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

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#include "builtin.h"
#include "config.h"
#include "delta.h"
#include "environment.h"
#include "gettext.h"
#include "hex.h"
#include "pack.h"
#include "csum-file.h"
#include "blob.h"
#include "commit.h"
#include "tree.h"
#include "progress.h"
#include "fsck.h"
#include "strbuf.h"
#include "streaming.h"
#include "thread-utils.h"
#include "packfile.h"
#include "pack-revindex.h"
#include "object-file.h"
#include "object-store-ll.h"
#include "oid-array.h"
#include "replace-object.h"
#include "promisor-remote.h"
#include "setup.h"

static const char index_pack_usage[] =
"git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--[no-]rev-index] [--verify] [--strict[=<msg-id>=<severity>...]] [--fsck-objects[=<msg-id>=<severity>...]] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";

struct object_entry {
  struct pack_idx_entry idx;
  unsigned long size;
  unsigned char hdr_size;
  signed char type;
  signed char real_type;
};

struct object_stat {
  unsigned delta_depth;
  int base_object_no;
};

struct base_data {
  /* Initialized by make_base(). */
  struct base_data *base;
  struct object_entry *obj;
  int ref_first, ref_last;
  int ofs_first, ofs_last;
  /*
   * Threads should increment retain_data if they are about to call
   * patch_delta() using this struct's data as a base, and decrement this
   * when they are done. While retain_data is nonzero, this struct's data
   * will not be freed even if the delta base cache limit is exceeded.
   */
  int retain_data;
  /*
   * The number of direct children that have not been fully processed
   * (entered work_head, entered done_head, left done_head). When this
   * number reaches zero, this struct base_data can be freed.
   */
  int children_remaining;

  /* Not initialized by make_base(). */
  struct list_head list;
  void *data;
  unsigned long size;
};

/*
 * Stack of struct base_data that have unprocessed children.
 * threaded_second_pass() uses this as a source of work (the other being the
 * objects array).
 *
 * Guarded by work_mutex.
 */
static LIST_HEAD(work_head);

/*
 * Stack of struct base_data that have children, all of whom have been
 * processed or are being processed, and at least one child is being processed.
 * These struct base_data must be kept around until the last child is
 * processed.
 *
 * Guarded by work_mutex.
 */
static LIST_HEAD(done_head);

/*
 * All threads share one delta base cache.
 *
 * base_cache_used is guarded by work_mutex, and base_cache_limit is read-only
 * in a thread.
 */
static size_t base_cache_used;
static size_t base_cache_limit;

struct thread_local {
  pthread_t thread;
  int pack_fd;
};

/* Remember to update object flag allocation in object.h */
#define FLAG_LINK (1u<<20)
#define FLAG_CHECKED (1u<<21)

struct ofs_delta_entry {
  off_t offset;
  int obj_no;
};

struct ref_delta_entry {
  struct object_id oid;
  int obj_no;
};

static struct object_entry *objects;
static struct object_stat *obj_stat;
static struct ofs_delta_entry *ofs_deltas;
static struct ref_delta_entry *ref_deltas;
static struct thread_local nothread_data;
static int nr_objects;
static int nr_ofs_deltas;
static int nr_ref_deltas;
static int ref_deltas_alloc;
static int nr_resolved_deltas;
static int nr_threads;

static int from_stdin;
static int strict;
static int do_fsck_object;
static struct fsck_options fsck_options = FSCK_OPTIONS_MISSING_GITMODULES;
static int verbose;
static const char *progress_title;
static int show_resolving_progress;
static int show_stat;
static int check_self_contained_and_connected;

static struct progress *progress;

/* We always read in 4kB chunks. */
static unsigned char input_buffer[4096];
static unsigned int input_offset, input_len;
static off_t consumed_bytes;
static off_t max_input_size;
static unsigned deepest_delta;
static git_hash_ctx input_ctx;
static uint32_t input_crc32;
static int input_fd, output_fd;
static const char *curr_pack;

static struct thread_local *thread_data;
static int nr_dispatched;
static int threads_active;

static pthread_mutex_t read_mutex;
#define read_lock()   lock_mutex(&read_mutex)
#define read_unlock()   unlock_mutex(&read_mutex)

static pthread_mutex_t counter_mutex;
#define counter_lock()    lock_mutex(&counter_mutex)
#define counter_unlock()  unlock_mutex(&counter_mutex)

static pthread_mutex_t work_mutex;
#define work_lock()   lock_mutex(&work_mutex)
#define work_unlock()   unlock_mutex(&work_mutex)

static pthread_mutex_t deepest_delta_mutex;
#define deepest_delta_lock()  lock_mutex(&deepest_delta_mutex)
#define deepest_delta_unlock()  unlock_mutex(&deepest_delta_mutex)

static pthread_key_t key;

static inline void lock_mutex(pthread_mutex_t *mutex)
{
  if (threads_active)
    pthread_mutex_lock(mutex);
}

static inline void unlock_mutex(pthread_mutex_t *mutex)
{
  if (threads_active)
    pthread_mutex_unlock(mutex);
}

/*
 * Mutex and conditional variable can't be statically-initialized on Windows.
 */
static void init_thread(void)
{
  int i;
  init_recursive_mutex(&read_mutex);
  pthread_mutex_init(&counter_mutex, NULL);
  pthread_mutex_init(&work_mutex, NULL);
  if (show_stat)
    pthread_mutex_init(&deepest_delta_mutex, NULL);
  pthread_key_create(&key, NULL);
  CALLOC_ARRAY(thread_data, nr_threads);
  for (i = 0; i < nr_threads; i++) {
    thread_data[i].pack_fd = xopen(curr_pack, O_RDONLY);
  }

  threads_active = 1;
}

static void cleanup_thread(void)
{
  int i;
  if (!threads_active)
    return;
  threads_active = 0;
  pthread_mutex_destroy(&read_mutex);
  pthread_mutex_destroy(&counter_mutex);
  pthread_mutex_destroy(&work_mutex);
  if (show_stat)
    pthread_mutex_destroy(&deepest_delta_mutex);
  for (i = 0; i < nr_threads; i++)
    close(thread_data[i].pack_fd);
  pthread_key_delete(key);
  free(thread_data);
}

static int mark_link(struct object *obj, enum object_type type,
         void *data UNUSED,
         struct fsck_options *options UNUSED)
{
  if (!obj)
    return -1;

  if (type != OBJ_ANY && obj->type != type)
    die(_("object type mismatch at %s"), oid_to_hex(&obj->oid));

  obj->flags |= FLAG_LINK;
  return 0;
}

/* The content of each linked object must have been checked
   or it must be already present in the object database */
static unsigned check_object(struct object *obj)
{
  if (!obj)
    return 0;

  if (!(obj->flags & FLAG_LINK))
    return 0;

  if (!(obj->flags & FLAG_CHECKED)) {
    unsigned long size;
    int type = oid_object_info(the_repository, &obj->oid, &size);
    if (type <= 0)
      die(_("did not receive expected object %s"),
            oid_to_hex(&obj->oid));
    if (type != obj->type)
      die(_("object %s: expected type %s, found %s"),
          oid_to_hex(&obj->oid),
          type_name(obj->type), type_name(type));
    obj->flags |= FLAG_CHECKED;
    return 1;
  }

  return 0;
}

static unsigned check_objects(void)
{
  unsigned i, max, foreign_nr = 0;

  max = get_max_object_index();

  if (verbose)
    progress = start_delayed_progress(_("Checking objects"), max);

  for (i = 0; i < max; i++) {
    foreign_nr += check_object(get_indexed_object(i));
    display_progress(progress, i + 1);
  }

  stop_progress(&progress);
  return foreign_nr;
}


/* Discard current buffer used content. */
static void flush(void)
{
  if (input_offset) {
    if (output_fd >= 0)
      write_or_die(output_fd, input_buffer, input_offset);
    the_hash_algo->update_fn(&input_ctx, input_buffer, input_offset);
    memmove(input_buffer, input_buffer + input_offset, input_len);
    input_offset = 0;
  }
}

/*
 * Make sure at least "min" bytes are available in the buffer, and
 * return the pointer to the buffer.
 */
static void *fill(int min)
{
  if (min <= input_len)
    return input_buffer + input_offset;
  if (min > sizeof(input_buffer))
    die(Q_("cannot fill %d byte",
           "cannot fill %d bytes",
           min),
        min);
  flush();
  do {
    ssize_t ret = xread(input_fd, input_buffer + input_len,
        sizeof(input_buffer) - input_len);
    if (ret <= 0) {
      if (!ret)
        die(_("early EOF"));
      die_errno(_("read error on input"));
    }
    input_len += ret;
    if (from_stdin)
      display_throughput(progress, consumed_bytes + input_len);
  } while (input_len < min);
  return input_buffer;
}

static void use(int bytes)
{
  if (bytes > input_len)
    die(_("used more bytes than were available"));
  input_crc32 = crc32(input_crc32, input_buffer + input_offset, bytes);
  input_len -= bytes;
  input_offset += bytes;

  /* make sure off_t is sufficiently large not to wrap */
  if (signed_add_overflows(consumed_bytes, bytes))
    die(_("pack too large for current definition of off_t"));
  consumed_bytes += bytes;
  if (max_input_size && consumed_bytes > max_input_size) {
    struct strbuf size_limit = STRBUF_INIT;
    strbuf_humanise_bytes(&size_limit, max_input_size);
    die(_("pack exceeds maximum allowed size (%s)"),
        size_limit.buf);
  }
}

static const char *open_pack_file(const char *pack_name)
{
  if (from_stdin) {
    input_fd = 0;
    if (!pack_name) {
      struct strbuf tmp_file = STRBUF_INIT;
      output_fd = odb_mkstemp(&tmp_file,
            "pack/tmp_pack_XXXXXX");
      pack_name = strbuf_detach(&tmp_file, NULL);
    } else {
      output_fd = xopen(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
    }
    nothread_data.pack_fd = output_fd;
  } else {
    input_fd = xopen(pack_name, O_RDONLY);
    output_fd = -1;
    nothread_data.pack_fd = input_fd;
  }
  the_hash_algo->init_fn(&input_ctx);
  return pack_name;
}

static void parse_pack_header(void)
{
  struct pack_header *hdr = fill(sizeof(struct pack_header));

  /* Header consistency check */
  if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
    die(_("pack signature mismatch"));
  if (!pack_version_ok(hdr->hdr_version))
    die(_("pack version %"PRIu32" unsupported"),
      ntohl(hdr->hdr_version));

  nr_objects = ntohl(hdr->hdr_entries);
  use(sizeof(struct pack_header));
}

__attribute__((format (printf, 2, 3)))
static NORETURN void bad_object(off_t offset, const char *format, ...)
{
  va_list params;
  char buf[1024];

  va_start(params, format);
  vsnprintf(buf, sizeof(buf), format, params);
  va_end(params);
  die(_("pack has bad object at offset %"PRIuMAX": %s"),
      (uintmax_t)offset, buf);
}

static inline struct thread_local *get_thread_data(void)
{
  if (HAVE_THREADS) {
    if (threads_active)
      return pthread_getspecific(key);
    assert(!threads_active &&
           "This should only be reached when all threads are gone");
  }
  return &nothread_data;
}

static void set_thread_data(struct thread_local *data)
{
  if (threads_active)
    pthread_setspecific(key, data);
}

static void free_base_data(struct base_data *c)
{
  if (c->data) {
    FREE_AND_NULL(c->data);
    base_cache_used -= c->size;
  }
}

static void prune_base_data(struct base_data *retain)
{
  struct list_head *pos;

  if (base_cache_used <= base_cache_limit)
    return;

  list_for_each_prev(pos, &done_head) {
    struct base_data *b = list_entry(pos, struct base_data, list);
    if (b->retain_data || b == retain)
      continue;
    if (b->data) {
      free_base_data(b);
      if (base_cache_used <= base_cache_limit)
        return;
    }
  }

  list_for_each_prev(pos, &work_head) {
    struct base_data *b = list_entry(pos, struct base_data, list);
    if (b->retain_data || b == retain)
      continue;
    if (b->data) {
      free_base_data(b);
      if (base_cache_used <= base_cache_limit)
        return;
    }
  }
}

static int is_delta_type(enum object_type type)
{
  return (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA);
}

static void *unpack_entry_data(off_t offset, unsigned long size,
             enum object_type type, struct object_id *oid)
{
  static char fixed_buf[8192];
  int status;
  git_zstream stream;
  void *buf;
  git_hash_ctx c;
  char hdr[32];
  int hdrlen;

  if (!is_delta_type(type)) {
    hdrlen = format_object_header(hdr, sizeof(hdr), type, size);
    the_hash_algo->init_fn(&c);
    the_hash_algo->update_fn(&c, hdr, hdrlen);
  } else
    oid = NULL;
  if (type == OBJ_BLOB && size > big_file_threshold)
    buf = fixed_buf;
  else
    buf = xmallocz(size);

  memset(&stream, 0, sizeof(stream));
  git_inflate_init(&stream);
  stream.next_out = buf;
  stream.avail_out = buf == fixed_buf ? sizeof(fixed_buf) : size;

  do {
    unsigned char *last_out = stream.next_out;
    stream.next_in = fill(1);
    stream.avail_in = input_len;
    status = git_inflate(&stream, 0);
    use(input_len - stream.avail_in);
    if (oid)
      the_hash_algo->update_fn(&c, last_out, stream.next_out - last_out);
    if (buf == fixed_buf) {
      stream.next_out = buf;
      stream.avail_out = sizeof(fixed_buf);
    }
  } while (status == Z_OK);
  if (stream.total_out != size || status != Z_STREAM_END)
    bad_object(offset, _("inflate returned %d"), status);
  git_inflate_end(&stream);
  if (oid)
    the_hash_algo->final_oid_fn(oid, &c);
  return buf == fixed_buf ? NULL : buf;
}

static void *unpack_raw_entry(struct object_entry *obj,
            off_t *ofs_offset,
            struct object_id *ref_oid,
            struct object_id *oid)
{
  unsigned char *p;
  unsigned long size, c;
  off_t base_offset;
  unsigned shift;
  void *data;

  obj->idx.offset = consumed_bytes;
  input_crc32 = crc32(0, NULL, 0);

  p = fill(1);
  c = *p;
  use(1);
  obj->type = (c >> 4) & 7;
  size = (c & 15);
  shift = 4;
  while (c & 0x80) {
    p = fill(1);
    c = *p;
    use(1);
    size += (c & 0x7f) << shift;
    shift += 7;
  }
  obj->size = size;

  switch (obj->type) {
  case OBJ_REF_DELTA:
    oidread(ref_oid, fill(the_hash_algo->rawsz),
      the_repository->hash_algo);
    use(the_hash_algo->rawsz);
    break;
  case OBJ_OFS_DELTA:
    p = fill(1);
    c = *p;
    use(1);
    base_offset = c & 127;
    while (c & 128) {
      base_offset += 1;
      if (!base_offset || MSB(base_offset, 7))
        bad_object(obj->idx.offset, _("offset value overflow for delta base object"));
      p = fill(1);
      c = *p;
      use(1);
      base_offset = (base_offset << 7) + (c & 127);
    }
    *ofs_offset = obj->idx.offset - base_offset;
    if (*ofs_offset <= 0 || *ofs_offset >= obj->idx.offset)
      bad_object(obj->idx.offset, _("delta base offset is out of bound"));
    break;
  case OBJ_COMMIT:
  case OBJ_TREE:
  case OBJ_BLOB:
  case OBJ_TAG:
    break;
  default:
    bad_object(obj->idx.offset, _("unknown object type %d"), obj->type);
  }
  obj->hdr_size = consumed_bytes - obj->idx.offset;

  data = unpack_entry_data(obj->idx.offset, obj->size, obj->type, oid);
  obj->idx.crc32 = input_crc32;
  return data;
}

static void *unpack_data(struct object_entry *obj,
       int (*consume)(const unsigned char *, unsigned long, void *),
       void *cb_data)
{
  off_t from = obj[0].idx.offset + obj[0].hdr_size;
  off_t len = obj[1].idx.offset - from;
  unsigned char *data, *inbuf;
  git_zstream stream;
  int status;

  data = xmallocz(consume ? 64*1024 : obj->size);
  inbuf = xmalloc((len < 64*1024) ? (int)len : 64*1024);

  memset(&stream, 0, sizeof(stream));
  git_inflate_init(&stream);
  stream.next_out = data;
  stream.avail_out = consume ? 64*1024 : obj->size;

  do {
    ssize_t n = (len < 64*1024) ? (ssize_t)len : 64*1024;
    n = xpread(get_thread_data()->pack_fd, inbuf, n, from);
    if (n < 0)
      die_errno(_("cannot pread pack file"));
    if (!n)
      die(Q_("premature end of pack file, %"PRIuMAX" byte missing",
             "premature end of pack file, %"PRIuMAX" bytes missing",
             len),
          (uintmax_t)len);
    from += n;
    len -= n;
    stream.next_in = inbuf;
    stream.avail_in = n;
    if (!consume)
      status = git_inflate(&stream, 0);
    else {
      do {
        status = git_inflate(&stream, 0);
        if (consume(data, stream.next_out - data, cb_data)) {
          free(inbuf);
          free(data);
          return NULL;
        }
        stream.next_out = data;
        stream.avail_out = 64*1024;
      } while (status == Z_OK && stream.avail_in);
    }
  } while (len && status == Z_OK && !stream.avail_in);

  /* This has been inflated OK when first encountered, so... */
  if (status != Z_STREAM_END || stream.total_out != obj->size)
    die(_("serious inflate inconsistency"));

  git_inflate_end(&stream);
  free(inbuf);
  if (consume) {
    FREE_AND_NULL(data);
  }
  return data;
}

static void *get_data_from_pack(struct object_entry *obj)
{
  return unpack_data(obj, NULL, NULL);
}

static int compare_ofs_delta_bases(off_t offset1, off_t offset2,
           enum object_type type1,
           enum object_type type2)
{
  int cmp = type1 - type2;
  if (cmp)
    return cmp;
  return offset1 < offset2 ? -1 :
         offset1 > offset2 ?  1 :
         0;
}

static int find_ofs_delta(const off_t offset)
{
  int first = 0, last = nr_ofs_deltas;

  while (first < last) {
    int next = first + (last - first) / 2;
    struct ofs_delta_entry *delta = &ofs_deltas[next];
    int cmp;

    cmp = compare_ofs_delta_bases(offset, delta->offset,
                OBJ_OFS_DELTA,
                objects[delta->obj_no].type);
    if (!cmp)
      return next;
    if (cmp < 0) {
      last = next;
      continue;
    }
    first = next+1;
  }
  return -first-1;
}

static void find_ofs_delta_children(off_t offset,
            int *first_index, int *last_index)
{
  int first = find_ofs_delta(offset);
  int last = first;
  int end = nr_ofs_deltas - 1;

  if (first < 0) {
    *first_index = 0;
    *last_index = -1;
    return;
  }
  while (first > 0 && ofs_deltas[first - 1].offset == offset)
    --first;
  while (last < end && ofs_deltas[last + 1].offset == offset)
    ++last;
  *first_index = first;
  *last_index = last;
}

static int compare_ref_delta_bases(const struct object_id *oid1,
           const struct object_id *oid2,
           enum object_type type1,
           enum object_type type2)
{
  int cmp = type1 - type2;
  if (cmp)
    return cmp;
  return oidcmp(oid1, oid2);
}

static int find_ref_delta(const struct object_id *oid)
{
  int first = 0, last = nr_ref_deltas;

  while (first < last) {
    int next = first + (last - first) / 2;
    struct ref_delta_entry *delta = &ref_deltas[next];
    int cmp;

    cmp = compare_ref_delta_bases(oid, &delta->oid,
                OBJ_REF_DELTA,
                objects[delta->obj_no].type);
    if (!cmp)
      return next;
    if (cmp < 0) {
      last = next;
      continue;
    }
    first = next+1;
  }
  return -first-1;
}

static void find_ref_delta_children(const struct object_id *oid,
            int *first_index, int *last_index)
{
  int first = find_ref_delta(oid);
  int last = first;
  int end = nr_ref_deltas - 1;

  if (first < 0) {
    *first_index = 0;
    *last_index = -1;
    return;
  }
  while (first > 0 && oideq(&ref_deltas[first - 1].oid, oid))
    --first;
  while (last < end && oideq(&ref_deltas[last + 1].oid, oid))
    ++last;
  *first_index = first;
  *last_index = last;
}

struct compare_data {
  struct object_entry *entry;
  struct git_istream *st;
  unsigned char *buf;
  unsigned long buf_size;
};

static int compare_objects(const unsigned char *buf, unsigned long size,
         void *cb_data)
{
  struct compare_data *data = cb_data;

  if (data->buf_size < size) {
    free(data->buf);
    data->buf = xmalloc(size);
    data->buf_size = size;
  }

  while (size) {
    ssize_t len = read_istream(data->st, data->buf, size);
    if (len == 0)
      die(_("SHA1 COLLISION FOUND WITH %s !"),
          oid_to_hex(&data->entry->idx.oid));
    if (len < 0)
      die(_("unable to read %s"),
          oid_to_hex(&data->entry->idx.oid));
    if (memcmp(buf, data->buf, len))
      die(_("SHA1 COLLISION FOUND WITH %s !"),
          oid_to_hex(&data->entry->idx.oid));
    size -= len;
    buf += len;
  }
  return 0;
}

static int check_collison(struct object_entry *entry)
{
  struct compare_data data;
  enum object_type type;
  unsigned long size;

  if (entry->size <= big_file_threshold || entry->type != OBJ_BLOB)
    return -1;

  memset(&data, 0, sizeof(data));
  data.entry = entry;
  data.st = open_istream(the_repository, &entry->idx.oid, &type, &size,
             NULL);
  if (!data.st)
    return -1;
  if (size != entry->size || type != entry->type)
    die(_("SHA1 COLLISION FOUND WITH %s !"),
        oid_to_hex(&entry->idx.oid));
  unpack_data(entry, compare_objects, &data);
  close_istream(data.st);
  free(data.buf);
  return 0;
}

static void sha1_object(const void *data, struct object_entry *obj_entry,
      unsigned long size, enum object_type type,
      const struct object_id *oid)
{
  void *new_data = NULL;
  int collision_test_needed = 0;

  assert(data || obj_entry);

  if (startup_info->have_repository) {
    read_lock();
    collision_test_needed =
      repo_has_object_file_with_flags(the_repository, oid,
              OBJECT_INFO_QUICK);
    read_unlock();
  }

  if (collision_test_needed && !data) {
    read_lock();
    if (!check_collison(obj_entry))
      collision_test_needed = 0;
    read_unlock();
  }
  if (collision_test_needed) {
    void *has_data;
    enum object_type has_type;
    unsigned long has_size;
    read_lock();
    has_type = oid_object_info(the_repository, oid, &has_size);
    if (has_type < 0)
      die(_("cannot read existing object info %s"), oid_to_hex(oid));
    if (has_type != type || has_size != size)
      die(_("SHA1 COLLISION FOUND WITH %s !"), oid_to_hex(oid));
    has_data = repo_read_object_file(the_repository, oid,
             &has_type, &has_size);
    read_unlock();
    if (!data)
      data = new_data = get_data_from_pack(obj_entry);
    if (!has_data)
      die(_("cannot read existing object %s"), oid_to_hex(oid));
    if (size != has_size || type != has_type ||
        memcmp(data, has_data, size) != 0)
      die(_("SHA1 COLLISION FOUND WITH %s !"), oid_to_hex(oid));
    free(has_data);
  }

  if (strict || do_fsck_object) {
    read_lock();
    if (type == OBJ_BLOB) {
      struct blob *blob = lookup_blob(the_repository, oid);
      if (blob)
        blob->object.flags |= FLAG_CHECKED;
      else
        die(_("invalid blob object %s"), oid_to_hex(oid));
      if (do_fsck_object &&
          fsck_object(&blob->object, (void *)data, size, &fsck_options))
        die(_("fsck error in packed object"));
    } else {
      struct object *obj;
      int eaten;
      void *buf = (void *) data;

      assert(data && "data can only be NULL for large _blobs_");

      /*
       * we do not need to free the memory here, as the
       * buf is deleted by the caller.
       */
      obj = parse_object_buffer(the_repository, oid, type,
              size, buf,
              &eaten);
      if (!obj)
        die(_("invalid %s"), type_name(type));
      if (do_fsck_object &&
          fsck_object(obj, buf, size, &fsck_options))
        die(_("fsck error in packed object"));
      if (strict && fsck_walk(obj, NULL, &fsck_options))
        die(_("Not all child objects of %s are reachable"), oid_to_hex(&obj->oid));

      if (obj->type == OBJ_TREE) {
        struct tree *item = (struct tree *) obj;
        item->buffer = NULL;
        obj->parsed = 0;
      }
      if (obj->type == OBJ_COMMIT) {
        struct commit *commit = (struct commit *) obj;
        if (detach_commit_buffer(commit, NULL) != data)
          BUG("parse_object_buffer transmogrified our buffer");
      }
      obj->flags |= FLAG_CHECKED;
    }
    read_unlock();
  }

  free(new_data);
}

/*
 * Ensure that this node has been reconstructed and return its contents.
 *
 * In the typical and best case, this node would already be reconstructed
 * (through the invocation to resolve_delta() in threaded_second_pass()) and it
 * would not be pruned. However, if pruning of this node was necessary due to
 * reaching delta_base_cache_limit, this function will find the closest
 * ancestor with reconstructed data that has not been pruned (or if there is
 * none, the ultimate base object), and reconstruct each node in the delta
 * chain in order to generate the reconstructed data for this node.
 */
static void *get_base_data(struct base_data *c)
{
  if (!c->data) {
    struct object_entry *obj = c->obj;
    struct base_data **delta = NULL;
    int delta_nr = 0, delta_alloc = 0;

    while (is_delta_type(c->obj->type) && !c->data) {
      ALLOC_GROW(delta, delta_nr + 1, delta_alloc);
      delta[delta_nr++] = c;
      c = c->base;
    }
    if (!delta_nr) {
      c->data = get_data_from_pack(obj);
      c->size = obj->size;
      base_cache_used += c->size;
      prune_base_data(c);
    }
    for (; delta_nr > 0; delta_nr--) {
      void *base, *raw;
      c = delta[delta_nr - 1];
      obj = c->obj;
      base = get_base_data(c->base);
      raw = get_data_from_pack(obj);
      c->data = patch_delta(
        base, c->base->size,
        raw, obj->size,
        &c->size);
      free(raw);
      if (!c->data)
        bad_object(obj->idx.offset, _("failed to apply delta"));
      base_cache_used += c->size;
      prune_base_data(c);
    }
    free(delta);
  }
  return c->data;
}

static struct base_data *make_base(struct object_entry *obj,
           struct base_data *parent)
{
  struct base_data *base = xcalloc(1, sizeof(struct base_data));
  base->base = parent;
  base->obj = obj;
  find_ref_delta_children(&obj->idx.oid,
        &base->ref_first, &base->ref_last);
  find_ofs_delta_children(obj->idx.offset,
        &base->ofs_first, &base->ofs_last);
  base->children_remaining = base->ref_last - base->ref_first +
    base->ofs_last - base->ofs_first + 2;
  return base;
}

static struct base_data *resolve_delta(struct object_entry *delta_obj,
               struct base_data *base)
{
  void *delta_data, *result_data;
  struct base_data *result;
  unsigned long result_size;

  if (show_stat) {
    int i = delta_obj - objects;
    int j = base->obj - objects;
    obj_stat[i].delta_depth = obj_stat[j].delta_depth + 1;
    deepest_delta_lock();
    if (deepest_delta < obj_stat[i].delta_depth)
      deepest_delta = obj_stat[i].delta_depth;
    deepest_delta_unlock();
    obj_stat[i].base_object_no = j;
  }
  delta_data = get_data_from_pack(delta_obj);
  assert(base->data);
  result_data = patch_delta(base->data, base->size,
          delta_data, delta_obj->size, &result_size);
  free(delta_data);
  if (!result_data)
    bad_object(delta_obj->idx.offset, _("failed to apply delta"));
  hash_object_file(the_hash_algo, result_data, result_size,
       delta_obj->real_type, &delta_obj->idx.oid);
  sha1_object(result_data, NULL, result_size, delta_obj->real_type,
        &delta_obj->idx.oid);

  result = make_base(delta_obj, base);
  result->data = result_data;
  result->size = result_size;

  counter_lock();
  nr_resolved_deltas++;
  counter_unlock();

  return result;
}

static int compare_ofs_delta_entry(const void *a, const void *b)
{
  const struct ofs_delta_entry *delta_a = a;
  const struct ofs_delta_entry *delta_b = b;

  return delta_a->offset < delta_b->offset ? -1 :
         delta_a->offset > delta_b->offset ?  1 :
         0;
}

static int compare_ref_delta_entry(const void *a, const void *b)
{
  const struct ref_delta_entry *delta_a = a;
  const struct ref_delta_entry *delta_b = b;

  return oidcmp(&delta_a->oid, &delta_b->oid);
}

static void *threaded_second_pass(void *data)
{
  if (data)
    set_thread_data(data);
  for (;;) {
    struct base_data *parent = NULL;
    struct object_entry *child_obj;
    struct base_data *child;

    counter_lock();
    display_progress(progress, nr_resolved_deltas);
    counter_unlock();

    work_lock();
    if (list_empty(&work_head)) {
      /*
       * Take an object from the object array.
       */
      while (nr_dispatched < nr_objects &&
             is_delta_type(objects[nr_dispatched].type))
        nr_dispatched++;
      if (nr_dispatched >= nr_objects) {
        work_unlock();
        break;
      }
      child_obj = &objects[nr_dispatched++];
    } else {
      /*
       * Peek at the top of the stack, and take a child from
       * it.
       */
      parent = list_first_entry(&work_head, struct base_data,
              list);

      if (parent->ref_first <= parent->ref_last) {
        int offset = ref_deltas[parent->ref_first++].obj_no;
        child_obj = objects + offset;
        if (child_obj->real_type != OBJ_REF_DELTA)
          die("REF_DELTA at offset %"PRIuMAX" already resolved (duplicate base %s?)",
              (uintmax_t) child_obj->idx.offset,
              oid_to_hex(&parent->obj->idx.oid));
        child_obj->real_type = parent->obj->real_type;
      } else {
        child_obj = objects +
          ofs_deltas[parent->ofs_first++].obj_no;
        assert(child_obj->real_type == OBJ_OFS_DELTA);
        child_obj->real_type = parent->obj->real_type;
      }

      if (parent->ref_first > parent->ref_last &&
          parent->ofs_first > parent->ofs_last) {
        /*
         * This parent has run out of children, so move
         * it to done_head.
         */
        list_del(&parent->list);
        list_add(&parent->list, &done_head);
      }

      /*
       * Ensure that the parent has data, since we will need
       * it later.
       *
       * NEEDSWORK: If parent data needs to be reloaded, this
       * prolongs the time that the current thread spends in
       * the mutex. A mitigating factor is that parent data
       * needs to be reloaded only if the delta base cache
       * limit is exceeded, so in the typical case, this does
       * not happen.
       */
      get_base_data(parent);
      parent->retain_data++;
    }
    work_unlock();

    if (parent) {
      child = resolve_delta(child_obj, parent);
      if (!child->children_remaining)
        FREE_AND_NULL(child->data);
    } else {
      child = make_base(child_obj, NULL);
      if (child->children_remaining) {
        /*
         * Since this child has its own delta children,
         * we will need this data in the future.
         * Inflate now so that future iterations will
         * have access to this object's data while
         * outside the work mutex.
         */
        child->data = get_data_from_pack(child_obj);
        child->size = child_obj->size;
      }
    }

    work_lock();
    if (parent)
      parent->retain_data--;
    if (child->data) {
      /*
       * This child has its own children, so add it to
       * work_head.
       */
      list_add(&child->list, &work_head);
      base_cache_used += child->size;
      prune_base_data(NULL);
      free_base_data(child);
    } else {
      /*
       * This child does not have its own children. It may be
       * the last descendant of its ancestors; free those
       * that we can.
       */
      struct base_data *p = parent;

      while (p) {
        struct base_data *next_p;

        p->children_remaining--;
        if (p->children_remaining)
          break;

        next_p = p->base;
        free_base_data(p);
        list_del(&p->list);
        free(p);

        p = next_p;
      }
      FREE_AND_NULL(child);
    }
    work_unlock();
  }
  return NULL;
}

/*
 * First pass:
 * - find locations of all objects;
 * - calculate SHA1 of all non-delta objects;
 * - remember base (SHA1 or offset) for all deltas.
 */
static void parse_pack_objects(unsigned char *hash)
{
  int i, nr_delays = 0;
  struct ofs_delta_entry *ofs_delta = ofs_deltas;
  struct object_id ref_delta_oid;
  struct stat st;
  git_hash_ctx tmp_ctx;

  if (verbose)
    progress = start_progress(
        progress_title ? progress_title :
        from_stdin ? _("Receiving objects") : _("Indexing objects"),
        nr_objects);
  for (i = 0; i < nr_objects; i++) {
    struct object_entry *obj = &objects[i];
    void *data = unpack_raw_entry(obj, &ofs_delta->offset,
                &ref_delta_oid,
                &obj->idx.oid);
    obj->real_type = obj->type;
    if (obj->type == OBJ_OFS_DELTA) {
      nr_ofs_deltas++;
      ofs_delta->obj_no = i;
      ofs_delta++;
    } else if (obj->type == OBJ_REF_DELTA) {
      ALLOC_GROW(ref_deltas, nr_ref_deltas + 1, ref_deltas_alloc);
      oidcpy(&ref_deltas[nr_ref_deltas].oid, &ref_delta_oid);
      ref_deltas[nr_ref_deltas].obj_no = i;
      nr_ref_deltas++;
    } else if (!data) {
      /* large blobs, check later */
      obj->real_type = OBJ_BAD;
      nr_delays++;
    } else
      sha1_object(data, NULL, obj->size, obj->type,
            &obj->idx.oid);
    free(data);
    display_progress(progress, i+1);
  }
  objects[i].idx.offset = consumed_bytes;
  stop_progress(&progress);

  /* Check pack integrity */
  flush();
  the_hash_algo->init_fn(&tmp_ctx);
  the_hash_algo->clone_fn(&tmp_ctx, &input_ctx);
  the_hash_algo->final_fn(hash, &tmp_ctx);
  if (!hasheq(fill(the_hash_algo->rawsz), hash, the_repository->hash_algo))
    die(_("pack is corrupted (SHA1 mismatch)"));
  use(the_hash_algo->rawsz);

  /* If input_fd is a file, we should have reached its end now. */
  if (fstat(input_fd, &st))
    die_errno(_("cannot fstat packfile"));
  if (S_ISREG(st.st_mode) &&
      lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
    die(_("pack has junk at the end"));

  for (i = 0; i < nr_objects; i++) {
    struct object_entry *obj = &objects[i];
    if (obj->real_type != OBJ_BAD)
      continue;
    obj->real_type = obj->type;
    sha1_object(NULL, obj, obj->size, obj->type,
          &obj->idx.oid);
    nr_delays--;
  }
  if (nr_delays)
    die(_("confusion beyond insanity in parse_pack_objects()"));
}

/*
 * Second pass:
 * - for all non-delta objects, look if it is used as a base for
 *   deltas;
 * - if used as a base, uncompress the object and apply all deltas,
 *   recursively checking if the resulting object is used as a base
 *   for some more deltas.
 */
static void resolve_deltas(void)
{
  int i;

  if (!nr_ofs_deltas && !nr_ref_deltas)
    return;

  /* Sort deltas by base SHA1/offset for fast searching */
  QSORT(ofs_deltas, nr_ofs_deltas, compare_ofs_delta_entry);
  QSORT(ref_deltas, nr_ref_deltas, compare_ref_delta_entry);

  if (verbose || show_resolving_progress)
    progress = start_progress(_("Resolving deltas"),
            nr_ref_deltas + nr_ofs_deltas);

  nr_dispatched = 0;
  base_cache_limit = delta_base_cache_limit * nr_threads;
  if (nr_threads > 1 || getenv("GIT_FORCE_THREADS")) {
    init_thread();
    work_lock();
    for (i = 0; i < nr_threads; i++) {
      int ret = pthread_create(&thread_data[i].thread, NULL,
             threaded_second_pass, thread_data + i);
      if (ret)
        die(_("unable to create thread: %s"),
            strerror(ret));
    }
    work_unlock();
    for (i = 0; i < nr_threads; i++)
      pthread_join(thread_data[i].thread, NULL);
    cleanup_thread();
    return;
  }
  threaded_second_pass(&nothread_data);
}

/*
 * Third pass:
 * - append objects to convert thin pack to full pack if required
 * - write the final pack hash
 */
static void fix_unresolved_deltas(struct hashfile *f);
static void conclude_pack(int fix_thin_pack, const char *curr_pack, unsigned char *pack_hash)
{
  if (nr_ref_deltas + nr_ofs_deltas == nr_resolved_deltas) {
    stop_progress(&progress);
    /* Flush remaining pack final hash. */
    flush();
    return;
  }

  if (fix_thin_pack) {
    struct hashfile *f;
    unsigned char read_hash[GIT_MAX_RAWSZ], tail_hash[GIT_MAX_RAWSZ];
    struct strbuf msg = STRBUF_INIT;
    int nr_unresolved = nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas;
    int nr_objects_initial = nr_objects;
    if (nr_unresolved <= 0)
      die(_("confusion beyond insanity"));
    REALLOC_ARRAY(objects, nr_objects + nr_unresolved + 1);
    memset(objects + nr_objects + 1, 0,
           nr_unresolved * sizeof(*objects));
    f = hashfd(output_fd, curr_pack);
    fix_unresolved_deltas(f);
    strbuf_addf(&msg, Q_("completed with %d local object",
             "completed with %d local objects",
             nr_objects - nr_objects_initial),
          nr_objects - nr_objects_initial);
    stop_progress_msg(&progress, msg.buf);
    strbuf_release(&msg);
    finalize_hashfile(f, tail_hash, FSYNC_COMPONENT_PACK, 0);
    hashcpy(read_hash, pack_hash, the_repository->hash_algo);
    fixup_pack_header_footer(output_fd, pack_hash,
           curr_pack, nr_objects,
           read_hash, consumed_bytes-the_hash_algo->rawsz);
    if (!hasheq(read_hash, tail_hash, the_repository->hash_algo))
      die(_("Unexpected tail checksum for %s "
            "(disk corruption?)"), curr_pack);
  }
  if (nr_ofs_deltas + nr_ref_deltas != nr_resolved_deltas)
    die(Q_("pack has %d unresolved delta",
           "pack has %d unresolved deltas",
           nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas),
        nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas);
}

static int write_compressed(struct hashfile *f, void *in, unsigned int size)
{
  git_zstream stream;
  int status;
  unsigned char outbuf[4096];

  git_deflate_init(&stream, zlib_compression_level);
  stream.next_in = in;
  stream.avail_in = size;

  do {
    stream.next_out = outbuf;
    stream.avail_out = sizeof(outbuf);
    status = git_deflate(&stream, Z_FINISH);
    hashwrite(f, outbuf, sizeof(outbuf) - stream.avail_out);
  } while (status == Z_OK);

  if (status != Z_STREAM_END)
    die(_("unable to deflate appended object (%d)"), status);
  size = stream.total_out;
  git_deflate_end(&stream);
  return size;
}

static struct object_entry *append_obj_to_pack(struct hashfile *f,
             const unsigned char *sha1, void *buf,
             unsigned long size, enum object_type type)
{
  struct object_entry *obj = &objects[nr_objects++];
  unsigned char header[10];
  unsigned long s = size;
  int n = 0;
  unsigned char c = (type << 4) | (s & 15);
  s >>= 4;
  while (s) {
    header[n++] = c | 0x80;
    c = s & 0x7f;
    s >>= 7;
  }
  header[n++] = c;
  crc32_begin(f);
  hashwrite(f, header, n);
  obj[0].size = size;
  obj[0].hdr_size = n;
  obj[0].type = type;
  obj[0].real_type = type;
  obj[1].idx.offset = obj[0].idx.offset + n;
  obj[1].idx.offset += write_compressed(f, buf, size);
  obj[0].idx.crc32 = crc32_end(f);
  hashflush(f);
  oidread(&obj->idx.oid, sha1, the_repository->hash_algo);
  return obj;
}

static int delta_pos_compare(const void *_a, const void *_b)
{
  struct ref_delta_entry *a = *(struct ref_delta_entry **)_a;
  struct ref_delta_entry *b = *(struct ref_delta_entry **)_b;
  return a->obj_no - b->obj_no;
}

static void fix_unresolved_deltas(struct hashfile *f)
{
  struct ref_delta_entry **sorted_by_pos;
  int i;

  /*
   * Since many unresolved deltas may well be themselves base objects
   * for more unresolved deltas, we really want to include the
   * smallest number of base objects that would cover as much delta
   * as possible by picking the
   * trunc deltas first, allowing for other deltas to resolve without
   * additional base objects.  Since most base objects are to be found
   * before deltas depending on them, a good heuristic is to start
   * resolving deltas in the same order as their position in the pack.
   */
  ALLOC_ARRAY(sorted_by_pos, nr_ref_deltas);
  for (i = 0; i < nr_ref_deltas; i++)
    sorted_by_pos[i] = &ref_deltas[i];
  QSORT(sorted_by_pos, nr_ref_deltas, delta_pos_compare);

  if (repo_has_promisor_remote(the_repository)) {
    /*
     * Prefetch the delta bases.
     */
    struct oid_array to_fetch = OID_ARRAY_INIT;
    for (i = 0; i < nr_ref_deltas; i++) {
      struct ref_delta_entry *d = sorted_by_pos[i];
      if (!oid_object_info_extended(the_repository, &d->oid,
                  NULL,
                  OBJECT_INFO_FOR_PREFETCH))
        continue;
      oid_array_append(&to_fetch, &d->oid);
    }
    promisor_remote_get_direct(the_repository,
             to_fetch.oid, to_fetch.nr);
    oid_array_clear(&to_fetch);
  }

  for (i = 0; i < nr_ref_deltas; i++) {
    struct ref_delta_entry *d = sorted_by_pos[i];
    enum object_type type;
    void *data;
    unsigned long size;

    if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
      continue;
    data = repo_read_object_file(the_repository, &d->oid, &type,
               &size);
    if (!data)
      continue;

    if (check_object_signature(the_repository, &d->oid, data, size,
             type) < 0)
      die(_("local object %s is corrupt"), oid_to_hex(&d->oid));

    /*
     * Add this as an object to the objects array and call
     * threaded_second_pass() (which will pick up the added
     * object).
     */
    append_obj_to_pack(f, d->oid.hash, data, size, type);
    free(data);
    threaded_second_pass(NULL);

    display_progress(progress, nr_resolved_deltas);
  }
  free(sorted_by_pos);
}

static const char *derive_filename(const char *pack_name, const char *strip,
           const char *suffix, struct strbuf *buf)
{
  size_t len;
  if (!strip_suffix(pack_name, strip, &len) || !len ||
      pack_name[len - 1] != '.')
    die(_("packfile name '%s' does not end with '.%s'"),
        pack_name, strip);
  strbuf_add(buf, pack_name, len);
  strbuf_addstr(buf, suffix);
  return buf->buf;
}

static void write_special_file(const char *suffix, const char *msg,
             const char *pack_name, const unsigned char *hash,
             const char **report)
{
  struct strbuf name_buf = STRBUF_INIT;
  const char *filename;
  int fd;
  int msg_len = strlen(msg);

  if (pack_name)
    filename = derive_filename(pack_name, "pack", suffix, &name_buf);
  else
    filename = odb_pack_name(&name_buf, hash, suffix);

  fd = odb_pack_keep(filename);
  if (fd < 0) {
    if (errno != EEXIST)
      die_errno(_("cannot write %s file '%s'"),
          suffix, filename);
  } else {
    if (msg_len > 0) {
      write_or_die(fd, msg, msg_len);
      write_or_die(fd, "\n", 1);
    }
    if (close(fd) != 0)
      die_errno(_("cannot close written %s file '%s'"),
          suffix, filename);
    if (report)
      *report = suffix;
  }
  strbuf_release(&name_buf);
}

static void rename_tmp_packfile(const char **final_name,
        const char *curr_name,
        struct strbuf *name, unsigned char *hash,
        const char *ext, int make_read_only_if_same)
{
  if (*final_name != curr_name) {
    if (!*final_name)
      *final_name = odb_pack_name(name, hash, ext);
    if (finalize_object_file(curr_name, *final_name))
      die(_("unable to rename temporary '*.%s' file to '%s'"),
          ext, *final_name);
  } else if (make_read_only_if_same) {
    chmod(*final_name, 0444);
  }
}

static void final(const char *final_pack_name, const char *curr_pack_name,
      const char *final_index_name, const char *curr_index_name,
      const char *final_rev_index_name, const char *curr_rev_index_name,
      const char *keep_msg, const char *promisor_msg,
      unsigned char *hash)
{
  const char *report = "pack";
  struct strbuf pack_name = STRBUF_INIT;
  struct strbuf index_name = STRBUF_INIT;
  struct strbuf rev_index_name = STRBUF_INIT;

  if (!from_stdin) {
    close(input_fd);
  } else {
    fsync_component_or_die(FSYNC_COMPONENT_PACK, output_fd, curr_pack_name);
    if (close(output_fd))
      die_errno(_("error while closing pack file"));
  }

  if (keep_msg)
    write_special_file("keep", keep_msg, final_pack_name, hash,
           &report);
  if (promisor_msg)
    write_special_file("promisor", promisor_msg, final_pack_name,
           hash, NULL);

  rename_tmp_packfile(&final_pack_name, curr_pack_name, &pack_name,
          hash, "pack", from_stdin);
  if (curr_rev_index_name)
    rename_tmp_packfile(&final_rev_index_name, curr_rev_index_name,
            &rev_index_name, hash, "rev", 1);
  rename_tmp_packfile(&final_index_name, curr_index_name, &index_name,
          hash, "idx", 1);

  if (do_fsck_object) {
    struct packed_git *p;
    p = add_packed_git(final_index_name, strlen(final_index_name), 0);
    if (p)
      install_packed_git(the_repository, p);
  }

  if (!from_stdin) {
    printf("%s\n", hash_to_hex(hash));
  } else {
    struct strbuf buf = STRBUF_INIT;

    strbuf_addf(&buf, "%s\t%s\n", report, hash_to_hex(hash));
    write_or_die(1, buf.buf, buf.len);
    strbuf_release(&buf);

    /* Write the last part of the buffer to stdout */
    write_in_full(1, input_buffer + input_offset, input_len);
  }

  strbuf_release(&rev_index_name);
  strbuf_release(&index_name);
  strbuf_release(&pack_name);
}

static int git_index_pack_config(const char *k, const char *v,
         const struct config_context *ctx, void *cb)
{
  struct pack_idx_option *opts = cb;

  if (!strcmp(k, "pack.indexversion")) {
    opts->version = git_config_int(k, v, ctx->kvi);
    if (opts->version > 2)
      die(_("bad pack.indexVersion=%"PRIu32), opts->version);
    return 0;
  }
  if (!strcmp(k, "pack.threads")) {
    nr_threads = git_config_int(k, v, ctx->kvi);
    if (nr_threads < 0)
      die(_("invalid number of threads specified (%d)"),
          nr_threads);
    if (!HAVE_THREADS && nr_threads != 1) {
      warning(_("no threads support, ignoring %s"), k);
      nr_threads = 1;
    }
    return 0;
  }
  if (!strcmp(k, "pack.writereverseindex")) {
    if (git_config_bool(k, v))
      opts->flags |= WRITE_REV;
    else
      opts->flags &= ~WRITE_REV;
  }
  return git_default_config(k, v, ctx, cb);
}

static int cmp_uint32(const void *a_, const void *b_)
{
  uint32_t a = *((uint32_t *)a_);
  uint32_t b = *((uint32_t *)b_);

  return (a < b) ? -1 : (a != b);
}

static void read_v2_anomalous_offsets(struct packed_git *p,
              struct pack_idx_option *opts)
{
  const uint32_t *idx1, *idx2;
  uint32_t i;

  /* The address of the 4-byte offset table */
  idx1 = (((const uint32_t *)((const uint8_t *)p->index_data + p->crc_offset))
    + (size_t)p->num_objects /* CRC32 table */
    );

  /* The address of the 8-byte offset table */
  idx2 = idx1 + p->num_objects;

  for (i = 0; i < p->num_objects; i++) {
    uint32_t off = ntohl(idx1[i]);
    if (!(off & 0x80000000))
      continue;
    off = off & 0x7fffffff;
    check_pack_index_ptr(p, &idx2[off * 2]);
    if (idx2[off * 2])
      continue;
    /*
     * The real offset is ntohl(idx2[off * 2]) in high 4
     * octets, and ntohl(idx2[off * 2 + 1]) in low 4
     * octets.  But idx2[off * 2] is Zero!!!
     */
    ALLOC_GROW(opts->anomaly, opts->anomaly_nr + 1, opts->anomaly_alloc);
    opts->anomaly[opts->anomaly_nr++] = ntohl(idx2[off * 2 + 1]);
  }

  QSORT(opts->anomaly, opts->anomaly_nr, cmp_uint32);
}

static void read_idx_option(struct pack_idx_option *opts, const char *pack_name)
{
  struct packed_git *p = add_packed_git(pack_name, strlen(pack_name), 1);

  if (!p)
    die(_("Cannot open existing pack file '%s'"), pack_name);
  if (open_pack_index(p))
    die(_("Cannot open existing pack idx file for '%s'"), pack_name);

  /* Read the attributes from the existing idx file */
  opts->version = p->index_version;

  if (opts->version == 2)
    read_v2_anomalous_offsets(p, opts);

  /*
   * Get rid of the idx file as we do not need it anymore.
   * NEEDSWORK: extract this bit from free_pack_by_name() in
   * object-file.c, perhaps?  It shouldn't matter very much as we
   * know we haven't installed this pack (hence we never have
   * read anything from it).
   */
  close_pack_index(p);
  free(p);
}

static void show_pack_info(int stat_only)
{
  int i, baseobjects = nr_objects - nr_ref_deltas - nr_ofs_deltas;
  unsigned long *chain_histogram = NULL;

  if (deepest_delta)
    CALLOC_ARRAY(chain_histogram, deepest_delta);

  for (i = 0; i < nr_objects; i++) {
    struct object_entry *obj = &objects[i];

    if (is_delta_type(obj->type))
      chain_histogram[obj_stat[i].delta_depth - 1]++;
    if (stat_only)
      continue;
    printf("%s %-6s %"PRIuMAX" %"PRIuMAX" %"PRIuMAX,
           oid_to_hex(&obj->idx.oid),
           type_name(obj->real_type), (uintmax_t)obj->size,
           (uintmax_t)(obj[1].idx.offset - obj->idx.offset),
           (uintmax_t)obj->idx.offset);
    if (is_delta_type(obj->type)) {
      struct object_entry *bobj = &objects[obj_stat[i].base_object_no];
      printf(" %u %s", obj_stat[i].delta_depth,
             oid_to_hex(&bobj->idx.oid));
    }
    putchar('\n');
  }

  if (baseobjects)
    printf_ln(Q_("non delta: %d object",
           "non delta: %d objects",
           baseobjects),
        baseobjects);
  for (i = 0; i < deepest_delta; i++) {
    if (!chain_histogram[i])
      continue;
    printf_ln(Q_("chain length = %d: %lu object",
           "chain length = %d: %lu objects",
           chain_histogram[i]),
        i + 1,
        chain_histogram[i]);
  }
  free(chain_histogram);
}

int cmd_index_pack(int argc, const char **argv, const char *prefix)
{
  int i, fix_thin_pack = 0, verify = 0, stat_only = 0, rev_index;
  const char *curr_index;
  const char *curr_rev_index = NULL;
  const char *index_name = NULL, *pack_name = NULL, *rev_index_name = NULL;
  const char *keep_msg = NULL;
  const char *promisor_msg = NULL;
  struct strbuf index_name_buf = STRBUF_INIT;
  struct strbuf rev_index_name_buf = STRBUF_INIT;
  struct pack_idx_entry **idx_objects;
  struct pack_idx_option opts;
  unsigned char pack_hash[GIT_MAX_RAWSZ];
  unsigned foreign_nr = 1;  /* zero is a "good" value, assume bad */
  int report_end_of_input = 0;
  int hash_algo = 0;

  /*
   * index-pack never needs to fetch missing objects except when
   * REF_DELTA bases are missing (which are explicitly handled). It only
   * accesses the repo to do hash collision checks and to check which
   * REF_DELTA bases need to be fetched.
   */
  fetch_if_missing = 0;

  if (argc == 2 && !strcmp(argv[1], "-h"))
    usage(index_pack_usage);

  disable_replace_refs();
  fsck_options.walk = mark_link;

  reset_pack_idx_option(&opts);
  opts.flags |= WRITE_REV;
  git_config(git_index_pack_config, &opts);
  if (prefix && chdir(prefix))
    die(_("Cannot come back to cwd"));

  if (git_env_bool(GIT_TEST_NO_WRITE_REV_INDEX, 0))
    rev_index = 0;
  else
    rev_index = !!(opts.flags & (WRITE_REV_VERIFY | WRITE_REV));

  for (i = 1; i < argc; i++) {
    const char *arg = argv[i];

    if (*arg == '-') {
      if (!strcmp(arg, "--stdin")) {
        from_stdin = 1;
      } else if (!strcmp(arg, "--fix-thin")) {
        fix_thin_pack = 1;
      } else if (skip_to_optional_arg(arg, "--strict", &arg)) {
        strict = 1;
        do_fsck_object = 1;
        fsck_set_msg_types(&fsck_options, arg);
      } else if (!strcmp(arg, "--check-self-contained-and-connected")) {
        strict = 1;
        check_self_contained_and_connected = 1;
      } else if (skip_to_optional_arg(arg, "--fsck-objects", &arg)) {
        do_fsck_object = 1;
        fsck_set_msg_types(&fsck_options, arg);
      } else if (!strcmp(arg, "--verify")) {
        verify = 1;
      } else if (!strcmp(arg, "--verify-stat")) {
        verify = 1;
        show_stat = 1;
      } else if (!strcmp(arg, "--verify-stat-only")) {
        verify = 1;
        show_stat = 1;
        stat_only = 1;
      } else if (skip_to_optional_arg(arg, "--keep", &keep_msg)) {
        ; /* nothing to do */
      } else if (skip_to_optional_arg(arg, "--promisor", &promisor_msg)) {
        ; /* already parsed */
      } else if (starts_with(arg, "--threads=")) {
        char *end;
        nr_threads = strtoul(arg+10, &end, 0);
        if (!arg[10] || *end || nr_threads < 0)
          usage(index_pack_usage);
        if (!HAVE_THREADS && nr_threads != 1) {
          warning(_("no threads support, ignoring %s"), arg);
          nr_threads = 1;
        }
      } else if (starts_with(arg, "--pack_header=")) {
        struct pack_header *hdr;
        char *c;

        hdr = (struct pack_header *)input_buffer;
        hdr->hdr_signature = htonl(PACK_SIGNATURE);
        hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
        if (*c != ',')
          die(_("bad %s"), arg);
        hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
        if (*c)
          die(_("bad %s"), arg);
        input_len = sizeof(*hdr);
      } else if (!strcmp(arg, "-v")) {
        verbose = 1;
      } else if (!strcmp(arg, "--progress-title")) {
        if (progress_title || (i+1) >= argc)
          usage(index_pack_usage);
        progress_title = argv[++i];
      } else if (!strcmp(arg, "--show-resolving-progress")) {
        show_resolving_progress = 1;
      } else if (!strcmp(arg, "--report-end-of-input")) {
        report_end_of_input = 1;
      } else if (!strcmp(arg, "-o")) {
        if (index_name || (i+1) >= argc)
          usage(index_pack_usage);
        index_name = argv[++i];
      } else if (starts_with(arg, "--index-version=")) {
        char *c;
        opts.version = strtoul(arg + 16, &c, 10);
        if (opts.version > 2)
          die(_("bad %s"), arg);
        if (*c == ',')
          opts.off32_limit = strtoul(c+1, &c, 0);
        if (*c || opts.off32_limit & 0x80000000)
          die(_("bad %s"), arg);
      } else if (skip_prefix(arg, "--max-input-size=", &arg)) {
        max_input_size = strtoumax(arg, NULL, 10);
      } else if (skip_prefix(arg, "--object-format=", &arg)) {
        hash_algo = hash_algo_by_name(arg);
        if (hash_algo == GIT_HASH_UNKNOWN)
          die(_("unknown hash algorithm '%s'"), arg);
        repo_set_hash_algo(the_repository, hash_algo);
      } else if (!strcmp(arg, "--rev-index")) {
        rev_index = 1;
      } else if (!strcmp(arg, "--no-rev-index")) {
        rev_index = 0;
      } else
        usage(index_pack_usage);
      continue;
    }

    if (pack_name)
      usage(index_pack_usage);
    pack_name = arg;
  }

  if (!pack_name && !from_stdin)
    usage(index_pack_usage);
  if (fix_thin_pack && !from_stdin)
    die(_("the option '%s' requires '%s'"), "--fix-thin", "--stdin");
  if (from_stdin && !startup_info->have_repository)
    die(_("--stdin requires a git repository"));
  if (from_stdin && hash_algo)
    die(_("options '%s' and '%s' cannot be used together"), "--object-format", "--stdin");
  if (!index_name && pack_name)
    index_name = derive_filename(pack_name, "pack", "idx", &index_name_buf);

  /*
   * Packfiles and indices do not carry enough information to be able to
   * identify their object hash. So when we are neither in a repository
   * nor has the user told us which object hash to use we have no other
   * choice but to guess the object hash.
   */
  if (!the_repository->hash_algo)
    repo_set_hash_algo(the_repository, GIT_HASH_SHA1);

  opts.flags &= ~(WRITE_REV | WRITE_REV_VERIFY);
  if (rev_index) {
    opts.flags |= verify ? WRITE_REV_VERIFY : WRITE_REV;
    if (index_name)
      rev_index_name = derive_filename(index_name,
               "idx", "rev",
               &rev_index_name_buf);
  }

  if (verify) {
    if (!index_name)
      die(_("--verify with no packfile name given"));
    read_idx_option(&opts, index_name);
    opts.flags |= WRITE_IDX_VERIFY | WRITE_IDX_STRICT;
  }
  if (strict)
    opts.flags |= WRITE_IDX_STRICT;

  if (HAVE_THREADS && !nr_threads) {
    nr_threads = online_cpus();
    /*
     * Experiments show that going above 20 threads doesn't help,
     * no matter how many cores you have. Below that, we tend to
     * max at half the number of online_cpus(), presumably because
     * half of those are hyperthreads rather than full cores. We'll
     * never reduce the level below "3", though, to match a
     * historical value that nobody complained about.
     */
    if (nr_threads < 4)
      ; /* too few cores to consider capping */
    else if (nr_threads < 6)
      nr_threads = 3; /* historic cap */
    else if (nr_threads < 40)
      nr_threads /= 2;
    else
      nr_threads = 20; /* hard cap */
  }

  curr_pack = open_pack_file(pack_name);
  parse_pack_header();
  CALLOC_ARRAY(objects, st_add(nr_objects, 1));
  if (show_stat)
    CALLOC_ARRAY(obj_stat, st_add(nr_objects, 1));
  CALLOC_ARRAY(ofs_deltas, nr_objects);
  parse_pack_objects(pack_hash);
  if (report_end_of_input)
    write_in_full(2, "\0", 1);
  resolve_deltas();
  conclude_pack(fix_thin_pack, curr_pack, pack_hash);
  free(ofs_deltas);
  free(ref_deltas);
  if (strict)
    foreign_nr = check_objects();

  if (show_stat)
    show_pack_info(stat_only);

  ALLOC_ARRAY(idx_objects, nr_objects);
  for (i = 0; i < nr_objects; i++)
    idx_objects[i] = &objects[i].idx;
  curr_index = write_idx_file(index_name, idx_objects, nr_objects, &opts, pack_hash);
  if (rev_index)
    curr_rev_index = write_rev_file(rev_index_name, idx_objects,
            nr_objects, pack_hash,
            opts.flags);
  free(idx_objects);

  if (!verify)
    final(pack_name, curr_pack,
          index_name, curr_index,
          rev_index_name, curr_rev_index,
          keep_msg, promisor_msg,
          pack_hash);
  else
    close(input_fd);

  if (do_fsck_object && fsck_finish(&fsck_options))
    die(_("fsck error in pack objects"));

  free(opts.anomaly);
  free(objects);
  strbuf_release(&index_name_buf);
  strbuf_release(&rev_index_name_buf);
  if (!pack_name)
    free((void *) curr_pack);
  if (!index_name)
    free((void *) curr_index);
  if (!rev_index_name)
    free((void *) curr_rev_index);

  /*
   * Let the caller know this pack is not self contained
   */
  if (check_self_contained_and_connected && foreign_nr)
    return 1;

  return 0;
}

Coverage Report

Created: 2024-09-08 06:24