Merge branch 'kw/write-index-reduce-alloc' into next

A hotfix to a topic already in 'master'.

* kw/write-index-reduce-alloc:
read-cache: fix index corruption with index v4
Add t/helper/test-write-cache to .gitignore

diff --combined read-cache.c
index b211c57af6b418a24bb2eef97dabed0c95e53599,633dafa21fc1b6c1389cab4c6a11974bdc589ccd..7d00265c494244a060e0104e9854d02fe1c6b44a
--- 1/read-cache.c
--- 2/read-cache.c
+++ b/read-cache.c
@@@ -160,9 -160,9 +160,9 @@@ static int ce_compare_data(const struc
        int fd = git_open_cloexec(ce->name, O_RDONLY);
  
        if (fd >= 0) {
 -              unsigned char sha1[20];
 -              if (!index_fd(sha1, fd, st, OBJ_BLOB, ce->name, 0))
 -                      match = hashcmp(sha1, ce->oid.hash);
 +              struct object_id oid;
 +              if (!index_fd(&oid, fd, st, OBJ_BLOB, ce->name, 0))
 +                      match = oidcmp(&oid, &ce->oid);
                /* index_fd() closed the file descriptor already */
        }
        return match;
@@@ -689,7 -689,7 +689,7 @@@ int add_to_index(struct index_state *is
                return 0;
        }
        if (!intent_only) {
 -              if (index_path(ce->oid.hash, path, st, HASH_WRITE_OBJECT)) {
 +              if (index_path(&ce->oid, path, st, HASH_WRITE_OBJECT)) {
                        free(ce);
                        return error("unable to index file %s", path);
                }
@@@ -2103,7 -2103,9 +2103,9 @@@ static int ce_write_entry(git_SHA_CTX *
                if (!result)
                        result = ce_write(c, fd, to_remove_vi, prefix_size);
                if (!result)
-                       result = ce_write(c, fd, ce->name + common, ce_namelen(ce) - common + 1);
+                       result = ce_write(c, fd, ce->name + common, ce_namelen(ce) - common);
+               if (!result)
+                       result = ce_write(c, fd, padding, 1);
  
                strbuf_splice(previous_name, common, to_remove,
                              ce->name + common, ce_namelen(ce) - common);
@@@ -2309,11 -2311,8 +2311,11 @@@ static int do_write_index(struct index_
  
        if (ce_flush(&c, newfd, istate->sha1))
                return -1;
 -      if (close_tempfile(tempfile))
 -              return error(_("could not close '%s'"), tempfile->filename.buf);
 +      if (close_tempfile_gently(tempfile)) {
 +              error(_("could not close '%s'"), tempfile->filename.buf);
 +              delete_tempfile(&tempfile);
 +              return -1;
 +      }
        if (stat(tempfile->filename.buf, &st))
                return -1;
        istate->timestamp.sec = (unsigned int)st.st_mtime;
@@@ -2337,7 -2336,7 +2339,7 @@@ static int commit_locked_index(struct l
  static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,
                                 unsigned flags)
  {
 -      int ret = do_write_index(istate, &lock->tempfile, 0);
 +      int ret = do_write_index(istate, lock->tempfile, 0);
        if (ret)
                return ret;
        assert((flags & (COMMIT_LOCK | CLOSE_LOCK)) !=
@@@ -2345,7 -2344,7 +2347,7 @@@
        if (flags & COMMIT_LOCK)
                return commit_locked_index(lock);
        else if (flags & CLOSE_LOCK)
 -              return close_lock_file(lock);
 +              return close_lock_file_gently(lock);
        else
                return ret;
  }
@@@ -2420,33 -2419,34 +2422,33 @@@ static int clean_shared_index_files(con
        return 0;
  }
  
 -static struct tempfile temporary_sharedindex;
 -
  static int write_shared_index(struct index_state *istate,
                              struct lock_file *lock, unsigned flags)
  {
 +      struct tempfile *temp;
        struct split_index *si = istate->split_index;
 -      int fd, ret;
 +      int ret;
  
 -      fd = mks_tempfile(&temporary_sharedindex, git_path("sharedindex_XXXXXX"));
 -      if (fd < 0) {
 +      temp = mks_tempfile(git_path("sharedindex_XXXXXX"));
 +      if (!temp) {
                hashclr(si->base_sha1);
                return do_write_locked_index(istate, lock, flags);
        }
        move_cache_to_base_index(istate);
 -      ret = do_write_index(si->base, &temporary_sharedindex, 1);
 +      ret = do_write_index(si->base, temp, 1);
        if (ret) {
 -              delete_tempfile(&temporary_sharedindex);
 +              delete_tempfile(&temp);
                return ret;
        }
 -      ret = adjust_shared_perm(get_tempfile_path(&temporary_sharedindex));
 +      ret = adjust_shared_perm(get_tempfile_path(temp));
        if (ret) {
                int save_errno = errno;
 -              error("cannot fix permission bits on %s", get_tempfile_path(&temporary_sharedindex));
 -              delete_tempfile(&temporary_sharedindex);
 +              error("cannot fix permission bits on %s", get_tempfile_path(temp));
 +              delete_tempfile(&temp);
                errno = save_errno;
                return ret;
        }
 -      ret = rename_tempfile(&temporary_sharedindex,
 +      ret = rename_tempfile(&temp,
                              git_path("sharedindex.%s", sha1_to_hex(si->base->sha1)));
        if (!ret) {
                hashcpy(si->base_sha1, si->base->sha1);