git.oblomov.eu Git - git/blob - submodule.c

   1 #include "cache.h"
   2 #include "submodule.h"
   3 #include "dir.h"
   4 #include "diff.h"
   5 #include "commit.h"
   6 #include "revision.h"
   7 #include "run-command.h"
   8 #include "diffcore.h"
   9 #include "refs.h"
  10 #include "string-list.h"
  11
  12 struct string_list config_name_for_path;
  13 struct string_list config_fetch_recurse_submodules_for_name;
  14 struct string_list config_ignore_for_name;
  15 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
  16 struct string_list changed_submodule_paths;
  17
  18 static int add_submodule_odb(const char *path)
  19 {
  20         struct strbuf objects_directory = STRBUF_INIT;
  21         struct alternate_object_database *alt_odb;
  22         int ret = 0;
  23         const char *git_dir;
  24
  25         strbuf_addf(&objects_directory, "%s/.git", path);
  26         git_dir = read_gitfile_gently(objects_directory.buf);
  27         if (git_dir) {
  28                 strbuf_reset(&objects_directory);
  29                 strbuf_addstr(&objects_directory, git_dir);
  30         }
  31         strbuf_addstr(&objects_directory, "/objects/");
  32         if (!is_directory(objects_directory.buf)) {
  33                 ret = -1;
  34                 goto done;
  35         }
  36         /* avoid adding it twice */
  37         for (alt_odb = alt_odb_list; alt_odb; alt_odb = alt_odb->next)
  38                 if (alt_odb->name - alt_odb->base == objects_directory.len &&
  39                                 !strncmp(alt_odb->base, objects_directory.buf,
  40                                         objects_directory.len))
  41                         goto done;
  42
  43         alt_odb = xmalloc(objects_directory.len + 42 + sizeof(*alt_odb));
  44         alt_odb->next = alt_odb_list;
  45         strcpy(alt_odb->base, objects_directory.buf);
  46         alt_odb->name = alt_odb->base + objects_directory.len;
  47         alt_odb->name[2] = '/';
  48         alt_odb->name[40] = '\0';
  49         alt_odb->name[41] = '\0';
  50         alt_odb_list = alt_odb;
  51         prepare_alt_odb();
  52 done:
  53         strbuf_release(&objects_directory);
  54         return ret;
  55 }
  56
  57 void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
  58                                              const char *path)
  59 {
  60         struct string_list_item *path_option, *ignore_option;
  61         path_option = unsorted_string_list_lookup(&config_name_for_path, path);
  62         if (path_option) {
  63                 ignore_option = unsorted_string_list_lookup(&config_ignore_for_name, path_option->util);
  64                 if (ignore_option)
  65                         handle_ignore_submodules_arg(diffopt, ignore_option->util);
  66         }
  67 }
  68
  69 int submodule_config(const char *var, const char *value, void *cb)
  70 {
  71         if (!prefixcmp(var, "submodule."))
  72                 return parse_submodule_config_option(var, value);
  73         else if (!strcmp(var, "fetch.recursesubmodules")) {
  74                 config_fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(var, value);
  75                 return 0;
  76         }
  77         return 0;
  78 }
  79
  80 void gitmodules_config(void)
  81 {
  82         const char *work_tree = get_git_work_tree();
  83         if (work_tree) {
  84                 struct strbuf gitmodules_path = STRBUF_INIT;
  85                 strbuf_addstr(&gitmodules_path, work_tree);
  86                 strbuf_addstr(&gitmodules_path, "/.gitmodules");
  87                 git_config_from_file(submodule_config, gitmodules_path.buf, NULL);
  88                 strbuf_release(&gitmodules_path);
  89         }
  90 }
  91
  92 int parse_submodule_config_option(const char *var, const char *value)
  93 {
  94         int len;
  95         struct string_list_item *config;
  96         struct strbuf submodname = STRBUF_INIT;
  97
  98         var += 10;              /* Skip "submodule." */
  99
 100         len = strlen(var);
 101         if ((len > 5) && !strcmp(var + len - 5, ".path")) {
 102                 strbuf_add(&submodname, var, len - 5);
 103                 config = unsorted_string_list_lookup(&config_name_for_path, value);
 104                 if (config)
 105                         free(config->util);
 106                 else
 107                         config = string_list_append(&config_name_for_path, xstrdup(value));
 108                 config->util = strbuf_detach(&submodname, NULL);
 109                 strbuf_release(&submodname);
 110         } else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
 111                 strbuf_add(&submodname, var, len - 23);
 112                 config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
 113                 if (!config)
 114                         config = string_list_append(&config_fetch_recurse_submodules_for_name,
 115                                                     strbuf_detach(&submodname, NULL));
 116                 config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
 117                 strbuf_release(&submodname);
 118         } else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
 119                 if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 120                     strcmp(value, "all") && strcmp(value, "none")) {
 121                         warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 122                         return 0;
 123                 }
 124
 125                 strbuf_add(&submodname, var, len - 7);
 126                 config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
 127                 if (config)
 128                         free(config->util);
 129                 else
 130                         config = string_list_append(&config_ignore_for_name,
 131                                                     strbuf_detach(&submodname, NULL));
 132                 strbuf_release(&submodname);
 133                 config->util = xstrdup(value);
 134                 return 0;
 135         }
 136         return 0;
 137 }
 138
 139 void handle_ignore_submodules_arg(struct diff_options *diffopt,
 140                                   const char *arg)
 141 {
 142         DIFF_OPT_CLR(diffopt, IGNORE_SUBMODULES);
 143         DIFF_OPT_CLR(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 144         DIFF_OPT_CLR(diffopt, IGNORE_DIRTY_SUBMODULES);
 145
 146         if (!strcmp(arg, "all"))
 147                 DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
 148         else if (!strcmp(arg, "untracked"))
 149                 DIFF_OPT_SET(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 150         else if (!strcmp(arg, "dirty"))
 151                 DIFF_OPT_SET(diffopt, IGNORE_DIRTY_SUBMODULES);
 152         else if (strcmp(arg, "none"))
 153                 die("bad --ignore-submodules argument: %s", arg);
 154 }
 155
 156 int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
 157 {
 158         switch (git_config_maybe_bool(opt, arg)) {
 159         case 1:
 160                 return RECURSE_SUBMODULES_ON;
 161         case 0:
 162                 return RECURSE_SUBMODULES_OFF;
 163         default:
 164                 if (!strcmp(arg, "on-demand"))
 165                         return RECURSE_SUBMODULES_ON_DEMAND;
 166                 die("bad %s argument: %s", opt, arg);
 167         }
 168 }
 169
 170 void show_submodule_summary(FILE *f, const char *path,
 171                 unsigned char one[20], unsigned char two[20],
 172                 unsigned dirty_submodule,
 173                 const char *del, const char *add, const char *reset)
 174 {
 175         struct rev_info rev;
 176         struct commit *commit, *left = left, *right = right;
 177         struct commit_list *merge_bases, *list;
 178         const char *message = NULL;
 179         struct strbuf sb = STRBUF_INIT;
 180         static const char *format = "  %m %s";
 181         int fast_forward = 0, fast_backward = 0;
 182
 183         if (is_null_sha1(two))
 184                 message = "(submodule deleted)";
 185         else if (add_submodule_odb(path))
 186                 message = "(not checked out)";
 187         else if (is_null_sha1(one))
 188                 message = "(new submodule)";
 189         else if (!(left = lookup_commit_reference(one)) ||
 190                  !(right = lookup_commit_reference(two)))
 191                 message = "(commits not present)";
 192
 193         if (!message) {
 194                 init_revisions(&rev, NULL);
 195                 setup_revisions(0, NULL, &rev, NULL);
 196                 rev.left_right = 1;
 197                 rev.first_parent_only = 1;
 198                 left->object.flags |= SYMMETRIC_LEFT;
 199                 add_pending_object(&rev, &left->object, path);
 200                 add_pending_object(&rev, &right->object, path);
 201                 merge_bases = get_merge_bases(left, right, 1);
 202                 if (merge_bases) {
 203                         if (merge_bases->item == left)
 204                                 fast_forward = 1;
 205                         else if (merge_bases->item == right)
 206                                 fast_backward = 1;
 207                 }
 208                 for (list = merge_bases; list; list = list->next) {
 209                         list->item->object.flags |= UNINTERESTING;
 210                         add_pending_object(&rev, &list->item->object,
 211                                 sha1_to_hex(list->item->object.sha1));
 212                 }
 213                 if (prepare_revision_walk(&rev))
 214                         message = "(revision walker failed)";
 215         }
 216
 217         if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
 218                 fprintf(f, "Submodule %s contains untracked content\n", path);
 219         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 220                 fprintf(f, "Submodule %s contains modified content\n", path);
 221
 222         if (!hashcmp(one, two)) {
 223                 strbuf_release(&sb);
 224                 return;
 225         }
 226
 227         strbuf_addf(&sb, "Submodule %s %s..", path,
 228                         find_unique_abbrev(one, DEFAULT_ABBREV));
 229         if (!fast_backward && !fast_forward)
 230                 strbuf_addch(&sb, '.');
 231         strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
 232         if (message)
 233                 strbuf_addf(&sb, " %s\n", message);
 234         else
 235                 strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
 236         fwrite(sb.buf, sb.len, 1, f);
 237
 238         if (!message) {
 239                 while ((commit = get_revision(&rev))) {
 240                         struct pretty_print_context ctx = {0};
 241                         ctx.date_mode = rev.date_mode;
 242                         strbuf_setlen(&sb, 0);
 243                         if (commit->object.flags & SYMMETRIC_LEFT) {
 244                                 if (del)
 245                                         strbuf_addstr(&sb, del);
 246                         }
 247                         else if (add)
 248                                 strbuf_addstr(&sb, add);
 249                         format_commit_message(commit, format, &sb, &ctx);
 250                         if (reset)
 251                                 strbuf_addstr(&sb, reset);
 252                         strbuf_addch(&sb, '\n');
 253                         fprintf(f, "%s", sb.buf);
 254                 }
 255                 clear_commit_marks(left, ~0);
 256                 clear_commit_marks(right, ~0);
 257         }
 258         strbuf_release(&sb);
 259 }
 260
 261 void set_config_fetch_recurse_submodules(int value)
 262 {
 263         config_fetch_recurse_submodules = value;
 264 }
 265
 266 static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
 267 {
 268         int is_present = 0;
 269         if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
 270                 /* Even if the submodule is checked out and the commit is
 271                  * present, make sure it is reachable from a ref. */
 272                 struct child_process cp;
 273                 const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
 274                 struct strbuf buf = STRBUF_INIT;
 275
 276                 argv[3] = sha1_to_hex(sha1);
 277                 memset(&cp, 0, sizeof(cp));
 278                 cp.argv = argv;
 279                 cp.env = local_repo_env;
 280                 cp.git_cmd = 1;
 281                 cp.no_stdin = 1;
 282                 cp.out = -1;
 283                 cp.dir = path;
 284                 if (!run_command(&cp) && !strbuf_read(&buf, cp.out, 1024))
 285                         is_present = 1;
 286
 287                 close(cp.out);
 288                 strbuf_release(&buf);
 289         }
 290         return is_present;
 291 }
 292
 293 static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 294                                          struct diff_options *options,
 295                                          void *data)
 296 {
 297         int i;
 298         for (i = 0; i < q->nr; i++) {
 299                 struct diff_filepair *p = q->queue[i];
 300                 if (!S_ISGITLINK(p->two->mode))
 301                         continue;
 302
 303                 if (S_ISGITLINK(p->one->mode)) {
 304                         /* NEEDSWORK: We should honor the name configured in
 305                          * the .gitmodules file of the commit we are examining
 306                          * here to be able to correctly follow submodules
 307                          * being moved around. */
 308                         struct string_list_item *path;
 309                         path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
 310                         if (!path && !is_submodule_commit_present(p->two->path, p->two->sha1))
 311                                 string_list_append(&changed_submodule_paths, xstrdup(p->two->path));
 312                 } else {
 313                         /* Submodule is new or was moved here */
 314                         /* NEEDSWORK: When the .git directories of submodules
 315                          * live inside the superprojects .git directory some
 316                          * day we should fetch new submodules directly into
 317                          * that location too when config or options request
 318                          * that so they can be checked out from there. */
 319                         continue;
 320                 }
 321         }
 322 }
 323
 324 void check_for_new_submodule_commits(unsigned char new_sha1[20])
 325 {
 326         struct rev_info rev;
 327         struct commit *commit;
 328         const char *argv[] = {NULL, NULL, "--not", "--all", NULL};
 329         int argc = ARRAY_SIZE(argv) - 1;
 330
 331         init_revisions(&rev, NULL);
 332         argv[1] = xstrdup(sha1_to_hex(new_sha1));
 333         setup_revisions(argc, argv, &rev, NULL);
 334         if (prepare_revision_walk(&rev))
 335                 die("revision walk setup failed");
 336
 337         /*
 338          * Collect all submodules (whether checked out or not) for which new
 339          * commits have been recorded upstream in "changed_submodule_paths".
 340          */
 341         while ((commit = get_revision(&rev))) {
 342                 struct commit_list *parent = commit->parents;
 343                 while (parent) {
 344                         struct diff_options diff_opts;
 345                         diff_setup(&diff_opts);
 346                         diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
 347                         diff_opts.format_callback = submodule_collect_changed_cb;
 348                         if (diff_setup_done(&diff_opts) < 0)
 349                                 die("diff_setup_done failed");
 350                         diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
 351                         diffcore_std(&diff_opts);
 352                         diff_flush(&diff_opts);
 353                         parent = parent->next;
 354                 }
 355         }
 356         free((char *)argv[1]);
 357 }
 358
 359 int fetch_populated_submodules(int num_options, const char **options,
 360                                const char *prefix, int command_line_option,
 361                                int quiet)
 362 {
 363         int i, result = 0, argc = 0, default_argc;
 364         struct child_process cp;
 365         const char **argv;
 366         struct string_list_item *name_for_path;
 367         const char *work_tree = get_git_work_tree();
 368         if (!work_tree)
 369                 goto out;
 370
 371         if (!the_index.initialized)
 372                 if (read_cache() < 0)
 373                         die("index file corrupt");
 374
 375         /* 6: "fetch" (options) --recurse-submodules-default default "--submodule-prefix" prefix NULL */
 376         argv = xcalloc(num_options + 6, sizeof(const char *));
 377         argv[argc++] = "fetch";
 378         for (i = 0; i < num_options; i++)
 379                 argv[argc++] = options[i];
 380         argv[argc++] = "--recurse-submodules-default";
 381         default_argc = argc++;
 382         argv[argc++] = "--submodule-prefix";
 383
 384         memset(&cp, 0, sizeof(cp));
 385         cp.argv = argv;
 386         cp.env = local_repo_env;
 387         cp.git_cmd = 1;
 388         cp.no_stdin = 1;
 389
 390         for (i = 0; i < active_nr; i++) {
 391                 struct strbuf submodule_path = STRBUF_INIT;
 392                 struct strbuf submodule_git_dir = STRBUF_INIT;
 393                 struct strbuf submodule_prefix = STRBUF_INIT;
 394                 struct cache_entry *ce = active_cache[i];
 395                 const char *git_dir, *name, *default_argv;
 396
 397                 if (!S_ISGITLINK(ce->ce_mode))
 398                         continue;
 399
 400                 name = ce->name;
 401                 name_for_path = unsorted_string_list_lookup(&config_name_for_path, ce->name);
 402                 if (name_for_path)
 403                         name = name_for_path->util;
 404
 405                 default_argv = "yes";
 406                 if (command_line_option == RECURSE_SUBMODULES_DEFAULT) {
 407                         struct string_list_item *fetch_recurse_submodules_option;
 408                         fetch_recurse_submodules_option = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name);
 409                         if (fetch_recurse_submodules_option) {
 410                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_OFF)
 411                                         continue;
 412                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_ON_DEMAND) {
 413                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 414                                                 continue;
 415                                         default_argv = "on-demand";
 416                                 }
 417                         } else {
 418                                 if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_OFF)
 419                                         continue;
 420                                 if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) {
 421                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 422                                                 continue;
 423                                         default_argv = "on-demand";
 424                                 }
 425                         }
 426                 } else if (command_line_option == RECURSE_SUBMODULES_ON_DEMAND) {
 427                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 428                                 continue;
 429                         default_argv = "on-demand";
 430                 }
 431
 432                 strbuf_addf(&submodule_path, "%s/%s", work_tree, ce->name);
 433                 strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
 434                 strbuf_addf(&submodule_prefix, "%s%s/", prefix, ce->name);
 435                 git_dir = read_gitfile_gently(submodule_git_dir.buf);
 436                 if (!git_dir)
 437                         git_dir = submodule_git_dir.buf;
 438                 if (is_directory(git_dir)) {
 439                         if (!quiet)
 440                                 printf("Fetching submodule %s%s\n", prefix, ce->name);
 441                         cp.dir = submodule_path.buf;
 442                         argv[default_argc] = default_argv;
 443                         argv[argc] = submodule_prefix.buf;
 444                         if (run_command(&cp))
 445                                 result = 1;
 446                 }
 447                 strbuf_release(&submodule_path);
 448                 strbuf_release(&submodule_git_dir);
 449                 strbuf_release(&submodule_prefix);
 450         }
 451         free(argv);
 452 out:
 453         string_list_clear(&changed_submodule_paths, 1);
 454         return result;
 455 }
 456
 457 unsigned is_submodule_modified(const char *path, int ignore_untracked)
 458 {
 459         ssize_t len;
 460         struct child_process cp;
 461         const char *argv[] = {
 462                 "status",
 463                 "--porcelain",
 464                 NULL,
 465                 NULL,
 466         };
 467         struct strbuf buf = STRBUF_INIT;
 468         unsigned dirty_submodule = 0;
 469         const char *line, *next_line;
 470         const char *git_dir;
 471
 472         strbuf_addf(&buf, "%s/.git", path);
 473         git_dir = read_gitfile_gently(buf.buf);
 474         if (!git_dir)
 475                 git_dir = buf.buf;
 476         if (!is_directory(git_dir)) {
 477                 strbuf_release(&buf);
 478                 /* The submodule is not checked out, so it is not modified */
 479                 return 0;
 480
 481         }
 482         strbuf_reset(&buf);
 483
 484         if (ignore_untracked)
 485                 argv[2] = "-uno";
 486
 487         memset(&cp, 0, sizeof(cp));
 488         cp.argv = argv;
 489         cp.env = local_repo_env;
 490         cp.git_cmd = 1;
 491         cp.no_stdin = 1;
 492         cp.out = -1;
 493         cp.dir = path;
 494         if (start_command(&cp))
 495                 die("Could not run git status --porcelain");
 496
 497         len = strbuf_read(&buf, cp.out, 1024);
 498         line = buf.buf;
 499         while (len > 2) {
 500                 if ((line[0] == '?') && (line[1] == '?')) {
 501                         dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
 502                         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 503                                 break;
 504                 } else {
 505                         dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
 506                         if (ignore_untracked ||
 507                             (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
 508                                 break;
 509                 }
 510                 next_line = strchr(line, '\n');
 511                 if (!next_line)
 512                         break;
 513                 next_line++;
 514                 len -= (next_line - line);
 515                 line = next_line;
 516         }
 517         close(cp.out);
 518
 519         if (finish_command(&cp))
 520                 die("git status --porcelain failed");
 521
 522         strbuf_release(&buf);
 523         return dirty_submodule;
 524 }
 525
 526 static int find_first_merges(struct object_array *result, const char *path,
 527                 struct commit *a, struct commit *b)
 528 {
 529         int i, j;
 530         struct object_array merges;
 531         struct commit *commit;
 532         int contains_another;
 533
 534         char merged_revision[42];
 535         const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 536                                    "--all", merged_revision, NULL };
 537         struct rev_info revs;
 538         struct setup_revision_opt rev_opts;
 539
 540         memset(&merges, 0, sizeof(merges));
 541         memset(result, 0, sizeof(struct object_array));
 542         memset(&rev_opts, 0, sizeof(rev_opts));
 543
 544         /* get all revisions that merge commit a */
 545         snprintf(merged_revision, sizeof(merged_revision), "^%s",
 546                         sha1_to_hex(a->object.sha1));
 547         init_revisions(&revs, NULL);
 548         rev_opts.submodule = path;
 549         setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);
 550
 551         /* save all revisions from the above list that contain b */
 552         if (prepare_revision_walk(&revs))
 553                 die("revision walk setup failed");
 554         while ((commit = get_revision(&revs)) != NULL) {
 555                 struct object *o = &(commit->object);
 556                 if (in_merge_bases(b, &commit, 1))
 557                         add_object_array(o, NULL, &merges);
 558         }
 559
 560         /* Now we've got all merges that contain a and b. Prune all
 561          * merges that contain another found merge and save them in
 562          * result.
 563          */
 564         for (i = 0; i < merges.nr; i++) {
 565                 struct commit *m1 = (struct commit *) merges.objects[i].item;
 566
 567                 contains_another = 0;
 568                 for (j = 0; j < merges.nr; j++) {
 569                         struct commit *m2 = (struct commit *) merges.objects[j].item;
 570                         if (i != j && in_merge_bases(m2, &m1, 1)) {
 571                                 contains_another = 1;
 572                                 break;
 573                         }
 574                 }
 575
 576                 if (!contains_another)
 577                         add_object_array(merges.objects[i].item,
 578                                          merges.objects[i].name, result);
 579         }
 580
 581         free(merges.objects);
 582         return result->nr;
 583 }
 584
 585 static void print_commit(struct commit *commit)
 586 {
 587         struct strbuf sb = STRBUF_INIT;
 588         struct pretty_print_context ctx = {0};
 589         ctx.date_mode = DATE_NORMAL;
 590         format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 591         fprintf(stderr, "%s\n", sb.buf);
 592         strbuf_release(&sb);
 593 }
 594
 595 #define MERGE_WARNING(path, msg) \
 596         warning("Failed to merge submodule %s (%s)", path, msg);
 597
 598 int merge_submodule(unsigned char result[20], const char *path,
 599                     const unsigned char base[20], const unsigned char a[20],
 600                     const unsigned char b[20])
 601 {
 602         struct commit *commit_base, *commit_a, *commit_b;
 603         int parent_count;
 604         struct object_array merges;
 605
 606         int i;
 607
 608         /* store a in result in case we fail */
 609         hashcpy(result, a);
 610
 611         /* we can not handle deletion conflicts */
 612         if (is_null_sha1(base))
 613                 return 0;
 614         if (is_null_sha1(a))
 615                 return 0;
 616         if (is_null_sha1(b))
 617                 return 0;
 618
 619         if (add_submodule_odb(path)) {
 620                 MERGE_WARNING(path, "not checked out");
 621                 return 0;
 622         }
 623
 624         if (!(commit_base = lookup_commit_reference(base)) ||
 625             !(commit_a = lookup_commit_reference(a)) ||
 626             !(commit_b = lookup_commit_reference(b))) {
 627                 MERGE_WARNING(path, "commits not present");
 628                 return 0;
 629         }
 630
 631         /* check whether both changes are forward */
 632         if (!in_merge_bases(commit_base, &commit_a, 1) ||
 633             !in_merge_bases(commit_base, &commit_b, 1)) {
 634                 MERGE_WARNING(path, "commits don't follow merge-base");
 635                 return 0;
 636         }
 637
 638         /* Case #1: a is contained in b or vice versa */
 639         if (in_merge_bases(commit_a, &commit_b, 1)) {
 640                 hashcpy(result, b);
 641                 return 1;
 642         }
 643         if (in_merge_bases(commit_b, &commit_a, 1)) {
 644                 hashcpy(result, a);
 645                 return 1;
 646         }
 647
 648         /*
 649          * Case #2: There are one or more merges that contain a and b in
 650          * the submodule. If there is only one, then present it as a
 651          * suggestion to the user, but leave it marked unmerged so the
 652          * user needs to confirm the resolution.
 653          */
 654
 655         /* find commit which merges them */
 656         parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 657         switch (parent_count) {
 658         case 0:
 659                 MERGE_WARNING(path, "merge following commits not found");
 660                 break;
 661
 662         case 1:
 663                 MERGE_WARNING(path, "not fast-forward");
 664                 fprintf(stderr, "Found a possible merge resolution "
 665                                 "for the submodule:\n");
 666                 print_commit((struct commit *) merges.objects[0].item);
 667                 fprintf(stderr,
 668                         "If this is correct simply add it to the index "
 669                         "for example\n"
 670                         "by using:\n\n"
 671                         "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 672                         "which will accept this suggestion.\n",
 673                         sha1_to_hex(merges.objects[0].item->sha1), path);
 674                 break;
 675
 676         default:
 677                 MERGE_WARNING(path, "multiple merges found");
 678                 for (i = 0; i < merges.nr; i++)
 679                         print_commit((struct commit *) merges.objects[i].item);
 680         }
 681
 682         free(merges.objects);
 683         return 0;
 684 }