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 static struct string_list config_name_for_path;
  13 static struct string_list config_fetch_recurse_submodules_for_name;
  14 static struct string_list config_ignore_for_name;
  15 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
  16 static 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 static int prepare_submodule_summary(struct rev_info *rev, const char *path,
 157                 struct commit *left, struct commit *right,
 158                 int *fast_forward, int *fast_backward)
 159 {
 160         struct commit_list *merge_bases, *list;
 161
 162         init_revisions(rev, NULL);
 163         setup_revisions(0, NULL, rev, NULL);
 164         rev->left_right = 1;
 165         rev->first_parent_only = 1;
 166         left->object.flags |= SYMMETRIC_LEFT;
 167         add_pending_object(rev, &left->object, path);
 168         add_pending_object(rev, &right->object, path);
 169         merge_bases = get_merge_bases(left, right, 1);
 170         if (merge_bases) {
 171                 if (merge_bases->item == left)
 172                         *fast_forward = 1;
 173                 else if (merge_bases->item == right)
 174                         *fast_backward = 1;
 175         }
 176         for (list = merge_bases; list; list = list->next) {
 177                 list->item->object.flags |= UNINTERESTING;
 178                 add_pending_object(rev, &list->item->object,
 179                         sha1_to_hex(list->item->object.sha1));
 180         }
 181         return prepare_revision_walk(rev);
 182 }
 183
 184 static void print_submodule_summary(struct rev_info *rev, FILE *f,
 185                 const char *del, const char *add, const char *reset)
 186 {
 187         static const char format[] = "  %m %s";
 188         struct strbuf sb = STRBUF_INIT;
 189         struct commit *commit;
 190
 191         while ((commit = get_revision(rev))) {
 192                 struct pretty_print_context ctx = {0};
 193                 ctx.date_mode = rev->date_mode;
 194                 strbuf_setlen(&sb, 0);
 195                 if (commit->object.flags & SYMMETRIC_LEFT) {
 196                         if (del)
 197                                 strbuf_addstr(&sb, del);
 198                 }
 199                 else if (add)
 200                         strbuf_addstr(&sb, add);
 201                 format_commit_message(commit, format, &sb, &ctx);
 202                 if (reset)
 203                         strbuf_addstr(&sb, reset);
 204                 strbuf_addch(&sb, '\n');
 205                 fprintf(f, "%s", sb.buf);
 206         }
 207         strbuf_release(&sb);
 208 }
 209
 210 int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
 211 {
 212         switch (git_config_maybe_bool(opt, arg)) {
 213         case 1:
 214                 return RECURSE_SUBMODULES_ON;
 215         case 0:
 216                 return RECURSE_SUBMODULES_OFF;
 217         default:
 218                 if (!strcmp(arg, "on-demand"))
 219                         return RECURSE_SUBMODULES_ON_DEMAND;
 220                 die("bad %s argument: %s", opt, arg);
 221         }
 222 }
 223
 224 void show_submodule_summary(FILE *f, const char *path,
 225                 unsigned char one[20], unsigned char two[20],
 226                 unsigned dirty_submodule,
 227                 const char *del, const char *add, const char *reset)
 228 {
 229         struct rev_info rev;
 230         struct commit *left = left, *right = right;
 231         const char *message = NULL;
 232         struct strbuf sb = STRBUF_INIT;
 233         int fast_forward = 0, fast_backward = 0;
 234
 235         if (is_null_sha1(two))
 236                 message = "(submodule deleted)";
 237         else if (add_submodule_odb(path))
 238                 message = "(not checked out)";
 239         else if (is_null_sha1(one))
 240                 message = "(new submodule)";
 241         else if (!(left = lookup_commit_reference(one)) ||
 242                  !(right = lookup_commit_reference(two)))
 243                 message = "(commits not present)";
 244
 245         if (!message &&
 246             prepare_submodule_summary(&rev, path, left, right,
 247                                         &fast_forward, &fast_backward))
 248                 message = "(revision walker failed)";
 249
 250         if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
 251                 fprintf(f, "Submodule %s contains untracked content\n", path);
 252         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 253                 fprintf(f, "Submodule %s contains modified content\n", path);
 254
 255         if (!hashcmp(one, two)) {
 256                 strbuf_release(&sb);
 257                 return;
 258         }
 259
 260         strbuf_addf(&sb, "Submodule %s %s..", path,
 261                         find_unique_abbrev(one, DEFAULT_ABBREV));
 262         if (!fast_backward && !fast_forward)
 263                 strbuf_addch(&sb, '.');
 264         strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
 265         if (message)
 266                 strbuf_addf(&sb, " %s\n", message);
 267         else
 268                 strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
 269         fwrite(sb.buf, sb.len, 1, f);
 270
 271         if (!message) {
 272                 print_submodule_summary(&rev, f, del, add, reset);
 273                 clear_commit_marks(left, ~0);
 274                 clear_commit_marks(right, ~0);
 275         }
 276
 277         strbuf_release(&sb);
 278 }
 279
 280 void set_config_fetch_recurse_submodules(int value)
 281 {
 282         config_fetch_recurse_submodules = value;
 283 }
 284
 285 static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
 286 {
 287         int is_present = 0;
 288         if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
 289                 /* Even if the submodule is checked out and the commit is
 290                  * present, make sure it is reachable from a ref. */
 291                 struct child_process cp;
 292                 const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
 293                 struct strbuf buf = STRBUF_INIT;
 294
 295                 argv[3] = sha1_to_hex(sha1);
 296                 memset(&cp, 0, sizeof(cp));
 297                 cp.argv = argv;
 298                 cp.env = local_repo_env;
 299                 cp.git_cmd = 1;
 300                 cp.no_stdin = 1;
 301                 cp.out = -1;
 302                 cp.dir = path;
 303                 if (!run_command(&cp) && !strbuf_read(&buf, cp.out, 1024))
 304                         is_present = 1;
 305
 306                 close(cp.out);
 307                 strbuf_release(&buf);
 308         }
 309         return is_present;
 310 }
 311
 312 static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 313                                          struct diff_options *options,
 314                                          void *data)
 315 {
 316         int i;
 317         for (i = 0; i < q->nr; i++) {
 318                 struct diff_filepair *p = q->queue[i];
 319                 if (!S_ISGITLINK(p->two->mode))
 320                         continue;
 321
 322                 if (S_ISGITLINK(p->one->mode)) {
 323                         /* NEEDSWORK: We should honor the name configured in
 324                          * the .gitmodules file of the commit we are examining
 325                          * here to be able to correctly follow submodules
 326                          * being moved around. */
 327                         struct string_list_item *path;
 328                         path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
 329                         if (!path && !is_submodule_commit_present(p->two->path, p->two->sha1))
 330                                 string_list_append(&changed_submodule_paths, xstrdup(p->two->path));
 331                 } else {
 332                         /* Submodule is new or was moved here */
 333                         /* NEEDSWORK: When the .git directories of submodules
 334                          * live inside the superprojects .git directory some
 335                          * day we should fetch new submodules directly into
 336                          * that location too when config or options request
 337                          * that so they can be checked out from there. */
 338                         continue;
 339                 }
 340         }
 341 }
 342
 343 void check_for_new_submodule_commits(unsigned char new_sha1[20])
 344 {
 345         struct rev_info rev;
 346         struct commit *commit;
 347         const char *argv[] = {NULL, NULL, "--not", "--all", NULL};
 348         int argc = ARRAY_SIZE(argv) - 1;
 349
 350         init_revisions(&rev, NULL);
 351         argv[1] = xstrdup(sha1_to_hex(new_sha1));
 352         setup_revisions(argc, argv, &rev, NULL);
 353         if (prepare_revision_walk(&rev))
 354                 die("revision walk setup failed");
 355
 356         /*
 357          * Collect all submodules (whether checked out or not) for which new
 358          * commits have been recorded upstream in "changed_submodule_paths".
 359          */
 360         while ((commit = get_revision(&rev))) {
 361                 struct commit_list *parent = commit->parents;
 362                 while (parent) {
 363                         struct diff_options diff_opts;
 364                         diff_setup(&diff_opts);
 365                         diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
 366                         diff_opts.format_callback = submodule_collect_changed_cb;
 367                         if (diff_setup_done(&diff_opts) < 0)
 368                                 die("diff_setup_done failed");
 369                         diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
 370                         diffcore_std(&diff_opts);
 371                         diff_flush(&diff_opts);
 372                         parent = parent->next;
 373                 }
 374         }
 375         free((char *)argv[1]);
 376 }
 377
 378 int fetch_populated_submodules(int num_options, const char **options,
 379                                const char *prefix, int command_line_option,
 380                                int quiet)
 381 {
 382         int i, result = 0, argc = 0, default_argc;
 383         struct child_process cp;
 384         const char **argv;
 385         struct string_list_item *name_for_path;
 386         const char *work_tree = get_git_work_tree();
 387         if (!work_tree)
 388                 goto out;
 389
 390         if (!the_index.initialized)
 391                 if (read_cache() < 0)
 392                         die("index file corrupt");
 393
 394         /* 6: "fetch" (options) --recurse-submodules-default default "--submodule-prefix" prefix NULL */
 395         argv = xcalloc(num_options + 6, sizeof(const char *));
 396         argv[argc++] = "fetch";
 397         for (i = 0; i < num_options; i++)
 398                 argv[argc++] = options[i];
 399         argv[argc++] = "--recurse-submodules-default";
 400         default_argc = argc++;
 401         argv[argc++] = "--submodule-prefix";
 402
 403         memset(&cp, 0, sizeof(cp));
 404         cp.argv = argv;
 405         cp.env = local_repo_env;
 406         cp.git_cmd = 1;
 407         cp.no_stdin = 1;
 408
 409         for (i = 0; i < active_nr; i++) {
 410                 struct strbuf submodule_path = STRBUF_INIT;
 411                 struct strbuf submodule_git_dir = STRBUF_INIT;
 412                 struct strbuf submodule_prefix = STRBUF_INIT;
 413                 struct cache_entry *ce = active_cache[i];
 414                 const char *git_dir, *name, *default_argv;
 415
 416                 if (!S_ISGITLINK(ce->ce_mode))
 417                         continue;
 418
 419                 name = ce->name;
 420                 name_for_path = unsorted_string_list_lookup(&config_name_for_path, ce->name);
 421                 if (name_for_path)
 422                         name = name_for_path->util;
 423
 424                 default_argv = "yes";
 425                 if (command_line_option == RECURSE_SUBMODULES_DEFAULT) {
 426                         struct string_list_item *fetch_recurse_submodules_option;
 427                         fetch_recurse_submodules_option = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name);
 428                         if (fetch_recurse_submodules_option) {
 429                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_OFF)
 430                                         continue;
 431                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_ON_DEMAND) {
 432                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 433                                                 continue;
 434                                         default_argv = "on-demand";
 435                                 }
 436                         } else {
 437                                 if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_OFF)
 438                                         continue;
 439                                 if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) {
 440                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 441                                                 continue;
 442                                         default_argv = "on-demand";
 443                                 }
 444                         }
 445                 } else if (command_line_option == RECURSE_SUBMODULES_ON_DEMAND) {
 446                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 447                                 continue;
 448                         default_argv = "on-demand";
 449                 }
 450
 451                 strbuf_addf(&submodule_path, "%s/%s", work_tree, ce->name);
 452                 strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
 453                 strbuf_addf(&submodule_prefix, "%s%s/", prefix, ce->name);
 454                 git_dir = read_gitfile_gently(submodule_git_dir.buf);
 455                 if (!git_dir)
 456                         git_dir = submodule_git_dir.buf;
 457                 if (is_directory(git_dir)) {
 458                         if (!quiet)
 459                                 printf("Fetching submodule %s%s\n", prefix, ce->name);
 460                         cp.dir = submodule_path.buf;
 461                         argv[default_argc] = default_argv;
 462                         argv[argc] = submodule_prefix.buf;
 463                         if (run_command(&cp))
 464                                 result = 1;
 465                 }
 466                 strbuf_release(&submodule_path);
 467                 strbuf_release(&submodule_git_dir);
 468                 strbuf_release(&submodule_prefix);
 469         }
 470         free(argv);
 471 out:
 472         string_list_clear(&changed_submodule_paths, 1);
 473         return result;
 474 }
 475
 476 unsigned is_submodule_modified(const char *path, int ignore_untracked)
 477 {
 478         ssize_t len;
 479         struct child_process cp;
 480         const char *argv[] = {
 481                 "status",
 482                 "--porcelain",
 483                 NULL,
 484                 NULL,
 485         };
 486         struct strbuf buf = STRBUF_INIT;
 487         unsigned dirty_submodule = 0;
 488         const char *line, *next_line;
 489         const char *git_dir;
 490
 491         strbuf_addf(&buf, "%s/.git", path);
 492         git_dir = read_gitfile_gently(buf.buf);
 493         if (!git_dir)
 494                 git_dir = buf.buf;
 495         if (!is_directory(git_dir)) {
 496                 strbuf_release(&buf);
 497                 /* The submodule is not checked out, so it is not modified */
 498                 return 0;
 499
 500         }
 501         strbuf_reset(&buf);
 502
 503         if (ignore_untracked)
 504                 argv[2] = "-uno";
 505
 506         memset(&cp, 0, sizeof(cp));
 507         cp.argv = argv;
 508         cp.env = local_repo_env;
 509         cp.git_cmd = 1;
 510         cp.no_stdin = 1;
 511         cp.out = -1;
 512         cp.dir = path;
 513         if (start_command(&cp))
 514                 die("Could not run git status --porcelain");
 515
 516         len = strbuf_read(&buf, cp.out, 1024);
 517         line = buf.buf;
 518         while (len > 2) {
 519                 if ((line[0] == '?') && (line[1] == '?')) {
 520                         dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
 521                         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 522                                 break;
 523                 } else {
 524                         dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
 525                         if (ignore_untracked ||
 526                             (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
 527                                 break;
 528                 }
 529                 next_line = strchr(line, '\n');
 530                 if (!next_line)
 531                         break;
 532                 next_line++;
 533                 len -= (next_line - line);
 534                 line = next_line;
 535         }
 536         close(cp.out);
 537
 538         if (finish_command(&cp))
 539                 die("git status --porcelain failed");
 540
 541         strbuf_release(&buf);
 542         return dirty_submodule;
 543 }
 544
 545 static int find_first_merges(struct object_array *result, const char *path,
 546                 struct commit *a, struct commit *b)
 547 {
 548         int i, j;
 549         struct object_array merges;
 550         struct commit *commit;
 551         int contains_another;
 552
 553         char merged_revision[42];
 554         const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 555                                    "--all", merged_revision, NULL };
 556         struct rev_info revs;
 557         struct setup_revision_opt rev_opts;
 558
 559         memset(&merges, 0, sizeof(merges));
 560         memset(result, 0, sizeof(struct object_array));
 561         memset(&rev_opts, 0, sizeof(rev_opts));
 562
 563         /* get all revisions that merge commit a */
 564         snprintf(merged_revision, sizeof(merged_revision), "^%s",
 565                         sha1_to_hex(a->object.sha1));
 566         init_revisions(&revs, NULL);
 567         rev_opts.submodule = path;
 568         setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);
 569
 570         /* save all revisions from the above list that contain b */
 571         if (prepare_revision_walk(&revs))
 572                 die("revision walk setup failed");
 573         while ((commit = get_revision(&revs)) != NULL) {
 574                 struct object *o = &(commit->object);
 575                 if (in_merge_bases(b, &commit, 1))
 576                         add_object_array(o, NULL, &merges);
 577         }
 578
 579         /* Now we've got all merges that contain a and b. Prune all
 580          * merges that contain another found merge and save them in
 581          * result.
 582          */
 583         for (i = 0; i < merges.nr; i++) {
 584                 struct commit *m1 = (struct commit *) merges.objects[i].item;
 585
 586                 contains_another = 0;
 587                 for (j = 0; j < merges.nr; j++) {
 588                         struct commit *m2 = (struct commit *) merges.objects[j].item;
 589                         if (i != j && in_merge_bases(m2, &m1, 1)) {
 590                                 contains_another = 1;
 591                                 break;
 592                         }
 593                 }
 594
 595                 if (!contains_another)
 596                         add_object_array(merges.objects[i].item,
 597                                          merges.objects[i].name, result);
 598         }
 599
 600         free(merges.objects);
 601         return result->nr;
 602 }
 603
 604 static void print_commit(struct commit *commit)
 605 {
 606         struct strbuf sb = STRBUF_INIT;
 607         struct pretty_print_context ctx = {0};
 608         ctx.date_mode = DATE_NORMAL;
 609         format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 610         fprintf(stderr, "%s\n", sb.buf);
 611         strbuf_release(&sb);
 612 }
 613
 614 #define MERGE_WARNING(path, msg) \
 615         warning("Failed to merge submodule %s (%s)", path, msg);
 616
 617 int merge_submodule(unsigned char result[20], const char *path,
 618                     const unsigned char base[20], const unsigned char a[20],
 619                     const unsigned char b[20])
 620 {
 621         struct commit *commit_base, *commit_a, *commit_b;
 622         int parent_count;
 623         struct object_array merges;
 624
 625         int i;
 626
 627         /* store a in result in case we fail */
 628         hashcpy(result, a);
 629
 630         /* we can not handle deletion conflicts */
 631         if (is_null_sha1(base))
 632                 return 0;
 633         if (is_null_sha1(a))
 634                 return 0;
 635         if (is_null_sha1(b))
 636                 return 0;
 637
 638         if (add_submodule_odb(path)) {
 639                 MERGE_WARNING(path, "not checked out");
 640                 return 0;
 641         }
 642
 643         if (!(commit_base = lookup_commit_reference(base)) ||
 644             !(commit_a = lookup_commit_reference(a)) ||
 645             !(commit_b = lookup_commit_reference(b))) {
 646                 MERGE_WARNING(path, "commits not present");
 647                 return 0;
 648         }
 649
 650         /* check whether both changes are forward */
 651         if (!in_merge_bases(commit_base, &commit_a, 1) ||
 652             !in_merge_bases(commit_base, &commit_b, 1)) {
 653                 MERGE_WARNING(path, "commits don't follow merge-base");
 654                 return 0;
 655         }
 656
 657         /* Case #1: a is contained in b or vice versa */
 658         if (in_merge_bases(commit_a, &commit_b, 1)) {
 659                 hashcpy(result, b);
 660                 return 1;
 661         }
 662         if (in_merge_bases(commit_b, &commit_a, 1)) {
 663                 hashcpy(result, a);
 664                 return 1;
 665         }
 666
 667         /*
 668          * Case #2: There are one or more merges that contain a and b in
 669          * the submodule. If there is only one, then present it as a
 670          * suggestion to the user, but leave it marked unmerged so the
 671          * user needs to confirm the resolution.
 672          */
 673
 674         /* find commit which merges them */
 675         parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 676         switch (parent_count) {
 677         case 0:
 678                 MERGE_WARNING(path, "merge following commits not found");
 679                 break;
 680
 681         case 1:
 682                 MERGE_WARNING(path, "not fast-forward");
 683                 fprintf(stderr, "Found a possible merge resolution "
 684                                 "for the submodule:\n");
 685                 print_commit((struct commit *) merges.objects[0].item);
 686                 fprintf(stderr,
 687                         "If this is correct simply add it to the index "
 688                         "for example\n"
 689                         "by using:\n\n"
 690                         "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 691                         "which will accept this suggestion.\n",
 692                         sha1_to_hex(merges.objects[0].item->sha1), path);
 693                 break;
 694
 695         default:
 696                 MERGE_WARNING(path, "multiple merges found");
 697                 for (i = 0; i < merges.nr; i++)
 698                         print_commit((struct commit *) merges.objects[i].item);
 699         }
 700
 701         free(merges.objects);
 702         return 0;
 703 }