#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"

#include "environment.h"

#include "hex.h"

#include "lockfile.h"

#include "tree.h"

#include "tree-walk.h"

#include "cache-tree.h"

#include "bulk-checkin.h"

#include "object-file.h"

#include "object-store-ll.h"

#include "read-cache-ll.h"

#include "replace-object.h"

#include "promisor-remote.h"

#include "trace.h"

#include "trace2.h"

#ifndef DEBUG_CACHE_TREE

#define DEBUG_CACHE_TREE 0

#endif

struct cache_tree *cache_tree(void)

{

  struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));

  it->entry_count = -1;

  return it;

}

void cache_tree_free(struct cache_tree **it_p)

{

  int i;

  struct cache_tree *it = *it_p;

  if (!it)

    return;

  for (i = 0; i < it->subtree_nr; i++)

    if (it->down[i]) {

      cache_tree_free(&it->down[i]->cache_tree);

      free(it->down[i]);

    }

  free(it->down);

  free(it);

  *it_p = NULL;

}

static int subtree_name_cmp(const char *one, int onelen,

          const char *two, int twolen)

{

  if (onelen < twolen)

    return -1;

  if (twolen < onelen)

    return 1;

  return memcmp(one, two, onelen);

}

int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen)

{

  struct cache_tree_sub **down = it->down;

  int lo, hi;

  lo = 0;

  hi = it->subtree_nr;

  while (lo < hi) {

    int mi = lo + (hi - lo) / 2;

    struct cache_tree_sub *mdl = down[mi];

    int cmp = subtree_name_cmp(path, pathlen,

             mdl->name, mdl->namelen);

    if (!cmp)

      return mi;

    if (cmp < 0)

      hi = mi;

    else

      lo = mi + 1;

  }

  return -lo-1;

}

static struct cache_tree_sub *find_subtree(struct cache_tree *it,

             const char *path,

             int pathlen,

             int create)

{

  struct cache_tree_sub *down;

  int pos = cache_tree_subtree_pos(it, path, pathlen);

  if (0 <= pos)

    return it->down[pos];

  if (!create)

    return NULL;

  pos = -pos-1;

  ALLOC_GROW(it->down, it->subtree_nr + 1, it->subtree_alloc);

  it->subtree_nr++;

  FLEX_ALLOC_MEM(down, name, path, pathlen);

  down->cache_tree = NULL;

  down->namelen = pathlen;

  if (pos < it->subtree_nr)

    MOVE_ARRAY(it->down + pos + 1, it->down + pos,

         it->subtree_nr - pos - 1);

  it->down[pos] = down;

  return down;

}

struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)

{

  int pathlen = strlen(path);

  return find_subtree(it, path, pathlen, 1);

}

static int do_invalidate_path(struct cache_tree *it, const char *path)

{

  /* a/b/c

   * ==> invalidate self

   * ==> find "a", have it invalidate "b/c"

   * a

   * ==> invalidate self

   * ==> if "a" exists as a subtree, remove it.

   */

  const char *slash;

  int namelen;

  struct cache_tree_sub *down;

#if DEBUG_CACHE_TREE

  fprintf(stderr, "cache-tree invalidate <%s>\n", path);

#endif

  if (!it)

    return 0;

  slash = strchrnul(path, '/');

  namelen = slash - path;

  it->entry_count = -1;

  if (!*slash) {

    int pos;

    pos = cache_tree_subtree_pos(it, path, namelen);

    if (0 <= pos) {

      cache_tree_free(&it->down[pos]->cache_tree);

      free(it->down[pos]);

      /* 0 1 2 3 4 5

       *       ^     ^subtree_nr = 6

       *       pos

       * move 4 and 5 up one place (2 entries)

       * 2 = 6 - 3 - 1 = subtree_nr - pos - 1

       */

      MOVE_ARRAY(it->down + pos, it->down + pos + 1,

           it->subtree_nr - pos - 1);

      it->subtree_nr--;

    }

    return 1;

  }

  down = find_subtree(it, path, namelen, 0);

  if (down)

    do_invalidate_path(down->cache_tree, slash + 1);

  return 1;

}

void cache_tree_invalidate_path(struct index_state *istate, const char *path)

{

  if (do_invalidate_path(istate->cache_tree, path))

    istate->cache_changed |= CACHE_TREE_CHANGED;

}

static int verify_cache(struct index_state *istate, int flags)

{

  unsigned i, funny;

  int silent = flags & WRITE_TREE_SILENT;

  /* Verify that the tree is merged */

  funny = 0;

  for (i = 0; i < istate->cache_nr; i++) {

    const struct cache_entry *ce = istate->cache[i];

    if (ce_stage(ce)) {

      if (silent)

        return -1;

      if (10 < ++funny) {

        fprintf(stderr, "...\n");

        break;

      }

      fprintf(stderr, "%s: unmerged (%s)\n",

        ce->name, oid_to_hex(&ce->oid));

    }

  }

  if (funny)

    return -1;

  /* Also verify that the cache does not have path and path/file

   * at the same time.  At this point we know the cache has only

   * stage 0 entries.

   */

  funny = 0;

  for (i = 0; i + 1 < istate->cache_nr; i++) {

    /* path/file always comes after path because of the way

     * the cache is sorted.  Also path can appear only once,

     * which means conflicting one would immediately follow.

     */

    const struct cache_entry *this_ce = istate->cache[i];

    const struct cache_entry *next_ce = istate->cache[i + 1];

    const char *this_name = this_ce->name;

    const char *next_name = next_ce->name;

    int this_len = ce_namelen(this_ce);

    if (this_len < ce_namelen(next_ce) &&

        next_name[this_len] == '/' &&

        strncmp(this_name, next_name, this_len) == 0) {

      if (10 < ++funny) {

        fprintf(stderr, "...\n");

        break;

      }

      fprintf(stderr, "You have both %s and %s\n",

        this_name, next_name);

    }

  }

  if (funny)

    return -1;

  return 0;

}

static void discard_unused_subtrees(struct cache_tree *it)

{

  struct cache_tree_sub **down = it->down;

  int nr = it->subtree_nr;

  int dst, src;

  for (dst = src = 0; src < nr; src++) {

    struct cache_tree_sub *s = down[src];

    if (s->used)

      down[dst++] = s;

    else {

      cache_tree_free(&s->cache_tree);

      free(s);

      it->subtree_nr--;

    }

  }

}

int cache_tree_fully_valid(struct cache_tree *it)

{

  int i;

  if (!it)

    return 0;

  if (it->entry_count < 0 || !repo_has_object_file(the_repository, &it->oid))

    return 0;

  for (i = 0; i < it->subtree_nr; i++) {

    if (!cache_tree_fully_valid(it->down[i]->cache_tree))

      return 0;

  }

  return 1;

}

static int must_check_existence(const struct cache_entry *ce)

{

  return !(repo_has_promisor_remote(the_repository) && ce_skip_worktree(ce));

}

static int update_one(struct cache_tree *it,

          struct cache_entry **cache,

          int entries,

          const char *base,

          int baselen,

          int *skip_count,

          int flags)

{

  struct strbuf buffer;

  int missing_ok = flags & WRITE_TREE_MISSING_OK;

  int dryrun = flags & WRITE_TREE_DRY_RUN;

  int repair = flags & WRITE_TREE_REPAIR;

  int to_invalidate = 0;

  int i;

  assert(!(dryrun && repair));

  *skip_count = 0;

  /*

   * If the first entry of this region is a sparse directory

   * entry corresponding exactly to 'base', then this cache_tree

   * struct is a "leaf" in the data structure, pointing to the

   * tree OID specified in the entry.

   */

  if (entries > 0) {

    const struct cache_entry *ce = cache[0];

    if (S_ISSPARSEDIR(ce->ce_mode) &&

        ce->ce_namelen == baselen &&

        !strncmp(ce->name, base, baselen)) {

      it->entry_count = 1;

      oidcpy(&it->oid, &ce->oid);

      return 1;

    }

  }

  if (0 <= it->entry_count && repo_has_object_file(the_repository, &it->oid))

    return it->entry_count;

  /*

   * We first scan for subtrees and update them; we start by

   * marking existing subtrees -- the ones that are unmarked

   * should not be in the result.

   */

  for (i = 0; i < it->subtree_nr; i++)

    it->down[i]->used = 0;

  /*

   * Find the subtrees and update them.

   */

  i = 0;

  while (i < entries) {

    const struct cache_entry *ce = cache[i];

    struct cache_tree_sub *sub;

    const char *path, *slash;

    int pathlen, sublen, subcnt, subskip;

    path = ce->name;

    pathlen = ce_namelen(ce);

    if (pathlen <= baselen || memcmp(base, path, baselen))

      break; /* at the end of this level */

    slash = strchr(path + baselen, '/');

    if (!slash) {

      i++;

      continue;

    }

    /*

     * a/bbb/c (base = a/, slash = /c)

     * ==>

     * path+baselen = bbb/c, sublen = 3

     */

    sublen = slash - (path + baselen);

    sub = find_subtree(it, path + baselen, sublen, 1);

    if (!sub->cache_tree)

      sub->cache_tree = cache_tree();

    subcnt = update_one(sub->cache_tree,

            cache + i, entries - i,

            path,

            baselen + sublen + 1,

            &subskip,

            flags);

    if (subcnt < 0)

      return subcnt;

    if (!subcnt)

      die("index cache-tree records empty sub-tree");

    i += subcnt;

    sub->count = subcnt; /* to be used in the next loop */

    *skip_count += subskip;

    sub->used = 1;

  }

  discard_unused_subtrees(it);

  /*

   * Then write out the tree object for this level.

   */

  strbuf_init(&buffer, 8192);

  i = 0;

  while (i < entries) {

    const struct cache_entry *ce = cache[i];

    struct cache_tree_sub *sub = NULL;

    const char *path, *slash;

    int pathlen, entlen;

    const struct object_id *oid;

    unsigned mode;

    int expected_missing = 0;

    int contains_ita = 0;

    int ce_missing_ok;

    path = ce->name;

    pathlen = ce_namelen(ce);

    if (pathlen <= baselen || memcmp(base, path, baselen))

      break; /* at the end of this level */

    slash = strchr(path + baselen, '/');

    if (slash) {

      entlen = slash - (path + baselen);

      sub = find_subtree(it, path + baselen, entlen, 0);

      if (!sub)

        die("cache-tree.c: '%.*s' in '%s' not found",

            entlen, path + baselen, path);

      i += sub->count;

      oid = &sub->cache_tree->oid;

      mode = S_IFDIR;

      contains_ita = sub->cache_tree->entry_count < 0;

      if (contains_ita) {

        to_invalidate = 1;

        expected_missing = 1;

      }

    }

    else {

      oid = &ce->oid;

      mode = ce->ce_mode;

      entlen = pathlen - baselen;

      i++;

    }

    ce_missing_ok = mode == S_IFGITLINK || missing_ok ||

      !must_check_existence(ce);

    if (is_null_oid(oid) ||

        (!ce_missing_ok && !repo_has_object_file(the_repository, oid))) {

      strbuf_release(&buffer);

      if (expected_missing)

        return -1;

      return error("invalid object %06o %s for '%.*s'",

        mode, oid_to_hex(oid), entlen+baselen, path);

    }

    /*

     * CE_REMOVE entries are removed before the index is

     * written to disk. Skip them to remain consistent

     * with the future on-disk index.

     */

    if (ce->ce_flags & CE_REMOVE) {

      *skip_count = *skip_count + 1;

      continue;

    }

    /*

     * CE_INTENT_TO_ADD entries exist in on-disk index but

     * they are not part of generated trees. Invalidate up

     * to root to force cache-tree users to read elsewhere.

     */

    if (!sub && ce_intent_to_add(ce)) {

      to_invalidate = 1;

      continue;

    }

    /*

     * "sub" can be an empty tree if all subentries are i-t-a.

     */

    if (contains_ita && is_empty_tree_oid(oid, the_repository->hash_algo))

      continue;

    strbuf_grow(&buffer, entlen + 100);

    strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');

    strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);

#if DEBUG_CACHE_TREE

    fprintf(stderr, "cache-tree update-one %o %.*s\n",

      mode, entlen, path + baselen);

#endif

  }

  if (repair) {

    struct object_id oid;

    hash_object_file(the_hash_algo, buffer.buf, buffer.len,

         OBJ_TREE, &oid);

    if (repo_has_object_file_with_flags(the_repository, &oid, OBJECT_INFO_SKIP_FETCH_OBJECT))

      oidcpy(&it->oid, &oid);

    else

      to_invalidate = 1;

  } else if (dryrun) {

    hash_object_file(the_hash_algo, buffer.buf, buffer.len,

         OBJ_TREE, &it->oid);

  } else if (write_object_file_flags(buffer.buf, buffer.len, OBJ_TREE,

             &it->oid, NULL, flags & WRITE_TREE_SILENT

             ? HASH_SILENT : 0)) {

    strbuf_release(&buffer);

    return -1;

  }

  strbuf_release(&buffer);

  it->entry_count = to_invalidate ? -1 : i - *skip_count;

#if DEBUG_CACHE_TREE

  fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",

    it->entry_count, it->subtree_nr,

    oid_to_hex(&it->oid));

#endif

  return i;

}

int cache_tree_update(struct index_state *istate, int flags)

{

  int skip, i;

  i = verify_cache(istate, flags);

  if (i)

    return i;

  if (!istate->cache_tree)

    istate->cache_tree = cache_tree();

  if (!(flags & WRITE_TREE_MISSING_OK) && repo_has_promisor_remote(the_repository))

    prefetch_cache_entries(istate, must_check_existence);

  trace_performance_enter();

  trace2_region_enter("cache_tree", "update", the_repository);

  begin_odb_transaction();

  i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,

           "", 0, &skip, flags);

  end_odb_transaction();

  trace2_region_leave("cache_tree", "update", the_repository);

  trace_performance_leave("cache_tree_update");

  if (i < 0)

    return i;

  istate->cache_changed |= CACHE_TREE_CHANGED;

  return 0;

}

static void write_one(struct strbuf *buffer, struct cache_tree *it,

          const char *path, int pathlen)

{

  int i;

  /* One "cache-tree" entry consists of the following:

   * path (NUL terminated)

   * entry_count, subtree_nr ("%d %d\n")

   * tree-sha1 (missing if invalid)

   * subtree_nr "cache-tree" entries for subtrees.

   */

  strbuf_grow(buffer, pathlen + 100);

  strbuf_add(buffer, path, pathlen);

  strbuf_addf(buffer, "%c%d %d\n", 0, it->entry_count, it->subtree_nr);

#if DEBUG_CACHE_TREE

  if (0 <= it->entry_count)

    fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",

      pathlen, path, it->entry_count, it->subtree_nr,

      oid_to_hex(&it->oid));

  else

    fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",

      pathlen, path, it->subtree_nr);

#endif

  if (0 <= it->entry_count) {

    strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);

  }

  for (i = 0; i < it->subtree_nr; i++) {

    struct cache_tree_sub *down = it->down[i];

    if (i) {

      struct cache_tree_sub *prev = it->down[i-1];

      if (subtree_name_cmp(down->name, down->namelen,

               prev->name, prev->namelen) <= 0)

        die("fatal - unsorted cache subtree");

    }

    write_one(buffer, down->cache_tree, down->name, down->namelen);

  }

}

void cache_tree_write(struct strbuf *sb, struct cache_tree *root)

{

  trace2_region_enter("cache_tree", "write", the_repository);

  write_one(sb, root, "", 0);

  trace2_region_leave("cache_tree", "write", the_repository);

}

static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)

{

  const char *buf = *buffer;

  unsigned long size = *size_p;

  const char *cp;

  char *ep;

  struct cache_tree *it;

  int i, subtree_nr;

  const unsigned rawsz = the_hash_algo->rawsz;

  it = NULL;

  /* skip name, but make sure name exists */

  while (size && *buf) {

    size--;

    buf++;

  }

  if (!size)

    goto free_return;

  buf++; size--;

  it = cache_tree();

  cp = buf;

  it->entry_count = strtol(cp, &ep, 10);

  if (cp == ep)

    goto free_return;

  cp = ep;

  subtree_nr = strtol(cp, &ep, 10);

  if (cp == ep)

    goto free_return;

  while (size && *buf && *buf != '\n') {

    size--;

    buf++;

  }

  if (!size)

    goto free_return;

  buf++; size--;

  if (0 <= it->entry_count) {

    if (size < rawsz)

      goto free_return;

    oidread(&it->oid, (const unsigned char *)buf,

      the_repository->hash_algo);

    buf += rawsz;

    size -= rawsz;

  }

#if DEBUG_CACHE_TREE

  if (0 <= it->entry_count)

    fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",

      *buffer, it->entry_count, subtree_nr,

      oid_to_hex(&it->oid));

  else

    fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",

      *buffer, subtree_nr);

#endif

  /*

   * Just a heuristic -- we do not add directories that often but

   * we do not want to have to extend it immediately when we do,

   * hence +2.

   */

  it->subtree_alloc = subtree_nr + 2;

  CALLOC_ARRAY(it->down, it->subtree_alloc);

  for (i = 0; i < subtree_nr; i++) {

    /* read each subtree */

    struct cache_tree *sub;

    struct cache_tree_sub *subtree;

    const char *name = buf;

    sub = read_one(&buf, &size);

    if (!sub)

      goto free_return;

    subtree = cache_tree_sub(it, name);

    subtree->cache_tree = sub;

  }

  if (subtree_nr != it->subtree_nr)

    die("cache-tree: internal error");

  *buffer = buf;

  *size_p = size;

  return it;

 free_return:

  cache_tree_free(&it);

  return NULL;

}

struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)

{

  struct cache_tree *result;

  if (buffer[0])

    return NULL; /* not the whole tree */

  trace2_region_enter("cache_tree", "read", the_repository);

  result = read_one(&buffer, &size);

  trace2_region_leave("cache_tree", "read", the_repository);

  return result;

}

static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)

{

  if (!it)

    return NULL;

  while (*path) {

    const char *slash;

    struct cache_tree_sub *sub;

    slash = strchrnul(path, '/');

    /*

     * Between path and slash is the name of the subtree

     * to look for.

     */

    sub = find_subtree(it, path, slash - path, 0);

    if (!sub)

      return NULL;

    it = sub->cache_tree;

    path = slash;

    while (*path == '/')

      path++;

  }

  return it;

}

static int write_index_as_tree_internal(struct object_id *oid,

          struct index_state *index_state,

          int cache_tree_valid,

          int flags,

          const char *prefix)

{

  if (flags & WRITE_TREE_IGNORE_CACHE_TREE) {

    cache_tree_free(&index_state->cache_tree);

    cache_tree_valid = 0;

  }

  if (!cache_tree_valid && cache_tree_update(index_state, flags) < 0)

    return WRITE_TREE_UNMERGED_INDEX;

  if (prefix) {

    struct cache_tree *subtree;

    subtree = cache_tree_find(index_state->cache_tree, prefix);

    if (!subtree)

      return WRITE_TREE_PREFIX_ERROR;

    oidcpy(oid, &subtree->oid);

  }

  else

    oidcpy(oid, &index_state->cache_tree->oid);

  return 0;

}

struct tree* write_in_core_index_as_tree(struct repository *repo) {

  struct object_id o;

  int was_valid, ret;

  struct index_state *index_state = repo->index;

  was_valid = index_state->cache_tree &&

        cache_tree_fully_valid(index_state->cache_tree);

  ret = write_index_as_tree_internal(&o, index_state, was_valid, 0, NULL);

  if (ret == WRITE_TREE_UNMERGED_INDEX) {

    int i;

    bug("there are unmerged index entries:");

    for (i = 0; i < index_state->cache_nr; i++) {

      const struct cache_entry *ce = index_state->cache[i];

      if (ce_stage(ce))

        bug("%d %.*s", ce_stage(ce),

            (int)ce_namelen(ce), ce->name);

    }

    BUG("unmerged index entries when writing in-core index");

  }

  return lookup_tree(repo, &index_state->cache_tree->oid);

}

int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)

{

  int entries, was_valid;

  struct lock_file lock_file = LOCK_INIT;

  int ret;

  hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);

  entries = read_index_from(index_state, index_path, get_git_dir());

  if (entries < 0) {

    ret = WRITE_TREE_UNREADABLE_INDEX;

    goto out;

  }

  was_valid = !(flags & WRITE_TREE_IGNORE_CACHE_TREE) &&

        index_state->cache_tree &&

        cache_tree_fully_valid(index_state->cache_tree);

  ret = write_index_as_tree_internal(oid, index_state, was_valid, flags,

             prefix);

  if (!ret && !was_valid) {

    write_locked_index(index_state, &lock_file, COMMIT_LOCK);

    /* Not being able to write is fine -- we are only interested

     * in updating the cache-tree part, and if the next caller

     * ends up using the old index with unupdated cache-tree part

     * it misses the work we did here, but that is just a

     * performance penalty and not a big deal.

     */

  }

out:

  rollback_lock_file(&lock_file);

  return ret;

}

static void prime_cache_tree_sparse_dir(struct cache_tree *it,

          struct tree *tree)

{

  oidcpy(&it->oid, &tree->object.oid);

  it->entry_count = 1;

}

static void prime_cache_tree_rec(struct repository *r,

         struct cache_tree *it,

         struct tree *tree,

         struct strbuf *tree_path)

{

  struct tree_desc desc;

  struct name_entry entry;

  int cnt;

  size_t base_path_len = tree_path->len;

  oidcpy(&it->oid, &tree->object.oid);

  init_tree_desc(&desc, &tree->object.oid, tree->buffer, tree->size);

  cnt = 0;

  while (tree_entry(&desc, &entry)) {

    if (!S_ISDIR(entry.mode))

      cnt++;

    else {

      struct cache_tree_sub *sub;

      struct tree *subtree = lookup_tree(r, &entry.oid);

      if (parse_tree(subtree) < 0)

        exit(128);

      sub = cache_tree_sub(it, entry.path);

      sub->cache_tree = cache_tree();

      /*

       * Recursively-constructed subtree path is only needed when working

       * in a sparse index (where it's used to determine whether the

       * subtree is a sparse directory in the index).

       */

      if (r->index->sparse_index) {

        strbuf_setlen(tree_path, base_path_len);

        strbuf_add(tree_path, entry.path, entry.pathlen);

        strbuf_addch(tree_path, '/');

      }

      /*

       * If a sparse index is in use, the directory being processed may be

       * sparse. To confirm that, we can check whether an entry with that

       * exact name exists in the index. If it does, the created subtree

       * should be sparse. Otherwise, cache tree expansion should continue

       * as normal.

       */

      if (r->index->sparse_index &&

          index_entry_exists(r->index, tree_path->buf, tree_path->len))

        prime_cache_tree_sparse_dir(sub->cache_tree, subtree);

      else

        prime_cache_tree_rec(r, sub->cache_tree, subtree, tree_path);

      cnt += sub->cache_tree->entry_count;

    }

  }

  it->entry_count = cnt;

}

void prime_cache_tree(struct repository *r,

          struct index_state *istate,

          struct tree *tree)

{

  struct strbuf tree_path = STRBUF_INIT;

  trace2_region_enter("cache-tree", "prime_cache_tree", r);

  cache_tree_free(&istate->cache_tree);

  istate->cache_tree = cache_tree();

  prime_cache_tree_rec(r, istate->cache_tree, tree, &tree_path);

  strbuf_release(&tree_path);

  istate->cache_changed |= CACHE_TREE_CHANGED;

  trace2_region_leave("cache-tree", "prime_cache_tree", r);

}

/*

 * find the cache_tree that corresponds to the current level without

 * exploding the full path into textual form.  The root of the

 * cache tree is given as "root", and our current level is "info".

 * (1) When at root level, info->prev is NULL, so it is "root" itself.

 * (2) Otherwise, find the cache_tree that corresponds to one level

 *     above us, and find ourselves in there.

 */

static struct cache_tree *find_cache_tree_from_traversal(struct cache_tree *root,

               struct traverse_info *info)

{

  struct cache_tree *our_parent;

  if (!info->prev)

    return root;

  our_parent = find_cache_tree_from_traversal(root, info->prev);

  return cache_tree_find(our_parent, info->name);

}

int cache_tree_matches_traversal(struct cache_tree *root,

         struct name_entry *ent,

         struct traverse_info *info)

{

  struct cache_tree *it;

  it = find_cache_tree_from_traversal(root, info);

  it = cache_tree_find(it, ent->path);

  if (it && it->entry_count > 0 && oideq(&ent->oid, &it->oid))

    return it->entry_count;

  return 0;

}

static void verify_one_sparse(struct index_state *istate,

            struct strbuf *path,

            int pos)

{

  struct cache_entry *ce = istate->cache[pos];

  if (!S_ISSPARSEDIR(ce->ce_mode))

    BUG("directory '%s' is present in index, but not sparse",

        path->buf);

}

/*

 * Returns:

 *  0 - Verification completed.

 *  1 - Restart verification - a call to ensure_full_index() freed the cache

 *      tree that is being verified and verification needs to be restarted from

 *      the new toplevel cache tree.

 */