Merge branch 'rj/warning-uninitialized-fix' into next
authorJunio C Hamano <gitster@pobox.com>
Tue, 20 Mar 2018 21:22:50 +0000 (14:22 -0700)
committerJunio C Hamano <gitster@pobox.com>
Tue, 20 Mar 2018 21:22:50 +0000 (14:22 -0700)
Compilation fix.

* rj/warning-uninitialized-fix:
read-cache: fix an -Wmaybe-uninitialized warning
-Wuninitialized: remove some 'init-self' workarounds

1  2 
builtin/rev-list.c
fast-import.c
merge-recursive.c
read-cache.c
diff --combined builtin/rev-list.c
index 2fd72c0be5a643c98d97ff779e449541e48434cd,fbfc62de41468bd96a7effe3b3aedcf4ecb0e314..fadd3ec14cbf0469c332a85278e5d1b4932ef788
@@@ -15,7 -15,6 +15,7 @@@
  #include "progress.h"
  #include "reflog-walk.h"
  #include "oidset.h"
 +#include "packfile.h"
  
  static const char rev_list_usage[] =
  "git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
@@@ -68,7 -67,6 +68,7 @@@ enum missing_action 
        MA_ERROR = 0,    /* fail if any missing objects are encountered */
        MA_ALLOW_ANY,    /* silently allow ALL missing objects */
        MA_PRINT,        /* print ALL missing objects in special section */
 +      MA_ALLOW_PROMISOR, /* silently allow all missing PROMISOR objects */
  };
  static enum missing_action arg_missing_action;
  
@@@ -108,7 -106,7 +108,7 @@@ static void show_commit(struct commit *
        if (!revs->graph)
                fputs(get_revision_mark(revs, commit), stdout);
        if (revs->abbrev_commit && revs->abbrev)
 -              fputs(find_unique_abbrev(commit->object.oid.hash, revs->abbrev),
 +              fputs(find_unique_abbrev(&commit->object.oid, revs->abbrev),
                      stdout);
        else
                fputs(oid_to_hex(&commit->object.oid), stdout);
        else
                putchar('\n');
  
 -      if (revs->verbose_header && get_cached_commit_buffer(commit, NULL)) {
 +      if (revs->verbose_header) {
                struct strbuf buf = STRBUF_INIT;
                struct pretty_print_context ctx = {0};
                ctx.abbrev = revs->abbrev;
@@@ -199,12 -197,6 +199,12 @@@ static void finish_commit(struct commi
  
  static inline void finish_object__ma(struct object *obj)
  {
 +      /*
 +       * Whether or not we try to dynamically fetch missing objects
 +       * from the server, we currently DO NOT have the object.  We
 +       * can either print, allow (ignore), or conditionally allow
 +       * (ignore) them.
 +       */
        switch (arg_missing_action) {
        case MA_ERROR:
                die("missing blob object '%s'", oid_to_hex(&obj->oid));
                oidset_insert(&missing_objects, &obj->oid);
                return;
  
 +      case MA_ALLOW_PROMISOR:
 +              if (is_promisor_object(&obj->oid))
 +                      return;
 +              die("unexpected missing blob object '%s'",
 +                  oid_to_hex(&obj->oid));
 +              return;
 +
        default:
                BUG("unhandled missing_action");
                return;
        }
  }
  
 -static void finish_object(struct object *obj, const char *name, void *cb_data)
 +static int finish_object(struct object *obj, const char *name, void *cb_data)
  {
        struct rev_list_info *info = cb_data;
 -      if (obj->type == OBJ_BLOB && !has_object_file(&obj->oid))
 +      if (obj->type == OBJ_BLOB && !has_object_file(&obj->oid)) {
                finish_object__ma(obj);
 +              return 1;
 +      }
        if (info->revs->verify_objects && !obj->parsed && obj->type != OBJ_COMMIT)
                parse_object(&obj->oid);
 +      return 0;
  }
  
  static void show_object(struct object *obj, const char *name, void *cb_data)
  {
        struct rev_list_info *info = cb_data;
 -      finish_object(obj, name, cb_data);
 +      if (finish_object(obj, name, cb_data))
 +              return;
        display_progress(progress, ++progress_counter);
        if (info->flags & REV_LIST_QUIET)
                return;
@@@ -334,19 -315,11 +334,19 @@@ static inline int parse_missing_action_
  
        if (!strcmp(value, "allow-any")) {
                arg_missing_action = MA_ALLOW_ANY;
 +              fetch_if_missing = 0;
                return 1;
        }
  
        if (!strcmp(value, "print")) {
                arg_missing_action = MA_PRINT;
 +              fetch_if_missing = 0;
 +              return 1;
 +      }
 +
 +      if (!strcmp(value, "allow-promisor")) {
 +              arg_missing_action = MA_ALLOW_PROMISOR;
 +              fetch_if_missing = 0;
                return 1;
        }
  
@@@ -371,35 -344,6 +371,35 @@@ int cmd_rev_list(int argc, const char *
        init_revisions(&revs, prefix);
        revs.abbrev = DEFAULT_ABBREV;
        revs.commit_format = CMIT_FMT_UNSPECIFIED;
 +
 +      /*
 +       * Scan the argument list before invoking setup_revisions(), so that we
 +       * know if fetch_if_missing needs to be set to 0.
 +       *
 +       * "--exclude-promisor-objects" acts as a pre-filter on missing objects
 +       * by not crossing the boundary from realized objects to promisor
 +       * objects.
 +       *
 +       * Let "--missing" to conditionally set fetch_if_missing.
 +       */
 +      for (i = 1; i < argc; i++) {
 +              const char *arg = argv[i];
 +              if (!strcmp(arg, "--exclude-promisor-objects")) {
 +                      fetch_if_missing = 0;
 +                      revs.exclude_promisor_objects = 1;
 +                      break;
 +              }
 +      }
 +      for (i = 1; i < argc; i++) {
 +              const char *arg = argv[i];
 +              if (skip_prefix(arg, "--missing=", &arg)) {
 +                      if (revs.exclude_promisor_objects)
 +                              die(_("cannot combine --exclude-promisor-objects and --missing"));
 +                      if (parse_missing_action_value(arg))
 +                              break;
 +              }
 +      }
 +
        argc = setup_revisions(argc, argv, &revs, NULL);
  
        memset(&info, 0, sizeof(info));
                        continue;
                }
                if (!strcmp(arg, ("--no-" CL_ARG__FILTER))) {
 -                      list_objects_filter_release(&filter_options);
 +                      list_objects_filter_set_no_filter(&filter_options);
                        continue;
                }
                if (!strcmp(arg, "--filter-print-omitted")) {
                        continue;
                }
  
 -              if (skip_prefix(arg, "--missing=", &arg) &&
 -                  parse_missing_action_value(arg))
 -                      continue;
 +              if (!strcmp(arg, "--exclude-promisor-objects"))
 +                      continue; /* already handled above */
 +              if (skip_prefix(arg, "--missing=", &arg))
 +                      continue; /* already handled above */
  
                usage(rev_list_usage);
  
                mark_edges_uninteresting(&revs, show_edge);
  
        if (bisect_list) {
-               int reaches = reaches, all = all;
+               int reaches, all;
  
                find_bisection(&revs.commits, &reaches, &all, bisect_find_all);
  
diff --combined fast-import.c
index b300e4416de38cf7f2bed96da988e7de861f0a09,1f01a2205506054a4d9e1c80e74a29aa0f974b0d..a2e8b1d763a30e1bbec97a92da46c82f0f33353d
@@@ -316,7 -316,7 +316,7 @@@ static struct atom_str **atom_table
  /* The .pack file being generated */
  static struct pack_idx_option pack_idx_opts;
  static unsigned int pack_id;
 -static struct sha1file *pack_file;
 +static struct hashfile *pack_file;
  static struct packed_git *pack_data;
  static struct packed_git **all_packs;
  static off_t pack_size;
@@@ -905,12 -905,12 +905,12 @@@ static void start_packfile(void
  
        p->pack_fd = pack_fd;
        p->do_not_close = 1;
 -      pack_file = sha1fd(pack_fd, p->pack_name);
 +      pack_file = hashfd(pack_fd, p->pack_name);
  
        hdr.hdr_signature = htonl(PACK_SIGNATURE);
        hdr.hdr_version = htonl(2);
        hdr.hdr_entries = 0;
 -      sha1write(pack_file, &hdr, sizeof(hdr));
 +      hashwrite(pack_file, &hdr, sizeof(hdr));
  
        pack_data = p;
        pack_size = sizeof(hdr);
@@@ -1016,7 -1016,7 +1016,7 @@@ static void end_packfile(void
                struct tag *t;
  
                close_pack_windows(pack_data);
 -              sha1close(pack_file, cur_pack_oid.hash, 0);
 +              hashclose(pack_file, cur_pack_oid.hash, 0);
                fixup_pack_header_footer(pack_data->pack_fd, pack_data->sha1,
                                    pack_data->pack_name, object_count,
                                    cur_pack_oid.hash, pack_size);
@@@ -1092,15 -1092,15 +1092,15 @@@ static int store_object
        unsigned char hdr[96];
        struct object_id oid;
        unsigned long hdrlen, deltalen;
 -      git_SHA_CTX c;
 +      git_hash_ctx c;
        git_zstream s;
  
        hdrlen = xsnprintf((char *)hdr, sizeof(hdr), "%s %lu",
 -                         typename(type), (unsigned long)dat->len) + 1;
 -      git_SHA1_Init(&c);
 -      git_SHA1_Update(&c, hdr, hdrlen);
 -      git_SHA1_Update(&c, dat->buf, dat->len);
 -      git_SHA1_Final(oid.hash, &c);
 +                         type_name(type), (unsigned long)dat->len) + 1;
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, hdr, hdrlen);
 +      the_hash_algo->update_fn(&c, dat->buf, dat->len);
 +      the_hash_algo->final_fn(oid.hash, &c);
        if (oidout)
                oidcpy(oidout, &oid);
  
                return 1;
        }
  
 -      if (last && last->data.buf && last->depth < max_depth && dat->len > 20) {
 +      if (last && last->data.buf && last->depth < max_depth
 +              && dat->len > the_hash_algo->rawsz) {
 +
                delta_count_attempts_by_type[type]++;
                delta = diff_delta(last->data.buf, last->data.len,
                        dat->buf, dat->len,
 -                      &deltalen, dat->len - 20);
 +                      &deltalen, dat->len - the_hash_algo->rawsz);
        } else
                delta = NULL;
  
  
                hdrlen = encode_in_pack_object_header(hdr, sizeof(hdr),
                                                      OBJ_OFS_DELTA, deltalen);
 -              sha1write(pack_file, hdr, hdrlen);
 +              hashwrite(pack_file, hdr, hdrlen);
                pack_size += hdrlen;
  
                hdr[pos] = ofs & 127;
                while (ofs >>= 7)
                        hdr[--pos] = 128 | (--ofs & 127);
 -              sha1write(pack_file, hdr + pos, sizeof(hdr) - pos);
 +              hashwrite(pack_file, hdr + pos, sizeof(hdr) - pos);
                pack_size += sizeof(hdr) - pos;
        } else {
                e->depth = 0;
                hdrlen = encode_in_pack_object_header(hdr, sizeof(hdr),
                                                      type, dat->len);
 -              sha1write(pack_file, hdr, hdrlen);
 +              hashwrite(pack_file, hdr, hdrlen);
                pack_size += hdrlen;
        }
  
 -      sha1write(pack_file, out, s.total_out);
 +      hashwrite(pack_file, out, s.total_out);
        pack_size += s.total_out;
  
        e->idx.crc32 = crc32_end(pack_file);
        return 0;
  }
  
 -static void truncate_pack(struct sha1file_checkpoint *checkpoint)
 +static void truncate_pack(struct hashfile_checkpoint *checkpoint)
  {
 -      if (sha1file_truncate(pack_file, checkpoint))
 +      if (hashfile_truncate(pack_file, checkpoint))
                die_errno("cannot truncate pack to skip duplicate");
        pack_size = checkpoint->offset;
  }
@@@ -1233,9 -1231,9 +1233,9 @@@ static void stream_blob(uintmax_t len, 
        struct object_id oid;
        unsigned long hdrlen;
        off_t offset;
 -      git_SHA_CTX c;
 +      git_hash_ctx c;
        git_zstream s;
 -      struct sha1file_checkpoint checkpoint;
 +      struct hashfile_checkpoint checkpoint;
        int status = Z_OK;
  
        /* Determine if we should auto-checkpoint. */
                || (pack_size + 60 + len) < pack_size)
                cycle_packfile();
  
 -      sha1file_checkpoint(pack_file, &checkpoint);
 +      hashfile_checkpoint(pack_file, &checkpoint);
        offset = checkpoint.offset;
  
        hdrlen = xsnprintf((char *)out_buf, out_sz, "blob %" PRIuMAX, len) + 1;
  
 -      git_SHA1_Init(&c);
 -      git_SHA1_Update(&c, out_buf, hdrlen);
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, out_buf, hdrlen);
  
        crc32_begin(pack_file);
  
                        if (!n && feof(stdin))
                                die("EOF in data (%" PRIuMAX " bytes remaining)", len);
  
 -                      git_SHA1_Update(&c, in_buf, n);
 +                      the_hash_algo->update_fn(&c, in_buf, n);
                        s.next_in = in_buf;
                        s.avail_in = n;
                        len -= n;
  
                if (!s.avail_out || status == Z_STREAM_END) {
                        size_t n = s.next_out - out_buf;
 -                      sha1write(pack_file, out_buf, n);
 +                      hashwrite(pack_file, out_buf, n);
                        pack_size += n;
                        s.next_out = out_buf;
                        s.avail_out = out_sz;
                }
        }
        git_deflate_end(&s);
 -      git_SHA1_Final(oid.hash, &c);
 +      the_hash_algo->final_fn(oid.hash, &c);
  
        if (oidout)
                oidcpy(oidout, &oid);
@@@ -1352,25 -1350,25 +1352,25 @@@ static void *gfi_unpack_entry
  {
        enum object_type type;
        struct packed_git *p = all_packs[oe->pack_id];
 -      if (p == pack_data && p->pack_size < (pack_size + 20)) {
 +      if (p == pack_data && p->pack_size < (pack_size + the_hash_algo->rawsz)) {
                /* The object is stored in the packfile we are writing to
                 * and we have modified it since the last time we scanned
                 * back to read a previously written object.  If an old
 -               * window covered [p->pack_size, p->pack_size + 20) its
 +               * window covered [p->pack_size, p->pack_size + rawsz) its
                 * data is stale and is not valid.  Closing all windows
                 * and updating the packfile length ensures we can read
                 * the newly written data.
                 */
                close_pack_windows(p);
 -              sha1flush(pack_file);
 +              hashflush(pack_file);
  
 -              /* We have to offer 20 bytes additional on the end of
 +              /* We have to offer rawsz bytes additional on the end of
                 * the packfile as the core unpacker code assumes the
                 * footer is present at the file end and must promise
 -               * at least 20 bytes within any window it maps.  But
 +               * at least rawsz bytes within any window it maps.  But
                 * we don't actually create the footer here.
                 */
 -              p->pack_size = pack_size + 20;
 +              p->pack_size = pack_size + the_hash_algo->rawsz;
        }
        return unpack_entry(p, oe->idx.offset, &type, sizep);
  }
@@@ -1412,7 -1410,7 +1412,7 @@@ static void load_tree(struct tree_entr
                        die("Can't load tree %s", oid_to_hex(oid));
        } else {
                enum object_type type;
 -              buf = read_sha1_file(oid->hash, &type, &size);
 +              buf = read_object_file(oid, &type, &size);
                if (!buf || type != OBJ_TREE)
                        die("Can't load tree %s", oid_to_hex(oid));
        }
@@@ -1913,7 -1911,7 +1913,7 @@@ static void read_marks(void
                        die("corrupt mark line: %s", line);
                e = find_object(&oid);
                if (!e) {
 -                      enum object_type type = sha1_object_info(oid.hash, NULL);
 +                      enum object_type type = oid_object_info(&oid, NULL);
                        if (type < 0)
                                die("object not found: %s", oid_to_hex(&oid));
                        e = insert_object(&oid);
@@@ -2206,7 -2204,7 +2206,7 @@@ static void construct_path_with_fanout(
                unsigned char fanout, char *path)
  {
        unsigned int i = 0, j = 0;
 -      if (fanout >= 20)
 +      if (fanout >= the_hash_algo->rawsz)
                die("Too large fanout (%u)", fanout);
        while (fanout) {
                path[i++] = hex_sha1[j++];
                path[i++] = '/';
                fanout--;
        }
 -      memcpy(path + i, hex_sha1 + j, GIT_SHA1_HEXSZ - j);
 -      path[i + GIT_SHA1_HEXSZ - j] = '\0';
 +      memcpy(path + i, hex_sha1 + j, the_hash_algo->hexsz - j);
 +      path[i + the_hash_algo->hexsz - j] = '\0';
  }
  
  static uintmax_t do_change_note_fanout(
@@@ -2423,7 -2421,7 +2423,7 @@@ static void file_change_m(const char *p
                else if (oe) {
                        if (oe->type != OBJ_COMMIT)
                                die("Not a commit (actually a %s): %s",
 -                                      typename(oe->type), command_buf.buf);
 +                                      type_name(oe->type), command_buf.buf);
                }
                /*
                 * Accept the sha1 without checking; it expected to be in
                enum object_type expected = S_ISDIR(mode) ?
                                                OBJ_TREE: OBJ_BLOB;
                enum object_type type = oe ? oe->type :
 -                                      sha1_object_info(oid.hash, NULL);
 +                                      oid_object_info(&oid, NULL);
                if (type < 0)
                        die("%s not found: %s",
                                        S_ISDIR(mode) ?  "Tree" : "Blob",
                                        command_buf.buf);
                if (type != expected)
                        die("Not a %s (actually a %s): %s",
 -                              typename(expected), typename(type),
 +                              type_name(expected), type_name(type),
                                command_buf.buf);
        }
  
@@@ -2583,9 -2581,8 +2583,9 @@@ static void note_change_n(const char *p
                oidcpy(&commit_oid, &commit_oe->idx.oid);
        } else if (!get_oid(p, &commit_oid)) {
                unsigned long size;
 -              char *buf = read_object_with_reference(commit_oid.hash,
 -                      commit_type, &size, commit_oid.hash);
 +              char *buf = read_object_with_reference(&commit_oid,
 +                                                     commit_type, &size,
 +                                                     &commit_oid);
                if (!buf || size < 46)
                        die("Not a valid commit: %s", p);
                free(buf);
        } else if (oe) {
                if (oe->type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
 -                              typename(oe->type), command_buf.buf);
 +                              type_name(oe->type), command_buf.buf);
        } else if (!is_null_oid(&oid)) {
 -              enum object_type type = sha1_object_info(oid.hash, NULL);
 +              enum object_type type = oid_object_info(&oid, NULL);
                if (type < 0)
                        die("Blob not found: %s", command_buf.buf);
                if (type != OBJ_BLOB)
                        die("Not a blob (actually a %s): %s",
 -                          typename(type), command_buf.buf);
 +                          type_name(type), command_buf.buf);
        }
  
        construct_path_with_fanout(oid_to_hex(&commit_oid), *old_fanout, path);
@@@ -2654,8 -2651,9 +2654,8 @@@ static void parse_from_existing(struct 
                unsigned long size;
                char *buf;
  
 -              buf = read_object_with_reference(b->oid.hash,
 -                                               commit_type, &size,
 -                                               b->oid.hash);
 +              buf = read_object_with_reference(&b->oid, commit_type, &size,
 +                                               &b->oid);
                parse_from_commit(b, buf, size);
                free(buf);
        }
@@@ -2732,9 -2730,8 +2732,9 @@@ static struct hash_list *parse_merge(un
                        oidcpy(&n->oid, &oe->idx.oid);
                } else if (!get_oid(from, &n->oid)) {
                        unsigned long size;
 -                      char *buf = read_object_with_reference(n->oid.hash,
 -                              commit_type, &size, n->oid.hash);
 +                      char *buf = read_object_with_reference(&n->oid,
 +                                                             commit_type,
 +                                                             &size, &n->oid);
                        if (!buf || size < 46)
                                die("Not a valid commit: %s", from);
                        free(buf);
@@@ -2891,7 -2888,7 +2891,7 @@@ static void parse_new_tag(const char *a
        } else if (!get_oid(from, &oid)) {
                struct object_entry *oe = find_object(&oid);
                if (!oe) {
 -                      type = sha1_object_info(oid.hash, NULL);
 +                      type = oid_object_info(&oid, NULL);
                        if (type < 0)
                                die("Not a valid object: %s", from);
                } else
                    "object %s\n"
                    "type %s\n"
                    "tag %s\n",
 -                  oid_to_hex(&oid), typename(type), t->name);
 +                  oid_to_hex(&oid), type_name(type), t->name);
        if (tagger)
                strbuf_addf(&new_data,
                            "tagger %s\n", tagger);
@@@ -2967,7 -2964,7 +2967,7 @@@ static void cat_blob(struct object_entr
        char *buf;
  
        if (!oe || oe->pack_id == MAX_PACK_ID) {
 -              buf = read_sha1_file(oid->hash, &type, &size);
 +              buf = read_object_file(oid, &type, &size);
        } else {
                type = oe->type;
                buf = gfi_unpack_entry(oe, &size);
                die("Can't read object %s", oid_to_hex(oid));
        if (type != OBJ_BLOB)
                die("Object %s is a %s but a blob was expected.",
 -                  oid_to_hex(oid), typename(type));
 +                  oid_to_hex(oid), type_name(type));
        strbuf_reset(&line);
        strbuf_addf(&line, "%s %s %lu\n", oid_to_hex(oid),
 -                                              typename(type), size);
 +                                              type_name(type), size);
        cat_blob_write(line.buf, line.len);
        strbuf_release(&line);
        cat_blob_write(buf, size);
  
  static void parse_get_mark(const char *p)
  {
-       struct object_entry *oe = oe;
+       struct object_entry *oe;
        char output[GIT_MAX_HEXSZ + 2];
  
        /* get-mark SP <object> LF */
  
  static void parse_cat_blob(const char *p)
  {
-       struct object_entry *oe = oe;
+       struct object_entry *oe;
        struct object_id oid;
  
        /* cat-blob SP <object> LF */
@@@ -3049,7 -3046,7 +3049,7 @@@ static struct object_entry *dereference
        unsigned long size;
        char *buf = NULL;
        if (!oe) {
 -              enum object_type type = sha1_object_info(oid->hash, NULL);
 +              enum object_type type = oid_object_info(oid, NULL);
                if (type < 0)
                        die("object not found: %s", oid_to_hex(oid));
                /* cache it! */
                buf = gfi_unpack_entry(oe, &size);
        } else {
                enum object_type unused;
 -              buf = read_sha1_file(oid->hash, &unused, &size);
 +              buf = read_object_file(oid, &unused, &size);
        }
        if (!buf)
                die("Can't load object %s", oid_to_hex(oid));
diff --combined merge-recursive.c
index 408d30e300742cd68de1e9461e47707779377054,7dad1646921d4f5c503646af40446de2edb09d1f..9c05eb7f700eed0dc3e20a4c22f3a60e0aa21488
@@@ -49,67 -49,6 +49,67 @@@ static unsigned int path_hash(const cha
        return ignore_case ? strihash(path) : strhash(path);
  }
  
 +static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
 +                                                    char *dir)
 +{
 +      struct dir_rename_entry key;
 +
 +      if (dir == NULL)
 +              return NULL;
 +      hashmap_entry_init(&key, strhash(dir));
 +      key.dir = dir;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int dir_rename_cmp(const void *unused_cmp_data,
 +                        const void *entry,
 +                        const void *entry_or_key,
 +                        const void *unused_keydata)
 +{
 +      const struct dir_rename_entry *e1 = entry;
 +      const struct dir_rename_entry *e2 = entry_or_key;
 +
 +      return strcmp(e1->dir, e2->dir);
 +}
 +
 +static void dir_rename_init(struct hashmap *map)
 +{
 +      hashmap_init(map, dir_rename_cmp, NULL, 0);
 +}
 +
 +static void dir_rename_entry_init(struct dir_rename_entry *entry,
 +                                char *directory)
 +{
 +      hashmap_entry_init(entry, strhash(directory));
 +      entry->dir = directory;
 +      entry->non_unique_new_dir = 0;
 +      strbuf_init(&entry->new_dir, 0);
 +      string_list_init(&entry->possible_new_dirs, 0);
 +}
 +
 +static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
 +                                                  char *target_file)
 +{
 +      struct collision_entry key;
 +
 +      hashmap_entry_init(&key, strhash(target_file));
 +      key.target_file = target_file;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int collision_cmp(void *unused_cmp_data,
 +                       const struct collision_entry *e1,
 +                       const struct collision_entry *e2,
 +                       const void *unused_keydata)
 +{
 +      return strcmp(e1->target_file, e2->target_file);
 +}
 +
 +static void collision_init(struct hashmap *map)
 +{
 +      hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
 +}
 +
  static void flush_output(struct merge_options *o)
  {
        if (o->buffer_output < 2 && o->obuf.len) {
@@@ -180,7 -119,6 +180,7 @@@ static int oid_eq(const struct object_i
  
  enum rename_type {
        RENAME_NORMAL = 0,
 +      RENAME_DIR,
        RENAME_DELETE,
        RENAME_ONE_FILE_TO_ONE,
        RENAME_ONE_FILE_TO_TWO,
@@@ -290,7 -228,7 +290,7 @@@ static void output_commit_title(struct 
                strbuf_addf(&o->obuf, "virtual %s\n",
                        merge_remote_util(commit)->name);
        else {
 -              strbuf_add_unique_abbrev(&o->obuf, commit->object.oid.hash,
 +              strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
                                         DEFAULT_ABBREV);
                strbuf_addch(&o->obuf, ' ');
                if (parse_commit(commit) != 0)
@@@ -337,37 -275,32 +337,37 @@@ static void init_tree_desc_from_tree(st
        init_tree_desc(desc, tree->buffer, tree->size);
  }
  
 -static int git_merge_trees(int index_only,
 +static int git_merge_trees(struct merge_options *o,
                           struct tree *common,
                           struct tree *head,
                           struct tree *merge)
  {
        int rc;
        struct tree_desc t[3];
 -      struct unpack_trees_options opts;
  
 -      memset(&opts, 0, sizeof(opts));
 -      if (index_only)
 -              opts.index_only = 1;
 +      memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
 +      if (o->call_depth)
 +              o->unpack_opts.index_only = 1;
        else
 -              opts.update = 1;
 -      opts.merge = 1;
 -      opts.head_idx = 2;
 -      opts.fn = threeway_merge;
 -      opts.src_index = &the_index;
 -      opts.dst_index = &the_index;
 -      setup_unpack_trees_porcelain(&opts, "merge");
 +              o->unpack_opts.update = 1;
 +      o->unpack_opts.merge = 1;
 +      o->unpack_opts.head_idx = 2;
 +      o->unpack_opts.fn = threeway_merge;
 +      o->unpack_opts.src_index = &the_index;
 +      o->unpack_opts.dst_index = &the_index;
 +      setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
  
        init_tree_desc_from_tree(t+0, common);
        init_tree_desc_from_tree(t+1, head);
        init_tree_desc_from_tree(t+2, merge);
  
 -      rc = unpack_trees(3, t, &opts);
 +      rc = unpack_trees(3, t, &o->unpack_opts);
 +      /*
 +       * unpack_trees NULLifies src_index, but it's used in verify_uptodate,
 +       * so set to the new index which will usually have modification
 +       * timestamp info copied over.
 +       */
 +      o->unpack_opts.src_index = &the_index;
        cache_tree_free(&active_cache_tree);
        return rc;
  }
@@@ -402,7 -335,7 +402,7 @@@ struct tree *write_tree_from_memory(str
        return result;
  }
  
 -static int save_files_dirs(const unsigned char *sha1,
 +static int save_files_dirs(const struct object_id *oid,
                struct strbuf *base, const char *path,
                unsigned int mode, int stage, void *context)
  {
@@@ -427,21 -360,6 +427,21 @@@ static void get_files_dirs(struct merge
        read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
  }
  
 +static int get_tree_entry_if_blob(struct tree *tree,
 +                                const char *path,
 +                                struct object_id *hashy,
 +                                unsigned int *mode_o)
 +{
 +      int ret;
 +
 +      ret = get_tree_entry(&tree->object.oid, path, hashy, mode_o);
 +      if (S_ISDIR(*mode_o)) {
 +              oidcpy(hashy, &null_oid);
 +              *mode_o = 0;
 +      }
 +      return ret;
 +}
 +
  /*
   * Returns an index_entry instance which doesn't have to correspond to
   * a real cache entry in Git's index.
@@@ -452,12 -370,12 +452,12 @@@ static struct stage_data *insert_stage_
  {
        struct string_list_item *item;
        struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 -      get_tree_entry(o->object.oid.hash, path,
 -                      e->stages[1].oid.hash, &e->stages[1].mode);
 -      get_tree_entry(a->object.oid.hash, path,
 -                      e->stages[2].oid.hash, &e->stages[2].mode);
 -      get_tree_entry(b->object.oid.hash, path,
 -                      e->stages[3].oid.hash, &e->stages[3].mode);
 +      get_tree_entry_if_blob(o, path,
 +                             &e->stages[1].oid, &e->stages[1].mode);
 +      get_tree_entry_if_blob(a, path,
 +                             &e->stages[2].oid, &e->stages[2].mode);
 +      get_tree_entry_if_blob(b, path,
 +                             &e->stages[3].oid, &e->stages[3].mode);
        item = string_list_insert(entries, path);
        item->util = e;
        return e;
@@@ -595,31 -513,80 +595,31 @@@ static void record_df_conflict_files(st
  
  struct rename {
        struct diff_filepair *pair;
 +      /*
 +       * Purpose of src_entry and dst_entry:
 +       *
 +       * If 'before' is renamed to 'after' then src_entry will contain
 +       * the versions of 'before' from the merge_base, HEAD, and MERGE in
 +       * stages 1, 2, and 3; dst_entry will contain the respective
 +       * versions of 'after' in corresponding locations.  Thus, we have a
 +       * total of six modes and oids, though some will be null.  (Stage 0
 +       * is ignored; we're interested in handling conflicts.)
 +       *
 +       * Since we don't turn on break-rewrites by default, neither
 +       * src_entry nor dst_entry can have all three of their stages have
 +       * non-null oids, meaning at most four of the six will be non-null.
 +       * Also, since this is a rename, both src_entry and dst_entry will
 +       * have at least one non-null oid, meaning at least two will be
 +       * non-null.  Of the six oids, a typical rename will have three be
 +       * non-null.  Only two implies a rename/delete, and four implies a
 +       * rename/add.
 +       */
        struct stage_data *src_entry;
        struct stage_data *dst_entry;
 +      unsigned add_turned_into_rename:1;
        unsigned processed:1;
  };
  
 -/*
 - * Get information of all renames which occurred between 'o_tree' and
 - * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 - * 'b_tree') to be able to associate the correct cache entries with
 - * the rename information. 'tree' is always equal to either a_tree or b_tree.
 - */
 -static struct string_list *get_renames(struct merge_options *o,
 -                                     struct tree *tree,
 -                                     struct tree *o_tree,
 -                                     struct tree *a_tree,
 -                                     struct tree *b_tree,
 -                                     struct string_list *entries)
 -{
 -      int i;
 -      struct string_list *renames;
 -      struct diff_options opts;
 -
 -      renames = xcalloc(1, sizeof(struct string_list));
 -      if (!o->detect_rename)
 -              return renames;
 -
 -      diff_setup(&opts);
 -      opts.flags.recursive = 1;
 -      opts.flags.rename_empty = 0;
 -      opts.detect_rename = DIFF_DETECT_RENAME;
 -      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 -                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 -                          1000;
 -      opts.rename_score = o->rename_score;
 -      opts.show_rename_progress = o->show_rename_progress;
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_setup_done(&opts);
 -      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 -      diffcore_std(&opts);
 -      if (opts.needed_rename_limit > o->needed_rename_limit)
 -              o->needed_rename_limit = opts.needed_rename_limit;
 -      for (i = 0; i < diff_queued_diff.nr; ++i) {
 -              struct string_list_item *item;
 -              struct rename *re;
 -              struct diff_filepair *pair = diff_queued_diff.queue[i];
 -              if (pair->status != 'R') {
 -                      diff_free_filepair(pair);
 -                      continue;
 -              }
 -              re = xmalloc(sizeof(*re));
 -              re->processed = 0;
 -              re->pair = pair;
 -              item = string_list_lookup(entries, re->pair->one->path);
 -              if (!item)
 -                      re->src_entry = insert_stage_data(re->pair->one->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->src_entry = item->util;
 -
 -              item = string_list_lookup(entries, re->pair->two->path);
 -              if (!item)
 -                      re->dst_entry = insert_stage_data(re->pair->two->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->dst_entry = item->util;
 -              item = string_list_insert(renames, pair->one->path);
 -              item->util = re;
 -      }
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_queued_diff.nr = 0;
 -      diff_flush(&opts);
 -      return renames;
 -}
 -
  static int update_stages(struct merge_options *opt, const char *path,
                         const struct diff_filespec *o,
                         const struct diff_filespec *a,
        return 0;
  }
  
 +static int update_stages_for_stage_data(struct merge_options *opt,
 +                                      const char *path,
 +                                      const struct stage_data *stage_data)
 +{
 +      struct diff_filespec o, a, b;
 +
 +      o.mode = stage_data->stages[1].mode;
 +      oidcpy(&o.oid, &stage_data->stages[1].oid);
 +
 +      a.mode = stage_data->stages[2].mode;
 +      oidcpy(&a.oid, &stage_data->stages[2].oid);
 +
 +      b.mode = stage_data->stages[3].mode;
 +      oidcpy(&b.oid, &stage_data->stages[3].oid);
 +
 +      return update_stages(opt, path,
 +                           is_null_oid(&o.oid) ? NULL : &o,
 +                           is_null_oid(&a.oid) ? NULL : &a,
 +                           is_null_oid(&b.oid) ? NULL : &b);
 +}
 +
  static void update_entry(struct stage_data *entry,
                         struct diff_filespec *o,
                         struct diff_filespec *a,
@@@ -800,20 -746,6 +800,20 @@@ static int would_lose_untracked(const c
        return !was_tracked(path) && file_exists(path);
  }
  
 +static int was_dirty(struct merge_options *o, const char *path)
 +{
 +      struct cache_entry *ce;
 +      int dirty = 1;
 +
 +      if (o->call_depth || !was_tracked(path))
 +              return !dirty;
 +
 +      ce = cache_file_exists(path, strlen(path), ignore_case);
 +      dirty = (ce->ce_stat_data.sd_mtime.sec > 0 &&
 +               verify_uptodate(ce, &o->unpack_opts) != 0);
 +      return dirty;
 +}
 +
  static int make_room_for_path(struct merge_options *o, const char *path)
  {
        int status, i;
@@@ -891,7 -823,7 +891,7 @@@ static int update_file_flags(struct mer
                        goto update_index;
                }
  
 -              buf = read_sha1_file(oid->hash, &type, &size);
 +              buf = read_object_file(oid, &type, &size);
                if (!buf)
                        return err(o, _("cannot read object %s '%s'"), oid_to_hex(oid), path);
                if (type != OBJ_BLOB) {
@@@ -1077,9 -1009,8 +1077,9 @@@ static int merge_file_1(struct merge_op
                        if ((merge_status < 0) || !result_buf.ptr)
                                ret = err(o, _("Failed to execute internal merge"));
  
 -                      if (!ret && write_sha1_file(result_buf.ptr, result_buf.size,
 -                                                  blob_type, result->oid.hash))
 +                      if (!ret &&
 +                          write_object_file(result_buf.ptr, result_buf.size,
 +                                            blob_type, &result->oid))
                                ret = err(o, _("Unable to add %s to database"),
                                          a->path);
  
@@@ -1163,38 -1094,6 +1163,38 @@@ static int merge_file_one(struct merge_
        return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
  }
  
 +static int conflict_rename_dir(struct merge_options *o,
 +                             struct diff_filepair *pair,
 +                             const char *rename_branch,
 +                             const char *other_branch)
 +{
 +      const struct diff_filespec *dest = pair->two;
 +
 +      if (!o->call_depth && would_lose_untracked(dest->path)) {
 +              char *alt_path = unique_path(o, dest->path, rename_branch);
 +
 +              output(o, 1, _("Error: Refusing to lose untracked file at %s; "
 +                             "writing to %s instead."),
 +                     dest->path, alt_path);
 +              /*
 +               * Write the file in worktree at alt_path, but not in the
 +               * index.  Instead, write to dest->path for the index but
 +               * only at the higher appropriate stage.
 +               */
 +              if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
 +                      return -1;
 +              free(alt_path);
 +              return update_stages(o, dest->path, NULL,
 +                                   rename_branch == o->branch1 ? dest : NULL,
 +                                   rename_branch == o->branch1 ? NULL : dest);
 +      }
 +
 +      /* Update dest->path both in index and in worktree */
 +      if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
 +              return -1;
 +      return 0;
 +}
 +
  static int handle_change_delete(struct merge_options *o,
                                 const char *path, const char *old_path,
                                 const struct object_id *o_oid, int o_mode,
        const char *update_path = path;
        int ret = 0;
  
 -      if (dir_in_way(path, !o->call_depth, 0)) {
 +      if (dir_in_way(path, !o->call_depth, 0) ||
 +          (!o->call_depth && would_lose_untracked(path))) {
                update_path = alt_path = unique_path(o, path, change_branch);
        }
  
@@@ -1324,34 -1222,17 +1324,34 @@@ static int handle_file(struct merge_opt
  
        add = filespec_from_entry(&other, dst_entry, stage ^ 1);
        if (add) {
 +              int ren_src_was_dirty = was_dirty(o, rename->path);
                char *add_name = unique_path(o, rename->path, other_branch);
                if (update_file(o, 0, &add->oid, add->mode, add_name))
                        return -1;
  
 -              remove_file(o, 0, rename->path, 0);
 +              if (ren_src_was_dirty) {
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             rename->path);
 +              }
 +              /*
 +               * Because the double negatives somehow keep confusing me...
 +               *    1) update_wd iff !ren_src_was_dirty.
 +               *    2) no_wd iff !update_wd
 +               *    3) so, no_wd == !!ren_src_was_dirty == ren_src_was_dirty
 +               */
 +              remove_file(o, 0, rename->path, ren_src_was_dirty);
                dst_name = unique_path(o, rename->path, cur_branch);
        } else {
                if (dir_in_way(rename->path, !o->call_depth, 0)) {
                        dst_name = unique_path(o, rename->path, cur_branch);
                        output(o, 1, _("%s is a directory in %s adding as %s instead"),
                               rename->path, other_branch, dst_name);
 +              } else if (!o->call_depth &&
 +                         would_lose_untracked(rename->path)) {
 +                      dst_name = unique_path(o, rename->path, cur_branch);
 +                      output(o, 1, _("Refusing to lose untracked file at %s; "
 +                                     "adding as %s instead"),
 +                             rename->path, dst_name);
                }
        }
        if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
@@@ -1477,43 -1358,11 +1477,43 @@@ static int conflict_rename_rename_2to1(
                char *new_path2 = unique_path(o, path, ci->branch2);
                output(o, 1, _("Renaming %s to %s and %s to %s instead"),
                       a->path, new_path1, b->path, new_path2);
 -              remove_file(o, 0, path, 0);
 +              if (was_dirty(o, path))
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             path);
 +              else if (would_lose_untracked(path))
 +                      /*
 +                       * Only way we get here is if both renames were from
 +                       * a directory rename AND user had an untracked file
 +                       * at the location where both files end up after the
 +                       * two directory renames.  See testcase 10d of t6043.
 +                       */
 +                      output(o, 1, _("Refusing to lose untracked file at "
 +                                     "%s, even though it's in the way."),
 +                             path);
 +              else
 +                      remove_file(o, 0, path, 0);
                ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
                if (!ret)
                        ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
                                          new_path2);
 +              /*
 +               * unpack_trees() actually populates the index for us for
 +               * "normal" rename/rename(2to1) situtations so that the
 +               * correct entries are at the higher stages, which would
 +               * make the call below to update_stages_for_stage_data
 +               * unnecessary.  However, if either of the renames came
 +               * from a directory rename, then unpack_trees() will not
 +               * have gotten the right data loaded into the index, so we
 +               * need to do so now.  (While it'd be tempting to move this
 +               * call to update_stages_for_stage_data() to
 +               * apply_directory_rename_modifications(), that would break
 +               * our intermediate calls to would_lose_untracked() since
 +               * those rely on the current in-memory index.  See also the
 +               * big "NOTE" in update_stages()).
 +               */
 +              if (update_stages_for_stage_data(o, path, ci->dst_entry1))
 +                      ret = -1;
 +
                free(new_path2);
                free(new_path1);
        }
        return ret;
  }
  
 +/*
 + * Get the diff_filepairs changed between o_tree and tree.
 + */
 +static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 +                                             struct tree *o_tree,
 +                                             struct tree *tree)
 +{
 +      struct diff_queue_struct *ret;
 +      struct diff_options opts;
 +
 +      diff_setup(&opts);
 +      opts.flags.recursive = 1;
 +      opts.flags.rename_empty = 0;
 +      opts.detect_rename = DIFF_DETECT_RENAME;
 +      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 +                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 +                          1000;
 +      opts.rename_score = o->rename_score;
 +      opts.show_rename_progress = o->show_rename_progress;
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_setup_done(&opts);
 +      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 +      diffcore_std(&opts);
 +      if (opts.needed_rename_limit > o->needed_rename_limit)
 +              o->needed_rename_limit = opts.needed_rename_limit;
 +
 +      ret = xmalloc(sizeof(*ret));
 +      *ret = diff_queued_diff;
 +
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_queued_diff.nr = 0;
 +      diff_queued_diff.queue = NULL;
 +      diff_flush(&opts);
 +      return ret;
 +}
 +
 +static int tree_has_path(struct tree *tree, const char *path)
 +{
 +      struct object_id hashy;
 +      unsigned int mode_o;
 +
 +      return !get_tree_entry(&tree->object.oid, path,
 +                             &hashy, &mode_o);
 +}
 +
 +/*
 + * Return a new string that replaces the beginning portion (which matches
 + * entry->dir), with entry->new_dir.  In perl-speak:
 + *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
 + * NOTE:
 + *   Caller must ensure that old_path starts with entry->dir + '/'.
 + */
 +static char *apply_dir_rename(struct dir_rename_entry *entry,
 +                            const char *old_path)
 +{
 +      struct strbuf new_path = STRBUF_INIT;
 +      int oldlen, newlen;
 +
 +      if (entry->non_unique_new_dir)
 +              return NULL;
 +
 +      oldlen = strlen(entry->dir);
 +      newlen = entry->new_dir.len + (strlen(old_path) - oldlen) + 1;
 +      strbuf_grow(&new_path, newlen);
 +      strbuf_addbuf(&new_path, &entry->new_dir);
 +      strbuf_addstr(&new_path, &old_path[oldlen]);
 +
 +      return strbuf_detach(&new_path, NULL);
 +}
 +
 +static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 +                                  char **old_dir, char **new_dir)
 +{
 +      char *end_of_old, *end_of_new;
 +      int old_len, new_len;
 +
 +      *old_dir = NULL;
 +      *new_dir = NULL;
 +
 +      /*
 +       * For
 +       *    "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
 +       * the "e/foo.c" part is the same, we just want to know that
 +       *    "a/b/c/d" was renamed to "a/b/some/thing/else"
 +       * so, for this example, this function returns "a/b/c/d" in
 +       * *old_dir and "a/b/some/thing/else" in *new_dir.
 +       *
 +       * Also, if the basename of the file changed, we don't care.  We
 +       * want to know which portion of the directory, if any, changed.
 +       */
 +      end_of_old = strrchr(old_path, '/');
 +      end_of_new = strrchr(new_path, '/');
 +
 +      if (end_of_old == NULL || end_of_new == NULL)
 +              return;
 +      while (*--end_of_new == *--end_of_old &&
 +             end_of_old != old_path &&
 +             end_of_new != new_path)
 +              ; /* Do nothing; all in the while loop */
 +      /*
 +       * We've found the first non-matching character in the directory
 +       * paths.  That means the current directory we were comparing
 +       * represents the rename.  Move end_of_old and end_of_new back
 +       * to the full directory name.
 +       */
 +      if (*end_of_old == '/')
 +              end_of_old++;
 +      if (*end_of_old != '/')
 +              end_of_new++;
 +      end_of_old = strchr(end_of_old, '/');
 +      end_of_new = strchr(end_of_new, '/');
 +
 +      /*
 +       * It may have been the case that old_path and new_path were the same
 +       * directory all along.  Don't claim a rename if they're the same.
 +       */
 +      old_len = end_of_old - old_path;
 +      new_len = end_of_new - new_path;
 +
 +      if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
 +              *old_dir = xstrndup(old_path, old_len);
 +              *new_dir = xstrndup(new_path, new_len);
 +      }
 +}
 +
 +static void remove_hashmap_entries(struct hashmap *dir_renames,
 +                                 struct string_list *items_to_remove)
 +{
 +      int i;
 +      struct dir_rename_entry *entry;
 +
 +      for (i = 0; i < items_to_remove->nr; i++) {
 +              entry = items_to_remove->items[i].util;
 +              hashmap_remove(dir_renames, entry, NULL);
 +      }
 +      string_list_clear(items_to_remove, 0);
 +}
 +
 +/*
 + * See if there is a directory rename for path, and if there are any file
 + * level conflicts for the renamed location.  If there is a rename and
 + * there are no conflicts, return the new name.  Otherwise, return NULL.
 + */
 +static char *handle_path_level_conflicts(struct merge_options *o,
 +                                       const char *path,
 +                                       struct dir_rename_entry *entry,
 +                                       struct hashmap *collisions,
 +                                       struct tree *tree)
 +{
 +      char *new_path = NULL;
 +      struct collision_entry *collision_ent;
 +      int clean = 1;
 +      struct strbuf collision_paths = STRBUF_INIT;
 +
 +      /*
 +       * entry has the mapping of old directory name to new directory name
 +       * that we want to apply to path.
 +       */
 +      new_path = apply_dir_rename(entry, path);
 +
 +      if (!new_path) {
 +              /* This should only happen when entry->non_unique_new_dir set */
 +              if (!entry->non_unique_new_dir)
 +                      BUG("entry->non_unqiue_dir not set and !new_path");
 +              output(o, 1, _("CONFLICT (directory rename split): "
 +                             "Unclear where to place %s because directory "
 +                             "%s was renamed to multiple other directories, "
 +                             "with no destination getting a majority of the "
 +                             "files."),
 +                     path, entry->dir);
 +              clean = 0;
 +              return NULL;
 +      }
 +
 +      /*
 +       * The caller needs to have ensured that it has pre-populated
 +       * collisions with all paths that map to new_path.  Do a quick check
 +       * to ensure that's the case.
 +       */
 +      collision_ent = collision_find_entry(collisions, new_path);
 +      if (collision_ent == NULL)
 +              BUG("collision_ent is NULL");
 +
 +      /*
 +       * Check for one-sided add/add/.../add conflicts, i.e.
 +       * where implicit renames from the other side doing
 +       * directory rename(s) can affect this side of history
 +       * to put multiple paths into the same location.  Warn
 +       * and bail on directory renames for such paths.
 +       */
 +      if (collision_ent->reported_already) {
 +              clean = 0;
 +      } else if (tree_has_path(tree, new_path)) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Existing "
 +                             "file/dir at %s in the way of implicit "
 +                             "directory rename(s) putting the following "
 +                             "path(s) there: %s."),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      } else if (collision_ent->source_files.nr > 1) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
 +                             "more than one path to %s; implicit directory "
 +                             "renames tried to put these paths there: %s"),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      }
 +
 +      /* Free memory we no longer need */
 +      strbuf_release(&collision_paths);
 +      if (!clean && new_path) {
 +              free(new_path);
 +              return NULL;
 +      }
 +
 +      return new_path;
 +}
 +
 +/*
 + * There are a couple things we want to do at the directory level:
 + *   1. Check for both sides renaming to the same thing, in order to avoid
 + *      implicit renaming of files that should be left in place.  (See
 + *      testcase 6b in t6043 for details.)
 + *   2. Prune directory renames if there are still files left in the
 + *      the original directory.  These represent a partial directory rename,
 + *      i.e. a rename where only some of the files within the directory
 + *      were renamed elsewhere.  (Technically, this could be done earlier
 + *      in get_directory_renames(), except that would prevent us from
 + *      doing the previous check and thus failing testcase 6b.)
 + *   3. Check for rename/rename(1to2) conflicts (at the directory level).
 + *      In the future, we could potentially record this info as well and
 + *      omit reporting rename/rename(1to2) conflicts for each path within
 + *      the affected directories, thus cleaning up the merge output.
 + *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
 + *         directory level, because merging directories is fine.  If it
 + *         causes conflicts for files within those merged directories, then
 + *         that should be detected at the individual path level.
 + */
 +static void handle_directory_level_conflicts(struct merge_options *o,
 +                                           struct hashmap *dir_re_head,
 +                                           struct tree *head,
 +                                           struct hashmap *dir_re_merge,
 +                                           struct tree *merge)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *head_ent;
 +      struct dir_rename_entry *merge_ent;
 +
 +      struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
 +      struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
 +
 +      hashmap_iter_init(dir_re_head, &iter);
 +      while ((head_ent = hashmap_iter_next(&iter))) {
 +              merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
 +              if (merge_ent &&
 +                  !head_ent->non_unique_new_dir &&
 +                  !merge_ent->non_unique_new_dir &&
 +                  !strbuf_cmp(&head_ent->new_dir, &merge_ent->new_dir)) {
 +                      /* 1. Renamed identically; remove it from both sides */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              } else if (tree_has_path(head, head_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +
 +      hashmap_iter_init(dir_re_merge, &iter);
 +      while ((merge_ent = hashmap_iter_next(&iter))) {
 +              head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
 +              if (tree_has_path(merge, merge_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +              } else if (head_ent &&
 +                         !head_ent->non_unique_new_dir &&
 +                         !merge_ent->non_unique_new_dir) {
 +                      /* 3. rename/rename(1to2) */
 +                      /*
 +                       * We can assume it's not rename/rename(1to1) because
 +                       * that was case (1), already checked above.  So we
 +                       * know that head_ent->new_dir and merge_ent->new_dir
 +                       * are different strings.
 +                       */
 +                      output(o, 1, _("CONFLICT (rename/rename): "
 +                                     "Rename directory %s->%s in %s. "
 +                                     "Rename directory %s->%s in %s"),
 +                             head_ent->dir, head_ent->new_dir.buf, o->branch1,
 +                             head_ent->dir, merge_ent->new_dir.buf, o->branch2);
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +}
 +
 +static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
 +                                           struct tree *tree)
 +{
 +      struct hashmap *dir_renames;
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *entry;
 +      int i;
 +
 +      /*
 +       * Typically, we think of a directory rename as all files from a
 +       * certain directory being moved to a target directory.  However,
 +       * what if someone first moved two files from the original
 +       * directory in one commit, and then renamed the directory
 +       * somewhere else in a later commit?  At merge time, we just know
 +       * that files from the original directory went to two different
 +       * places, and that the bulk of them ended up in the same place.
 +       * We want each directory rename to represent where the bulk of the
 +       * files from that directory end up; this function exists to find
 +       * where the bulk of the files went.
 +       *
 +       * The first loop below simply iterates through the list of file
 +       * renames, finding out how often each directory rename pair
 +       * possibility occurs.
 +       */
 +      dir_renames = xmalloc(sizeof(struct hashmap));
 +      dir_rename_init(dir_renames);
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              int *count;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *old_dir, *new_dir;
 +
 +              /* File not part of directory rename if it wasn't renamed */
 +              if (pair->status != 'R')
 +                      continue;
 +
 +              get_renamed_dir_portion(pair->one->path, pair->two->path,
 +                                      &old_dir,        &new_dir);
 +              if (!old_dir)
 +                      /* Directory didn't change at all; ignore this one. */
 +                      continue;
 +
 +              entry = dir_rename_find_entry(dir_renames, old_dir);
 +              if (!entry) {
 +                      entry = xmalloc(sizeof(struct dir_rename_entry));
 +                      dir_rename_entry_init(entry, old_dir);
 +                      hashmap_put(dir_renames, entry);
 +              } else {
 +                      free(old_dir);
 +              }
 +              item = string_list_lookup(&entry->possible_new_dirs, new_dir);
 +              if (!item) {
 +                      item = string_list_insert(&entry->possible_new_dirs,
 +                                                new_dir);
 +                      item->util = xcalloc(1, sizeof(int));
 +              } else {
 +                      free(new_dir);
 +              }
 +              count = item->util;
 +              *count += 1;
 +      }
 +
 +      /*
 +       * For each directory with files moved out of it, we find out which
 +       * target directory received the most files so we can declare it to
 +       * be the "winning" target location for the directory rename.  This
 +       * winner gets recorded in new_dir.  If there is no winner
 +       * (multiple target directories received the same number of files),
 +       * we set non_unique_new_dir.  Once we've determined the winner (or
 +       * that there is no winner), we no longer need possible_new_dirs.
 +       */
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((entry = hashmap_iter_next(&iter))) {
 +              int max = 0;
 +              int bad_max = 0;
 +              char *best = NULL;
 +
 +              for (i = 0; i < entry->possible_new_dirs.nr; i++) {
 +                      int *count = entry->possible_new_dirs.items[i].util;
 +
 +                      if (*count == max)
 +                              bad_max = max;
 +                      else if (*count > max) {
 +                              max = *count;
 +                              best = entry->possible_new_dirs.items[i].string;
 +                      }
 +              }
 +              if (bad_max == max)
 +                      entry->non_unique_new_dir = 1;
 +              else {
 +                      assert(entry->new_dir.len == 0);
 +                      strbuf_addstr(&entry->new_dir, best);
 +              }
 +              /*
 +               * The relevant directory sub-portion of the original full
 +               * filepaths were xstrndup'ed before inserting into
 +               * possible_new_dirs, and instead of manually iterating the
 +               * list and free'ing each, just lie and tell
 +               * possible_new_dirs that it did the strdup'ing so that it
 +               * will free them for us.
 +               */
 +              entry->possible_new_dirs.strdup_strings = 1;
 +              string_list_clear(&entry->possible_new_dirs, 1);
 +      }
 +
 +      return dir_renames;
 +}
 +
 +static struct dir_rename_entry *check_dir_renamed(const char *path,
 +                                                struct hashmap *dir_renames)
 +{
 +      char temp[PATH_MAX];
 +      char *end;
 +      struct dir_rename_entry *entry;
 +
 +      strcpy(temp, path);
 +      while ((end = strrchr(temp, '/'))) {
 +              *end = '\0';
 +              entry = dir_rename_find_entry(dir_renames, temp);
 +              if (entry)
 +                      return entry;
 +      }
 +      return NULL;
 +}
 +
 +static void compute_collisions(struct hashmap *collisions,
 +                             struct hashmap *dir_renames,
 +                             struct diff_queue_struct *pairs)
 +{
 +      int i;
 +
 +      /*
 +       * Multiple files can be mapped to the same path due to directory
 +       * renames done by the other side of history.  Since that other
 +       * side of history could have merged multiple directories into one,
 +       * if our side of history added the same file basename to each of
 +       * those directories, then all N of them would get implicitly
 +       * renamed by the directory rename detection into the same path,
 +       * and we'd get an add/add/.../add conflict, and all those adds
 +       * from *this* side of history.  This is not representable in the
 +       * index, and users aren't going to easily be able to make sense of
 +       * it.  So we need to provide a good warning about what's
 +       * happening, and fall back to no-directory-rename detection
 +       * behavior for those paths.
 +       *
 +       * See testcases 9e and all of section 5 from t6043 for examples.
 +       */
 +      collision_init(collisions);
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct dir_rename_entry *dir_rename_ent;
 +              struct collision_entry *collision_ent;
 +              char *new_path;
 +              struct diff_filepair *pair = pairs->queue[i];
 +
 +              if (pair->status != 'A' && pair->status != 'R')
 +                      continue;
 +              dir_rename_ent = check_dir_renamed(pair->two->path,
 +                                                 dir_renames);
 +              if (!dir_rename_ent)
 +                      continue;
 +
 +              new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
 +              if (!new_path)
 +                      /*
 +                       * dir_rename_ent->non_unique_new_path is true, which
 +                       * means there is no directory rename for us to use,
 +                       * which means it won't cause us any additional
 +                       * collisions.
 +                       */
 +                      continue;
 +              collision_ent = collision_find_entry(collisions, new_path);
 +              if (!collision_ent) {
 +                      collision_ent = xcalloc(1,
 +                                              sizeof(struct collision_entry));
 +                      hashmap_entry_init(collision_ent, strhash(new_path));
 +                      hashmap_put(collisions, collision_ent);
 +                      collision_ent->target_file = new_path;
 +              } else {
 +                      free(new_path);
 +              }
 +              string_list_insert(&collision_ent->source_files,
 +                                 pair->two->path);
 +      }
 +}
 +
 +static char *check_for_directory_rename(struct merge_options *o,
 +                                      const char *path,
 +                                      struct tree *tree,
 +                                      struct hashmap *dir_renames,
 +                                      struct hashmap *dir_rename_exclusions,
 +                                      struct hashmap *collisions,
 +                                      int *clean_merge)
 +{
 +      char *new_path = NULL;
 +      struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
 +      struct dir_rename_entry *oentry = NULL;
 +
 +      if (!entry)
 +              return new_path;
 +
 +      /*
 +       * This next part is a little weird.  We do not want to do an
 +       * implicit rename into a directory we renamed on our side, because
 +       * that will result in a spurious rename/rename(1to2) conflict.  An
 +       * example:
 +       *   Base commit: dumbdir/afile, otherdir/bfile
 +       *   Side 1:      smrtdir/afile, otherdir/bfile
 +       *   Side 2:      dumbdir/afile, dumbdir/bfile
 +       * Here, while working on Side 1, we could notice that otherdir was
 +       * renamed/merged to dumbdir, and change the diff_filepair for
 +       * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
 +       * 2 will notice the rename from dumbdir to smrtdir, and do the
 +       * transitive rename to move it from dumbdir/bfile to
 +       * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
 +       * smrtdir, a rename/rename(1to2) conflict.  We really just want
 +       * the file to end up in smrtdir.  And the way to achieve that is
 +       * to not let Side1 do the rename to dumbdir, since we know that is
 +       * the source of one of our directory renames.
 +       *
 +       * That's why oentry and dir_rename_exclusions is here.
 +       *
 +       * As it turns out, this also prevents N-way transient rename
 +       * confusion; See testcases 9c and 9d of t6043.
 +       */
 +      oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir.buf);
 +      if (oentry) {
 +              output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
 +                             "to %s, because %s itself was renamed."),
 +                     entry->dir, entry->new_dir.buf, path, entry->new_dir.buf);
 +      } else {
 +              new_path = handle_path_level_conflicts(o, path, entry,
 +                                                     collisions, tree);
 +              *clean_merge &= (new_path != NULL);
 +      }
 +
 +      return new_path;
 +}
 +
 +static void apply_directory_rename_modifications(struct merge_options *o,
 +                                               struct diff_filepair *pair,
 +                                               char *new_path,
 +                                               struct rename *re,
 +                                               struct tree *tree,
 +                                               struct tree *o_tree,
 +                                               struct tree *a_tree,
 +                                               struct tree *b_tree,
 +                                               struct string_list *entries,
 +                                               int *clean)
 +{
 +      struct string_list_item *item;
 +      int stage = (tree == a_tree ? 2 : 3);
 +      int update_wd;
 +
 +      /*
 +       * In all cases where we can do directory rename detection,
 +       * unpack_trees() will have read pair->two->path into the
 +       * index and the working copy.  We need to remove it so that
 +       * we can instead place it at new_path.  It is guaranteed to
 +       * not be untracked (unpack_trees() would have errored out
 +       * saying the file would have been overwritten), but it might
 +       * be dirty, though.
 +       */
 +      update_wd = !was_dirty(o, pair->two->path);
 +      if (!update_wd)
 +              output(o, 1, _("Refusing to lose dirty file at %s"),
 +                     pair->two->path);
 +      remove_file(o, 1, pair->two->path, !update_wd);
 +
 +      /* Find or create a new re->dst_entry */
 +      item = string_list_lookup(entries, new_path);
 +      if (item) {
 +              /*
 +               * Since we're renaming on this side of history, and it's
 +               * due to a directory rename on the other side of history
 +               * (which we only allow when the directory in question no
 +               * longer exists on the other side of history), the
 +               * original entry for re->dst_entry is no longer
 +               * necessary...
 +               */
 +              re->dst_entry->processed = 1;
 +
 +              /*
 +               * ...because we'll be using this new one.
 +               */
 +              re->dst_entry = item->util;
 +      } else {
 +              /*
 +               * re->dst_entry is for the before-dir-rename path, and we
 +               * need it to hold information for the after-dir-rename
 +               * path.  Before creating a new entry, we need to mark the
 +               * old one as unnecessary (...unless it is shared by
 +               * src_entry, i.e. this didn't use to be a rename, in which
 +               * case we can just allow the normal processing to happen
 +               * for it).
 +               */
 +              if (pair->status == 'R')
 +                      re->dst_entry->processed = 1;
 +
 +              re->dst_entry = insert_stage_data(new_path,
 +                                                o_tree, a_tree, b_tree,
 +                                                entries);
 +              item = string_list_insert(entries, new_path);
 +              item->util = re->dst_entry;
 +      }
 +
 +      /*
 +       * Update the stage_data with the information about the path we are
 +       * moving into place.  That slot will be empty and available for us
 +       * to write to because of the collision checks in
 +       * handle_path_level_conflicts().  In other words,
 +       * re->dst_entry->stages[stage].oid will be the null_oid, so it's
 +       * open for us to write to.
 +       *
 +       * It may be tempting to actually update the index at this point as
 +       * well, using update_stages_for_stage_data(), but as per the big
 +       * "NOTE" in update_stages(), doing so will modify the current
 +       * in-memory index which will break calls to would_lose_untracked()
 +       * that we need to make.  Instead, we need to just make sure that
 +       * the various conflict_rename_*() functions update the index
 +       * explicitly rather than relying on unpack_trees() to have done it.
 +       */
 +      get_tree_entry(&tree->object.oid,
 +                     pair->two->path,
 +                     &re->dst_entry->stages[stage].oid,
 +                     &re->dst_entry->stages[stage].mode);
 +
 +      /* Update pair status */
 +      if (pair->status == 'A') {
 +              /*
 +               * Recording rename information for this add makes it look
 +               * like a rename/delete conflict.  Make sure we can
 +               * correctly handle this as an add that was moved to a new
 +               * directory instead of reporting a rename/delete conflict.
 +               */
 +              re->add_turned_into_rename = 1;
 +      }
 +      /*
 +       * We don't actually look at pair->status again, but it seems
 +       * pedagogically correct to adjust it.
 +       */
 +      pair->status = 'R';
 +
 +      /*
 +       * Finally, record the new location.
 +       */
 +      pair->two->path = new_path;
 +}
 +
 +/*
 + * Get information of all renames which occurred in 'pairs', making use of
 + * any implicit directory renames inferred from the other side of history.
 + * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
 + * to be able to associate the correct cache entries with the rename
 + * information; tree is always equal to either a_tree or b_tree.
 + */
 +static struct string_list *get_renames(struct merge_options *o,
 +                                     struct diff_queue_struct *pairs,
 +                                     struct hashmap *dir_renames,
 +                                     struct hashmap *dir_rename_exclusions,
 +                                     struct tree *tree,
 +                                     struct tree *o_tree,
 +                                     struct tree *a_tree,
 +                                     struct tree *b_tree,
 +                                     struct string_list *entries,
 +                                     int *clean_merge)
 +{
 +      int i;
 +      struct hashmap collisions;
 +      struct hashmap_iter iter;
 +      struct collision_entry *e;
 +      struct string_list *renames;
 +
 +      compute_collisions(&collisions, dir_renames, pairs);
 +      renames = xcalloc(1, sizeof(struct string_list));
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              struct rename *re;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *new_path; /* non-NULL only with directory renames */
 +
 +              if (pair->status != 'A' && pair->status != 'R') {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +              new_path = check_for_directory_rename(o, pair->two->path, tree,
 +                                                    dir_renames,
 +                                                    dir_rename_exclusions,
 +                                                    &collisions,
 +                                                    clean_merge);
 +              if (pair->status != 'R' && !new_path) {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +
 +              re = xmalloc(sizeof(*re));
 +              re->processed = 0;
 +              re->add_turned_into_rename = 0;
 +              re->pair = pair;
 +              item = string_list_lookup(entries, re->pair->one->path);
 +              if (!item)
 +                      re->src_entry = insert_stage_data(re->pair->one->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->src_entry = item->util;
 +
 +              item = string_list_lookup(entries, re->pair->two->path);
 +              if (!item)
 +                      re->dst_entry = insert_stage_data(re->pair->two->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->dst_entry = item->util;
 +              item = string_list_insert(renames, pair->one->path);
 +              item->util = re;
 +              if (new_path)
 +                      apply_directory_rename_modifications(o, pair, new_path,
 +                                                           re, tree, o_tree,
 +                                                           a_tree, b_tree,
 +                                                           entries,
 +                                                           clean_merge);
 +      }
 +
 +      hashmap_iter_init(&collisions, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->target_file);
 +              string_list_clear(&e->source_files, 0);
 +      }
 +      hashmap_free(&collisions, 1);
 +      return renames;
 +}
 +
  static int process_renames(struct merge_options *o,
                           struct string_list *a_renames,
                           struct string_list *b_renames)
                        dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
                        try_merge = 0;
  
 -                      if (oid_eq(&src_other.oid, &null_oid)) {
 +                      if (oid_eq(&src_other.oid, &null_oid) &&
 +                          ren1->add_turned_into_rename) {
 +                              setup_rename_conflict_info(RENAME_DIR,
 +                                                         ren1->pair,
 +                                                         NULL,
 +                                                         branch1,
 +                                                         branch2,
 +                                                         ren1->dst_entry,
 +                                                         NULL,
 +                                                         o,
 +                                                         NULL,
 +                                                         NULL);
 +                      } else if (oid_eq(&src_other.oid, &null_oid)) {
                                setup_rename_conflict_info(RENAME_DELETE,
                                                           ren1->pair,
                                                           NULL,
@@@ -2536,105 -1625,6 +2536,105 @@@ cleanup_and_return
        return clean_merge;
  }
  
 +struct rename_info {
 +      struct string_list *head_renames;
 +      struct string_list *merge_renames;
 +};
 +
 +static void initial_cleanup_rename(struct diff_queue_struct *pairs,
 +                                 struct hashmap *dir_renames)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *e;
 +
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->dir);
 +              strbuf_release(&e->new_dir);
 +              /* possible_new_dirs already cleared in get_directory_renames */
 +      }
 +      hashmap_free(dir_renames, 1);
 +      free(dir_renames);
 +
 +      free(pairs->queue);
 +      free(pairs);
 +}
 +
 +static int handle_renames(struct merge_options *o,
 +                        struct tree *common,
 +                        struct tree *head,
 +                        struct tree *merge,
 +                        struct string_list *entries,
 +                        struct rename_info *ri)
 +{
 +      struct diff_queue_struct *head_pairs, *merge_pairs;
 +      struct hashmap *dir_re_head, *dir_re_merge;
 +      int clean = 1;
 +
 +      ri->head_renames = NULL;
 +      ri->merge_renames = NULL;
 +
 +      if (!o->detect_rename)
 +              return 1;
 +
 +      head_pairs = get_diffpairs(o, common, head);
 +      merge_pairs = get_diffpairs(o, common, merge);
 +
 +      dir_re_head = get_directory_renames(head_pairs, head);
 +      dir_re_merge = get_directory_renames(merge_pairs, merge);
 +
 +      handle_directory_level_conflicts(o,
 +                                       dir_re_head, head,
 +                                       dir_re_merge, merge);
 +
 +      ri->head_renames  = get_renames(o, head_pairs,
 +                                      dir_re_merge, dir_re_head, head,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      ri->merge_renames = get_renames(o, merge_pairs,
 +                                      dir_re_head, dir_re_merge, merge,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      clean &= process_renames(o, ri->head_renames, ri->merge_renames);
 +
 +cleanup:
 +      /*
 +       * Some cleanup is deferred until cleanup_renames() because the
 +       * data structures are still needed and referenced in
 +       * process_entry().  But there are a few things we can free now.
 +       */
 +      initial_cleanup_rename(head_pairs, dir_re_head);
 +      initial_cleanup_rename(merge_pairs, dir_re_merge);
 +
 +      return clean;
 +}
 +
 +static void final_cleanup_rename(struct string_list *rename)
 +{
 +      const struct rename *re;
 +      int i;
 +
 +      if (rename == NULL)
 +              return;
 +
 +      for (i = 0; i < rename->nr; i++) {
 +              re = rename->items[i].util;
 +              diff_free_filepair(re->pair);
 +      }
 +      string_list_clear(rename, 1);
 +      free(rename);
 +}
 +
 +static void final_cleanup_renames(struct rename_info *re_info)
 +{
 +      final_cleanup_rename(re_info->head_renames);
 +      final_cleanup_rename(re_info->merge_renames);
 +}
 +
  static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
  {
        return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
@@@ -2646,7 -1636,7 +2646,7 @@@ static int read_oid_strbuf(struct merge
        void *buf;
        enum object_type type;
        unsigned long size;
 -      buf = read_sha1_file(oid->hash, &type, &size);
 +      buf = read_object_file(oid, &type, &size);
        if (!buf)
                return err(o, _("cannot read object %s"), oid_to_hex(oid));
        if (type != OBJ_BLOB) {
@@@ -2725,7 -1715,6 +2725,7 @@@ static int handle_modify_delete(struct 
  
  static int merge_content(struct merge_options *o,
                         const char *path,
 +                       int file_in_way,
                         struct object_id *o_oid, int o_mode,
                         struct object_id *a_oid, int a_mode,
                         struct object_id *b_oid, int b_mode,
  
        if (mfi.clean && !df_conflict_remains &&
            oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
 -              int path_renamed_outside_HEAD;
                output(o, 3, _("Skipped %s (merged same as existing)"), path);
                /*
                 * The content merge resulted in the same file contents we
                 * are recorded at the correct path (which may not be true
                 * if the merge involves a rename).
                 */
 -              path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
 -              if (!path_renamed_outside_HEAD) {
 +              if (was_tracked(path)) {
                        add_cacheinfo(o, mfi.mode, &mfi.oid, path,
                                      0, (!o->call_depth), 0);
                        return mfi.clean;
                                return -1;
        }
  
 -      if (df_conflict_remains) {
 +      if (df_conflict_remains || file_in_way) {
                char *new_path;
                if (o->call_depth) {
                        remove_file_from_cache(path);
        return mfi.clean;
  }
  
 +static int conflict_rename_normal(struct merge_options *o,
 +                                const char *path,
 +                                struct object_id *o_oid, unsigned int o_mode,
 +                                struct object_id *a_oid, unsigned int a_mode,
 +                                struct object_id *b_oid, unsigned int b_mode,
 +                                struct rename_conflict_info *ci)
 +{
 +      int clean_merge;
 +      int file_in_the_way = 0;
 +
 +      if (was_dirty(o, path)) {
 +              file_in_the_way = 1;
 +              output(o, 1, _("Refusing to lose dirty file at %s"), path);
 +      }
 +
 +      /* Merge the content and write it out */
 +      clean_merge = merge_content(o, path, file_in_the_way,
 +                                  o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 +                                  ci);
 +      if (clean_merge > 0 && file_in_the_way)
 +              clean_merge = 0;
 +      return clean_merge;
 +}
 +
  /* Per entry merge function */
  static int process_entry(struct merge_options *o,
                         const char *path, struct stage_data *entry)
                switch (conflict_info->rename_type) {
                case RENAME_NORMAL:
                case RENAME_ONE_FILE_TO_ONE:
 -                      clean_merge = merge_content(o, path,
 -                                                  o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 -                                                  conflict_info);
 +                      clean_merge = conflict_rename_normal(o,
 +                                                           path,
 +                                                           o_oid, o_mode,
 +                                                           a_oid, a_mode,
 +                                                           b_oid, b_mode,
 +                                                           conflict_info);
 +                      break;
 +              case RENAME_DIR:
 +                      clean_merge = 1;
 +                      if (conflict_rename_dir(o,
 +                                              conflict_info->pair1,
 +                                              conflict_info->branch1,
 +                                              conflict_info->branch2))
 +                              clean_merge = -1;
                        break;
                case RENAME_DELETE:
                        clean_merge = 0;
        } else if (a_oid && b_oid) {
                /* Case C: Added in both (check for same permissions) and */
                /* case D: Modified in both, but differently. */
 -              clean_merge = merge_content(o, path,
 +              clean_merge = merge_content(o, path, 0 /* file_in_way */,
                                            o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
                                            NULL);
        } else if (!o_oid && !a_oid && !b_oid) {
@@@ -3017,7 -1973,7 +3017,7 @@@ int merge_trees(struct merge_options *o
                return 1;
        }
  
 -      code = git_merge_trees(o->call_depth, common, head, merge);
 +      code = git_merge_trees(o, common, head, merge);
  
        if (code != 0) {
                if (show(o, 4) || o->call_depth)
        }
  
        if (unmerged_cache()) {
 -              struct string_list *entries, *re_head, *re_merge;
 +              struct string_list *entries;
 +              struct rename_info re_info;
                int i;
                /*
                 * Only need the hashmap while processing entries, so
                get_files_dirs(o, merge);
  
                entries = get_unmerged();
 +              clean = handle_renames(o, common, head, merge, entries,
 +                                     &re_info);
                record_df_conflict_files(o, entries);
 -              re_head  = get_renames(o, head, common, head, merge, entries);
 -              re_merge = get_renames(o, merge, common, head, merge, entries);
 -              clean = process_renames(o, re_head, re_merge);
                if (clean < 0)
                        goto cleanup;
                for (i = entries->nr-1; 0 <= i; i--) {
                }
  
  cleanup:
 -              string_list_clear(re_merge, 0);
 -              string_list_clear(re_head, 0);
 +              final_cleanup_renames(&re_info);
 +
                string_list_clear(entries, 1);
 +              free(entries);
  
                hashmap_free(&o->current_file_dir_set, 1);
  
 -              free(re_merge);
 -              free(re_head);
 -              free(entries);
 -
                if (clean < 0)
                        return clean;
        }
@@@ -3111,7 -2070,7 +3111,7 @@@ int merge_recursive(struct merge_option
  {
        struct commit_list *iter;
        struct commit *merged_common_ancestors;
-       struct tree *mrtree = mrtree;
+       struct tree *mrtree;
        int clean;
  
        if (show(o, 4)) {
@@@ -3239,13 -2198,11 +3239,13 @@@ int merge_recursive_generic(struct merg
        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
        clean = merge_recursive(o, head_commit, next_commit, ca,
                        result);
 -      if (clean < 0)
 +      if (clean < 0) {
 +              rollback_lock_file(&lock);
                return clean;
 +      }
  
 -      if (active_cache_changed &&
 -          write_locked_index(&the_index, &lock, COMMIT_LOCK))
 +      if (write_locked_index(&the_index, &lock,
 +                             COMMIT_LOCK | SKIP_IF_UNCHANGED))
                return err(o, _("Unable to write index."));
  
        return clean ? 0 : 1;
diff --combined read-cache.c
index f23d9a4731e761f7486adbf03542fe40b90c9315,49607ddcd7078fb47bac660c39a777a5569d3f80..10f1c6bb8a316e85448445afc3478c832d61709c
@@@ -62,7 -62,6 +62,7 @@@ static void replace_index_entry(struct 
        replace_index_entry_in_base(istate, old, ce);
        remove_name_hash(istate, old);
        free(old);
 +      ce->ce_flags &= ~CE_HASHED;
        set_index_entry(istate, nr, ce);
        ce->ce_flags |= CE_UPDATE_IN_BASE;
        mark_fsmonitor_invalid(istate, ce);
  
  void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
  {
 -      struct cache_entry *old = istate->cache[nr], *new;
 +      struct cache_entry *old_entry = istate->cache[nr], *new_entry;
        int namelen = strlen(new_name);
  
 -      new = xmalloc(cache_entry_size(namelen));
 -      copy_cache_entry(new, old);
 -      new->ce_flags &= ~CE_HASHED;
 -      new->ce_namelen = namelen;
 -      new->index = 0;
 -      memcpy(new->name, new_name, namelen + 1);
 +      new_entry = xmalloc(cache_entry_size(namelen));
 +      copy_cache_entry(new_entry, old_entry);
 +      new_entry->ce_flags &= ~CE_HASHED;
 +      new_entry->ce_namelen = namelen;
 +      new_entry->index = 0;
 +      memcpy(new_entry->name, new_name, namelen + 1);
  
 -      cache_tree_invalidate_path(istate, old->name);
 -      untracked_cache_remove_from_index(istate, old->name);
 +      cache_tree_invalidate_path(istate, old_entry->name);
 +      untracked_cache_remove_from_index(istate, old_entry->name);
        remove_index_entry_at(istate, nr);
 -      add_index_entry(istate, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 +      add_index_entry(istate, new_entry, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  }
  
  void fill_stat_data(struct stat_data *sd, struct stat *st)
@@@ -185,7 -184,7 +185,7 @@@ static int ce_compare_link(const struc
        if (strbuf_readlink(&sb, ce->name, expected_size))
                return -1;
  
 -      buffer = read_sha1_file(ce->oid.hash, &type, &size);
 +      buffer = read_object_file(&ce->oid, &type, &size);
        if (buffer) {
                if (size == sb.len)
                        match = memcmp(buffer, sb.buf, size);
@@@ -616,26 -615,26 +616,26 @@@ static struct cache_entry *create_alias
                                           struct cache_entry *alias)
  {
        int len;
 -      struct cache_entry *new;
 +      struct cache_entry *new_entry;
  
        if (alias->ce_flags & CE_ADDED)
                die("Will not add file alias '%s' ('%s' already exists in index)", ce->name, alias->name);
  
        /* Ok, create the new entry using the name of the existing alias */
        len = ce_namelen(alias);
 -      new = xcalloc(1, cache_entry_size(len));
 -      memcpy(new->name, alias->name, len);
 -      copy_cache_entry(new, ce);
 +      new_entry = xcalloc(1, cache_entry_size(len));
 +      memcpy(new_entry->name, alias->name, len);
 +      copy_cache_entry(new_entry, ce);
        save_or_free_index_entry(istate, ce);
 -      return new;
 +      return new_entry;
  }
  
  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))
 +      struct object_id oid;
 +      if (write_object_file("", 0, blob_type, &oid))
                die("cannot create an empty blob in the object database");
 -      hashcpy(ce->oid.hash, sha1);
 +      oidcpy(&ce->oid, &oid);
  }
  
  int add_to_index(struct index_state *istate, const char *path, struct stat *st, int flags)
@@@ -1218,8 -1217,9 +1218,8 @@@ int add_index_entry(struct index_state 
        /* Add it in.. */
        istate->cache_nr++;
        if (istate->cache_nr > pos + 1)
 -              memmove(istate->cache + pos + 1,
 -                      istate->cache + pos,
 -                      (istate->cache_nr - pos - 1) * sizeof(ce));
 +              MOVE_ARRAY(istate->cache + pos + 1, istate->cache + pos,
 +                         istate->cache_nr - pos - 1);
        set_index_entry(istate, pos, ce);
        istate->cache_changed |= CE_ENTRY_ADDED;
        return 0;
@@@ -1325,8 -1325,7 +1325,8 @@@ static struct cache_entry *refresh_cach
  
        size = ce_size(ce);
        updated = xmalloc(size);
 -      memcpy(updated, ce, size);
 +      copy_cache_entry(updated, ce);
 +      memcpy(updated->name, ce->name, ce->ce_namelen + 1);
        fill_stat_cache_info(updated, &st);
        /*
         * If ignore_valid is not set, we should leave CE_VALID bit
@@@ -1373,7 -1372,6 +1373,7 @@@ int refresh_index(struct index_state *i
        const char *typechange_fmt;
        const char *added_fmt;
        const char *unmerged_fmt;
 +      uint64_t start = getnanotime();
  
        modified_fmt = (in_porcelain ? "M\t%s\n" : "%s: needs update\n");
        deleted_fmt = (in_porcelain ? "D\t%s\n" : "%s: needs update\n");
        added_fmt = (in_porcelain ? "A\t%s\n" : "%s needs update\n");
        unmerged_fmt = (in_porcelain ? "U\t%s\n" : "%s: needs merge\n");
        for (i = 0; i < istate->cache_nr; i++) {
 -              struct cache_entry *ce, *new;
 +              struct cache_entry *ce, *new_entry;
                int cache_errno = 0;
                int changed = 0;
                int filtered = 0;
                if (filtered)
                        continue;
  
 -              new = refresh_cache_ent(istate, ce, options, &cache_errno, &changed);
 -              if (new == ce)
 +              new_entry = refresh_cache_ent(istate, ce, options, &cache_errno, &changed);
 +              if (new_entry == ce)
                        continue;
 -              if (!new) {
 +              if (!new_entry) {
                        const char *fmt;
  
                        if (really && cache_errno == EINVAL) {
                        continue;
                }
  
 -              replace_index_entry(istate, i, new);
 +              replace_index_entry(istate, i, new_entry);
        }
 +      trace_performance_since(start, "refresh index");
        return has_errors;
  }
  
@@@ -1548,8 -1545,8 +1548,8 @@@ int verify_ce_order
  
  static int verify_hdr(struct cache_header *hdr, unsigned long size)
  {
 -      git_SHA_CTX c;
 -      unsigned char sha1[20];
 +      git_hash_ctx c;
 +      unsigned char hash[GIT_MAX_RAWSZ];
        int hdr_version;
  
        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
        if (!verify_index_checksum)
                return 0;
  
 -      git_SHA1_Init(&c);
 -      git_SHA1_Update(&c, hdr, size - 20);
 -      git_SHA1_Final(sha1, &c);
 -      if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
 +      the_hash_algo->init_fn(&c);
 +      the_hash_algo->update_fn(&c, hdr, size - the_hash_algo->rawsz);
 +      the_hash_algo->final_fn(hash, &c);
 +      if (hashcmp(hash, (unsigned char *)hdr + size - the_hash_algo->rawsz))
                return error("bad index file sha1 signature");
        return 0;
  }
@@@ -1606,7 -1603,7 +1606,7 @@@ int hold_locked_index(struct lock_file 
  
  int read_index(struct index_state *istate)
  {
 -      return read_index_from(istate, get_index_file());
 +      return read_index_from(istate, get_index_file(), get_git_dir());
  }
  
  static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry *ondisk,
@@@ -1794,7 -1791,7 +1794,7 @@@ int do_read_index(struct index_state *i
                die_errno("cannot stat the open index");
  
        mmap_size = xsize_t(st.st_size);
 -      if (mmap_size < sizeof(struct cache_header) + 20)
 +      if (mmap_size < sizeof(struct cache_header) + the_hash_algo->rawsz)
                die("index file smaller than expected");
  
        mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
        if (verify_hdr(hdr, mmap_size) < 0)
                goto unmap;
  
 -      hashcpy(istate->sha1, (const unsigned char *)hdr + mmap_size - 20);
 +      hashcpy(istate->sha1, (const unsigned char *)hdr + mmap_size - the_hash_algo->rawsz);
        istate->version = ntohl(hdr->hdr_version);
        istate->cache_nr = ntohl(hdr->hdr_entries);
        istate->cache_alloc = alloc_nr(istate->cache_nr);
        istate->timestamp.sec = st.st_mtime;
        istate->timestamp.nsec = ST_MTIME_NSEC(st);
  
 -      while (src_offset <= mmap_size - 20 - 8) {
 +      while (src_offset <= mmap_size - the_hash_algo->rawsz - 8) {
                /* After an array of active_nr index entries,
                 * there can be arbitrary number of extended
                 * sections, each of which is prefixed with
@@@ -1866,27 -1863,26 +1866,27 @@@ unmap
   * This way, shared index can be removed if they have not been used
   * for some time.
   */
 -static void freshen_shared_index(char *base_sha1_hex, int warn)
 +static void freshen_shared_index(const char *shared_index, int warn)
  {
 -      char *shared_index = git_pathdup("sharedindex.%s", base_sha1_hex);
        if (!check_and_freshen_file(shared_index, 1) && warn)
                warning("could not freshen shared index '%s'", shared_index);
 -      free(shared_index);
  }
  
 -int read_index_from(struct index_state *istate, const char *path)
 +int read_index_from(struct index_state *istate, const char *path,
 +                  const char *gitdir)
  {
 +      uint64_t start = getnanotime();
        struct split_index *split_index;
        int ret;
        char *base_sha1_hex;
 -      const char *base_path;
 +      char *base_path;
  
        /* istate->initialized covers both .git/index and .git/sharedindex.xxx */
        if (istate->initialized)
                return istate->cache_nr;
  
        ret = do_read_index(istate, path, 0);
 +      trace_performance_since(start, "read cache %s", path);
  
        split_index = istate->split_index;
        if (!split_index || is_null_sha1(split_index->base_sha1)) {
                split_index->base = xcalloc(1, sizeof(*split_index->base));
  
        base_sha1_hex = sha1_to_hex(split_index->base_sha1);
 -      base_path = git_path("sharedindex.%s", base_sha1_hex);
 +      base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_sha1_hex);
        ret = do_read_index(split_index->base, base_path, 1);
        if (hashcmp(split_index->base_sha1, split_index->base->sha1))
                die("broken index, expect %s in %s, got %s",
                    base_sha1_hex, base_path,
                    sha1_to_hex(split_index->base->sha1));
  
 -      freshen_shared_index(base_sha1_hex, 0);
 +      freshen_shared_index(base_path, 0);
        merge_base_index(istate);
        post_read_index_from(istate);
 +      trace_performance_since(start, "read cache %s", base_path);
 +      free(base_path);
        return ret;
  }
  
@@@ -1963,11 -1957,11 +1963,11 @@@ int unmerged_index(const struct index_s
  static unsigned char write_buffer[WRITE_BUFFER_SIZE];
  static unsigned long write_buffer_len;
  
 -static int ce_write_flush(git_SHA_CTX *context, int fd)
 +static int ce_write_flush(git_hash_ctx *context, int fd)
  {
        unsigned int buffered = write_buffer_len;
        if (buffered) {
 -              git_SHA1_Update(context, write_buffer, buffered);
 +              the_hash_algo->update_fn(context, write_buffer, buffered);
                if (write_in_full(fd, write_buffer, buffered) < 0)
                        return -1;
                write_buffer_len = 0;
        return 0;
  }
  
 -static int ce_write(git_SHA_CTX *context, int fd, void *data, unsigned int len)
 +static int ce_write(git_hash_ctx *context, int fd, void *data, unsigned int len)
  {
        while (len) {
                unsigned int buffered = write_buffer_len;
        return 0;
  }
  
 -static int write_index_ext_header(git_SHA_CTX *context, int fd,
 +static int write_index_ext_header(git_hash_ctx *context, int fd,
                                  unsigned int ext, unsigned int sz)
  {
        ext = htonl(ext);
                (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
  }
  
 -static int ce_flush(git_SHA_CTX *context, int fd, unsigned char *sha1)
 +static int ce_flush(git_hash_ctx *context, int fd, unsigned char *hash)
  {
        unsigned int left = write_buffer_len;
  
        if (left) {
                write_buffer_len = 0;
 -              git_SHA1_Update(context, write_buffer, left);
 +              the_hash_algo->update_fn(context, write_buffer, left);
        }
  
 -      /* Flush first if not enough space for SHA1 signature */
 -      if (left + 20 > WRITE_BUFFER_SIZE) {
 +      /* Flush first if not enough space for hash signature */
 +      if (left + the_hash_algo->rawsz > WRITE_BUFFER_SIZE) {
                if (write_in_full(fd, write_buffer, left) < 0)
                        return -1;
                left = 0;
        }
  
 -      /* Append the SHA1 signature at the end */
 -      git_SHA1_Final(write_buffer + left, context);
 -      hashcpy(sha1, write_buffer + left);
 -      left += 20;
 +      /* Append the hash signature at the end */
 +      the_hash_algo->final_fn(write_buffer + left, context);
 +      hashcpy(hash, write_buffer + left);
 +      left += the_hash_algo->rawsz;
        return (write_in_full(fd, write_buffer, left) < 0) ? -1 : 0;
  }
  
@@@ -2106,17 -2100,19 +2106,19 @@@ static void copy_cache_entry_to_ondisk(
        }
  }
  
 -static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce,
 +static int ce_write_entry(git_hash_ctx *c, int fd, struct cache_entry *ce,
                          struct strbuf *previous_name, struct ondisk_cache_entry *ondisk)
  {
        int size;
-       int saved_namelen = saved_namelen; /* compiler workaround */
        int result;
+       unsigned int saved_namelen;
+       int stripped_name = 0;
        static unsigned char padding[8] = { 0x00 };
  
        if (ce->ce_flags & CE_STRIP_NAME) {
                saved_namelen = ce_namelen(ce);
                ce->ce_namelen = 0;
+               stripped_name = 1;
        }
  
        if (ce->ce_flags & CE_EXTENDED)
                strbuf_splice(previous_name, common, to_remove,
                              ce->name + common, ce_namelen(ce) - common);
        }
-       if (ce->ce_flags & CE_STRIP_NAME) {
+       if (stripped_name) {
                ce->ce_namelen = saved_namelen;
                ce->ce_flags &= ~CE_STRIP_NAME;
        }
@@@ -2173,7 -2169,7 +2175,7 @@@ static int verify_index_from(const stru
        int fd;
        ssize_t n;
        struct stat st;
 -      unsigned char sha1[20];
 +      unsigned char hash[GIT_MAX_RAWSZ];
  
        if (!istate->initialized)
                return 0;
        if (fstat(fd, &st))
                goto out;
  
 -      if (st.st_size < sizeof(struct cache_header) + 20)
 +      if (st.st_size < sizeof(struct cache_header) + the_hash_algo->rawsz)
                goto out;
  
 -      n = pread_in_full(fd, sha1, 20, st.st_size - 20);
 -      if (n != 20)
 +      n = pread_in_full(fd, hash, the_hash_algo->rawsz, st.st_size - the_hash_algo->rawsz);
 +      if (n != the_hash_algo->rawsz)
                goto out;
  
 -      if (hashcmp(istate->sha1, sha1))
 +      if (hashcmp(istate->sha1, hash))
                goto out;
  
        close(fd);
@@@ -2240,9 -2236,8 +2242,9 @@@ void update_index_if_able(struct index_
  static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
                          int strip_extensions)
  {
 +      uint64_t start = getnanotime();
        int newfd = tempfile->fd;
 -      git_SHA_CTX c;
 +      git_hash_ctx c;
        struct cache_header hdr;
        int i, err = 0, removed, extended, hdr_version;
        struct cache_entry **cache = istate->cache;
        struct stat st;
        struct ondisk_cache_entry_extended ondisk;
        struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
 -      int drop_cache_tree = 0;
 +      int drop_cache_tree = istate->drop_cache_tree;
  
        for (i = removed = extended = 0; i < entries; i++) {
                if (cache[i]->ce_flags & CE_REMOVE)
        hdr.hdr_version = htonl(hdr_version);
        hdr.hdr_entries = htonl(entries - removed);
  
 -      git_SHA1_Init(&c);
 +      the_hash_algo->init_fn(&c);
        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
                return -1;
  
                return -1;
        istate->timestamp.sec = (unsigned int)st.st_mtime;
        istate->timestamp.nsec = ST_MTIME_NSEC(st);
 +      trace_performance_since(start, "write index, changed mask = %x", istate->cache_changed);
        return 0;
  }
  
@@@ -2480,21 -2474,32 +2482,21 @@@ static int clean_shared_index_files(con
  }
  
  static int write_shared_index(struct index_state *istate,
 -                            struct lock_file *lock, unsigned flags)
 +                            struct tempfile **temp)
  {
 -      struct tempfile *temp;
        struct split_index *si = istate->split_index;
        int ret;
  
 -      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, temp, 1);
 -      if (ret) {
 -              delete_tempfile(&temp);
 +      ret = do_write_index(si->base, *temp, 1);
 +      if (ret)
                return ret;
 -      }
 -      ret = adjust_shared_perm(get_tempfile_path(temp));
 +      ret = adjust_shared_perm(get_tempfile_path(*temp));
        if (ret) {
 -              int save_errno = errno;
 -              error("cannot fix permission bits on %s", get_tempfile_path(temp));
 -              delete_tempfile(&temp);
 -              errno = save_errno;
 +              error("cannot fix permission bits on %s", get_tempfile_path(*temp));
                return ret;
        }
 -      ret = rename_tempfile(&temp,
 +      ret = rename_tempfile(temp,
                              git_path("sharedindex.%s", sha1_to_hex(si->base->sha1)));
        if (!ret) {
                hashcpy(si->base_sha1, si->base->sha1);
@@@ -2540,12 -2545,6 +2542,12 @@@ int write_locked_index(struct index_sta
        int new_shared_index, ret;
        struct split_index *si = istate->split_index;
  
 +      if ((flags & SKIP_IF_UNCHANGED) && !istate->cache_changed) {
 +              if (flags & COMMIT_LOCK)
 +                      rollback_lock_file(lock);
 +              return 0;
 +      }
 +
        if (istate->fsmonitor_last_update)
                fill_fsmonitor_bitmap(istate);
  
        new_shared_index = istate->cache_changed & SPLIT_INDEX_ORDERED;
  
        if (new_shared_index) {
 -              ret = write_shared_index(istate, lock, flags);
 +              struct tempfile *temp;
 +              int saved_errno;
 +
 +              temp = mks_tempfile(git_path("sharedindex_XXXXXX"));
 +              if (!temp) {
 +                      hashclr(si->base_sha1);
 +                      ret = do_write_locked_index(istate, lock, flags);
 +                      goto out;
 +              }
 +              ret = write_shared_index(istate, &temp);
 +
 +              saved_errno = errno;
 +              if (is_tempfile_active(temp))
 +                      delete_tempfile(&temp);
 +              errno = saved_errno;
 +
                if (ret)
                        goto out;
        }
        ret = write_split_index(istate, lock, flags);
  
        /* Freshen the shared index only if the split-index was written */
 -      if (!ret && !new_shared_index)
 -              freshen_shared_index(sha1_to_hex(si->base_sha1), 1);
 +      if (!ret && !new_shared_index) {
 +              const char *shared_index = git_path("sharedindex.%s",
 +                                                  sha1_to_hex(si->base_sha1));
 +              freshen_shared_index(shared_index, 1);
 +      }
  
  out:
        if (flags & COMMIT_LOCK)
@@@ -2691,7 -2672,7 +2693,7 @@@ void *read_blob_data_from_index(const s
        }
        if (pos < 0)
                return NULL;
 -      data = read_sha1_file(istate->cache[pos]->oid.hash, &type, &sz);
 +      data = read_object_file(&istate->cache[pos]->oid, &type, &sz);
        if (!data || type != OBJ_BLOB) {
                free(data);
                return NULL;