

  if (pos > end)
    pos = end;

  if (reuse_packfile->bitmap_pos < pos) {
    off_t pack_start_off = pack_pos_to_offset(reuse_packfile->p, 0);
    off_t pack_end_off = pack_pos_to_offset(reuse_packfile->p,
              pos - reuse_packfile->bitmap_pos);

    written += pos - reuse_packfile->bitmap_pos;

    /* We're recording one chunk, not one object. */
    record_reused_object(pack_start_off,
             pack_start_off - (hashfile_total(out) - pack_start));
    hashflush(out);
    copy_pack_data(out, reuse_packfile->p, w_curs,
      pack_start_off, pack_end_off - pack_start_off);

    display_progress(progress_state, written);
  }
  if (pos % BITS_IN_EWORD)
    BUG("attempted to jump past a word boundary to %"PRIuMAX,
        (uintmax_t)pos);
  return pos / BITS_IN_EWORD;
}

static void write_reused_pack(struct bitmapped_pack *reuse_packfile,
            struct hashfile *f)
{
  size_t i = reuse_packfile->bitmap_pos / BITS_IN_EWORD;
  uint32_t offset;
  off_t pack_start = hashfile_total(f) - sizeof(struct pack_header);
  struct pack_window *w_curs = NULL;

  if (allow_ofs_delta)
    i = write_reused_pack_verbatim(reuse_packfile, f, pack_start,
                 &w_curs);

  for (; i < reuse_packfile_bitmap->word_alloc; ++i) {
    eword_t word = reuse_packfile_bitmap->words[i];
    size_t pos = (i * BITS_IN_EWORD);

    for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
      uint32_t pack_pos;
      if ((word >> offset) == 0)
        break;

      offset += ewah_bit_ctz64(word >> offset);
      if (pos + offset < reuse_packfile->bitmap_pos)
        continue;
      if (pos + offset >= reuse_packfile->bitmap_pos + reuse_packfile->bitmap_nr)
        goto done;

      if (reuse_packfile->bitmap_pos) {
        /*
         * When doing multi-pack reuse on a
         * non-preferred pack, translate bit positions
         * from the MIDX pseudo-pack order back to their
         * pack-relative positions before attempting
         * reuse.
         */
        struct multi_pack_index *m = reuse_packfile->from_midx;
        uint32_t midx_pos;
        off_t pack_ofs;

        if (!m)
          BUG("non-zero bitmap position without MIDX");

        midx_pos = pack_pos_to_midx(m, pos + offset);
        pack_ofs = nth_midxed_offset(m, midx_pos);

        if (offset_to_pack_pos(reuse_packfile->p,
                   pack_ofs, &pack_pos) < 0)
          BUG("could not find expected object at offset %"PRIuMAX" in pack %s",
              (uintmax_t)pack_ofs,
              pack_basename(reuse_packfile->p));
      } else {
        /*
         * Can use bit positions directly, even for MIDX
         * bitmaps. See comment in try_partial_reuse()
         * for why.
         */
        pack_pos = pos + offset;
      }

      write_reused_pack_one(reuse_packfile->p, pack_pos, f,
                pack_start, &w_curs);
      display_progress(progress_state, ++written);
    }
  }

done:
  unuse_pack(&w_curs);
}

static void write_excluded_by_configs(void)
{
  struct oidset_iter iter;
  const struct object_id *oid;

  oidset_iter_init(&excluded_by_config, &iter);
  while ((oid = oidset_iter_next(&iter))) {
    struct configured_exclusion *ex =
      oidmap_get(&configured_exclusions, oid);

    if (!ex)
      BUG("configured exclusion wasn't configured");
    write_in_full(1, ex->pack_hash_hex, strlen(ex->pack_hash_hex));
    write_in_full(1, " ", 1);
    write_in_full(1, ex->uri, strlen(ex->uri));
    write_in_full(1, "\n", 1);
  }
}

static const char no_split_warning[] = N_(
"disabling bitmap writing, packs are split due to pack.packSizeLimit"
);

static void write_pack_file(void)
{
  uint32_t i = 0, j;
  struct hashfile *f;
  off_t offset;
  uint32_t nr_remaining = nr_result;
  time_t last_mtime = 0;
  struct object_entry **write_order;

  if (progress > pack_to_stdout)
    progress_state = start_progress(_("Writing objects"), nr_result);
  ALLOC_ARRAY(written_list, to_pack.nr_objects);
  write_order = compute_write_order();

  do {
    unsigned char hash[GIT_MAX_RAWSZ];
    char *pack_tmp_name = NULL;

    if (pack_to_stdout)
      f = hashfd_throughput(1, "<stdout>", progress_state);
    else
      f = create_tmp_packfile(&pack_tmp_name);

    offset = write_pack_header(f, nr_remaining);

    if (reuse_packfiles_nr) {
      assert(pack_to_stdout);
      for (j = 0; j < reuse_packfiles_nr; j++) {
        reused_chunks_nr = 0;
        write_reused_pack(&reuse_packfiles[j], f);
        if (reused_chunks_nr)
          reuse_packfiles_used_nr++;
      }
      offset = hashfile_total(f);
    }

    nr_written = 0;
    for (; i < to_pack.nr_objects; i++) {
      struct object_entry *e = write_order[i];
      if (write_one(f, e, &offset) == WRITE_ONE_BREAK)
        break;
      display_progress(progress_state, written);
    }

    if (pack_to_stdout) {
      /*
       * We never fsync when writing to stdout since we may
       * not be writing to an actual pack file. For instance,
       * the upload-pack code passes a pipe here. Calling
       * fsync on a pipe results in unnecessary
       * synchronization with the reader on some platforms.
       */
      finalize_hashfile(f, hash, FSYNC_COMPONENT_NONE,
            CSUM_HASH_IN_STREAM | CSUM_CLOSE);
    } else if (nr_written == nr_remaining) {
      finalize_hashfile(f, hash, FSYNC_COMPONENT_PACK,
            CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
    } else {
      /*
       * If we wrote the wrong number of entries in the
       * header, rewrite it like in fast-import.
       */

      int fd = finalize_hashfile(f, hash, FSYNC_COMPONENT_PACK, 0);
      fixup_pack_header_footer(fd, hash, pack_tmp_name,
             nr_written, hash, offset);
      close(fd);
      if (write_bitmap_index) {
        if (write_bitmap_index != WRITE_BITMAP_QUIET)
          warning(_(no_split_warning));
        write_bitmap_index = 0;
      }
    }

    if (!pack_to_stdout) {
      struct stat st;
      struct strbuf tmpname = STRBUF_INIT;
      struct bitmap_writer bitmap_writer;
      char *idx_tmp_name = NULL;

      /*
       * Packs are runtime accessed in their mtime
       * order since newer packs are more likely to contain
       * younger objects.  So if we are creating multiple
       * packs then we should modify the mtime of later ones
       * to preserve this property.
       */
      if (stat(pack_tmp_name, &st) < 0) {
        warning_errno(_("failed to stat %s"), pack_tmp_name);
      } else if (!last_mtime) {
        last_mtime = st.st_mtime;
      } else {
        struct utimbuf utb;
        utb.actime = st.st_atime;
        utb.modtime = --last_mtime;
        if (utime(pack_tmp_name, &utb) < 0)
          warning_errno(_("failed utime() on %s"), pack_tmp_name);
      }

      strbuf_addf(&tmpname, "%s-%s.", base_name,
            hash_to_hex(hash));

      if (write_bitmap_index) {
        bitmap_writer_init(&bitmap_writer,
               the_repository, &to_pack);
        bitmap_writer_set_checksum(&bitmap_writer, hash);
        bitmap_writer_build_type_index(&bitmap_writer,
                     written_list);
      }

      if (cruft)
        pack_idx_opts.flags |= WRITE_MTIMES;

      stage_tmp_packfiles(&tmpname, pack_tmp_name,
              written_list, nr_written,
              &to_pack, &pack_idx_opts, hash,
              &idx_tmp_name);

      if (write_bitmap_index) {
        size_t tmpname_len = tmpname.len;

        strbuf_addstr(&tmpname, "bitmap");
        stop_progress(&progress_state);

        bitmap_writer_show_progress(&bitmap_writer,
                  progress);
        bitmap_writer_select_commits(&bitmap_writer,
                   indexed_commits,
                   indexed_commits_nr);
        if (bitmap_writer_build(&bitmap_writer) < 0)
          die(_("failed to write bitmap index"));
        bitmap_writer_finish(&bitmap_writer,
                 written_list,
                 tmpname.buf, write_bitmap_options);
        bitmap_writer_free(&bitmap_writer);
        write_bitmap_index = 0;
        strbuf_setlen(&tmpname, tmpname_len);
      }

      rename_tmp_packfile_idx(&tmpname, &idx_tmp_name);

      free(idx_tmp_name);
      strbuf_release(&tmpname);
      free(pack_tmp_name);
      puts(hash_to_hex(hash));
    }

    /* mark written objects as written to previous pack */
    for (j = 0; j < nr_written; j++) {
      written_list[j]->offset = (off_t)-1;
    }
    nr_remaining -= nr_written;
  } while (nr_remaining && i < to_pack.nr_objects);

  free(written_list);
  free(write_order);
  stop_progress(&progress_state);
  if (written != nr_result)
    die(_("wrote %"PRIu32" objects while expecting %"PRIu32),
        written, nr_result);
  trace2_data_intmax("pack-objects", the_repository,
         "write_pack_file/wrote", nr_result);
}

static int no_try_delta(const char *path)
{
  static struct attr_check *check;

  if (!check)
    check = attr_check_initl("delta", NULL);
  git_check_attr(the_repository->index, path, check);
  if (ATTR_FALSE(check->items[0].value))
    return 1;
  return 0;
}

/*
 * When adding an object, check whether we have already added it
 * to our packing list. If so, we can skip. However, if we are
 * being asked to excludei t, but the previous mention was to include
 * it, make sure to adjust its flags and tweak our numbers accordingly.
 *
 * As an optimization, we pass out the index position where we would have
 * found the item, since that saves us from having to look it up again a
 * few lines later when we want to add the new entry.
 */
static int have_duplicate_entry(const struct object_id *oid,
        int exclude)
{
  struct object_entry *entry;

  if (reuse_packfile_bitmap &&
      bitmap_walk_contains(bitmap_git, reuse_packfile_bitmap, oid))
    return 1;

  entry = packlist_find(&to_pack, oid);
  if (!entry)
    return 0;

  if (exclude) {
    if (!entry->preferred_base)
      nr_result--;
    entry->preferred_base = 1;
  }

  return 1;
}

static int want_found_object(const struct object_id *oid, int exclude,
           struct packed_git *p)
{
  if (exclude)
    return 1;
  if (incremental)
    return 0;

  if (!is_pack_valid(p))
    return -1;

  /*
   * When asked to do --local (do not include an object that appears in a
   * pack we borrow from elsewhere) or --honor-pack-keep (do not include
   * an object that appears in a pack marked with .keep), finding a pack
   * that matches the criteria is sufficient for us to decide to omit it.
   * However, even if this pack does not satisfy the criteria, we need to
   * make sure no copy of this object appears in _any_ pack that makes us
   * to omit the object, so we need to check all the packs.
   *
   * We can however first check whether these options can possibly matter;
   * if they do not matter we know we want the object in generated pack.
   * Otherwise, we signal "-1" at the end to tell the caller that we do
   * not know either way, and it needs to check more packs.
   */

  /*
   * Objects in packs borrowed from elsewhere are discarded regardless of
   * if they appear in other packs that weren't borrowed.
   */
  if (local && !p->pack_local)
    return 0;

  /*
   * Then handle .keep first, as we have a fast(er) path there.
   */
  if (ignore_packed_keep_on_disk || ignore_packed_keep_in_core) {
    /*
     * Set the flags for the kept-pack cache to be the ones we want
     * to ignore.
     *
     * That is, if we are ignoring objects in on-disk keep packs,
     * then we want to search through the on-disk keep and ignore
     * the in-core ones.
     */
    unsigned flags = 0;
    if (ignore_packed_keep_on_disk)
      flags |= ON_DISK_KEEP_PACKS;
    if (ignore_packed_keep_in_core)
      flags |= IN_CORE_KEEP_PACKS;

    if (ignore_packed_keep_on_disk && p->pack_keep)
      return 0;
    if (ignore_packed_keep_in_core && p->pack_keep_in_core)
      return 0;
    if (has_object_kept_pack(oid, flags))
      return 0;
  }

  /*
   * At this point we know definitively that either we don't care about
   * keep-packs, or the object is not in one. Keep checking other
   * conditions...
   */
  if (!local || !have_non_local_packs)
    return 1;

  /* we don't know yet; keep looking for more packs */
  return -1;
}

static int want_object_in_pack_one(struct packed_git *p,
           const struct object_id *oid,
           int exclude,
           struct packed_git **found_pack,
           off_t *found_offset)
{
  off_t offset;

  if (p == *found_pack)
    offset = *found_offset;
  else
    offset = find_pack_entry_one(oid->hash, p);

  if (offset) {
    if (!*found_pack) {
      if (!is_pack_valid(p))
        return -1;
      *found_offset = offset;
      *found_pack = p;
    }
    return want_found_object(oid, exclude, p);
  }
  return -1;
}

/*
 * Check whether we want the object in the pack (e.g., we do not want
 * objects found in non-local stores if the "--local" option was used).
 *
 * If the caller already knows an existing pack it wants to take the object
 * from, that is passed in *found_pack and *found_offset; otherwise this
 * function finds if there is any pack that has the object and returns the pack
 * and its offset in these variables.
 */
static int want_object_in_pack(const struct object_id *oid,
             int exclude,
             struct packed_git **found_pack,
             off_t *found_offset)
{
  int want;
  struct list_head *pos;
  struct multi_pack_index *m;

  if (!exclude && local && has_loose_object_nonlocal(oid))
    return 0;

  /*
   * If we already know the pack object lives in, start checks from that
   * pack - in the usual case when neither --local was given nor .keep files
   * are present we will determine the answer right now.
   */
  if (*found_pack) {
    want = want_found_object(oid, exclude, *found_pack);
    if (want != -1)
      return want;

    *found_pack = NULL;
    *found_offset = 0;
  }

  for (m = get_multi_pack_index(the_repository); m; m = m->next) {
    struct pack_entry e;
    if (fill_midx_entry(the_repository, oid, &e, m)) {
      want = want_object_in_pack_one(e.p, oid, exclude, found_pack, found_offset);
      if (want != -1)
        return want;
    }
  }

  list_for_each(pos, get_packed_git_mru(the_repository)) {
    struct packed_git *p = list_entry(pos, struct packed_git, mru);
    want = want_object_in_pack_one(p, oid, exclude, found_pack, found_offset);
    if (!exclude && want > 0)
      list_move(&p->mru,
          get_packed_git_mru(the_repository));
    if (want != -1)
      return want;
  }

  if (uri_protocols.nr) {
    struct configured_exclusion *ex =
      oidmap_get(&configured_exclusions, oid);
    int i;
    const char *p;

    if (ex) {
      for (i = 0; i < uri_protocols.nr; i++) {
        if (skip_prefix(ex->uri,
            uri_protocols.items[i].string,
            &p) &&
            *p == ':') {
          oidset_insert(&excluded_by_config, oid);
          return 0;
        }
      }
    }
  }

  return 1;
}

static struct object_entry *create_object_entry(const struct object_id *oid,
            enum object_type type,
            uint32_t hash,
            int exclude,
            int no_try_delta,
            struct packed_git *found_pack,
            off_t found_offset)
{
  struct object_entry *entry;

  entry = packlist_alloc(&to_pack, oid);
  entry->hash = hash;
  oe_set_type(entry, type);
  if (exclude)
    entry->preferred_base = 1;
  else
    nr_result++;
  if (found_pack) {
    oe_set_in_pack(&to_pack, entry, found_pack);
    entry->in_pack_offset = found_offset;
  }

  entry->no_try_delta = no_try_delta;

  return entry;
}

static const char no_closure_warning[] = N_(
"disabling bitmap writing, as some objects are not being packed"
);

static int add_object_entry(const struct object_id *oid, enum object_type type,
          const char *name, int exclude)
{
  struct packed_git *found_pack = NULL;
  off_t found_offset = 0;

  display_progress(progress_state, ++nr_seen);

  if (have_duplicate_entry(oid, exclude))
    return 0;

  if (!want_object_in_pack(oid, exclude, &found_pack, &found_offset)) {
    /* The pack is missing an object, so it will not have closure */
    if (write_bitmap_index) {
      if (write_bitmap_index != WRITE_BITMAP_QUIET)
        warning(_(no_closure_warning));
      write_bitmap_index = 0;
    }
    return 0;
  }

  create_object_entry(oid, type, pack_name_hash(name),
          exclude, name && no_try_delta(name),
          found_pack, found_offset);
  return 1;
}

static int add_object_entry_from_bitmap(const struct object_id *oid,
          enum object_type type,
          int flags UNUSED, uint32_t name_hash,
          struct packed_git *pack, off_t offset)
{
  display_progress(progress_state, ++nr_seen);

  if (have_duplicate_entry(oid, 0))
    return 0;

  if (!want_object_in_pack(oid, 0, &pack, &offset))
    return 0;

  create_object_entry(oid, type, name_hash, 0, 0, pack, offset);
  return 1;
}

struct pbase_tree_cache {
  struct object_id oid;
  int ref;
  int temporary;
  void *tree_data;
  unsigned long tree_size;
};

static struct pbase_tree_cache *(pbase_tree_cache[256]);
static int pbase_tree_cache_ix(const struct object_id *oid)
{
  return oid->hash[0] % ARRAY_SIZE(pbase_tree_cache);
}
static int pbase_tree_cache_ix_incr(int ix)
{
  return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
}

static struct pbase_tree {
  struct pbase_tree *next;
  /* This is a phony "cache" entry; we are not
   * going to evict it or find it through _get()
   * mechanism -- this is for the toplevel node that
   * would almost always change with any commit.
   */
  struct pbase_tree_cache pcache;
} *pbase_tree;

static struct pbase_tree_cache *pbase_tree_get(const struct object_id *oid)
{
  struct pbase_tree_cache *ent, *nent;
  void *data;
  unsigned long size;
  enum object_type type;
  int neigh;
  int my_ix = pbase_tree_cache_ix(oid);
  int available_ix = -1;

  /* pbase-tree-cache acts as a limited hashtable.
   * your object will be found at your index or within a few
   * slots after that slot if it is cached.
   */
  for (neigh = 0; neigh < 8; neigh++) {
    ent = pbase_tree_cache[my_ix];
    if (ent && oideq(&ent->oid, oid)) {
      ent->ref++;
      return ent;
    }
    else if (((available_ix < 0) && (!ent || !ent->ref)) ||
       ((0 <= available_ix) &&
        (!ent && pbase_tree_cache[available_ix])))
      available_ix = my_ix;
    if (!ent)
      break;
    my_ix = pbase_tree_cache_ix_incr(my_ix);
  }

  /* Did not find one.  Either we got a bogus request or
   * we need to read and perhaps cache.
   */
  data = repo_read_object_file(the_repository, oid, &type, &size);
  if (!data)
    return NULL;
  if (type != OBJ_TREE) {
    free(data);
    return NULL;
  }

  /* We need to either cache or return a throwaway copy */

  if (available_ix < 0)
    ent = NULL;
  else {
    ent = pbase_tree_cache[available_ix];
    my_ix = available_ix;
  }

  if (!ent) {
    nent = xmalloc(sizeof(*nent));
    nent->temporary = (available_ix < 0);
  }
  else {
    /* evict and reuse */
    free(ent->tree_data);
    nent = ent;
  }
  oidcpy(&nent->oid, oid);
  nent->tree_data = data;
  nent->tree_size = size;
  nent->ref = 1;
  if (!nent->temporary)
    pbase_tree_cache[my_ix] = nent;
  return nent;
}

static void pbase_tree_put(struct pbase_tree_cache *cache)
{
  if (!cache->temporary) {
    cache->ref--;
    return;
  }
  free(cache->tree_data);
  free(cache);
}

static size_t name_cmp_len(const char *name)
{
  return strcspn(name, "\n/");
}

static void add_pbase_object(struct tree_desc *tree,
           const char *name,
           size_t cmplen,
           const char *fullname)
{
  struct name_entry entry;
  int cmp;

  while (tree_entry(tree,&entry)) {
    if (S_ISGITLINK(entry.mode))
      continue;
    cmp = tree_entry_len(&entry) != cmplen ? 1 :
          memcmp(name, entry.path, cmplen);
    if (cmp > 0)
      continue;
    if (cmp < 0)
      return;
    if (name[cmplen] != '/') {
      add_object_entry(&entry.oid,
           object_type(entry.mode),
           fullname, 1);
      return;
    }
    if (S_ISDIR(entry.mode)) {
      struct tree_desc sub;
      struct pbase_tree_cache *tree;
      const char *down = name+cmplen+1;
      size_t downlen = name_cmp_len(down);

      tree = pbase_tree_get(&entry.oid);
      if (!tree)
        return;
      init_tree_desc(&sub, &tree->oid,
               tree->tree_data, tree->tree_size);

      add_pbase_object(&sub, down, downlen, fullname);
      pbase_tree_put(tree);
    }
  }
}

static unsigned *done_pbase_paths;
static int done_pbase_paths_num;
static int done_pbase_paths_alloc;
static int done_pbase_path_pos(unsigned hash)
{
  int lo = 0;
  int hi = done_pbase_paths_num;
  while (lo < hi) {
    int mi = lo + (hi - lo) / 2;
    if (done_pbase_paths[mi] == hash)
      return mi;
    if (done_pbase_paths[mi] < hash)
      hi = mi;
    else
      lo = mi + 1;
  }
  return -lo-1;
}

static int check_pbase_path(unsigned hash)
{
  int pos = done_pbase_path_pos(hash);
  if (0 <= pos)
    return 1;
  pos = -pos - 1;
  ALLOC_GROW(done_pbase_paths,
       done_pbase_paths_num + 1,
       done_pbase_paths_alloc);
  done_pbase_paths_num++;
  if (pos < done_pbase_paths_num)
    MOVE_ARRAY(done_pbase_paths + pos + 1, done_pbase_paths + pos,
         done_pbase_paths_num - pos - 1);
  done_pbase_paths[pos] = hash;
  return 0;
}

static void add_preferred_base_object(const char *name)
{
  struct pbase_tree *it;
  size_t cmplen;
  unsigned hash = pack_name_hash(name);

  if (!num_preferred_base || check_pbase_path(hash))
    return;

  cmplen = name_cmp_len(name);
  for (it = pbase_tree; it; it = it->next) {
    if (cmplen == 0) {
      add_object_entry(&it->pcache.oid, OBJ_TREE, NULL, 1);
    }
    else {
      struct tree_desc tree;
      init_tree_desc(&tree, &it->pcache.oid,
               it->pcache.tree_data, it->pcache.tree_size);
      add_pbase_object(&tree, name, cmplen, name);
    }
  }
}

static void add_preferred_base(struct object_id *oid)
{
  struct pbase_tree *it;
  void *data;
  unsigned long size;
  struct object_id tree_oid;

  if (window <= num_preferred_base++)
    return;

  data = read_object_with_reference(the_repository, oid,
            OBJ_TREE, &size, &tree_oid);
  if (!data)
    return;

  for (it = pbase_tree; it; it = it->next) {
    if (oideq(&it->pcache.oid, &tree_oid)) {
      free(data);
      return;
    }
  }

  CALLOC_ARRAY(it, 1);
  it->next = pbase_tree;
  pbase_tree = it;

  oidcpy(&it->pcache.oid, &tree_oid);
  it->pcache.tree_data = data;
  it->pcache.tree_size = size;
}

static void cleanup_preferred_base(void)
{
  struct pbase_tree *it;
  unsigned i;

  it = pbase_tree;
  pbase_tree = NULL;
  while (it) {
    struct pbase_tree *tmp = it;
    it = tmp->next;
    free(tmp->pcache.tree_data);
    free(tmp);
  }

  for (i = 0; i < ARRAY_SIZE(pbase_tree_cache); i++) {
    if (!pbase_tree_cache[i])
      continue;
    free(pbase_tree_cache[i]->tree_data);
    FREE_AND_NULL(pbase_tree_cache[i]);
  }

  FREE_AND_NULL(done_pbase_paths);
  done_pbase_paths_num = done_pbase_paths_alloc = 0;
}

/*
 * Return 1 iff the object specified by "delta" can be sent
 * literally as a delta against the base in "base_sha1". If
 * so, then *base_out will point to the entry in our packing
 * list, or NULL if we must use the external-base list.
 *
 * Depth value does not matter - find_deltas() will
 * never consider reused delta as the base object to
 * deltify other objects against, in order to avoid
 * circular deltas.
 */
static int can_reuse_delta(const struct object_id *base_oid,
         struct object_entry *delta,
         struct object_entry **base_out)
{
  struct object_entry *base;

  /*
   * First see if we're already sending the base (or it's explicitly in
   * our "excluded" list).
   */
  base = packlist_find(&to_pack, base_oid);
  if (base) {
    if (!in_same_island(&delta->idx.oid, &base->idx.oid))
      return 0;
    *base_out = base;
    return 1;
  }

  /*
   * Otherwise, reachability bitmaps may tell us if the receiver has it,
   * even if it was buried too deep in history to make it into the
   * packing list.
   */
  if (thin && bitmap_has_oid_in_uninteresting(bitmap_git, base_oid)) {
    if (use_delta_islands) {
      if (!in_same_island(&delta->idx.oid, base_oid))
        return 0;
    }
    *base_out = NULL;
    return 1;
  }

  return 0;
}

static void prefetch_to_pack(uint32_t object_index_start) {
  struct oid_array to_fetch = OID_ARRAY_INIT;
  uint32_t i;

  for (i = object_index_start; i < to_pack.nr_objects; i++) {
    struct object_entry *entry = to_pack.objects + i;

    if (!oid_object_info_extended(the_repository,
                &entry->idx.oid,
                NULL,
                OBJECT_INFO_FOR_PREFETCH))
      continue;
    oid_array_append(&to_fetch, &entry->idx.oid);
  }
  promisor_remote_get_direct(the_repository,
           to_fetch.oid, to_fetch.nr);
  oid_array_clear(&to_fetch);
}

static void check_object(struct object_entry *entry, uint32_t object_index)
{
  unsigned long canonical_size;
  enum object_type type;
  struct object_info oi = {.typep = &type, .sizep = &canonical_size};

  if (IN_PACK(entry)) {
    struct packed_git *p = IN_PACK(entry);
    struct pack_window *w_curs = NULL;
    int have_base = 0;
    struct object_id base_ref;
    struct object_entry *base_entry;
    unsigned long used, used_0;
    unsigned long avail;
    off_t ofs;
    unsigned char *buf, c;
    enum object_type type;
    unsigned long in_pack_size;

    buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);

    /*
     * We want in_pack_type even if we do not reuse delta
     * since non-delta representations could still be reused.
     */
    used = unpack_object_header_buffer(buf, avail,
               &type,
               &in_pack_size);
    if (used == 0)
      goto give_up;

    if (type < 0)
      BUG("invalid type %d", type);
    entry->in_pack_type = type;

    /*
     * Determine if this is a delta and if so whether we can
     * reuse it or not.  Otherwise let's find out as cheaply as
     * possible what the actual type and size for this object is.
     */
    switch (entry->in_pack_type) {
    default:
      /* Not a delta hence we've already got all we need. */
      oe_set_type(entry, entry->in_pack_type);
      SET_SIZE(entry, in_pack_size);
      entry->in_pack_header_size = used;
      if (oe_type(entry) < OBJ_COMMIT || oe_type(entry) > OBJ_BLOB)
        goto give_up;
      unuse_pack(&w_curs);
      return;
    case OBJ_REF_DELTA:
      if (reuse_delta && !entry->preferred_base) {
        oidread(&base_ref,
          use_pack(p, &w_curs,
             entry->in_pack_offset + used,
             NULL),
          the_repository->hash_algo);
        have_base = 1;
      }
      entry->in_pack_header_size = used + the_hash_algo->rawsz;
      break;
    case OBJ_OFS_DELTA:
      buf = use_pack(p, &w_curs,
               entry->in_pack_offset + used, NULL);
      used_0 = 0;
      c = buf[used_0++];
      ofs = c & 127;
      while (c & 128) {
        ofs += 1;
        if (!ofs || MSB(ofs, 7)) {
          error(_("delta base offset overflow in pack for %s"),
                oid_to_hex(&entry->idx.oid));
          goto give_up;
        }
        c = buf[used_0++];
        ofs = (ofs << 7) + (c & 127);
      }
      ofs = entry->in_pack_offset - ofs;
      if (ofs <= 0 || ofs >= entry->in_pack_offset) {
        error(_("delta base offset out of bound for %s"),
              oid_to_hex(&entry->idx.oid));
        goto give_up;
      }
      if (reuse_delta && !entry->preferred_base) {
        uint32_t pos;
        if (offset_to_pack_pos(p, ofs, &pos) < 0)
          goto give_up;
        if (!nth_packed_object_id(&base_ref, p,
                pack_pos_to_index(p, pos)))
          have_base = 1;
      }
      entry->in_pack_header_size = used + used_0;
      break;
    }

    if (have_base &&
        can_reuse_delta(&base_ref, entry, &base_entry)) {
      oe_set_type(entry, entry->in_pack_type);
      SET_SIZE(entry, in_pack_size); /* delta size */
      SET_DELTA_SIZE(entry, in_pack_size);

      if (base_entry) {
        SET_DELTA(entry, base_entry);
        entry->delta_sibling_idx = base_entry->delta_child_idx;
        SET_DELTA_CHILD(base_entry, entry);
      } else {
        SET_DELTA_EXT(entry, &base_ref);
      }

      unuse_pack(&w_curs);
      return;
    }

    if (oe_type(entry)) {
      off_t delta_pos;

      /*
       * This must be a delta and we already know what the
       * final object type is.  Let's extract the actual
       * object size from the delta header.
       */
      delta_pos = entry->in_pack_offset + entry->in_pack_header_size;
      canonical_size = get_size_from_delta(p, &w_curs, delta_pos);
      if (canonical_size == 0)
        goto give_up;
      SET_SIZE(entry, canonical_size);
      unuse_pack(&w_curs);
      return;
    }

    /*
     * No choice but to fall back to the recursive delta walk
     * with oid_object_info() to find about the object type
     * at this point...
     */
    give_up:
    unuse_pack(&w_curs);
  }

  if (oid_object_info_extended(the_repository, &entry->idx.oid, &oi,
             OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_LOOKUP_REPLACE) < 0) {
    if (repo_has_promisor_remote(the_repository)) {
      prefetch_to_pack(object_index);
      if (oid_object_info_extended(the_repository, &entry->idx.oid, &oi,
                 OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_LOOKUP_REPLACE) < 0)
        type = -1;
    } else {
      type = -1;
    }
  }
  oe_set_type(entry, type);
  if (entry->type_valid) {
    SET_SIZE(entry, canonical_size);
  } else {
    /*
     * Bad object type is checked in prepare_pack().  This is
     * to permit a missing preferred base object to be ignored
     * as a preferred base.  Doing so can result in a larger
     * pack file, but the transfer will still take place.
     */
  }
}

static int pack_offset_sort(const void *_a, const void *_b)
{
  const struct object_entry *a = *(struct object_entry **)_a;
  const struct object_entry *b = *(struct object_entry **)_b;
  const struct packed_git *a_in_pack = IN_PACK(a);
  const struct packed_git *b_in_pack = IN_PACK(b);

  /* avoid filesystem trashing with loose objects */
  if (!a_in_pack && !b_in_pack)
    return oidcmp(&a->idx.oid, &b->idx.oid);

  if (a_in_pack < b_in_pack)
    return -1;
  if (a_in_pack > b_in_pack)
    return 1;
  return a->in_pack_offset < b->in_pack_offset ? -1 :
      (a->in_pack_offset > b->in_pack_offset);
}

/*
 * Drop an on-disk delta we were planning to reuse. Naively, this would
 * just involve blanking out the "delta" field, but we have to deal
 * with some extra book-keeping:
 *
 *   1. Removing ourselves from the delta_sibling linked list.
 *
 *   2. Updating our size/type to the non-delta representation. These were
 *      either not recorded initially (size) or overwritten with the delta type
 *      (type) when check_object() decided to reuse the delta.
 *
 *   3. Resetting our delta depth, as we are now a base object.
 */
static void drop_reused_delta(struct object_entry *entry)
{
  unsigned *idx = &to_pack.objects[entry->delta_idx - 1].delta_child_idx;
  struct object_info oi = OBJECT_INFO_INIT;
  enum object_type type;
  unsigned long size;

  while (*idx) {
    struct object_entry *oe = &to_pack.objects[*idx - 1];

    if (oe == entry)
      *idx = oe->delta_sibling_idx;
    else
      idx = &oe->delta_sibling_idx;
  }
  SET_DELTA(entry, NULL);
  entry->depth = 0;

  oi.sizep = &size;
  oi.typep = &type;
  if (packed_object_info(the_repository, IN_PACK(entry), entry->in_pack_offset, &oi) < 0) {
    /*
     * We failed to get the info from this pack for some reason;
     * fall back to oid_object_info, which may find another copy.
     * And if that fails, the error will be recorded in oe_type(entry)
     * and dealt with in prepare_pack().
     */
    oe_set_type(entry,
          oid_object_info(the_repository, &entry->idx.oid, &size));
  } else {
    oe_set_type(entry, type);
  }
  SET_SIZE(entry, size);
}

/*
 * Follow the chain of deltas from this entry onward, throwing away any links
 * that cause us to hit a cycle (as determined by the DFS state flags in
 * the entries).
 *
 * We also detect too-long reused chains that would violate our --depth
 * limit.
 */
static void break_delta_chains(struct object_entry *entry)
{
  /*
   * The actual depth of each object we will write is stored as an int,
   * as it cannot exceed our int "depth" limit. But before we break
   * changes based no that limit, we may potentially go as deep as the
   * number of objects, which is elsewhere bounded to a uint32_t.
   */
  uint32_t total_depth;
  struct object_entry *cur, *next;

  for (cur = entry, total_depth = 0;
       cur;
       cur = DELTA(cur), total_depth++) {
    if (cur->dfs_state == DFS_DONE) {
      /*
       * We've already seen this object and know it isn't
       * part of a cycle. We do need to append its depth
       * to our count.
       */
      total_depth += cur->depth;
      break;
    }

    /*
     * We break cycles before looping, so an ACTIVE state (or any
     * other cruft which made its way into the state variable)
     * is a bug.
     */
    if (cur->dfs_state != DFS_NONE)
      BUG("confusing delta dfs state in first pass: %d",
          cur->dfs_state);

    /*
     * Now we know this is the first time we've seen the object. If
     * it's not a delta, we're done traversing, but we'll mark it
     * done to save time on future traversals.
     */
    if (!DELTA(cur)) {
      cur->dfs_state = DFS_DONE;
      break;
    }

    /*
     * Mark ourselves as active and see if the next step causes
     * us to cycle to another active object. It's important to do
     * this _before_ we loop, because it impacts where we make the
     * cut, and thus how our total_depth counter works.
     * E.g., We may see a partial loop like:
     *
     *   A -> B -> C -> D -> B
     *
     * Cutting B->C breaks the cycle. But now the depth of A is
     * only 1, and our total_depth counter is at 3. The size of the
     * error is always one less than the size of the cycle we
     * broke. Commits C and D were "lost" from A's chain.
     *
     * If we instead cut D->B, then the depth of A is correct at 3.
     * We keep all commits in the chain that we examined.
     */
    cur->dfs_state = DFS_ACTIVE;
    if (DELTA(cur)->dfs_state == DFS_ACTIVE) {
      drop_reused_delta(cur);
      cur->dfs_state = DFS_DONE;
      break;
    }
  }

  /*
   * And now that we've gone all the way to the bottom of the chain, we
   * need to clear the active flags and set the depth fields as
   * appropriate. Unlike the loop above, which can quit when it drops a
   * delta, we need to keep going to look for more depth cuts. So we need
   * an extra "next" pointer to keep going after we reset cur->delta.
   */
  for (cur = entry; cur; cur = next) {
    next = DELTA(cur);

    /*
     * We should have a chain of zero or more ACTIVE states down to
     * a final DONE. We can quit after the DONE, because either it
     * has no bases, or we've already handled them in a previous
     * call.
     */
    if (cur->dfs_state == DFS_DONE)
      break;
    else if (cur->dfs_state != DFS_ACTIVE)
      BUG("confusing delta dfs state in second pass: %d",
          cur->dfs_state);

    /*
     * If the total_depth is more than depth, then we need to snip
     * the chain into two or more smaller chains that don't exceed
     * the maximum depth. Most of the resulting chains will contain
     * (depth + 1) entries (i.e., depth deltas plus one base), and
     * the last chain (i.e., the one containing entry) will contain
     * whatever entries are left over, namely
     * (total_depth % (depth + 1)) of them.
     *
     * Since we are iterating towards decreasing depth, we need to
     * decrement total_depth as we go, and we need to write to the
     * entry what its final depth will be after all of the
     * snipping. Since we're snipping into chains of length (depth
     * + 1) entries, the final depth of an entry will be its
     * original depth modulo (depth + 1). Any time we encounter an
     * entry whose final depth is supposed to be zero, we snip it
     * from its delta base, thereby making it so.
     */
    cur->depth = (total_depth--) % (depth + 1);
    if (!cur->depth)
      drop_reused_delta(cur);

    cur->dfs_state = DFS_DONE;
  }
}

static void get_object_details(void)
{
  uint32_t i;
  struct object_entry **sorted_by_offset;

  if (progress)
    progress_state = start_progress(_("Counting objects"),
            to_pack.nr_objects);

  CALLOC_ARRAY(sorted_by_offset, to_pack.nr_objects);
  for (i = 0; i < to_pack.nr_objects; i++)
    sorted_by_offset[i] = to_pack.objects + i;
  QSORT(sorted_by_offset, to_pack.nr_objects, pack_offset_sort);

  for (i = 0; i < to_pack.nr_objects; i++) {
    struct object_entry *entry = sorted_by_offset[i];
    check_object(entry, i);
    if (entry->type_valid &&
        oe_size_greater_than(&to_pack, entry, big_file_threshold))
      entry->no_try_delta = 1;
    display_progress(progress_state, i + 1);
  }
  stop_progress(&progress_state);

  /*
   * This must happen in a second pass, since we rely on the delta
   * information for the whole list being completed.
   */
  for (i = 0; i < to_pack.nr_objects; i++)
    break_delta_chains(&to_pack.objects[i]);

  free(sorted_by_offset);
}

/*
 * We search for deltas in a list sorted by type, by filename hash, and then
 * by size, so that we see progressively smaller and smaller files.
 * That's because we prefer deltas to be from the bigger file
 * to the smaller -- deletes are potentially cheaper, but perhaps
 * more importantly, the bigger file is likely the more recent
 * one.  The deepest deltas are therefore the oldest objects which are
 * less susceptible to be accessed often.
 */
static int type_size_sort(const void *_a, const void *_b)
{
  const struct object_entry *a = *(struct object_entry **)_a;
  const struct object_entry *b = *(struct object_entry **)_b;
  const enum object_type a_type = oe_type(a);
  const enum object_type b_type = oe_type(b);
  const unsigned long a_size = SIZE(a);
  const unsigned long b_size = SIZE(b);

  if (a_type > b_type)
    return -1;
  if (a_type < b_type)
    return 1;
  if (a->hash > b->hash)
    return -1;
  if (a->hash < b->hash)
    return 1;
  if (a->preferred_base > b->preferred_base)
    return -1;
  if (a->preferred_base < b->preferred_base)
    return 1;
  if (use_delta_islands) {
    const int island_cmp = island_delta_cmp(&a->idx.oid, &b->idx.oid);
    if (island_cmp)
      return island_cmp;
  }
  if (a_size > b_size)
    return -1;
  if (a_size < b_size)
    return 1;
  return a < b ? -1 : (a > b);  /* newest first */
}

struct unpacked {
  struct object_entry *entry;
  void *data;
  struct delta_index *index;
  unsigned depth;
};

static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
         unsigned long delta_size)
{
  if (max_delta_cache_size && delta_cache_size + delta_size > max_delta_cache_size)
    return 0;

  if (delta_size < cache_max_small_delta_size)
    return 1;

  /* cache delta, if objects are large enough compared to delta size */
  if ((src_size >> 20) + (trg_size >> 21) > (delta_size >> 10))
    return 1;

  return 0;
}

/* Protect delta_cache_size */
static pthread_mutex_t cache_mutex;
#define cache_lock()    pthread_mutex_lock(&cache_mutex)
#define cache_unlock()    pthread_mutex_unlock(&cache_mutex)

/*
 * Protect object list partitioning (e.g. struct thread_param) and
 * progress_state
 */
static pthread_mutex_t progress_mutex;
#define progress_lock()   pthread_mutex_lock(&progress_mutex)
#define progress_unlock() pthread_mutex_unlock(&progress_mutex)

/*
 * Access to struct object_entry is unprotected since each thread owns
 * a portion of the main object list. Just don't access object entries
 * ahead in the list because they can be stolen and would need
 * progress_mutex for protection.
 */

static inline int oe_size_less_than(struct packing_data *pack,
            const struct object_entry *lhs,
            unsigned long rhs)
{
  if (lhs->size_valid)
    return lhs->size_ < rhs;
  if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
    return 0;
  return oe_get_size_slow(pack, lhs) < rhs;
}

static inline void oe_set_tree_depth(struct packing_data *pack,
             struct object_entry *e,
             unsigned int tree_depth)
{
  if (!pack->tree_depth)
    CALLOC_ARRAY(pack->tree_depth, pack->nr_alloc);
  pack->tree_depth[e - pack->objects] = tree_depth;
}

/*
 * Return the size of the object without doing any delta
 * reconstruction (so non-deltas are true object sizes, but deltas
 * return the size of the delta data).
 */
unsigned long oe_get_size_slow(struct packing_data *pack,
             const struct object_entry *e)
{
  struct packed_git *p;
  struct pack_window *w_curs;
  unsigned char *buf;
  enum object_type type;
  unsigned long used, avail, size;

  if (e->type_ != OBJ_OFS_DELTA && e->type_ != OBJ_REF_DELTA) {
    packing_data_lock(&to_pack);
    if (oid_object_info(the_repository, &e->idx.oid, &size) < 0)
      die(_("unable to get size of %s"),
          oid_to_hex(&e->idx.oid));
    packing_data_unlock(&to_pack);
    return size;
  }

  p = oe_in_pack(pack, e);
  if (!p)
    BUG("when e->type is a delta, it must belong to a pack");

  packing_data_lock(&to_pack);
  w_curs = NULL;
  buf = use_pack(p, &w_curs, e->in_pack_offset, &avail);
  used = unpack_object_header_buffer(buf, avail, &type, &size);
  if (used == 0)
    die(_("unable to parse object header of %s"),
        oid_to_hex(&e->idx.oid));

  unuse_pack(&w_curs);
  packing_data_unlock(&to_pack);
  return size;
}

static int try_delta(struct unpacked *trg, struct unpacked *src,
         unsigned max_depth, unsigned long *mem_usage)
{
  struct object_entry *trg_entry = trg->entry;
  struct object_entry *src_entry = src->entry;
  unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
  unsigned ref_depth;
  enum object_type type;
  void *delta_buf;

  /* Don't bother doing diffs between different types */
  if (oe_type(trg_entry) != oe_type(src_entry))
    return -1;

  /*
   * We do not bother to try a delta that we discarded on an
   * earlier try, but only when reusing delta data.  Note that
   * src_entry that is marked as the preferred_base should always
   * be considered, as even if we produce a suboptimal delta against
   * it, we will still save the transfer cost, as we already know
   * the other side has it and we won't send src_entry at all.
   */
  if (reuse_delta && IN_PACK(trg_entry) &&
      IN_PACK(trg_entry) == IN_PACK(src_entry) &&
      !src_entry->preferred_base &&
      trg_entry->in_pack_type != OBJ_REF_DELTA &&
      trg_entry->in_pack_type != OBJ_OFS_DELTA)
    return 0;

  /* Let's not bust the allowed depth. */
  if (src->depth >= max_depth)
    return 0;

  /* Now some size filtering heuristics. */
  trg_size = SIZE(trg_entry);
  if (!DELTA(trg_entry)) {
    max_size = trg_size/2 - the_hash_algo->rawsz;
    ref_depth = 1;
  } else {
    max_size = DELTA_SIZE(trg_entry);
    ref_depth = trg->depth;
  }
  max_size = (uint64_t)max_size * (max_depth - src->depth) /
            (max_depth - ref_depth + 1);
  if (max_size == 0)
    return 0;
  src_size = SIZE(src_entry);
  sizediff = src_size < trg_size ? trg_size - src_size : 0;
  if (sizediff >= max_size)
    return 0;
  if (trg_size < src_size / 32)
    return 0;

  if (!in_same_island(&trg->entry->idx.oid, &src->entry->idx.oid))
    return 0;

  /* Load data if not already done */
  if (!trg->data) {
    packing_data_lock(&to_pack);
    trg->data = repo_read_object_file(the_repository,
              &trg_entry->idx.oid, &type,
              &sz);
    packing_data_unlock(&to_pack);
    if (!trg->data)
      die(_("object %s cannot be read"),
          oid_to_hex(&trg_entry->idx.oid));
    if (sz != trg_size)
      die(_("object %s inconsistent object length (%"PRIuMAX" vs %"PRIuMAX")"),
          oid_to_hex(&trg_entry->idx.oid), (uintmax_t)sz,
          (uintmax_t)trg_size);
    *mem_usage += sz;
  }
  if (!src->data) {
    packing_data_lock(&to_pack);
    src->data = repo_read_object_file(the_repository,
              &src_entry->idx.oid, &type,
              &sz);
    packing_data_unlock(&to_pack);
    if (!src->data) {
      if (src_entry->preferred_base) {
        static int warned = 0;
        if (!warned++)
          warning(_("object %s cannot be read"),
            oid_to_hex(&src_entry->idx.oid));
        /*
         * Those objects are not included in the
         * resulting pack.  Be resilient and ignore
         * them if they can't be read, in case the
         * pack could be created nevertheless.
         */
        return 0;
      }
      die(_("object %s cannot be read"),
          oid_to_hex(&src_entry->idx.oid));
    }
    if (sz != src_size)
      die(_("object %s inconsistent object length (%"PRIuMAX" vs %"PRIuMAX")"),
          oid_to_hex(&src_entry->idx.oid), (uintmax_t)sz,
          (uintmax_t)src_size);
    *mem_usage += sz;
  }
  if (!src->index) {
    src->index = create_delta_index(src->data, src_size);
    if (!src->index) {
      static int warned = 0;
      if (!warned++)
        warning(_("suboptimal pack - out of memory"));
      return 0;
    }
    *mem_usage += sizeof_delta_index(src->index);
  }

  delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
  if (!delta_buf)
    return 0;

  if (DELTA(trg_entry)) {
    /* Prefer only shallower same-sized deltas. */
    if (delta_size == DELTA_SIZE(trg_entry) &&
        src->depth + 1 >= trg->depth) {
      free(delta_buf);
      return 0;
    }
  }

  /*
   * Handle memory allocation outside of the cache
   * accounting lock.  Compiler will optimize the strangeness
   * away when NO_PTHREADS is defined.
   */
  free(trg_entry->delta_data);
  cache_lock();
  if (trg_entry->delta_data) {
    delta_cache_size -= DELTA_SIZE(trg_entry);
    trg_entry->delta_data = NULL;
  }
  if (delta_cacheable(src_size, trg_size, delta_size)) {
    delta_cache_size += delta_size;
    cache_unlock();
    trg_entry->delta_data = xrealloc(delta_buf, delta_size);
  } else {
    cache_unlock();
    free(delta_buf);
  }

  SET_DELTA(trg_entry, src_entry);
  SET_DELTA_SIZE(trg_entry, delta_size);
  trg->depth = src->depth + 1;

  return 1;
}

static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
{
  struct object_entry *child = DELTA_CHILD(me);
  unsigned int m = n;
  while (child) {
    const unsigned int c = check_delta_limit(child, n + 1);
    if (m < c)
      m = c;
    child = DELTA_SIBLING(child);
  }
  return m;
}

static unsigned long free_unpacked(struct unpacked *n)
{
  unsigned long freed_mem = sizeof_delta_index(n->index);
  free_delta_index(n->index);
  n->index = NULL;
  if (n->data) {
    freed_mem += SIZE(n->entry);
    FREE_AND_NULL(n->data);
  }
  n->entry = NULL;
  n->depth = 0;
  return freed_mem;
}

static void find_deltas(struct object_entry **list, unsigned *list_size,
      int window, int depth, unsigned *processed)
{
  uint32_t i, idx = 0, count = 0;
  struct unpacked *array;
  unsigned long mem_usage = 0;

  CALLOC_ARRAY(array, window);

  for (;;) {
    struct object_entry *entry;
    struct unpacked *n = array + idx;
    int j, max_depth, best_base = -1;

    progress_lock();
    if (!*list_size) {
      progress_unlock();
      break;
    }
    entry = *list++;
    (*list_size)--;
    if (!entry->preferred_base) {
      (*processed)++;
      display_progress(progress_state, *processed);
    }
    progress_unlock();

    mem_usage -= free_unpacked(n);
    n->entry = entry;

    while (window_memory_limit &&
           mem_usage > window_memory_limit &&
           count > 1) {
      const uint32_t tail = (idx + window - count) % window;
      mem_usage -= free_unpacked(array + tail);
      count--;
    }

    /* We do not compute delta to *create* objects we are not
     * going to pack.
     */
    if (entry->preferred_base)
      goto next;

    /*
     * If the current object is at pack edge, take the depth the
     * objects that depend on the current object into account
     * otherwise they would become too deep.
     */
    max_depth = depth;
    if (DELTA_CHILD(entry)) {
      max_depth -= check_delta_limit(entry, 0);
      if (max_depth <= 0)
        goto next;
    }

    j = window;
    while (--j > 0) {
      int ret;
      uint32_t other_idx = idx + j;
      struct unpacked *m;
      if (other_idx >= window)
        other_idx -= window;
      m = array + other_idx;
      if (!m->entry)
        break;
      ret = try_delta(n, m, max_depth, &mem_usage);
      if (ret < 0)
        break;
      else if (ret > 0)
        best_base = other_idx;
    }

    /*
     * If we decided to cache the delta data, then it is best
     * to compress it right away.  First because we have to do
     * it anyway, and doing it here while we're threaded will
     * save a lot of time in the non threaded write phase,
     * as well as allow for caching more deltas within
     * the same cache size limit.
     * ...
     * But only if not writing to stdout, since in that case
     * the network is most likely throttling writes anyway,
     * and therefore it is best to go to the write phase ASAP
     * instead, as we can afford spending more time compressing
     * between writes at that moment.
     */
    if (entry->delta_data && !pack_to_stdout) {
      unsigned long size;

      size = do_compress(&entry->delta_data, DELTA_SIZE(entry));
      if (size < (1U << OE_Z_DELTA_BITS)) {
        entry->z_delta_size = size;
        cache_lock();
        delta_cache_size -= DELTA_SIZE(entry);
        delta_cache_size += entry->z_delta_size;
        cache_unlock();
      } else {
        FREE_AND_NULL(entry->delta_data);
        entry->z_delta_size = 0;
      }
    }

    /* if we made n a delta, and if n is already at max
     * depth, leaving it in the window is pointless.  we
     * should evict it first.
     */
    if (DELTA(entry) && max_depth <= n->depth)
      continue;

    /*
     * Move the best delta base up in the window, after the
     * currently deltified object, to keep it longer.  It will
     * be the first base object to be attempted next.
     */
    if (DELTA(entry)) {
      struct unpacked swap = array[best_base];
      int dist = (window + idx - best_base) % window;
      int dst = best_base;
      while (dist--) {
        int src = (dst + 1) % window;
        array[dst] = array[src];
        dst = src;
      }
      array[dst] = swap;
    }

    next:
    idx++;
    if (count + 1 < window)
      count++;
    if (idx >= window)
      idx = 0;
  }

  for (i = 0; i < window; ++i) {
    free_delta_index(array[i].index);
    free(array[i].data);
  }
  free(array);
}

/*
 * The main object list is split into smaller lists, each is handed to
 * one worker.
 *
 * The main thread waits on the condition that (at least) one of the workers
 * has stopped working (which is indicated in the .working member of
 * struct thread_params).
 *
 * When a work thread has completed its work, it sets .working to 0 and
 * signals the main thread and waits on the condition that .data_ready
 * becomes 1.
 *
 * The main thread steals half of the work from the worker that has
 * most work left to hand it to the idle worker.
 */

struct thread_params {
  pthread_t thread;
  struct object_entry **list;
  unsigned list_size;
  unsigned remaining;
  int window;
  int depth;
  int working;
  int data_ready;
  pthread_mutex_t mutex;
  pthread_cond_t cond;
  unsigned *processed;
};

static pthread_cond_t progress_cond;

/*
 * Mutex and conditional variable can't be statically-initialized on Windows.
 */
static void init_threaded_search(void)
{
  pthread_mutex_init(&cache_mutex, NULL);
  pthread_mutex_init(&progress_mutex, NULL);
  pthread_cond_init(&progress_cond, NULL);
}

static void cleanup_threaded_search(void)
{
  pthread_cond_destroy(&progress_cond);
  pthread_mutex_destroy(&cache_mutex);
  pthread_mutex_destroy(&progress_mutex);
}

static void *threaded_find_deltas(void *arg)
{
  struct thread_params *me = arg;

  progress_lock();
  while (me->remaining) {
    progress_unlock();

    find_deltas(me->list, &me->remaining,
          me->window, me->depth, me->processed);

    progress_lock();
    me->working = 0;
    pthread_cond_signal(&progress_cond);
    progress_unlock();

    /*
     * We must not set ->data_ready before we wait on the
     * condition because the main thread may have set it to 1
     * before we get here. In order to be sure that new
     * work is available if we see 1 in ->data_ready, it
     * was initialized to 0 before this thread was spawned
     * and we reset it to 0 right away.
     */
    pthread_mutex_lock(&me->mutex);
    while (!me->data_ready)
      pthread_cond_wait(&me->cond, &me->mutex);
    me->data_ready = 0;
    pthread_mutex_unlock(&me->mutex);

    progress_lock();
  }
  progress_unlock();
  /* leave ->working 1 so that this doesn't get more work assigned */
  return NULL;
}

static void ll_find_deltas(struct object_entry **list, unsigned list_size,
         int window, int depth, unsigned *processed)
{
  struct thread_params *p;
  int i, ret, active_threads = 0;

  init_threaded_search();

  if (delta_search_threads <= 1) {
    find_deltas(list, &list_size, window, depth, processed);
    cleanup_threaded_search();
    return;
  }
  if (progress > pack_to_stdout)
    fprintf_ln(stderr, _("Delta compression using up to %d threads"),
         delta_search_threads);
  CALLOC_ARRAY(p, delta_search_threads);

  /* Partition the work amongst work threads. */
  for (i = 0; i < delta_search_threads; i++) {
    unsigned sub_size = list_size / (delta_search_threads - i);

    /* don't use too small segments or no deltas will be found */
    if (sub_size < 2*window && i+1 < delta_search_threads)
      sub_size = 0;

    p[i].window = window;
    p[i].depth = depth;
    p[i].processed = processed;
    p[i].working = 1;
    p[i].data_ready = 0;

    /* try to split chunks on "path" boundaries */
    while (sub_size && sub_size < list_size &&
           list[sub_size]->hash &&
           list[sub_size]->hash == list[sub_size-1]->hash)
      sub_size++;

    p[i].list = list;
    p[i].list_size = sub_size;
    p[i].remaining = sub_size;

    list += sub_size;
    list_size -= sub_size;
  }

  /* Start work threads. */
  for (i = 0; i < delta_search_threads; i++) {
    if (!p[i].list_size)
      continue;
    pthread_mutex_init(&p[i].mutex, NULL);
    pthread_cond_init(&p[i].cond, NULL);
    ret = pthread_create(&p[i].thread, NULL,
             threaded_find_deltas, &p[i]);
    if (ret)
      die(_("unable to create thread: %s"), strerror(ret));
    active_threads++;
  }

  /*
   * Now let's wait for work completion.  Each time a thread is done
   * with its work, we steal half of the remaining work from the
   * thread with the largest number of unprocessed objects and give
   * it to that newly idle thread.  This ensure good load balancing
   * until the remaining object list segments are simply too short
   * to be worth splitting anymore.
   */
  while (active_threads) {
    struct thread_params *target = NULL;
    struct thread_params *victim = NULL;
    unsigned sub_size = 0;

    progress_lock();
    for (;;) {
      for (i = 0; !target && i < delta_search_threads; i++)
        if (!p[i].working)
          target = &p[i];
      if (target)
        break;
      pthread_cond_wait(&progress_cond, &progress_mutex);
    }

    for (i = 0; i < delta_search_threads; i++)
      if (p[i].remaining > 2*window &&
          (!victim || victim->remaining < p[i].remaining))
        victim = &p[i];
    if (victim) {
      sub_size = victim->remaining / 2;
      list = victim->list + victim->list_size - sub_size;
      while (sub_size && list[0]->hash &&
             list[0]->hash == list[-1]->hash) {
        list++;
        sub_size--;
      }
      if (!sub_size) {
        /*
         * It is possible for some "paths" to have
         * so many objects that no hash boundary
         * might be found.  Let's just steal the
         * exact half in that case.
         */
        sub_size = victim->remaining / 2;
        list -= sub_size;
      }
      target->list = list;
      victim->list_size -= sub_size;
      victim->remaining -= sub_size;
    }
    target->list_size = sub_size;
    target->remaining = sub_size;
    target->working = 1;
    progress_unlock();

    pthread_mutex_lock(&target->mutex);
    target->data_ready = 1;
    pthread_cond_signal(&target->cond);
    pthread_mutex_unlock(&target->mutex);

    if (!sub_size) {
      pthread_join(target->thread, NULL);
      pthread_cond_destroy(&target->cond);
      pthread_mutex_destroy(&target->mutex);
      active_threads--;
    }
  }
  cleanup_threaded_search();
  free(p);
}

static int obj_is_packed(const struct object_id *oid)
{
  return packlist_find(&to_pack, oid) ||
    (reuse_packfile_bitmap &&
     bitmap_walk_contains(bitmap_git, reuse_packfile_bitmap, oid));
}

static void add_tag_chain(const struct object_id *oid)
{
  struct tag *tag;

  /*
   * We catch duplicates already in add_object_entry(), but we'd
   * prefer to do this extra check to avoid having to parse the
   * tag at all if we already know that it's being packed (e.g., if
   * it was included via bitmaps, we would not have parsed it
   * previously).
   */
  if (obj_is_packed(oid))
    return;

  tag = lookup_tag(the_repository, oid);
  while (1) {
    if (!tag || parse_tag(tag) || !tag->tagged)
      die(_("unable to pack objects reachable from tag %s"),
          oid_to_hex(oid));

    add_object_entry(&tag->object.oid, OBJ_TAG, NULL, 0);

    if (tag->tagged->type != OBJ_TAG)
      return;

    tag = (struct tag *)tag->tagged;
  }
}

static int add_ref_tag(const char *tag UNUSED, const char *referent UNUSED, const struct object_id *oid,
           int flag UNUSED, void *cb_data UNUSED)
{
  struct object_id peeled;

  if (!peel_iterated_oid(the_repository, oid, &peeled) && obj_is_packed(&peeled))
    add_tag_chain(oid);
  return 0;
}

static void prepare_pack(int window, int depth)
{
  struct object_entry **delta_list;
  uint32_t i, nr_deltas;
  unsigned n;

  if (use_delta_islands)
    resolve_tree_islands(the_repository, progress, &to_pack);

  get_object_details();

  /*
   * If we're locally repacking then we need to be doubly careful
   * from now on in order to make sure no stealth corruption gets
   * propagated to the new pack.  Clients receiving streamed packs
   * should validate everything they get anyway so no need to incur
   * the additional cost here in that case.
   */
  if (!pack_to_stdout)
    do_check_packed_object_crc = 1;

  if (!to_pack.nr_objects || !window || !depth)
    return;

  ALLOC_ARRAY(delta_list, to_pack.nr_objects);
  nr_deltas = n = 0;

  for (i = 0; i < to_pack.nr_objects; i++) {
    struct object_entry *entry = to_pack.objects + i;

    if (DELTA(entry))
      /* This happens if we decided to reuse existing
       * delta from a pack.  "reuse_delta &&" is implied.
       */
      continue;

    if (!entry->type_valid ||
        oe_size_less_than(&to_pack, entry, 50))
      continue;

    if (entry->no_try_delta)
      continue;

    if (!entry->preferred_base) {
      nr_deltas++;
      if (oe_type(entry) < 0)
        die(_("unable to get type of object %s"),
            oid_to_hex(&entry->idx.oid));
    } else {
      if (oe_type(entry) < 0) {
        /*
         * This object is not found, but we
         * don't have to include it anyway.
         */
        continue;
      }
    }

    delta_list[n++] = entry;
  }

  if (nr_deltas && n > 1) {
    unsigned nr_done = 0;

    if (progress)
      progress_state = start_progress(_("Compressing objects"),
              nr_deltas);
    QSORT(delta_list, n, type_size_sort);
    ll_find_deltas(delta_list, n, window+1, depth, &nr_done);
    stop_progress(&progress_state);
    if (nr_done != nr_deltas)
      die(_("inconsistency with delta count"));
  }
  free(delta_list);
}

static int git_pack_config(const char *k, const char *v,
         const struct config_context *ctx, void *cb)
{
  if (!strcmp(k, "pack.window")) {
    window = git_config_int(k, v, ctx->kvi);
    return 0;
  }
  if (!strcmp(k, "pack.windowmemory")) {
    window_memory_limit = git_config_ulong(k, v, ctx->kvi);
    return 0;
  }
  if (!strcmp(k, "pack.depth")) {
    depth = git_config_int(k, v, ctx->kvi);
    return 0;
  }
  if (!strcmp(k, "pack.deltacachesize")) {
    max_delta_cache_size = git_config_int(k, v, ctx->kvi);
    return 0;
  }
  if (!strcmp(k, "pack.deltacachelimit")) {
    cache_max_small_delta_size = git_config_int(k, v, ctx->kvi);
    return 0;
  }
  if (!strcmp(k, "pack.writebitmaphashcache")) {
    if (git_config_bool(k, v))
      write_bitmap_options |= BITMAP_OPT_HASH_CACHE;
    else
      write_bitmap_options &= ~BITMAP_OPT_HASH_CACHE;
  }

  if (!strcmp(k, "pack.writebitmaplookuptable")) {
    if (git_config_bool(k, v))
      write_bitmap_options |= BITMAP_OPT_LOOKUP_TABLE;
    else
      write_bitmap_options &= ~BITMAP_OPT_LOOKUP_TABLE;
  }

  if (!strcmp(k, "pack.usebitmaps")) {
    use_bitmap_index_default = git_config_bool(k, v);
    return 0;
  }
  if (!strcmp(k, "pack.allowpackreuse")) {
    int res = git_parse_maybe_bool_text(v);
    if (res < 0) {
      if (!strcasecmp(v, "single"))
        allow_pack_reuse = SINGLE_PACK_REUSE;
      else if (!strcasecmp(v, "multi"))
        allow_pack_reuse = MULTI_PACK_REUSE;
      else
        die(_("invalid pack.allowPackReuse value: '%s'"), v);
    } else if (res) {
      allow_pack_reuse = SINGLE_PACK_REUSE;
    } else {
      allow_pack_reuse = NO_PACK_REUSE;
    }
    return 0;
  }
  if (!strcmp(k, "pack.threads")) {
    delta_search_threads = git_config_int(k, v, ctx->kvi);
    if (delta_search_threads < 0)
      die(_("invalid number of threads specified (%d)"),
          delta_search_threads);
    if (!HAVE_THREADS && delta_search_threads != 1) {
      warning(_("no threads support, ignoring %s"), k);
      delta_search_threads = 0;
    }
    return 0;
  }
  if (!strcmp(k, "pack.indexversion")) {
    pack_idx_opts.version = git_config_int(k, v, ctx->kvi);
    if (pack_idx_opts.version > 2)
      die(_("bad pack.indexVersion=%"PRIu32),
          pack_idx_opts.version);
    return 0;
  }
  if (!strcmp(k, "pack.writereverseindex")) {
    if (git_config_bool(k, v))
      pack_idx_opts.flags |= WRITE_REV;
    else
      pack_idx_opts.flags &= ~WRITE_REV;
    return 0;
  }
  if (!strcmp(k, "uploadpack.blobpackfileuri")) {
    struct configured_exclusion *ex;
    const char *oid_end, *pack_end;
    /*
     * Stores the pack hash. This is not a true object ID, but is
     * of the same form.
     */
    struct object_id pack_hash;

    if (!v)
      return config_error_nonbool(k);

    ex = xmalloc(sizeof(*ex));
    if (parse_oid_hex(v, &ex->e.oid, &oid_end) ||
        *oid_end != ' ' ||
        parse_oid_hex(oid_end + 1, &pack_hash, &pack_end) ||
        *pack_end != ' ')
      die(_("value of uploadpack.blobpackfileuri must be "
            "of the form '<object-hash> <pack-hash> <uri>' (got '%s')"), v);
    if (oidmap_get(&configured_exclusions, &ex->e.oid))
      die(_("object already configured in another "
            "uploadpack.blobpackfileuri (got '%s')"), v);
    ex->pack_hash_hex = xcalloc(1, pack_end - oid_end);
    memcpy(ex->pack_hash_hex, oid_end + 1, pack_end - oid_end - 1);
    ex->uri = xstrdup(pack_end + 1);
    oidmap_put(&configured_exclusions, ex);
  }
  return git_default_config(k, v, ctx, cb);
}

/* Counters for trace2 output when in --stdin-packs mode. */
static int stdin_packs_found_nr;
static int stdin_packs_hints_nr;

static int add_object_entry_from_pack(const struct object_id *oid,
              struct packed_git *p,
              uint32_t pos,
              void *_data)
{
  off_t ofs;
  enum object_type type = OBJ_NONE;

  display_progress(progress_state, ++nr_seen);

  if (have_duplicate_entry(oid, 0))
    return 0;

  ofs = nth_packed_object_offset(p, pos);
  if (!want_object_in_pack(oid, 0, &p, &ofs))
    return 0;

  if (p) {
    struct rev_info *revs = _data;
    struct object_info oi = OBJECT_INFO_INIT;

    oi.typep = &type;
    if (packed_object_info(the_repository, p, ofs, &oi) < 0) {
      die(_("could not get type of object %s in pack %s"),
          oid_to_hex(oid), p->pack_name);
    } else if (type == OBJ_COMMIT) {
      /*
       * commits in included packs are used as starting points for the
       * subsequent revision walk
       */
      add_pending_oid(revs, NULL, oid, 0);
    }

    stdin_packs_found_nr++;
  }

  create_object_entry(oid, type, 0, 0, 0, p, ofs);

  return 0;
}

static void show_commit_pack_hint(struct commit *commit UNUSED,
          void *data UNUSED)
{
  /* nothing to do; commits don't have a namehash */
}

static void show_object_pack_hint(struct object *object, const char *name,
          void *data UNUSED)
{
  struct object_entry *oe = packlist_find(&to_pack, &object->oid);
  if (!oe)
    return;

  /*
   * Our 'to_pack' list was constructed by iterating all objects packed in
   * included packs, and so doesn't have a non-zero hash field that you
   * would typically pick up during a reachability traversal.
   *
   * Make a best-effort attempt to fill in the ->hash and ->no_try_delta
   * here using a now in order to perhaps improve the delta selection
   * process.
   */
  oe->hash = pack_name_hash(name);
  oe->no_try_delta = name && no_try_delta(name);

  stdin_packs_hints_nr++;
}

static int pack_mtime_cmp(const void *_a, const void *_b)
{
  struct packed_git *a = ((const struct string_list_item*)_a)->util;
  struct packed_git *b = ((const struct string_list_item*)_b)->util;

  /*
   * order packs by descending mtime so that objects are laid out
   * roughly as newest-to-oldest
   */
  if (a->mtime < b->mtime)
    return 1;
  else if (b->mtime < a->mtime)
    return -1;
  else
    return 0;
}

static void read_packs_list_from_stdin(void)
{
  struct strbuf buf = STRBUF_INIT;
  struct string_list include_packs = STRING_LIST_INIT_DUP;
  struct string_list exclude_packs = STRING_LIST_INIT_DUP;
  struct string_list_item *item = NULL;

  struct packed_git *p;
  struct rev_info revs;

  repo_init_revisions(the_repository, &revs, NULL);
  /*
   * Use a revision walk to fill in the namehash of objects in the include
   * packs. To save time, we'll avoid traversing through objects that are
   * in excluded packs.
   *
   * That may cause us to avoid populating all of the namehash fields of
   * all included objects, but our goal is best-effort, since this is only
   * an optimization during delta selection.
   */
  revs.no_kept_objects = 1;
  revs.keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
  revs.blob_objects = 1;
  revs.tree_objects = 1;
  revs.tag_objects = 1;
  revs.ignore_missing_links = 1;

  while (strbuf_getline(&buf, stdin) != EOF) {
    if (!buf.len)
      continue;

    if (*buf.buf == '^')
      string_list_append(&exclude_packs, buf.buf + 1);
    else
      string_list_append(&include_packs, buf.buf);

    strbuf_reset(&buf);
  }

  string_list_sort(&include_packs);
  string_list_remove_duplicates(&include_packs, 0);
  string_list_sort(&exclude_packs);
  string_list_remove_duplicates(&exclude_packs, 0);

  for (p = get_all_packs(the_repository); p; p = p->next) {
    const char *pack_name = pack_basename(p);

    if ((item = string_list_lookup(&include_packs, pack_name)))
      item->util = p;
    if ((item = string_list_lookup(&exclude_packs, pack_name)))
      item->util = p;
  }

  /*
   * Arguments we got on stdin may not even be packs. First
   * check that to avoid segfaulting later on in
   * e.g. pack_mtime_cmp(), excluded packs are handled below.
   *
   * Since we first parsed our STDIN and then sorted the input
   * lines the pack we error on will be whatever line happens to
   * sort first. This is lazy, it's enough that we report one
   * bad case here, we don't need to report the first/last one,
   * or all of them.
   */
  for_each_string_list_item(item, &include_packs) {
    struct packed_git *p = item->util;
    if (!p)
      die(_("could not find pack '%s'"), item->string);
    if (!is_pack_valid(p))
      die(_("packfile %s cannot be accessed"), p->pack_name);
  }

  /*
   * Then, handle all of the excluded packs, marking them as
   * kept in-core so that later calls to add_object_entry()
   * discards any objects that are also found in excluded packs.
   */
  for_each_string_list_item(item, &exclude_packs) {
    struct packed_git *p = item->util;
    if (!p)
      die(_("could not find pack '%s'"), item->string);
    p->pack_keep_in_core = 1;
  }

  /*
   * Order packs by ascending mtime; use QSORT directly to access the
   * string_list_item's ->util pointer, which string_list_sort() does not
   * provide.
   */
  QSORT(include_packs.items, include_packs.nr, pack_mtime_cmp);

  for_each_string_list_item(item, &include_packs) {
    struct packed_git *p = item->util;
    for_each_object_in_pack(p,
          add_object_entry_from_pack,
          &revs,
          FOR_EACH_OBJECT_PACK_ORDER);
  }

  if (prepare_revision_walk(&revs))
    die(_("revision walk setup failed"));
  traverse_commit_list(&revs,
           show_commit_pack_hint,
           show_object_pack_hint,
           NULL);

  trace2_data_intmax("pack-objects", the_repository, "stdin_packs_found",
         stdin_packs_found_nr);
  trace2_data_intmax("pack-objects", the_repository, "stdin_packs_hints",
         stdin_packs_hints_nr);

  strbuf_release(&buf);
  string_list_clear(&include_packs, 0);
  string_list_clear(&exclude_packs, 0);
}

static void add_cruft_object_entry(const struct object_id *oid, enum object_type type,
           struct packed_git *pack, off_t offset,
           const char *name, uint32_t mtime)
{
  struct object_entry *entry;

  display_progress(progress_state, ++nr_seen);

  entry = packlist_find(&to_pack, oid);
  if (entry) {
    if (name) {
      entry->hash = pack_name_hash(name);
      entry->no_try_delta = no_try_delta(name);
    }
  } else {
    if (!want_object_in_pack(oid, 0, &pack, &offset))
      return;
    if (!pack && type == OBJ_BLOB && !has_loose_object(oid)) {
      /*
       * If a traversed tree has a missing blob then we want
       * to avoid adding that missing object to our pack.
       *
       * This only applies to missing blobs, not trees,
       * because the traversal needs to parse sub-trees but
       * not blobs.
       *
       * Note we only perform this check when we couldn't
       * already find the object in a pack, so we're really
       * limited to "ensure non-tip blobs which don't exist in
       * packs do exist via loose objects". Confused?
       */
      return;
    }

    entry = create_object_entry(oid, type, pack_name_hash(name),
              0, name && no_try_delta(name),
              pack, offset);
  }

  if (mtime > oe_cruft_mtime(&to_pack, entry))
    oe_set_cruft_mtime(&to_pack, entry, mtime);
  return;
}

static void show_cruft_object(struct object *obj, const char *name, void *data UNUSED)
{
  /*
   * if we did not record it earlier, it's at least as old as our
   * expiration value. Rather than find it exactly, just use that
   * value.  This may bump it forward from its real mtime, but it
   * will still be "too old" next time we run with the same
   * expiration.
   *
   * if obj does appear in the packing list, this call is a noop (or may
   * set the namehash).
   */
  add_cruft_object_entry(&obj->oid, obj->type, NULL, 0, name, cruft_expiration);
}

static void show_cruft_commit(struct commit *commit, void *data)
{
  show_cruft_object((struct object*)commit, NULL, data);
}

static int cruft_include_check_obj(struct object *obj, void *data UNUSED)
{
  return !has_object_kept_pack(&obj->oid, IN_CORE_KEEP_PACKS);
}

static int cruft_include_check(struct commit *commit, void *data)
{
  return cruft_include_check_obj((struct object*)commit, data);
}

static void set_cruft_mtime(const struct object *object,
          struct packed_git *pack,
          off_t offset, time_t mtime)
{
  add_cruft_object_entry(&object->oid, object->type, pack, offset, NULL,
             mtime);
}

static void mark_pack_kept_in_core(struct string_list *packs, unsigned keep)
{
  struct string_list_item *item = NULL;
  for_each_string_list_item(item, packs) {
    struct packed_git *p = item->util;
    if (!p)
      die(_("could not find pack '%s'"), item->string);
    p->pack_keep_in_core = keep;
  }
}

static void add_unreachable_loose_objects(void);
static void add_objects_in_unpacked_packs(void);

static void enumerate_cruft_objects(void)
{
  if (progress)
    progress_state = start_progress(_("Enumerating cruft objects"), 0);

  add_objects_in_unpacked_packs();
  add_unreachable_loose_objects();

  stop_progress(&progress_state);
}

static void enumerate_and_traverse_cruft_objects(struct string_list *fresh_packs)
{
  struct packed_git *p;
  struct rev_info revs;
  int ret;

  repo_init_revisions(the_repository, &revs, NULL);

  revs.tag_objects = 1;
  revs.tree_objects = 1;
  revs.blob_objects = 1;

  revs.include_check = cruft_include_check;
  revs.include_check_obj = cruft_include_check_obj;

  revs.ignore_missing_links = 1;

  if (progress)
    progress_state = start_progress(_("Enumerating cruft objects"), 0);
  ret = add_unseen_recent_objects_to_traversal(&revs, cruft_expiration,
                 set_cruft_mtime, 1);
  stop_progress(&progress_state);

  if (ret)
    die(_("unable to add cruft objects"));

  /*
   * Re-mark only the fresh packs as kept so that objects in
   * unknown packs do not halt the reachability traversal early.
   */
  for (p = get_all_packs(the_repository); p; p = p->next)
    p->pack_keep_in_core = 0;
  mark_pack_kept_in_core(fresh_packs, 1);

  if (prepare_revision_walk(&revs))
    die(_("revision walk setup failed"));
  if (progress)
    progress_state = start_progress(_("Traversing cruft objects"), 0);
  nr_seen = 0;
  traverse_commit_list(&revs, show_cruft_commit, show_cruft_object, NULL);

  stop_progress(&progress_state);
}

static void read_cruft_objects(void)
{
  struct strbuf buf = STRBUF_INIT;
  struct string_list discard_packs = STRING_LIST_INIT_DUP;
  struct string_list fresh_packs = STRING_LIST_INIT_DUP;
  struct packed_git *p;

  ignore_packed_keep_in_core = 1;

  while (strbuf_getline(&buf, stdin) != EOF) {
    if (!buf.len)
      continue;

    if (*buf.buf == '-')
      string_list_append(&discard_packs, buf.buf + 1);
    else
      string_list_append(&fresh_packs, buf.buf);
  }

  string_list_sort(&discard_packs);
  string_list_sort(&fresh_packs);

  for (p = get_all_packs(the_repository); p; p = p->next) {
    const char *pack_name = pack_basename(p);
    struct string_list_item *item;

    item = string_list_lookup(&fresh_packs, pack_name);
    if (!item)
      item = string_list_lookup(&discard_packs, pack_name);

    if (item) {
      item->util = p;
    } else {
      /*
       * This pack wasn't mentioned in either the "fresh" or
       * "discard" list, so the caller didn't know about it.
       *
       * Mark it as kept so that its objects are ignored by
       * add_unseen_recent_objects_to_traversal(). We'll
       * unmark it before starting the traversal so it doesn't
       * halt the traversal early.
       */
      p->pack_keep_in_core = 1;
    }
  }

  mark_pack_kept_in_core(&fresh_packs, 1);
  mark_pack_kept_in_core(&discard_packs, 0);

  if (cruft_expiration)
    enumerate_and_traverse_cruft_objects(&fresh_packs);
  else
    enumerate_cruft_objects();

  strbuf_release(&buf);
  string_list_clear(&discard_packs, 0);
  string_list_clear(&fresh_packs, 0);
}

static void read_object_list_from_stdin(void)
{
  char line[GIT_MAX_HEXSZ + 1 + PATH_MAX + 2];
  struct object_id oid;
  const char *p;

  for (;;) {
    if (!fgets(line, sizeof(line), stdin)) {
      if (feof(stdin))
        break;
      if (!ferror(stdin))
        BUG("fgets returned NULL, not EOF, not error!");
      if (errno != EINTR)
        die_errno("fgets");
      clearerr(stdin);
      continue;
    }
    if (line[0] == '-') {
      if (get_oid_hex(line+1, &oid))
        die(_("expected edge object ID, got garbage:\n %s"),
            line);
      add_preferred_base(&oid);
      continue;
    }
    if (parse_oid_hex(line, &oid, &p))
      die(_("expected object ID, got garbage:\n %s"), line);

    add_preferred_base_object(p + 1);
    add_object_entry(&oid, OBJ_NONE, p + 1, 0);
  }
}

static void show_commit(struct commit *commit, void *data UNUSED)
{
  add_object_entry(&commit->object.oid, OBJ_COMMIT, NULL, 0);

  if (write_bitmap_index)
    index_commit_for_bitmap(commit);

  if (use_delta_islands)
    propagate_island_marks(commit);
}

static void show_object(struct object *obj, const char *name,
      void *data UNUSED)
{
  add_preferred_base_object(name);
  add_object_entry(&obj->oid, obj->type, name, 0);

  if (use_delta_islands) {
    const char *p;
    unsigned depth;
    struct object_entry *ent;

    /* the empty string is a root tree, which is depth 0 */
    depth = *name ? 1 : 0;
    for (p = strchr(name, '/'); p; p = strchr(p + 1, '/'))
      depth++;

    ent = packlist_find(&to_pack, &obj->oid);
    if (ent && depth > oe_tree_depth(&to_pack, ent))
      oe_set_tree_depth(&to_pack, ent, depth);
  }
}

static void show_object__ma_allow_any(struct object *obj, const char *name, void *data)
{
  assert(arg_missing_action == MA_ALLOW_ANY);

  /*
   * Quietly ignore ALL missing objects.  This avoids problems with
   * staging them now and getting an odd error later.
   */
  if (!has_object(the_repository, &obj->oid, 0))
    return;

  show_object(obj, name, data);
}

static void show_object__ma_allow_promisor(struct object *obj, const char *name, void *data)
{
  assert(arg_missing_action == MA_ALLOW_PROMISOR);

  /*
   * Quietly ignore EXPECTED missing objects.  This avoids problems with
   * staging them now and getting an odd error later.
   */
  if (!has_object(the_repository, &obj->oid, 0) && is_promisor_object(&obj->oid))
    return;

  show_object(obj, name, data);
}

static int option_parse_missing_action(const struct option *opt UNUSED,
               const char *arg, int unset)
{
  assert(arg);
  assert(!unset);

  if (!strcmp(arg, "error")) {
    arg_missing_action = MA_ERROR;
    fn_show_object = show_object;
    return 0;
  }

  if (!strcmp(arg, "allow-any")) {
    arg_missing_action = MA_ALLOW_ANY;
    fetch_if_missing = 0;
    fn_show_object = show_object__ma_allow_any;
    return 0;
  }

  if (!strcmp(arg, "allow-promisor")) {
    arg_missing_action = MA_ALLOW_PROMISOR;
    fetch_if_missing = 0;
    fn_show_object = show_object__ma_allow_promisor;
    return 0;
  }

  die(_("invalid value for '%s': '%s'"), "--missing", arg);
  return 0;
}

static void show_edge(struct commit *commit)
{
  add_preferred_base(&commit->object.oid);
}

static int add_object_in_unpacked_pack(const struct object_id *oid,
               struct packed_git *pack,
               uint32_t pos,
               void *data UNUSED)
{
  if (cruft) {
    off_t offset;
    time_t mtime;

    if (pack->is_cruft) {
      if (load_pack_mtimes(pack) < 0)
        die(_("could not load cruft pack .mtimes"));
      mtime = nth_packed_mtime(pack, pos);
    } else {
      mtime = pack->mtime;
    }
    offset = nth_packed_object_offset(pack, pos);

    add_cruft_object_entry(oid, OBJ_NONE, pack, offset,
               NULL, mtime);
  } else {
    add_object_entry(oid, OBJ_NONE, "", 0);
  }
  return 0;
}

static void add_objects_in_unpacked_packs(void)
{
  if (for_each_packed_object(add_object_in_unpacked_pack, NULL,
           FOR_EACH_OBJECT_PACK_ORDER |
           FOR_EACH_OBJECT_LOCAL_ONLY |
           FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS |
           FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS))
    die(_("cannot open pack index"));
}

static int add_loose_object(const struct object_id *oid, const char *path,
          void *data UNUSED)
{
  enum object_type type = oid_object_info(the_repository, oid, NULL);

  if (type < 0) {
    warning(_("loose object at %s could not be examined"), path);
    return 0;
  }

  if (cruft) {
    struct stat st;
    if (stat(path, &st) < 0) {
      if (errno == ENOENT)
        return 0;
      return error_errno("unable to stat %s", oid_to_hex(oid));
    }

    add_cruft_object_entry(oid, type, NULL, 0, NULL,
               st.st_mtime);
  } else {
    add_object_entry(oid, type, "", 0);
  }
  return 0;
}

/*
 * We actually don't even have to worry about reachability here.
 * add_object_entry will weed out duplicates, so we just add every
 * loose object we find.
 */
static void add_unreachable_loose_objects(void)
{
  for_each_loose_file_in_objdir(get_object_directory(),
              add_loose_object,
              NULL, NULL, NULL);
}

static int has_sha1_pack_kept_or_nonlocal(const struct object_id *oid)
{
  static struct packed_git *last_found = (void *)1;
  struct packed_git *p;

  p = (last_found != (void *)1) ? last_found :
          get_all_packs(the_repository);

  while (p) {
    if ((!p->pack_local || p->pack_keep ||
        p->pack_keep_in_core) &&
      find_pack_entry_one(oid->hash, p)) {
      last_found = p;
      return 1;
    }
    if (p == last_found)
      p = get_all_packs(the_repository);
    else
      p = p->next;
    if (p == last_found)
      p = p->next;
  }
  return 0;
}

/*
 * Store a list of sha1s that are should not be discarded
 * because they are either written too recently, or are
 * reachable from another object that was.
 *
 * This is filled by get_object_list.
 */
static struct oid_array recent_objects;

static int loosened_object_can_be_discarded(const struct object_id *oid,
              timestamp_t mtime)
{
  if (!unpack_unreachable_expiration)
    return 0;
  if (mtime > unpack_unreachable_expiration)
    return 0;
  if (oid_array_lookup(&recent_objects, oid) >= 0)
    return 0;
  return 1;
}

static void loosen_unused_packed_objects(void)
{
  struct packed_git *p;
  uint32_t i;
  uint32_t loosened_objects_nr = 0;
  struct object_id oid;

  for (p = get_all_packs(the_repository); p; p = p->next) {
    if (!p->pack_local || p->pack_keep || p->pack_keep_in_core)
      continue;

    if (open_pack_index(p))
      die(_("cannot open pack index"));

    for (i = 0; i < p->num_objects; i++) {
      nth_packed_object_id(&oid, p, i);
      if (!packlist_find(&to_pack, &oid) &&
          !has_sha1_pack_kept_or_nonlocal(&oid) &&
          !loosened_object_can_be_discarded(&oid, p->mtime)) {
        if (force_object_loose(&oid, p->mtime))
          die(_("unable to force loose object"));
        loosened_objects_nr++;
      }
    }
  }

  trace2_data_intmax("pack-objects", the_repository,
         "loosen_unused_packed_objects/loosened", loosened_objects_nr);
}

/*
 * This tracks any options which pack-reuse code expects to be on, or which a
 * reader of the pack might not understand, and which would therefore prevent
 * blind reuse of what we have on disk.
 */
static int pack_options_allow_reuse(void)
{
  return allow_pack_reuse != NO_PACK_REUSE &&
         pack_to_stdout &&
         !ignore_packed_keep_on_disk &&
         !ignore_packed_keep_in_core &&
         (!local || !have_non_local_packs) &&
         !incremental;
}

static int get_object_list_from_bitmap(struct rev_info *revs)
{
  if (!(bitmap_git = prepare_bitmap_walk(revs, 0)))
    return -1;

  if (pack_options_allow_reuse())
    reuse_partial_packfile_from_bitmap(bitmap_git,
               &reuse_packfiles,
               &reuse_packfiles_nr,
               &reuse_packfile_bitmap,
               allow_pack_reuse == MULTI_PACK_REUSE);

  if (reuse_packfiles) {
    reuse_packfile_objects = bitmap_popcount(reuse_packfile_bitmap);
    if (!reuse_packfile_objects)
      BUG("expected non-empty reuse bitmap");

    nr_result += reuse_packfile_objects;
    nr_seen += reuse_packfile_objects;
    display_progress(progress_state, nr_seen);
  }

  traverse_bitmap_commit_list(bitmap_git, revs,
            &add_object_entry_from_bitmap);
  return 0;
}

static void record_recent_object(struct object *obj,
         const char *name UNUSED,
         void *data UNUSED)
{
  oid_array_append(&recent_objects, &obj->oid);
}

static void record_recent_commit(struct commit *commit, void *data UNUSED)
{
  oid_array_append(&recent_objects, &commit->object.oid);
}

static int mark_bitmap_preferred_tip(const char *refname,
             const char *referent UNUSED,
             const struct object_id *oid,
             int flags UNUSED,
             void *data UNUSED)
{
  struct object_id peeled;
  struct object *object;

  if (!peel_iterated_oid(the_repository, oid, &peeled))
    oid = &peeled;

  object = parse_object_or_die(oid, refname);
  if (object->type == OBJ_COMMIT)
    object->flags |= NEEDS_BITMAP;

  return 0;
}

static void mark_bitmap_preferred_tips(void)
{
  struct string_list_item *item;
  const struct string_list *preferred_tips;

  preferred_tips = bitmap_preferred_tips(the_repository);
  if (!preferred_tips)
    return;

  for_each_string_list_item(item, preferred_tips) {
    refs_for_each_ref_in(get_main_ref_store(the_repository),
             item->string, mark_bitmap_preferred_tip,
             NULL);
  }
}

static void get_object_list(struct rev_info *revs, int ac, const char **av)
{
  struct setup_revision_opt s_r_opt = {
    .allow_exclude_promisor_objects = 1,
  };
  char line[1000];
  int flags = 0;
  int save_warning;

  save_commit_buffer = 0;
  setup_revisions(ac, av, revs, &s_r_opt);

  /* make sure shallows are read */
  is_repository_shallow(the_repository);

  save_warning = warn_on_object_refname_ambiguity;
  warn_on_object_refname_ambiguity = 0;

  while (fgets(line, sizeof(line), stdin) != NULL) {
    int len = strlen(line);
    if (len && line[len - 1] == '\n')
      line[--len] = 0;
    if (!len)
      break;
    if (*line == '-') {
      if (!strcmp(line, "--not")) {
        flags ^= UNINTERESTING;
        write_bitmap_index = 0;
        continue;
      }
      if (starts_with(line, "--shallow ")) {
        struct object_id oid;
        if (get_oid_hex(line + 10, &oid))
          die("not an object name '%s'", line + 10);
        register_shallow(the_repository, &oid);
        use_bitmap_index = 0;
        continue;
      }
      die(_("not a rev '%s'"), line);
    }
    if (handle_revision_arg(line, revs, flags, REVARG_CANNOT_BE_FILENAME))
      die(_("bad revision '%s'"), line);
  }

  warn_on_object_refname_ambiguity = save_warning;

  if (use_bitmap_index && !get_object_list_from_bitmap(revs))
    return;

  if (use_delta_islands)
    load_delta_islands(the_repository, progress);

  if (write_bitmap_index)
    mark_bitmap_preferred_tips();

  if (prepare_revision_walk(revs))
    die(_("revision walk setup failed"));
  mark_edges_uninteresting(revs, show_edge, sparse);

  if (!fn_show_object)
    fn_show_object = show_object;
  traverse_commit_list(revs,
           show_commit, fn_show_object,
           NULL);

  if (unpack_unreachable_expiration) {
    revs->ignore_missing_links = 1;
    if (add_unseen_recent_objects_to_traversal(revs,
        unpack_unreachable_expiration, NULL, 0))
      die(_("unable to add recent objects"));
    if (prepare_revision_walk(revs))
      die(_("revision walk setup failed"));
    traverse_commit_list(revs, record_recent_commit,
             record_recent_object, NULL);
  }

  if (keep_unreachable)
    add_objects_in_unpacked_packs();
  if (pack_loose_unreachable)
    add_unreachable_loose_objects();
  if (unpack_unreachable)
    loosen_unused_packed_objects();

  oid_array_clear(&recent_objects);
}

static void add_extra_kept_packs(const struct string_list *names)
{
  struct packed_git *p;

  if (!names->nr)
    return;

  for (p = get_all_packs(the_repository); p; p = p->next) {
    const char *name = basename(p->pack_name);
    int i;

    if (!p->pack_local)
      continue;

    for (i = 0; i < names->nr; i++)
      if (!fspathcmp(name, names->items[i].string))
        break;

    if (i < names->nr) {
      p->pack_keep_in_core = 1;
      ignore_packed_keep_in_core = 1;
      continue;
    }
  }
}

static int option_parse_quiet(const struct option *opt, const char *arg,
            int unset)
{
  int *val = opt->value;

  BUG_ON_OPT_ARG(arg);

  if (!unset)
    *val = 0;
  else if (!*val)
    *val = 1;
  return 0;
}

static int option_parse_index_version(const struct option *opt,
              const char *arg, int unset)
{
  struct pack_idx_option *popts = opt->value;
  char *c;
  const char *val = arg;

  BUG_ON_OPT_NEG(unset);

  popts->version = strtoul(val, &c, 10);
  if (popts->version > 2)
    die(_("unsupported index version %s"), val);
  if (*c == ',' && c[1])
    popts->off32_limit = strtoul(c+1, &c, 0);
  if (*c || popts->off32_limit & 0x80000000)
    die(_("bad index version '%s'"), val);
  return 0;
}

static int option_parse_unpack_unreachable(const struct option *opt UNUSED,
             const char *arg, int unset)
{
  if (unset) {
    unpack_unreachable = 0;
    unpack_unreachable_expiration = 0;
  }
  else {
    unpack_unreachable = 1;
    if (arg)
      unpack_unreachable_expiration = approxidate(arg);
  }
  return 0;
}

static int option_parse_cruft_expiration(const struct option *opt UNUSED,
           const char *arg, int unset)
{
  if (unset) {
    cruft = 0;
    cruft_expiration = 0;
  } else {
    cruft = 1;
    if (arg)
      cruft_expiration = approxidate(arg);
  }
  return 0;
}

int cmd_pack_objects(int argc, const char **argv, const char *prefix)
{
  int use_internal_rev_list = 0;
  int shallow = 0;
  int all_progress_implied = 0;
  struct strvec rp = STRVEC_INIT;
  int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
  int rev_list_index = 0;
  int stdin_packs = 0;
  struct string_list keep_pack_list = STRING_LIST_INIT_NODUP;
  struct list_objects_filter_options filter_options =
    LIST_OBJECTS_FILTER_INIT;

  struct option pack_objects_options[] = {
    OPT_CALLBACK_F('q', "quiet", &progress, NULL,
             N_("do not show progress meter"),
             PARSE_OPT_NOARG, option_parse_quiet),
    OPT_SET_INT(0, "progress", &progress,
          N_("show progress meter"), 1),
    OPT_SET_INT(0, "all-progress", &progress,
          N_("show progress meter during object writing phase"), 2),
    OPT_BOOL(0, "all-progress-implied",
       &all_progress_implied,
       N_("similar to --all-progress when progress meter is shown")),
    OPT_CALLBACK_F(0, "index-version", &pack_idx_opts, N_("<version>[,<offset>]"),
      N_("write the pack index file in the specified idx format version"),
      PARSE_OPT_NONEG, option_parse_index_version),
    OPT_MAGNITUDE(0, "max-pack-size", &pack_size_limit,
            N_("maximum size of each output pack file")),
    OPT_BOOL(0, "local", &local,
       N_("ignore borrowed objects from alternate object store")),
    OPT_BOOL(0, "incremental", &incremental,
       N_("ignore packed objects")),
    OPT_INTEGER(0, "window", &window,
          N_("limit pack window by objects")),
    OPT_MAGNITUDE(0, "window-memory", &window_memory_limit,
            N_("limit pack window by memory in addition to object limit")),
    OPT_INTEGER(0, "depth", &depth,
          N_("maximum length of delta chain allowed in the resulting pack")),
    OPT_BOOL(0, "reuse-delta", &reuse_delta,
       N_("reuse existing deltas")),
    OPT_BOOL(0, "reuse-object", &reuse_object,
       N_("reuse existing objects")),
    OPT_BOOL(0, "delta-base-offset", &allow_ofs_delta,
       N_("use OFS_DELTA objects")),
    OPT_INTEGER(0, "threads", &delta_search_threads,
          N_("use threads when searching for best delta matches")),
    OPT_BOOL(0, "non-empty", &non_empty,
       N_("do not create an empty pack output")),
    OPT_BOOL(0, "revs", &use_internal_rev_list,
       N_("read revision arguments from standard input")),
    OPT_SET_INT_F(0, "unpacked", &rev_list_unpacked,
            N_("limit the objects to those that are not yet packed"),
            1, PARSE_OPT_NONEG),
    OPT_SET_INT_F(0, "all", &rev_list_all,
            N_("include objects reachable from any reference"),
            1, PARSE_OPT_NONEG),
    OPT_SET_INT_F(0, "reflog", &rev_list_reflog,
            N_("include objects referred by reflog entries"),
            1, PARSE_OPT_NONEG),
    OPT_SET_INT_F(0, "indexed-objects", &rev_list_index,
            N_("include objects referred to by the index"),
            1, PARSE_OPT_NONEG),
    OPT_BOOL(0, "stdin-packs", &stdin_packs,
       N_("read packs from stdin")),
    OPT_BOOL(0, "stdout", &pack_to_stdout,
       N_("output pack to stdout")),
    OPT_BOOL(0, "include-tag", &include_tag,
       N_("include tag objects that refer to objects to be packed")),
    OPT_BOOL(0, "keep-unreachable", &keep_unreachable,
       N_("keep unreachable objects")),
    OPT_BOOL(0, "pack-loose-unreachable", &pack_loose_unreachable,
       N_("pack loose unreachable objects")),
    OPT_CALLBACK_F(0, "unpack-unreachable", NULL, N_("time"),
      N_("unpack unreachable objects newer than <time>"),
      PARSE_OPT_OPTARG, option_parse_unpack_unreachable),
    OPT_BOOL(0, "cruft", &cruft, N_("create a cruft pack")),
    OPT_CALLBACK_F(0, "cruft-expiration", NULL, N_("time"),
      N_("expire cruft objects older than <time>"),
      PARSE_OPT_OPTARG, option_parse_cruft_expiration),
    OPT_BOOL(0, "sparse", &sparse,
       N_("use the sparse reachability algorithm")),
    OPT_BOOL(0, "thin", &thin,
       N_("create thin packs")),
    OPT_BOOL(0, "shallow", &shallow,
       N_("create packs suitable for shallow fetches")),
    OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep_on_disk,
       N_("ignore packs that have companion .keep file")),
    OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
        N_("ignore this pack")),
    OPT_INTEGER(0, "compression", &pack_compression_level,
          N_("pack compression level")),
    OPT_BOOL(0, "keep-true-parents", &grafts_keep_true_parents,
       N_("do not hide commits by grafts")),
    OPT_BOOL(0, "use-bitmap-index", &use_bitmap_index,
       N_("use a bitmap index if available to speed up counting objects")),
    OPT_SET_INT(0, "write-bitmap-index", &write_bitmap_index,
          N_("write a bitmap index together with the pack index"),
          WRITE_BITMAP_TRUE),
    OPT_SET_INT_F(0, "write-bitmap-index-quiet",
            &write_bitmap_index,
            N_("write a bitmap index if possible"),
            WRITE_BITMAP_QUIET, PARSE_OPT_HIDDEN),
    OPT_PARSE_LIST_OBJECTS_FILTER(&filter_options),
    OPT_CALLBACK_F(0, "missing", NULL, N_("action"),
      N_("handling for missing objects"), PARSE_OPT_NONEG,
      option_parse_missing_action),
    OPT_BOOL(0, "exclude-promisor-objects", &exclude_promisor_objects,
       N_("do not pack objects in promisor packfiles")),
    OPT_BOOL(0, "delta-islands", &use_delta_islands,
       N_("respect islands during delta compression")),
    OPT_STRING_LIST(0, "uri-protocol", &uri_protocols,
        N_("protocol"),
        N_("exclude any configured uploadpack.blobpackfileuri with this protocol")),
    OPT_END(),
  };

  if (DFS_NUM_STATES > (1 << OE_DFS_STATE_BITS))
    BUG("too many dfs states, increase OE_DFS_STATE_BITS");

  disable_replace_refs();

  sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1);
  if (the_repository->gitdir) {
    prepare_repo_settings(the_repository);
    if (sparse < 0)
      sparse = the_repository->settings.pack_use_sparse;
    if (the_repository->settings.pack_use_multi_pack_reuse)
      allow_pack_reuse = MULTI_PACK_REUSE;
  }

  reset_pack_idx_option(&pack_idx_opts);
  pack_idx_opts.flags |= WRITE_REV;
  git_config(git_pack_config, NULL);
  if (git_env_bool(GIT_TEST_NO_WRITE_REV_INDEX, 0))
    pack_idx_opts.flags &= ~WRITE_REV;

  progress = isatty(2);
  argc = parse_options(argc, argv, prefix, pack_objects_options,
           pack_usage, 0);

  if (argc) {
    base_name = argv[0];
    argc--;
  }
  if (pack_to_stdout != !base_name || argc)
    usage_with_options(pack_usage, pack_objects_options);

  if (depth < 0)
    depth = 0;
  if (depth >= (1 << OE_DEPTH_BITS)) {
    warning(_("delta chain depth %d is too deep, forcing %d"),
      depth, (1 << OE_DEPTH_BITS) - 1);
    depth = (1 << OE_DEPTH_BITS) - 1;
  }
  if (cache_max_small_delta_size >= (1U << OE_Z_DELTA_BITS)) {
    warning(_("pack.deltaCacheLimit is too high, forcing %d"),
      (1U << OE_Z_DELTA_BITS) - 1);
    cache_max_small_delta_size = (1U << OE_Z_DELTA_BITS) - 1;
  }
  if (window < 0)
    window = 0;

  strvec_push(&rp, "pack-objects");
  if (thin) {
    use_internal_rev_list = 1;
    strvec_push(&rp, shallow
        ? "--objects-edge-aggressive"
        : "--objects-edge");
  } else
    strvec_push(&rp, "--objects");

  if (rev_list_all) {
    use_internal_rev_list = 1;
    strvec_push(&rp, "--all");
  }
  if (rev_list_reflog) {
    use_internal_rev_list = 1;
    strvec_push(&rp, "--reflog");
  }
  if (rev_list_index) {
    use_internal_rev_list = 1;
    strvec_push(&rp, "--indexed-objects");
  }
  if (rev_list_unpacked && !stdin_packs) {
    use_internal_rev_list = 1;
    strvec_push(&rp, "--unpacked");
  }

  if (exclude_promisor_objects) {
    use_internal_rev_list = 1;
    fetch_if_missing = 0;
    strvec_push(&rp, "--exclude-promisor-objects");
  }
  if (unpack_unreachable || keep_unreachable || pack_loose_unreachable)
    use_internal_rev_list = 1;

  if (!reuse_object)
    reuse_delta = 0;
  if (pack_compression_level == -1)
    pack_compression_level = Z_DEFAULT_COMPRESSION;
  else if (pack_compression_level < 0 || pack_compression_level > Z_BEST_COMPRESSION)
    die(_("bad pack compression level %d"), pack_compression_level);

  if (!delta_search_threads) /* --threads=0 means autodetect */
    delta_search_threads = online_cpus();

  if (!HAVE_THREADS && delta_search_threads != 1)
    warning(_("no threads support, ignoring --threads"));
  if (!pack_to_stdout && !pack_size_limit)
    pack_size_limit = pack_size_limit_cfg;
  if (pack_to_stdout && pack_size_limit)
    die(_("--max-pack-size cannot be used to build a pack for transfer"));
  if (pack_size_limit && pack_size_limit < 1024*1024) {
    warning(_("minimum pack size limit is 1 MiB"));
    pack_size_limit = 1024*1024;
  }

  if (!pack_to_stdout && thin)
    die(_("--thin cannot be used to build an indexable pack"));

  if (keep_unreachable && unpack_unreachable)
    die(_("options '%s' and '%s' cannot be used together"), "--keep-unreachable", "--unpack-unreachable");
  if (!rev_list_all || !rev_list_reflog || !rev_list_index)
    unpack_unreachable_expiration = 0;

  if (stdin_packs && filter_options.choice)
    die(_("cannot use --filter with --stdin-packs"));

  if (stdin_packs && use_internal_rev_list)
    die(_("cannot use internal rev list with --stdin-packs"));

  if (cruft) {
    if (use_internal_rev_list)
      die(_("cannot use internal rev list with --cruft"));
    if (stdin_packs)
      die(_("cannot use --stdin-packs with --cruft"));
  }

  /*
   * "soft" reasons not to use bitmaps - for on-disk repack by default we want
   *
   * - to produce good pack (with bitmap index not-yet-packed objects are
   *   packed in suboptimal order).
   *
   * - to use more robust pack-generation codepath (avoiding possible
   *   bugs in bitmap code and possible bitmap index corruption).
   */
  if (!pack_to_stdout)
    use_bitmap_index_default = 0;

  if (use_bitmap_index < 0)
    use_bitmap_index = use_bitmap_index_default;

  /* "hard" reasons not to use bitmaps; these just won't work at all */
  if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow(the_repository))
    use_bitmap_index = 0;

  if (pack_to_stdout || !rev_list_all)
    write_bitmap_index = 0;

  if (use_delta_islands)
    strvec_push(&rp, "--topo-order");

  if (progress && all_progress_implied)
    progress = 2;

  add_extra_kept_packs(&keep_pack_list);
  if (ignore_packed_keep_on_disk) {
    struct packed_git *p;
    for (p = get_all_packs(the_repository); p; p = p->next)
      if (p->pack_local && p->pack_keep)
        break;
    if (!p) /* no keep-able packs found */
      ignore_packed_keep_on_disk = 0;
  }
  if (local) {
    /*
     * unlike ignore_packed_keep_on_disk above, we do not
     * want to unset "local" based on looking at packs, as
     * it also covers non-local objects
     */
    struct packed_git *p;
    for (p = get_all_packs(the_repository); p; p = p->next) {
      if (!p->pack_local) {
        have_non_local_packs = 1;
        break;
      }
    }
  }

  trace2_region_enter("pack-objects", "enumerate-objects",
          the_repository);
  prepare_packing_data(the_repository, &to_pack);

  if (progress && !cruft)
    progress_state = start_progress(_("Enumerating objects"), 0);
  if (stdin_packs) {
    /* avoids adding objects in excluded packs */
    ignore_packed_keep_in_core = 1;
    read_packs_list_from_stdin();
    if (rev_list_unpacked)
      add_unreachable_loose_objects();
  } else if (cruft) {
    read_cruft_objects();
  } else if (!use_internal_rev_list) {
    read_object_list_from_stdin();
  } else {
    struct rev_info revs;

    repo_init_revisions(the_repository, &revs, NULL);
    list_objects_filter_copy(&revs.filter, &filter_options);
    get_object_list(&revs, rp.nr, rp.v);
    release_revisions(&revs);
  }
  cleanup_preferred_base();
  if (include_tag && nr_result)
    refs_for_each_tag_ref(get_main_ref_store(the_repository),
              add_ref_tag, NULL);
  stop_progress(&progress_state);
  trace2_region_leave("pack-objects", "enumerate-objects",
          the_repository);

  if (non_empty && !nr_result)
    goto cleanup;
  if (nr_result) {
    trace2_region_enter("pack-objects", "prepare-pack",
            the_repository);
    prepare_pack(window, depth);
    trace2_region_leave("pack-objects", "prepare-pack",
            the_repository);
  }

  trace2_region_enter("pack-objects", "write-pack-file", the_repository);
  write_excluded_by_configs();
  write_pack_file();
  trace2_region_leave("pack-objects", "write-pack-file", the_repository);

  if (progress)
    fprintf_ln(stderr,
         _("Total %"PRIu32" (delta %"PRIu32"),"
           " reused %"PRIu32" (delta %"PRIu32"),"
           " pack-reused %"PRIu32" (from %"PRIuMAX")"),
         written, written_delta, reused, reused_delta,
         reuse_packfile_objects,
         (uintmax_t)reuse_packfiles_used_nr);

  trace2_data_intmax("pack-objects", the_repository, "written", written);
  trace2_data_intmax("pack-objects", the_repository, "written/delta", written_delta);
  trace2_data_intmax("pack-objects", the_repository, "reused", reused);
  trace2_data_intmax("pack-objects", the_repository, "reused/delta", reused_delta);
  trace2_data_intmax("pack-objects", the_repository, "pack-reused", reuse_packfile_objects);
  trace2_data_intmax("pack-objects", the_repository, "packs-reused", reuse_packfiles_used_nr);

cleanup:
  clear_packing_data(&to_pack);
  list_objects_filter_release(&filter_options);
  strvec_clear(&rp);

  return 0;
}

Coverage Report

Created: 2024-09-08 06:23