Merge branch 'rs/refresh-beyond-symlink' into maint
authorJunio C Hamano <gitster@pobox.com>
Fri, 19 Sep 2014 21:05:11 +0000 (14:05 -0700)
committerJunio C Hamano <gitster@pobox.com>
Fri, 19 Sep 2014 21:05:11 +0000 (14:05 -0700)
* rs/refresh-beyond-symlink:
read-cache: check for leading symlinks when refreshing index

1  2 
read-cache.c
diff --combined read-cache.c
index 5d3c8bd4aaffda9915a3fd62d9d9800f4ac8baff,5c234cbd70d088b94fd6c19eb6a96d7b852b963d..6f0057fe66a59e1239703ee4458de200304f727a
@@@ -14,8 -14,6 +14,8 @@@
  #include "resolve-undo.h"
  #include "strbuf.h"
  #include "varint.h"
 +#include "split-index.h"
 +#include "sigchain.h"
  
  static struct cache_entry *refresh_cache_entry(struct cache_entry *ce,
                                               unsigned int options);
  #define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
  #define CACHE_EXT_TREE 0x54524545     /* "TREE" */
  #define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUC" */
 +#define CACHE_EXT_LINK 0x6c696e6b       /* "link" */
 +
 +/* changes that can be kept in $GIT_DIR/index (basically all extensions) */
 +#define EXTMASK (RESOLVE_UNDO_CHANGED | CACHE_TREE_CHANGED | \
 +               CE_ENTRY_ADDED | CE_ENTRY_REMOVED | CE_ENTRY_CHANGED | \
 +               SPLIT_INDEX_ORDERED)
  
  struct index_state the_index;
 +static const char *alternate_index_output;
  
  static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
  {
@@@ -56,12 -47,9 +56,12 @@@ static void replace_index_entry(struct 
  {
        struct cache_entry *old = istate->cache[nr];
  
 +      replace_index_entry_in_base(istate, old, ce);
        remove_name_hash(istate, old);
 +      free(old);
        set_index_entry(istate, nr, ce);
 -      istate->cache_changed = 1;
 +      ce->ce_flags |= CE_UPDATE_IN_BASE;
 +      istate->cache_changed |= CE_ENTRY_CHANGED;
  }
  
  void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
  
        new = xmalloc(cache_entry_size(namelen));
        copy_cache_entry(new, old);
 -      new->ce_flags &= ~CE_STATE_MASK;
 +      new->ce_flags &= ~CE_HASHED;
        new->ce_namelen = namelen;
 +      new->index = 0;
        memcpy(new->name, new_name, namelen + 1);
  
 -      cache_tree_invalidate_path(istate->cache_tree, old->name);
 +      cache_tree_invalidate_path(istate, old->name);
        remove_index_entry_at(istate, nr);
        add_index_entry(istate, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  }
@@@ -434,26 -421,18 +434,26 @@@ int df_name_compare(const char *name1, 
        return c1 - c2;
  }
  
 -int cache_name_stage_compare(const char *name1, int len1, int stage1, const char *name2, int len2, int stage2)
 +int name_compare(const char *name1, size_t len1, const char *name2, size_t len2)
  {
 -      int len = len1 < len2 ? len1 : len2;
 -      int cmp;
 -
 -      cmp = memcmp(name1, name2, len);
 +      size_t min_len = (len1 < len2) ? len1 : len2;
 +      int cmp = memcmp(name1, name2, min_len);
        if (cmp)
                return cmp;
        if (len1 < len2)
                return -1;
        if (len1 > len2)
                return 1;
 +      return 0;
 +}
 +
 +int cache_name_stage_compare(const char *name1, int len1, int stage1, const char *name2, int len2, int stage2)
 +{
 +      int cmp;
 +
 +      cmp = name_compare(name1, len1, name2, len2);
 +      if (cmp)
 +              return cmp;
  
        if (stage1 < stage2)
                return -1;
        return 0;
  }
  
 -int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
 -{
 -      return cache_name_stage_compare(name1, len1, 0, name2, len2, 0);
 -}
 -
  static int index_name_stage_pos(const struct index_state *istate, const char *name, int namelen, int stage)
  {
        int first, last;
@@@ -495,8 -479,7 +495,8 @@@ int remove_index_entry_at(struct index_
  
        record_resolve_undo(istate, ce);
        remove_name_hash(istate, ce);
 -      istate->cache_changed = 1;
 +      save_or_free_index_entry(istate, ce);
 +      istate->cache_changed |= CE_ENTRY_REMOVED;
        istate->cache_nr--;
        if (pos >= istate->cache_nr)
                return 0;
@@@ -517,16 -500,12 +517,16 @@@ void remove_marked_cache_entries(struc
        unsigned int i, j;
  
        for (i = j = 0; i < istate->cache_nr; i++) {
 -              if (ce_array[i]->ce_flags & CE_REMOVE)
 +              if (ce_array[i]->ce_flags & CE_REMOVE) {
                        remove_name_hash(istate, ce_array[i]);
 +                      save_or_free_index_entry(istate, ce_array[i]);
 +              }
                else
                        ce_array[j++] = ce_array[i];
        }
 -      istate->cache_changed = 1;
 +      if (j == istate->cache_nr)
 +              return;
 +      istate->cache_changed |= CE_ENTRY_REMOVED;
        istate->cache_nr = j;
  }
  
@@@ -535,7 -514,7 +535,7 @@@ int remove_file_from_index(struct index
        int pos = index_name_pos(istate, path, strlen(path));
        if (pos < 0)
                pos = -pos-1;
 -      cache_tree_invalidate_path(istate->cache_tree, path);
 +      cache_tree_invalidate_path(istate, path);
        while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
                remove_index_entry_at(istate, pos);
        return 0;
@@@ -584,9 -563,7 +584,9 @@@ static int different_name(struct cache_
   * So we use the CE_ADDED flag to verify that the alias was an old
   * one before we accept it as
   */
 -static struct cache_entry *create_alias_ce(struct cache_entry *ce, struct cache_entry *alias)
 +static struct cache_entry *create_alias_ce(struct index_state *istate,
 +                                         struct cache_entry *ce,
 +                                         struct cache_entry *alias)
  {
        int len;
        struct cache_entry *new;
        new = xcalloc(1, cache_entry_size(len));
        memcpy(new->name, alias->name, len);
        copy_cache_entry(new, ce);
 -      free(ce);
 +      save_or_free_index_entry(istate, ce);
        return new;
  }
  
 -static void record_intent_to_add(struct cache_entry *ce)
 +void set_object_name_for_intent_to_add_entry(struct cache_entry *ce)
  {
        unsigned char sha1[20];
        if (write_sha1_file("", 0, blob_type, sha1))
@@@ -689,10 -666,10 +689,10 @@@ int add_to_index(struct index_state *is
                if (index_path(ce->sha1, path, st, HASH_WRITE_OBJECT))
                        return error("unable to index file %s", path);
        } else
 -              record_intent_to_add(ce);
 +              set_object_name_for_intent_to_add_entry(ce);
  
        if (ignore_case && alias && different_name(ce, alias))
 -              ce = create_alias_ce(ce, alias);
 +              ce = create_alias_ce(istate, ce, alias);
        ce->ce_flags |= CE_ADDED;
  
        /* It was suspected to be racily clean, but it turns out to be Ok */
@@@ -955,8 -932,7 +955,8 @@@ static int add_index_entry_with_check(s
        int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
        int new_only = option & ADD_CACHE_NEW_ONLY;
  
 -      cache_tree_invalidate_path(istate->cache_tree, ce->name);
 +      if (!(option & ADD_CACHE_KEEP_CACHE_TREE))
 +              cache_tree_invalidate_path(istate, ce->name);
        pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
  
        /* existing match? Just replace it. */
@@@ -1010,7 -986,11 +1010,7 @@@ int add_index_entry(struct index_state 
        }
  
        /* Make sure the array is big enough .. */
 -      if (istate->cache_nr == istate->cache_alloc) {
 -              istate->cache_alloc = alloc_nr(istate->cache_alloc);
 -              istate->cache = xrealloc(istate->cache,
 -                                      istate->cache_alloc * sizeof(*istate->cache));
 -      }
 +      ALLOC_GROW(istate->cache, istate->cache_nr + 1, istate->cache_alloc);
  
        /* Add it in.. */
        istate->cache_nr++;
                        istate->cache + pos,
                        (istate->cache_nr - pos - 1) * sizeof(ce));
        set_index_entry(istate, pos, ce);
 -      istate->cache_changed = 1;
 +      istate->cache_changed |= CE_ENTRY_ADDED;
        return 0;
  }
  
@@@ -1064,6 -1044,14 +1064,14 @@@ static struct cache_entry *refresh_cach
                return ce;
        }
  
+       if (has_symlink_leading_path(ce->name, ce_namelen(ce))) {
+               if (ignore_missing)
+                       return ce;
+               if (err)
+                       *err = ENOENT;
+               return NULL;
+       }
        if (lstat(ce->name, &st) < 0) {
                if (ignore_missing && errno == ENOENT)
                        return ce;
            !(ce->ce_flags & CE_VALID))
                updated->ce_flags &= ~CE_VALID;
  
 +      /* istate->cache_changed is updated in the caller */
        return updated;
  }
  
@@@ -1200,8 -1187,7 +1208,8 @@@ int refresh_index(struct index_state *i
                                 * means the index is not valid anymore.
                                 */
                                ce->ce_flags &= ~CE_VALID;
 -                              istate->cache_changed = 1;
 +                              ce->ce_flags |= CE_UPDATE_IN_BASE;
 +                              istate->cache_changed |= CE_ENTRY_CHANGED;
                        }
                        if (quiet)
                                continue;
@@@ -1238,42 -1224,6 +1246,42 @@@ static struct cache_entry *refresh_cach
  
  #define INDEX_FORMAT_DEFAULT 3
  
 +static int index_format_config(const char *var, const char *value, void *cb)
 +{
 +      unsigned int *version = cb;
 +      if (!strcmp(var, "index.version")) {
 +              *version = git_config_int(var, value);
 +              return 0;
 +      }
 +      return 1;
 +}
 +
 +static unsigned int get_index_format_default(void)
 +{
 +      char *envversion = getenv("GIT_INDEX_VERSION");
 +      char *endp;
 +      unsigned int version = INDEX_FORMAT_DEFAULT;
 +
 +      if (!envversion) {
 +              git_config(index_format_config, &version);
 +              if (version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < version) {
 +                      warning(_("index.version set, but the value is invalid.\n"
 +                                "Using version %i"), INDEX_FORMAT_DEFAULT);
 +                      return INDEX_FORMAT_DEFAULT;
 +              }
 +              return version;
 +      }
 +
 +      version = strtoul(envversion, &endp, 10);
 +      if (*endp ||
 +          version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < version) {
 +              warning(_("GIT_INDEX_VERSION set, but the value is invalid.\n"
 +                        "Using version %i"), INDEX_FORMAT_DEFAULT);
 +              version = INDEX_FORMAT_DEFAULT;
 +      }
 +      return version;
 +}
 +
  /*
   * dev/ino/uid/gid/size are also just tracked to the low 32 bits
   * Again - this is just a (very strong in practice) heuristic that
@@@ -1353,10 -1303,6 +1361,10 @@@ static int read_index_extension(struct 
        case CACHE_EXT_RESOLVE_UNDO:
                istate->resolve_undo = resolve_undo_read(data, sz);
                break;
 +      case CACHE_EXT_LINK:
 +              if (read_link_extension(istate, data, sz))
 +                      return -1;
 +              break;
        default:
                if (*ext < 'A' || 'Z' < *ext)
                        return error("index uses %.4s extension, which we do not understand",
@@@ -1372,6 -1318,26 +1380,6 @@@ int read_index(struct index_state *ista
        return read_index_from(istate, get_index_file());
  }
  
 -#ifndef NEEDS_ALIGNED_ACCESS
 -#define ntoh_s(var) ntohs(var)
 -#define ntoh_l(var) ntohl(var)
 -#else
 -static inline uint16_t ntoh_s_force_align(void *p)
 -{
 -      uint16_t x;
 -      memcpy(&x, p, sizeof(x));
 -      return ntohs(x);
 -}
 -static inline uint32_t ntoh_l_force_align(void *p)
 -{
 -      uint32_t x;
 -      memcpy(&x, p, sizeof(x));
 -      return ntohl(x);
 -}
 -#define ntoh_s(var) ntoh_s_force_align(&(var))
 -#define ntoh_l(var) ntoh_l_force_align(&(var))
 -#endif
 -
  static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry *ondisk,
                                                   unsigned int flags,
                                                   const char *name,
  {
        struct cache_entry *ce = xmalloc(cache_entry_size(len));
  
 -      ce->ce_stat_data.sd_ctime.sec = ntoh_l(ondisk->ctime.sec);
 -      ce->ce_stat_data.sd_mtime.sec = ntoh_l(ondisk->mtime.sec);
 -      ce->ce_stat_data.sd_ctime.nsec = ntoh_l(ondisk->ctime.nsec);
 -      ce->ce_stat_data.sd_mtime.nsec = ntoh_l(ondisk->mtime.nsec);
 -      ce->ce_stat_data.sd_dev   = ntoh_l(ondisk->dev);
 -      ce->ce_stat_data.sd_ino   = ntoh_l(ondisk->ino);
 -      ce->ce_mode  = ntoh_l(ondisk->mode);
 -      ce->ce_stat_data.sd_uid   = ntoh_l(ondisk->uid);
 -      ce->ce_stat_data.sd_gid   = ntoh_l(ondisk->gid);
 -      ce->ce_stat_data.sd_size  = ntoh_l(ondisk->size);
 +      ce->ce_stat_data.sd_ctime.sec = get_be32(&ondisk->ctime.sec);
 +      ce->ce_stat_data.sd_mtime.sec = get_be32(&ondisk->mtime.sec);
 +      ce->ce_stat_data.sd_ctime.nsec = get_be32(&ondisk->ctime.nsec);
 +      ce->ce_stat_data.sd_mtime.nsec = get_be32(&ondisk->mtime.nsec);
 +      ce->ce_stat_data.sd_dev   = get_be32(&ondisk->dev);
 +      ce->ce_stat_data.sd_ino   = get_be32(&ondisk->ino);
 +      ce->ce_mode  = get_be32(&ondisk->mode);
 +      ce->ce_stat_data.sd_uid   = get_be32(&ondisk->uid);
 +      ce->ce_stat_data.sd_gid   = get_be32(&ondisk->gid);
 +      ce->ce_stat_data.sd_size  = get_be32(&ondisk->size);
        ce->ce_flags = flags & ~CE_NAMEMASK;
        ce->ce_namelen = len;
 +      ce->index = 0;
        hashcpy(ce->sha1, ondisk->sha1);
        memcpy(ce->name, name, len);
        ce->name[len] = '\0';
@@@ -1429,14 -1394,14 +1437,14 @@@ static struct cache_entry *create_from_
        unsigned int flags;
  
        /* On-disk flags are just 16 bits */
 -      flags = ntoh_s(ondisk->flags);
 +      flags = get_be16(&ondisk->flags);
        len = flags & CE_NAMEMASK;
  
        if (flags & CE_EXTENDED) {
                struct ondisk_cache_entry_extended *ondisk2;
                int extended_flags;
                ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
 -              extended_flags = ntoh_s(ondisk2->flags2) << 16;
 +              extended_flags = get_be16(&ondisk2->flags2) << 16;
                /* We do not yet understand any bit out of CE_EXTENDED_FLAGS */
                if (extended_flags & ~CE_EXTENDED_FLAGS)
                        die("Unknown index entry format %08x", extended_flags);
  }
  
  /* remember to discard_cache() before reading a different cache! */
 -int read_index_from(struct index_state *istate, const char *path)
 +int do_read_index(struct index_state *istate, const char *path, int must_exist)
  {
        int fd, i;
        struct stat st;
        istate->timestamp.nsec = 0;
        fd = open(path, O_RDONLY);
        if (fd < 0) {
 -              if (errno == ENOENT)
 +              if (!must_exist && errno == ENOENT)
                        return 0;
 -              die_errno("index file open failed");
 +              die_errno("%s: index file open failed", path);
        }
  
        if (fstat(fd, &st))
        if (verify_hdr(hdr, mmap_size) < 0)
                goto unmap;
  
 +      hashcpy(istate->sha1, (const unsigned char *)hdr + mmap_size - 20);
        istate->version = ntohl(hdr->hdr_version);
        istate->cache_nr = ntohl(hdr->hdr_entries);
        istate->cache_alloc = alloc_nr(istate->cache_nr);
@@@ -1558,40 -1522,6 +1566,40 @@@ unmap
        die("index file corrupt");
  }
  
 +int read_index_from(struct index_state *istate, const char *path)
 +{
 +      struct split_index *split_index;
 +      int ret;
 +
 +      /* istate->initialized covers both .git/index and .git/sharedindex.xxx */
 +      if (istate->initialized)
 +              return istate->cache_nr;
 +
 +      ret = do_read_index(istate, path, 0);
 +      split_index = istate->split_index;
 +      if (!split_index)
 +              return ret;
 +
 +      if (is_null_sha1(split_index->base_sha1))
 +              return ret;
 +
 +      if (split_index->base)
 +              discard_index(split_index->base);
 +      else
 +              split_index->base = xcalloc(1, sizeof(*split_index->base));
 +      ret = do_read_index(split_index->base,
 +                          git_path("sharedindex.%s",
 +                                   sha1_to_hex(split_index->base_sha1)), 1);
 +      if (hashcmp(split_index->base_sha1, split_index->base->sha1))
 +              die("broken index, expect %s in %s, got %s",
 +                  sha1_to_hex(split_index->base_sha1),
 +                  git_path("sharedindex.%s",
 +                                   sha1_to_hex(split_index->base_sha1)),
 +                  sha1_to_hex(split_index->base->sha1));
 +      merge_base_index(istate);
 +      return ret;
 +}
 +
  int is_index_unborn(struct index_state *istate)
  {
        return (!istate->cache_nr && !istate->timestamp.sec);
@@@ -1601,15 -1531,8 +1609,15 @@@ int discard_index(struct index_state *i
  {
        int i;
  
 -      for (i = 0; i < istate->cache_nr; i++)
 +      for (i = 0; i < istate->cache_nr; i++) {
 +              if (istate->cache[i]->index &&
 +                  istate->split_index &&
 +                  istate->split_index->base &&
 +                  istate->cache[i]->index <= istate->split_index->base->cache_nr &&
 +                  istate->cache[i] == istate->split_index->base->cache[istate->cache[i]->index - 1])
 +                      continue;
                free(istate->cache[i]);
 +      }
        resolve_undo_clear_index(istate);
        istate->cache_nr = 0;
        istate->cache_changed = 0;
        free(istate->cache);
        istate->cache = NULL;
        istate->cache_alloc = 0;
 +      discard_split_index(istate);
        return 0;
  }
  
@@@ -1682,7 -1604,7 +1690,7 @@@ static int write_index_ext_header(git_S
                (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
  }
  
 -static int ce_flush(git_SHA_CTX *context, int fd)
 +static int ce_flush(git_SHA_CTX *context, int fd, unsigned char *sha1)
  {
        unsigned int left = write_buffer_len;
  
  
        /* Append the SHA1 signature at the end */
        git_SHA1_Final(write_buffer + left, context);
 +      hashcpy(sha1, write_buffer + left);
        left += 20;
        return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
  }
@@@ -1772,7 -1693,7 +1780,7 @@@ static char *copy_cache_entry_to_ondisk
        ondisk->size = htonl(ce->ce_stat_data.sd_size);
        hashcpy(ondisk->sha1, ce->sha1);
  
 -      flags = ce->ce_flags;
 +      flags = ce->ce_flags & ~CE_NAMEMASK;
        flags |= (ce_namelen(ce) >= CE_NAMEMASK ? CE_NAMEMASK : ce_namelen(ce));
        ondisk->flags = htons(flags);
        if (ce->ce_flags & CE_EXTENDED) {
@@@ -1791,15 -1712,9 +1799,15 @@@ static int ce_write_entry(git_SHA_CTX *
  {
        int size;
        struct ondisk_cache_entry *ondisk;
 +      int saved_namelen = saved_namelen; /* compiler workaround */
        char *name;
        int result;
  
 +      if (ce->ce_flags & CE_STRIP_NAME) {
 +              saved_namelen = ce_namelen(ce);
 +              ce->ce_namelen = 0;
 +      }
 +
        if (!previous_name) {
                size = ondisk_ce_size(ce);
                ondisk = xcalloc(1, size);
                strbuf_splice(previous_name, common, to_remove,
                              ce->name + common, ce_namelen(ce) - common);
        }
 +      if (ce->ce_flags & CE_STRIP_NAME) {
 +              ce->ce_namelen = saved_namelen;
 +              ce->ce_flags &= ~CE_STRIP_NAME;
 +      }
  
        result = ce_write(c, fd, ondisk, size);
        free(ondisk);
        return result;
  }
  
 +/*
 + * This function verifies if index_state has the correct sha1 of the
 + * index file.  Don't die if we have any other failure, just return 0.
 + */
 +static int verify_index_from(const struct index_state *istate, const char *path)
 +{
 +      int fd;
 +      ssize_t n;
 +      struct stat st;
 +      unsigned char sha1[20];
 +
 +      if (!istate->initialized)
 +              return 0;
 +
 +      fd = open(path, O_RDONLY);
 +      if (fd < 0)
 +              return 0;
 +
 +      if (fstat(fd, &st))
 +              goto out;
 +
 +      if (st.st_size < sizeof(struct cache_header) + 20)
 +              goto out;
 +
 +      n = pread_in_full(fd, sha1, 20, st.st_size - 20);
 +      if (n != 20)
 +              goto out;
 +
 +      if (hashcmp(istate->sha1, sha1))
 +              goto out;
 +
 +      close(fd);
 +      return 1;
 +
 +out:
 +      close(fd);
 +      return 0;
 +}
 +
 +static int verify_index(const struct index_state *istate)
 +{
 +      return verify_index_from(istate, get_index_file());
 +}
 +
  static int has_racy_timestamp(struct index_state *istate)
  {
        int entries = istate->cache_nr;
  void update_index_if_able(struct index_state *istate, struct lock_file *lockfile)
  {
        if ((istate->cache_changed || has_racy_timestamp(istate)) &&
 -          !write_index(istate, lockfile->fd))
 -              commit_locked_index(lockfile);
 -      else
 +          verify_index(istate) &&
 +          write_locked_index(istate, lockfile, COMMIT_LOCK))
                rollback_lock_file(lockfile);
  }
  
 -int write_index(struct index_state *istate, int newfd)
 +static int do_write_index(struct index_state *istate, int newfd,
 +                        int strip_extensions)
  {
        git_SHA_CTX c;
        struct cache_header hdr;
                }
        }
  
 -      if (!istate->version)
 -              istate->version = INDEX_FORMAT_DEFAULT;
 +      if (!istate->version) {
 +              istate->version = get_index_format_default();
 +              if (getenv("GIT_TEST_SPLIT_INDEX"))
 +                      init_split_index(istate);
 +      }
  
        /* demote version 3 to version 2 when the latter suffices */
        if (istate->version == 3 || istate->version == 2)
        strbuf_release(&previous_name_buf);
  
        /* Write extension data here */
 -      if (istate->cache_tree) {
 +      if (!strip_extensions && istate->split_index) {
 +              struct strbuf sb = STRBUF_INIT;
 +
 +              err = write_link_extension(&sb, istate) < 0 ||
 +                      write_index_ext_header(&c, newfd, CACHE_EXT_LINK,
 +                                             sb.len) < 0 ||
 +                      ce_write(&c, newfd, sb.buf, sb.len) < 0;
 +              strbuf_release(&sb);
 +              if (err)
 +                      return -1;
 +      }
 +      if (!strip_extensions && istate->cache_tree) {
                struct strbuf sb = STRBUF_INIT;
  
                cache_tree_write(&sb, istate->cache_tree);
                if (err)
                        return -1;
        }
 -      if (istate->resolve_undo) {
 +      if (!strip_extensions && istate->resolve_undo) {
                struct strbuf sb = STRBUF_INIT;
  
                resolve_undo_write(&sb, istate->resolve_undo);
                        return -1;
        }
  
 -      if (ce_flush(&c, newfd) || fstat(newfd, &st))
 +      if (ce_flush(&c, newfd, istate->sha1) || fstat(newfd, &st))
                return -1;
        istate->timestamp.sec = (unsigned int)st.st_mtime;
        istate->timestamp.nsec = ST_MTIME_NSEC(st);
        return 0;
  }
  
 +void set_alternate_index_output(const char *name)
 +{
 +      alternate_index_output = name;
 +}
 +
 +static int commit_locked_index(struct lock_file *lk)
 +{
 +      if (alternate_index_output) {
 +              if (lk->fd >= 0 && close_lock_file(lk))
 +                      return -1;
 +              if (rename(lk->filename, alternate_index_output))
 +                      return -1;
 +              lk->filename[0] = 0;
 +              return 0;
 +      } else {
 +              return commit_lock_file(lk);
 +      }
 +}
 +
 +static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,
 +                               unsigned flags)
 +{
 +      int ret = do_write_index(istate, lock->fd, 0);
 +      if (ret)
 +              return ret;
 +      assert((flags & (COMMIT_LOCK | CLOSE_LOCK)) !=
 +             (COMMIT_LOCK | CLOSE_LOCK));
 +      if (flags & COMMIT_LOCK)
 +              return commit_locked_index(lock);
 +      else if (flags & CLOSE_LOCK)
 +              return close_lock_file(lock);
 +      else
 +              return ret;
 +}
 +
 +static int write_split_index(struct index_state *istate,
 +                           struct lock_file *lock,
 +                           unsigned flags)
 +{
 +      int ret;
 +      prepare_to_write_split_index(istate);
 +      ret = do_write_locked_index(istate, lock, flags);
 +      finish_writing_split_index(istate);
 +      return ret;
 +}
 +
 +static char *temporary_sharedindex;
 +
 +static void remove_temporary_sharedindex(void)
 +{
 +      if (temporary_sharedindex) {
 +              unlink_or_warn(temporary_sharedindex);
 +              free(temporary_sharedindex);
 +              temporary_sharedindex = NULL;
 +      }
 +}
 +
 +static void remove_temporary_sharedindex_on_signal(int signo)
 +{
 +      remove_temporary_sharedindex();
 +      sigchain_pop(signo);
 +      raise(signo);
 +}
 +
 +static int write_shared_index(struct index_state *istate,
 +                            struct lock_file *lock, unsigned flags)
 +{
 +      struct split_index *si = istate->split_index;
 +      static int installed_handler;
 +      int fd, ret;
 +
 +      temporary_sharedindex = git_pathdup("sharedindex_XXXXXX");
 +      fd = mkstemp(temporary_sharedindex);
 +      if (fd < 0) {
 +              free(temporary_sharedindex);
 +              temporary_sharedindex = NULL;
 +              hashclr(si->base_sha1);
 +              return do_write_locked_index(istate, lock, flags);
 +      }
 +      if (!installed_handler) {
 +              atexit(remove_temporary_sharedindex);
 +              sigchain_push_common(remove_temporary_sharedindex_on_signal);
 +      }
 +      move_cache_to_base_index(istate);
 +      ret = do_write_index(si->base, fd, 1);
 +      close(fd);
 +      if (ret) {
 +              remove_temporary_sharedindex();
 +              return ret;
 +      }
 +      ret = rename(temporary_sharedindex,
 +                   git_path("sharedindex.%s", sha1_to_hex(si->base->sha1)));
 +      free(temporary_sharedindex);
 +      temporary_sharedindex = NULL;
 +      if (!ret)
 +              hashcpy(si->base_sha1, si->base->sha1);
 +      return ret;
 +}
 +
 +int write_locked_index(struct index_state *istate, struct lock_file *lock,
 +                     unsigned flags)
 +{
 +      struct split_index *si = istate->split_index;
 +
 +      if (!si || alternate_index_output ||
 +          (istate->cache_changed & ~EXTMASK)) {
 +              if (si)
 +                      hashclr(si->base_sha1);
 +              return do_write_locked_index(istate, lock, flags);
 +      }
 +
 +      if (getenv("GIT_TEST_SPLIT_INDEX")) {
 +              int v = si->base_sha1[0];
 +              if ((v & 15) < 6)
 +                      istate->cache_changed |= SPLIT_INDEX_ORDERED;
 +      }
 +      if (istate->cache_changed & SPLIT_INDEX_ORDERED) {
 +              int ret = write_shared_index(istate, lock, flags);
 +              if (ret)
 +                      return ret;
 +      }
 +
 +      return write_split_index(istate, lock, flags);
 +}
 +
  /*
   * Read the index file that is potentially unmerged into given
   * index_state, dropping any unmerged entries.  Returns true if
@@@ -2171,7 -1899,7 +2179,7 @@@ int read_index_unmerged(struct index_st
                new_ce->ce_mode = ce->ce_mode;
                if (add_index_entry(istate, new_ce, 0))
                        return error("%s: cannot drop to stage #0",
 -                                   ce->name);
 +                                   new_ce->name);
                i = index_name_pos(istate, new_ce->name, len);
        }
        return unmerged;