#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"

#include "gettext.h"

#include "hash.h"

#include "mem-pool.h"

#include "read-cache-ll.h"

#include "split-index.h"

#include "strbuf.h"

#include "ewah/ewok.h"

struct split_index *init_split_index(struct index_state *istate)

{

  if (!istate->split_index) {

    if (istate->sparse_index)

      die(_("cannot use split index with a sparse index"));

    CALLOC_ARRAY(istate->split_index, 1);

    istate->split_index->refcount = 1;

  }

  return istate->split_index;

}

int read_link_extension(struct index_state *istate,

       const void *data_, unsigned long sz)

{

  const unsigned char *data = data_;

  struct split_index *si;

  int ret;

  if (sz < the_hash_algo->rawsz)

    return error("corrupt link extension (too short)");

  si = init_split_index(istate);

  oidread(&si->base_oid, data, the_repository->hash_algo);

  data += the_hash_algo->rawsz;

  sz -= the_hash_algo->rawsz;

  if (!sz)

    return 0;

  si->delete_bitmap = ewah_new();

  ret = ewah_read_mmap(si->delete_bitmap, data, sz);

  if (ret < 0)

    return error("corrupt delete bitmap in link extension");

  data += ret;

  sz -= ret;

  si->replace_bitmap = ewah_new();

  ret = ewah_read_mmap(si->replace_bitmap, data, sz);

  if (ret < 0)

    return error("corrupt replace bitmap in link extension");

  if (ret != sz)

    return error("garbage at the end of link extension");

  return 0;

}

int write_link_extension(struct strbuf *sb,

       struct index_state *istate)

{

  struct split_index *si = istate->split_index;

  strbuf_add(sb, si->base_oid.hash, the_hash_algo->rawsz);

  if (!si->delete_bitmap && !si->replace_bitmap)

    return 0;

  ewah_serialize_strbuf(si->delete_bitmap, sb);

  ewah_serialize_strbuf(si->replace_bitmap, sb);

  return 0;

}

static void mark_base_index_entries(struct index_state *base)

{

  int i;

  /*

   * To keep track of the shared entries between

   * istate->base->cache[] and istate->cache[], base entry

   * position is stored in each base entry. All positions start

   * from 1 instead of 0, which is reserved to say "this is a new

   * entry".

   */

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

    base->cache[i]->index = i + 1;

}

void move_cache_to_base_index(struct index_state *istate)

{

  struct split_index *si = istate->split_index;

  int i;

  /*

   * If there was a previous base index, then transfer ownership of allocated

   * entries to the parent index.

   */

  if (si->base &&

    si->base->ce_mem_pool) {

    if (!istate->ce_mem_pool) {

      istate->ce_mem_pool = xmalloc(sizeof(struct mem_pool));

      mem_pool_init(istate->ce_mem_pool, 0);

    }

    mem_pool_combine(istate->ce_mem_pool, istate->split_index->base->ce_mem_pool);

  }

  ALLOC_ARRAY(si->base, 1);

  index_state_init(si->base, istate->repo);

  si->base->version = istate->version;

  /* zero timestamp disables racy test in ce_write_index() */

  si->base->timestamp = istate->timestamp;

  ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);

  si->base->cache_nr = istate->cache_nr;

  /*

   * The mem_pool needs to move with the allocated entries.

   */

  si->base->ce_mem_pool = istate->ce_mem_pool;

  istate->ce_mem_pool = NULL;

  COPY_ARRAY(si->base->cache, istate->cache, istate->cache_nr);

  mark_base_index_entries(si->base);

  for (i = 0; i < si->base->cache_nr; i++)

    si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;

}

static void mark_entry_for_delete(size_t pos, void *data)

{

  struct index_state *istate = data;

  if (pos >= istate->cache_nr)

    die("position for delete %d exceeds base index size %d",

        (int)pos, istate->cache_nr);

  istate->cache[pos]->ce_flags |= CE_REMOVE;

  istate->split_index->nr_deletions++;

}

static void replace_entry(size_t pos, void *data)

{

  struct index_state *istate = data;

  struct split_index *si = istate->split_index;

  struct cache_entry *dst, *src;

  if (pos >= istate->cache_nr)

    die("position for replacement %d exceeds base index size %d",

        (int)pos, istate->cache_nr);

  if (si->nr_replacements >= si->saved_cache_nr)

    die("too many replacements (%d vs %d)",

        si->nr_replacements, si->saved_cache_nr);

  dst = istate->cache[pos];

  if (dst->ce_flags & CE_REMOVE)

    die("entry %d is marked as both replaced and deleted",

        (int)pos);

  src = si->saved_cache[si->nr_replacements];

  if (ce_namelen(src))

    die("corrupt link extension, entry %d should have "

        "zero length name", (int)pos);

  src->index = pos + 1;

  src->ce_flags |= CE_UPDATE_IN_BASE;

  src->ce_namelen = dst->ce_namelen;

  copy_cache_entry(dst, src);

  discard_cache_entry(src);

  si->nr_replacements++;

}

void merge_base_index(struct index_state *istate)

{

  struct split_index *si = istate->split_index;

  unsigned int i;

  mark_base_index_entries(si->base);

  si->saved_cache     = istate->cache;

  si->saved_cache_nr  = istate->cache_nr;

  istate->cache_nr    = si->base->cache_nr;

  istate->cache     = NULL;

  istate->cache_alloc = 0;

  ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);

  COPY_ARRAY(istate->cache, si->base->cache, istate->cache_nr);

  si->nr_deletions = 0;

  si->nr_replacements = 0;

  ewah_each_bit(si->replace_bitmap, replace_entry, istate);

  ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);

  if (si->nr_deletions)

    remove_marked_cache_entries(istate, 0);

  for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {

    if (!ce_namelen(si->saved_cache[i]))

      die("corrupt link extension, entry %d should "

          "have non-zero length name", i);

    add_index_entry(istate, si->saved_cache[i],

        ADD_CACHE_OK_TO_ADD |

        ADD_CACHE_KEEP_CACHE_TREE |

        /*

         * we may have to replay what

         * merge-recursive.c:update_stages()

         * does, which has this flag on

         */

        ADD_CACHE_SKIP_DFCHECK);

    si->saved_cache[i] = NULL;

  }

  ewah_free(si->delete_bitmap);

  ewah_free(si->replace_bitmap);

  FREE_AND_NULL(si->saved_cache);

  si->delete_bitmap  = NULL;

  si->replace_bitmap = NULL;

  si->saved_cache_nr = 0;

}

/*

 * Compare most of the fields in two cache entries, i.e. all except the

 * hashmap_entry and the name.

 */

static int compare_ce_content(struct cache_entry *a, struct cache_entry *b)

{

  const unsigned int ondisk_flags = CE_STAGEMASK | CE_VALID |

            CE_EXTENDED_FLAGS;

  unsigned int ce_flags = a->ce_flags;

  unsigned int base_flags = b->ce_flags;

  int ret;

  /* only on-disk flags matter */

  a->ce_flags &= ondisk_flags;

  b->ce_flags &= ondisk_flags;

  ret = memcmp(&a->ce_stat_data, &b->ce_stat_data,

         offsetof(struct cache_entry, name) -

         offsetof(struct cache_entry, oid)) ||

    !oideq(&a->oid, &b->oid);

  a->ce_flags = ce_flags;

  b->ce_flags = base_flags;

  return ret;

}

void prepare_to_write_split_index(struct index_state *istate)

{

  struct split_index *si = init_split_index(istate);

  struct cache_entry **entries = NULL, *ce;

  int i, nr_entries = 0, nr_alloc = 0;

  si->delete_bitmap = ewah_new();

  si->replace_bitmap = ewah_new();

  if (si->base) {

    /* Go through istate->cache[] and mark CE_MATCHED to

     * entry with positive index. We'll go through

     * base->cache[] later to delete all entries in base

     * that are not marked with either CE_MATCHED or

     * CE_UPDATE_IN_BASE. If istate->cache[i] is a

     * duplicate, deduplicate it.

     */

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

      struct cache_entry *base;

      ce = istate->cache[i];

      if (!ce->index) {

        /*

         * During simple update index operations this

         * is a cache entry that is not present in

         * the shared index.  It will be added to the

         * split index.

         *

         * However, it might also represent a file

         * that already has a cache entry in the

         * shared index, but a new index has just

         * been constructed by unpack_trees(), and

         * this entry now refers to different content

         * than what was recorded in the original

         * index, e.g. during 'read-tree -m HEAD^' or

         * 'checkout HEAD^'.  In this case the

         * original entry in the shared index will be

         * marked as deleted, and this entry will be

         * added to the split index.

         */

        continue;

      }

      if (ce->index > si->base->cache_nr) {

        BUG("ce refers to a shared ce at %d, which is beyond the shared index size %d",

            ce->index, si->base->cache_nr);

      }

      ce->ce_flags |= CE_MATCHED; /* or "shared" */

      base = si->base->cache[ce->index - 1];

      if (ce == base) {

        /* The entry is present in the shared index. */

        if (ce->ce_flags & CE_UPDATE_IN_BASE) {

          /*

           * Already marked for inclusion in

           * the split index, either because

           * the corresponding file was

           * modified and the cached stat data

           * was refreshed, or because there

           * is already a replacement entry in

           * the split index.

           * Nothing more to do here.

           */

        } else if (!ce_uptodate(ce) &&

             is_racy_timestamp(istate, ce)) {

          /*

           * A racily clean cache entry stored

           * only in the shared index: it must

           * be added to the split index, so

           * the subsequent do_write_index()

           * can smudge its stat data.

           */

          ce->ce_flags |= CE_UPDATE_IN_BASE;

        } else {

          /*

           * The entry is only present in the

           * shared index and it was not

           * refreshed.

           * Just leave it there.

           */

        }

        continue;

      }

      if (ce->ce_namelen != base->ce_namelen ||

          strcmp(ce->name, base->name)) {

        ce->index = 0;

        continue;

      }

      /*

       * This is the copy of a cache entry that is present

       * in the shared index, created by unpack_trees()

       * while it constructed a new index.

       */

      if (ce->ce_flags & CE_UPDATE_IN_BASE) {

        /*

         * Already marked for inclusion in the split

         * index, either because the corresponding

         * file was modified and the cached stat data

         * was refreshed, or because the original

         * entry already had a replacement entry in

         * the split index.

         * Nothing to do.

         */

      } else if (!ce_uptodate(ce) &&

           is_racy_timestamp(istate, ce)) {

        /*

         * A copy of a racily clean cache entry from

         * the shared index.  It must be added to

         * the split index, so the subsequent

         * do_write_index() can smudge its stat data.

         */

        ce->ce_flags |= CE_UPDATE_IN_BASE;

      } else {

        /*

         * Thoroughly compare the cached data to see

         * whether it should be marked for inclusion

         * in the split index.

         *

         * This comparison might be unnecessary, as

         * code paths modifying the cached data do

         * set CE_UPDATE_IN_BASE as well.

         */

        if (compare_ce_content(ce, base))

          ce->ce_flags |= CE_UPDATE_IN_BASE;

      }

      discard_cache_entry(base);

      si->base->cache[ce->index - 1] = ce;

    }

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

      ce = si->base->cache[i];

      if ((ce->ce_flags & CE_REMOVE) ||

          !(ce->ce_flags & CE_MATCHED))

        ewah_set(si->delete_bitmap, i);

      else if (ce->ce_flags & CE_UPDATE_IN_BASE) {

        ewah_set(si->replace_bitmap, i);

        ce->ce_flags |= CE_STRIP_NAME;

        ALLOC_GROW(entries, nr_entries+1, nr_alloc);

        entries[nr_entries++] = ce;

      }

      if (is_null_oid(&ce->oid))

        istate->drop_cache_tree = 1;

    }

  }

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

    ce = istate->cache[i];

    if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {

      assert(!(ce->ce_flags & CE_STRIP_NAME));

      ALLOC_GROW(entries, nr_entries+1, nr_alloc);

      entries[nr_entries++] = ce;

    }

    ce->ce_flags &= ~CE_MATCHED;

  }

  /*

   * take cache[] out temporarily, put entries[] in its place

   * for writing

   */

  si->saved_cache = istate->cache;

  si->saved_cache_nr = istate->cache_nr;

  istate->cache = entries;

  istate->cache_nr = nr_entries;

}

void finish_writing_split_index(struct index_state *istate)

{

  struct split_index *si = init_split_index(istate);

  ewah_free(si->delete_bitmap);

  ewah_free(si->replace_bitmap);

  si->delete_bitmap = NULL;

  si->replace_bitmap = NULL;

  free(istate->cache);

  istate->cache = si->saved_cache;

  istate->cache_nr = si->saved_cache_nr;

}

void discard_split_index(struct index_state *istate)

{

  struct split_index *si = istate->split_index;

  if (!si)

    return;

  istate->split_index = NULL;

  si->refcount--;

  if (si->refcount)

    return;

  if (si->base) {

    discard_index(si->base);

    free(si->base);

  }

  free(si);

}

void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)

{

  if (ce->index &&

      istate->split_index &&

      istate->split_index->base &&

      ce->index <= istate->split_index->base->cache_nr &&

      ce == istate->split_index->base->cache[ce->index - 1])

    ce->ce_flags |= CE_REMOVE;

  else

    discard_cache_entry(ce);

}

void replace_index_entry_in_base(struct index_state *istate,

         struct cache_entry *old_entry,

         struct cache_entry *new_entry)

{

  if (old_entry->index &&

      istate->split_index &&

      istate->split_index->base &&

      old_entry->index <= istate->split_index->base->cache_nr) {

    new_entry->index = old_entry->index;

    if (old_entry != istate->split_index->base->cache[new_entry->index - 1])

      discard_cache_entry(istate->split_index->base->cache[new_entry->index - 1]);

    istate->split_index->base->cache[new_entry->index - 1] = new_entry;

  }

}

void add_split_index(struct index_state *istate)

{

  if (!istate->split_index) {

    init_split_index(istate);

    istate->cache_changed |= SPLIT_INDEX_ORDERED;

  }

}

void remove_split_index(struct index_state *istate)

{

  if (istate->split_index) {

    if (istate->split_index->base) {

      /*

       * When removing the split index, we need to move

       * ownership of the mem_pool associated with the

       * base index to the main index. There may be cache entries

       * allocated from the base's memory pool that are shared with

       * the_index.cache[].

       */

      mem_pool_combine(istate->ce_mem_pool,

           istate->split_index->base->ce_mem_pool);

      /*

       * The split index no longer owns the mem_pool backing

       * its cache array. As we are discarding this index,

       * mark the index as having no cache entries, so it

       * will not attempt to clean up the cache entries or

       * validate them.

       */

      istate->split_index->base->cache_nr = 0;

    }

    /*

     * We can discard the split index because its

     * memory pool has been incorporated into the

     * memory pool associated with the the_index.

     */

    discard_split_index(istate);

    istate->cache_changed |= SOMETHING_CHANGED;

  }

}