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 #include "sha1-array.h"
  12
  13 static struct string_list config_name_for_path;
  14 static struct string_list config_fetch_recurse_submodules_for_name;
  15 static struct string_list config_ignore_for_name;
  16 static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
  17 static struct string_list changed_submodule_paths;
  18 static int initialized_fetch_ref_tips;
  19 static struct sha1_array ref_tips_before_fetch;
  20 static struct sha1_array ref_tips_after_fetch;
  21
  22 /*
  23  * The following flag is set if the .gitmodules file is unmerged. We then
  24  * disable recursion for all submodules where .git/config doesn't have a
  25  * matching config entry because we can't guess what might be configured in
  26  * .gitmodules unless the user resolves the conflict. When a command line
  27  * option is given (which always overrides configuration) this flag will be
  28  * ignored.
  29  */
  30 static int gitmodules_is_unmerged;
  31
  32 static int add_submodule_odb(const char *path)
  33 {
  34         struct strbuf objects_directory = STRBUF_INIT;
  35         struct alternate_object_database *alt_odb;
  36         int ret = 0;
  37         const char *git_dir;
  38
  39         strbuf_addf(&objects_directory, "%s/.git", path);
  40         git_dir = read_gitfile_gently(objects_directory.buf);
  41         if (git_dir) {
  42                 strbuf_reset(&objects_directory);
  43                 strbuf_addstr(&objects_directory, git_dir);
  44         }
  45         strbuf_addstr(&objects_directory, "/objects/");
  46         if (!is_directory(objects_directory.buf)) {
  47                 ret = -1;
  48                 goto done;
  49         }
  50         /* avoid adding it twice */
  51         for (alt_odb = alt_odb_list; alt_odb; alt_odb = alt_odb->next)
  52                 if (alt_odb->name - alt_odb->base == objects_directory.len &&
  53                                 !strncmp(alt_odb->base, objects_directory.buf,
  54                                         objects_directory.len))
  55                         goto done;
  56
  57         alt_odb = xmalloc(objects_directory.len + 42 + sizeof(*alt_odb));
  58         alt_odb->next = alt_odb_list;
  59         strcpy(alt_odb->base, objects_directory.buf);
  60         alt_odb->name = alt_odb->base + objects_directory.len;
  61         alt_odb->name[2] = '/';
  62         alt_odb->name[40] = '\0';
  63         alt_odb->name[41] = '\0';
  64         alt_odb_list = alt_odb;
  65         prepare_alt_odb();
  66 done:
  67         strbuf_release(&objects_directory);
  68         return ret;
  69 }
  70
  71 void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
  72                                              const char *path)
  73 {
  74         struct string_list_item *path_option, *ignore_option;
  75         path_option = unsorted_string_list_lookup(&config_name_for_path, path);
  76         if (path_option) {
  77                 ignore_option = unsorted_string_list_lookup(&config_ignore_for_name, path_option->util);
  78                 if (ignore_option)
  79                         handle_ignore_submodules_arg(diffopt, ignore_option->util);
  80                 else if (gitmodules_is_unmerged)
  81                         DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
  82         }
  83 }
  84
  85 int submodule_config(const char *var, const char *value, void *cb)
  86 {
  87         if (!prefixcmp(var, "submodule."))
  88                 return parse_submodule_config_option(var, value);
  89         else if (!strcmp(var, "fetch.recursesubmodules")) {
  90                 config_fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(var, value);
  91                 return 0;
  92         }
  93         return 0;
  94 }
  95
  96 void gitmodules_config(void)
  97 {
  98         const char *work_tree = get_git_work_tree();
  99         if (work_tree) {
 100                 struct strbuf gitmodules_path = STRBUF_INIT;
 101                 int pos;
 102                 strbuf_addstr(&gitmodules_path, work_tree);
 103                 strbuf_addstr(&gitmodules_path, "/.gitmodules");
 104                 if (read_cache() < 0)
 105                         die("index file corrupt");
 106                 pos = cache_name_pos(".gitmodules", 11);
 107                 if (pos < 0) { /* .gitmodules not found or isn't merged */
 108                         pos = -1 - pos;
 109                         if (active_nr > pos) {  /* there is a .gitmodules */
 110                                 const struct cache_entry *ce = active_cache[pos];
 111                                 if (ce_namelen(ce) == 11 &&
 112                                     !memcmp(ce->name, ".gitmodules", 11))
 113                                         gitmodules_is_unmerged = 1;
 114                         }
 115                 }
 116
 117                 if (!gitmodules_is_unmerged)
 118                         git_config_from_file(submodule_config, gitmodules_path.buf, NULL);
 119                 strbuf_release(&gitmodules_path);
 120         }
 121 }
 122
 123 int parse_submodule_config_option(const char *var, const char *value)
 124 {
 125         int len;
 126         struct string_list_item *config;
 127         struct strbuf submodname = STRBUF_INIT;
 128
 129         var += 10;              /* Skip "submodule." */
 130
 131         len = strlen(var);
 132         if ((len > 5) && !strcmp(var + len - 5, ".path")) {
 133                 strbuf_add(&submodname, var, len - 5);
 134                 config = unsorted_string_list_lookup(&config_name_for_path, value);
 135                 if (config)
 136                         free(config->util);
 137                 else
 138                         config = string_list_append(&config_name_for_path, xstrdup(value));
 139                 config->util = strbuf_detach(&submodname, NULL);
 140                 strbuf_release(&submodname);
 141         } else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
 142                 strbuf_add(&submodname, var, len - 23);
 143                 config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
 144                 if (!config)
 145                         config = string_list_append(&config_fetch_recurse_submodules_for_name,
 146                                                     strbuf_detach(&submodname, NULL));
 147                 config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
 148                 strbuf_release(&submodname);
 149         } else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
 150                 if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 151                     strcmp(value, "all") && strcmp(value, "none")) {
 152                         warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 153                         return 0;
 154                 }
 155
 156                 strbuf_add(&submodname, var, len - 7);
 157                 config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
 158                 if (config)
 159                         free(config->util);
 160                 else
 161                         config = string_list_append(&config_ignore_for_name,
 162                                                     strbuf_detach(&submodname, NULL));
 163                 strbuf_release(&submodname);
 164                 config->util = xstrdup(value);
 165                 return 0;
 166         }
 167         return 0;
 168 }
 169
 170 void handle_ignore_submodules_arg(struct diff_options *diffopt,
 171                                   const char *arg)
 172 {
 173         DIFF_OPT_CLR(diffopt, IGNORE_SUBMODULES);
 174         DIFF_OPT_CLR(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 175         DIFF_OPT_CLR(diffopt, IGNORE_DIRTY_SUBMODULES);
 176
 177         if (!strcmp(arg, "all"))
 178                 DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
 179         else if (!strcmp(arg, "untracked"))
 180                 DIFF_OPT_SET(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 181         else if (!strcmp(arg, "dirty"))
 182                 DIFF_OPT_SET(diffopt, IGNORE_DIRTY_SUBMODULES);
 183         else if (strcmp(arg, "none"))
 184                 die("bad --ignore-submodules argument: %s", arg);
 185 }
 186
 187 static int prepare_submodule_summary(struct rev_info *rev, const char *path,
 188                 struct commit *left, struct commit *right,
 189                 int *fast_forward, int *fast_backward)
 190 {
 191         struct commit_list *merge_bases, *list;
 192
 193         init_revisions(rev, NULL);
 194         setup_revisions(0, NULL, rev, NULL);
 195         rev->left_right = 1;
 196         rev->first_parent_only = 1;
 197         left->object.flags |= SYMMETRIC_LEFT;
 198         add_pending_object(rev, &left->object, path);
 199         add_pending_object(rev, &right->object, path);
 200         merge_bases = get_merge_bases(left, right, 1);
 201         if (merge_bases) {
 202                 if (merge_bases->item == left)
 203                         *fast_forward = 1;
 204                 else if (merge_bases->item == right)
 205                         *fast_backward = 1;
 206         }
 207         for (list = merge_bases; list; list = list->next) {
 208                 list->item->object.flags |= UNINTERESTING;
 209                 add_pending_object(rev, &list->item->object,
 210                         sha1_to_hex(list->item->object.sha1));
 211         }
 212         return prepare_revision_walk(rev);
 213 }
 214
 215 static void print_submodule_summary(struct rev_info *rev, FILE *f,
 216                 const char *del, const char *add, const char *reset)
 217 {
 218         static const char format[] = "  %m %s";
 219         struct strbuf sb = STRBUF_INIT;
 220         struct commit *commit;
 221
 222         while ((commit = get_revision(rev))) {
 223                 struct pretty_print_context ctx = {0};
 224                 ctx.date_mode = rev->date_mode;
 225                 strbuf_setlen(&sb, 0);
 226                 if (commit->object.flags & SYMMETRIC_LEFT) {
 227                         if (del)
 228                                 strbuf_addstr(&sb, del);
 229                 }
 230                 else if (add)
 231                         strbuf_addstr(&sb, add);
 232                 format_commit_message(commit, format, &sb, &ctx);
 233                 if (reset)
 234                         strbuf_addstr(&sb, reset);
 235                 strbuf_addch(&sb, '\n');
 236                 fprintf(f, "%s", sb.buf);
 237         }
 238         strbuf_release(&sb);
 239 }
 240
 241 int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
 242 {
 243         switch (git_config_maybe_bool(opt, arg)) {
 244         case 1:
 245                 return RECURSE_SUBMODULES_ON;
 246         case 0:
 247                 return RECURSE_SUBMODULES_OFF;
 248         default:
 249                 if (!strcmp(arg, "on-demand"))
 250                         return RECURSE_SUBMODULES_ON_DEMAND;
 251                 die("bad %s argument: %s", opt, arg);
 252         }
 253 }
 254
 255 void show_submodule_summary(FILE *f, const char *path,
 256                 unsigned char one[20], unsigned char two[20],
 257                 unsigned dirty_submodule,
 258                 const char *del, const char *add, const char *reset)
 259 {
 260         struct rev_info rev;
 261         struct commit *left = left, *right = right;
 262         const char *message = NULL;
 263         struct strbuf sb = STRBUF_INIT;
 264         int fast_forward = 0, fast_backward = 0;
 265
 266         if (is_null_sha1(two))
 267                 message = "(submodule deleted)";
 268         else if (add_submodule_odb(path))
 269                 message = "(not checked out)";
 270         else if (is_null_sha1(one))
 271                 message = "(new submodule)";
 272         else if (!(left = lookup_commit_reference(one)) ||
 273                  !(right = lookup_commit_reference(two)))
 274                 message = "(commits not present)";
 275
 276         if (!message &&
 277             prepare_submodule_summary(&rev, path, left, right,
 278                                         &fast_forward, &fast_backward))
 279                 message = "(revision walker failed)";
 280
 281         if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
 282                 fprintf(f, "Submodule %s contains untracked content\n", path);
 283         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 284                 fprintf(f, "Submodule %s contains modified content\n", path);
 285
 286         if (!hashcmp(one, two)) {
 287                 strbuf_release(&sb);
 288                 return;
 289         }
 290
 291         strbuf_addf(&sb, "Submodule %s %s..", path,
 292                         find_unique_abbrev(one, DEFAULT_ABBREV));
 293         if (!fast_backward && !fast_forward)
 294                 strbuf_addch(&sb, '.');
 295         strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
 296         if (message)
 297                 strbuf_addf(&sb, " %s\n", message);
 298         else
 299                 strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
 300         fwrite(sb.buf, sb.len, 1, f);
 301
 302         if (!message) {
 303                 print_submodule_summary(&rev, f, del, add, reset);
 304                 clear_commit_marks(left, ~0);
 305                 clear_commit_marks(right, ~0);
 306         }
 307
 308         strbuf_release(&sb);
 309 }
 310
 311 void set_config_fetch_recurse_submodules(int value)
 312 {
 313         config_fetch_recurse_submodules = value;
 314 }
 315
 316 static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
 317 {
 318         int is_present = 0;
 319         if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
 320                 /* Even if the submodule is checked out and the commit is
 321                  * present, make sure it is reachable from a ref. */
 322                 struct child_process cp;
 323                 const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
 324                 struct strbuf buf = STRBUF_INIT;
 325
 326                 argv[3] = sha1_to_hex(sha1);
 327                 memset(&cp, 0, sizeof(cp));
 328                 cp.argv = argv;
 329                 cp.env = local_repo_env;
 330                 cp.git_cmd = 1;
 331                 cp.no_stdin = 1;
 332                 cp.out = -1;
 333                 cp.dir = path;
 334                 if (!run_command(&cp) && !strbuf_read(&buf, cp.out, 1024))
 335                         is_present = 1;
 336
 337                 close(cp.out);
 338                 strbuf_release(&buf);
 339         }
 340         return is_present;
 341 }
 342
 343 static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 344                                          struct diff_options *options,
 345                                          void *data)
 346 {
 347         int i;
 348         for (i = 0; i < q->nr; i++) {
 349                 struct diff_filepair *p = q->queue[i];
 350                 if (!S_ISGITLINK(p->two->mode))
 351                         continue;
 352
 353                 if (S_ISGITLINK(p->one->mode)) {
 354                         /* NEEDSWORK: We should honor the name configured in
 355                          * the .gitmodules file of the commit we are examining
 356                          * here to be able to correctly follow submodules
 357                          * being moved around. */
 358                         struct string_list_item *path;
 359                         path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
 360                         if (!path && !is_submodule_commit_present(p->two->path, p->two->sha1))
 361                                 string_list_append(&changed_submodule_paths, xstrdup(p->two->path));
 362                 } else {
 363                         /* Submodule is new or was moved here */
 364                         /* NEEDSWORK: When the .git directories of submodules
 365                          * live inside the superprojects .git directory some
 366                          * day we should fetch new submodules directly into
 367                          * that location too when config or options request
 368                          * that so they can be checked out from there. */
 369                         continue;
 370                 }
 371         }
 372 }
 373
 374 static int add_sha1_to_array(const char *ref, const unsigned char *sha1,
 375                              int flags, void *data)
 376 {
 377         sha1_array_append(data, sha1);
 378         return 0;
 379 }
 380
 381 void check_for_new_submodule_commits(unsigned char new_sha1[20])
 382 {
 383         if (!initialized_fetch_ref_tips) {
 384                 for_each_ref(add_sha1_to_array, &ref_tips_before_fetch);
 385                 initialized_fetch_ref_tips = 1;
 386         }
 387
 388         sha1_array_append(&ref_tips_after_fetch, new_sha1);
 389 }
 390
 391 struct argv_array {
 392         const char **argv;
 393         unsigned int argc;
 394         unsigned int alloc;
 395 };
 396
 397 static void init_argv(struct argv_array *array)
 398 {
 399         array->argv = NULL;
 400         array->argc = 0;
 401         array->alloc = 0;
 402 }
 403
 404 static void push_argv(struct argv_array *array, const char *value)
 405 {
 406         ALLOC_GROW(array->argv, array->argc + 2, array->alloc);
 407         array->argv[array->argc++] = xstrdup(value);
 408         array->argv[array->argc] = NULL;
 409 }
 410
 411 static void clear_argv(struct argv_array *array)
 412 {
 413         int i;
 414         for (i = 0; i < array->argc; i++)
 415                 free((char **)array->argv[i]);
 416         free(array->argv);
 417         init_argv(array);
 418 }
 419
 420 static void add_sha1_to_argv(const unsigned char sha1[20], void *data)
 421 {
 422         push_argv(data, sha1_to_hex(sha1));
 423 }
 424
 425 static void calculate_changed_submodule_paths(void)
 426 {
 427         struct rev_info rev;
 428         struct commit *commit;
 429         struct argv_array argv;
 430
 431         init_revisions(&rev, NULL);
 432         init_argv(&argv);
 433         push_argv(&argv, "--"); /* argv[0] program name */
 434         sha1_array_for_each_unique(&ref_tips_after_fetch,
 435                                    add_sha1_to_argv, &argv);
 436         push_argv(&argv, "--not");
 437         sha1_array_for_each_unique(&ref_tips_before_fetch,
 438                                    add_sha1_to_argv, &argv);
 439         setup_revisions(argv.argc, argv.argv, &rev, NULL);
 440         if (prepare_revision_walk(&rev))
 441                 die("revision walk setup failed");
 442
 443         /*
 444          * Collect all submodules (whether checked out or not) for which new
 445          * commits have been recorded upstream in "changed_submodule_paths".
 446          */
 447         while ((commit = get_revision(&rev))) {
 448                 struct commit_list *parent = commit->parents;
 449                 while (parent) {
 450                         struct diff_options diff_opts;
 451                         diff_setup(&diff_opts);
 452                         diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
 453                         diff_opts.format_callback = submodule_collect_changed_cb;
 454                         if (diff_setup_done(&diff_opts) < 0)
 455                                 die("diff_setup_done failed");
 456                         diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
 457                         diffcore_std(&diff_opts);
 458                         diff_flush(&diff_opts);
 459                         parent = parent->next;
 460                 }
 461         }
 462
 463         clear_argv(&argv);
 464         sha1_array_clear(&ref_tips_before_fetch);
 465         sha1_array_clear(&ref_tips_after_fetch);
 466         initialized_fetch_ref_tips = 0;
 467 }
 468
 469 int fetch_populated_submodules(int num_options, const char **options,
 470                                const char *prefix, int command_line_option,
 471                                int quiet)
 472 {
 473         int i, result = 0, argc = 0, default_argc;
 474         struct child_process cp;
 475         const char **argv;
 476         struct string_list_item *name_for_path;
 477         const char *work_tree = get_git_work_tree();
 478         if (!work_tree)
 479                 goto out;
 480
 481         if (!the_index.initialized)
 482                 if (read_cache() < 0)
 483                         die("index file corrupt");
 484
 485         /* 6: "fetch" (options) --recurse-submodules-default default "--submodule-prefix" prefix NULL */
 486         argv = xcalloc(num_options + 6, sizeof(const char *));
 487         argv[argc++] = "fetch";
 488         for (i = 0; i < num_options; i++)
 489                 argv[argc++] = options[i];
 490         argv[argc++] = "--recurse-submodules-default";
 491         default_argc = argc++;
 492         argv[argc++] = "--submodule-prefix";
 493
 494         memset(&cp, 0, sizeof(cp));
 495         cp.argv = argv;
 496         cp.env = local_repo_env;
 497         cp.git_cmd = 1;
 498         cp.no_stdin = 1;
 499
 500         calculate_changed_submodule_paths();
 501
 502         for (i = 0; i < active_nr; i++) {
 503                 struct strbuf submodule_path = STRBUF_INIT;
 504                 struct strbuf submodule_git_dir = STRBUF_INIT;
 505                 struct strbuf submodule_prefix = STRBUF_INIT;
 506                 struct cache_entry *ce = active_cache[i];
 507                 const char *git_dir, *name, *default_argv;
 508
 509                 if (!S_ISGITLINK(ce->ce_mode))
 510                         continue;
 511
 512                 name = ce->name;
 513                 name_for_path = unsorted_string_list_lookup(&config_name_for_path, ce->name);
 514                 if (name_for_path)
 515                         name = name_for_path->util;
 516
 517                 default_argv = "yes";
 518                 if (command_line_option == RECURSE_SUBMODULES_DEFAULT) {
 519                         struct string_list_item *fetch_recurse_submodules_option;
 520                         fetch_recurse_submodules_option = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name);
 521                         if (fetch_recurse_submodules_option) {
 522                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_OFF)
 523                                         continue;
 524                                 if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_ON_DEMAND) {
 525                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 526                                                 continue;
 527                                         default_argv = "on-demand";
 528                                 }
 529                         } else {
 530                                 if ((config_fetch_recurse_submodules == RECURSE_SUBMODULES_OFF) ||
 531                                     gitmodules_is_unmerged)
 532                                         continue;
 533                                 if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) {
 534                                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 535                                                 continue;
 536                                         default_argv = "on-demand";
 537                                 }
 538                         }
 539                 } else if (command_line_option == RECURSE_SUBMODULES_ON_DEMAND) {
 540                         if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 541                                 continue;
 542                         default_argv = "on-demand";
 543                 }
 544
 545                 strbuf_addf(&submodule_path, "%s/%s", work_tree, ce->name);
 546                 strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
 547                 strbuf_addf(&submodule_prefix, "%s%s/", prefix, ce->name);
 548                 git_dir = read_gitfile_gently(submodule_git_dir.buf);
 549                 if (!git_dir)
 550                         git_dir = submodule_git_dir.buf;
 551                 if (is_directory(git_dir)) {
 552                         if (!quiet)
 553                                 printf("Fetching submodule %s%s\n", prefix, ce->name);
 554                         cp.dir = submodule_path.buf;
 555                         argv[default_argc] = default_argv;
 556                         argv[argc] = submodule_prefix.buf;
 557                         if (run_command(&cp))
 558                                 result = 1;
 559                 }
 560                 strbuf_release(&submodule_path);
 561                 strbuf_release(&submodule_git_dir);
 562                 strbuf_release(&submodule_prefix);
 563         }
 564         free(argv);
 565 out:
 566         string_list_clear(&changed_submodule_paths, 1);
 567         return result;
 568 }
 569
 570 unsigned is_submodule_modified(const char *path, int ignore_untracked)
 571 {
 572         ssize_t len;
 573         struct child_process cp;
 574         const char *argv[] = {
 575                 "status",
 576                 "--porcelain",
 577                 NULL,
 578                 NULL,
 579         };
 580         struct strbuf buf = STRBUF_INIT;
 581         unsigned dirty_submodule = 0;
 582         const char *line, *next_line;
 583         const char *git_dir;
 584
 585         strbuf_addf(&buf, "%s/.git", path);
 586         git_dir = read_gitfile_gently(buf.buf);
 587         if (!git_dir)
 588                 git_dir = buf.buf;
 589         if (!is_directory(git_dir)) {
 590                 strbuf_release(&buf);
 591                 /* The submodule is not checked out, so it is not modified */
 592                 return 0;
 593
 594         }
 595         strbuf_reset(&buf);
 596
 597         if (ignore_untracked)
 598                 argv[2] = "-uno";
 599
 600         memset(&cp, 0, sizeof(cp));
 601         cp.argv = argv;
 602         cp.env = local_repo_env;
 603         cp.git_cmd = 1;
 604         cp.no_stdin = 1;
 605         cp.out = -1;
 606         cp.dir = path;
 607         if (start_command(&cp))
 608                 die("Could not run git status --porcelain");
 609
 610         len = strbuf_read(&buf, cp.out, 1024);
 611         line = buf.buf;
 612         while (len > 2) {
 613                 if ((line[0] == '?') && (line[1] == '?')) {
 614                         dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
 615                         if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 616                                 break;
 617                 } else {
 618                         dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
 619                         if (ignore_untracked ||
 620                             (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
 621                                 break;
 622                 }
 623                 next_line = strchr(line, '\n');
 624                 if (!next_line)
 625                         break;
 626                 next_line++;
 627                 len -= (next_line - line);
 628                 line = next_line;
 629         }
 630         close(cp.out);
 631
 632         if (finish_command(&cp))
 633                 die("git status --porcelain failed");
 634
 635         strbuf_release(&buf);
 636         return dirty_submodule;
 637 }
 638
 639 static int find_first_merges(struct object_array *result, const char *path,
 640                 struct commit *a, struct commit *b)
 641 {
 642         int i, j;
 643         struct object_array merges;
 644         struct commit *commit;
 645         int contains_another;
 646
 647         char merged_revision[42];
 648         const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 649                                    "--all", merged_revision, NULL };
 650         struct rev_info revs;
 651         struct setup_revision_opt rev_opts;
 652
 653         memset(&merges, 0, sizeof(merges));
 654         memset(result, 0, sizeof(struct object_array));
 655         memset(&rev_opts, 0, sizeof(rev_opts));
 656
 657         /* get all revisions that merge commit a */
 658         snprintf(merged_revision, sizeof(merged_revision), "^%s",
 659                         sha1_to_hex(a->object.sha1));
 660         init_revisions(&revs, NULL);
 661         rev_opts.submodule = path;
 662         setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);
 663
 664         /* save all revisions from the above list that contain b */
 665         if (prepare_revision_walk(&revs))
 666                 die("revision walk setup failed");
 667         while ((commit = get_revision(&revs)) != NULL) {
 668                 struct object *o = &(commit->object);
 669                 if (in_merge_bases(b, &commit, 1))
 670                         add_object_array(o, NULL, &merges);
 671         }
 672
 673         /* Now we've got all merges that contain a and b. Prune all
 674          * merges that contain another found merge and save them in
 675          * result.
 676          */
 677         for (i = 0; i < merges.nr; i++) {
 678                 struct commit *m1 = (struct commit *) merges.objects[i].item;
 679
 680                 contains_another = 0;
 681                 for (j = 0; j < merges.nr; j++) {
 682                         struct commit *m2 = (struct commit *) merges.objects[j].item;
 683                         if (i != j && in_merge_bases(m2, &m1, 1)) {
 684                                 contains_another = 1;
 685                                 break;
 686                         }
 687                 }
 688
 689                 if (!contains_another)
 690                         add_object_array(merges.objects[i].item,
 691                                          merges.objects[i].name, result);
 692         }
 693
 694         free(merges.objects);
 695         return result->nr;
 696 }
 697
 698 static void print_commit(struct commit *commit)
 699 {
 700         struct strbuf sb = STRBUF_INIT;
 701         struct pretty_print_context ctx = {0};
 702         ctx.date_mode = DATE_NORMAL;
 703         format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 704         fprintf(stderr, "%s\n", sb.buf);
 705         strbuf_release(&sb);
 706 }
 707
 708 #define MERGE_WARNING(path, msg) \
 709         warning("Failed to merge submodule %s (%s)", path, msg);
 710
 711 int merge_submodule(unsigned char result[20], const char *path,
 712                     const unsigned char base[20], const unsigned char a[20],
 713                     const unsigned char b[20])
 714 {
 715         struct commit *commit_base, *commit_a, *commit_b;
 716         int parent_count;
 717         struct object_array merges;
 718
 719         int i;
 720
 721         /* store a in result in case we fail */
 722         hashcpy(result, a);
 723
 724         /* we can not handle deletion conflicts */
 725         if (is_null_sha1(base))
 726                 return 0;
 727         if (is_null_sha1(a))
 728                 return 0;
 729         if (is_null_sha1(b))
 730                 return 0;
 731
 732         if (add_submodule_odb(path)) {
 733                 MERGE_WARNING(path, "not checked out");
 734                 return 0;
 735         }
 736
 737         if (!(commit_base = lookup_commit_reference(base)) ||
 738             !(commit_a = lookup_commit_reference(a)) ||
 739             !(commit_b = lookup_commit_reference(b))) {
 740                 MERGE_WARNING(path, "commits not present");
 741                 return 0;
 742         }
 743
 744         /* check whether both changes are forward */
 745         if (!in_merge_bases(commit_base, &commit_a, 1) ||
 746             !in_merge_bases(commit_base, &commit_b, 1)) {
 747                 MERGE_WARNING(path, "commits don't follow merge-base");
 748                 return 0;
 749         }
 750
 751         /* Case #1: a is contained in b or vice versa */
 752         if (in_merge_bases(commit_a, &commit_b, 1)) {
 753                 hashcpy(result, b);
 754                 return 1;
 755         }
 756         if (in_merge_bases(commit_b, &commit_a, 1)) {
 757                 hashcpy(result, a);
 758                 return 1;
 759         }
 760
 761         /*
 762          * Case #2: There are one or more merges that contain a and b in
 763          * the submodule. If there is only one, then present it as a
 764          * suggestion to the user, but leave it marked unmerged so the
 765          * user needs to confirm the resolution.
 766          */
 767
 768         /* find commit which merges them */
 769         parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 770         switch (parent_count) {
 771         case 0:
 772                 MERGE_WARNING(path, "merge following commits not found");
 773                 break;
 774
 775         case 1:
 776                 MERGE_WARNING(path, "not fast-forward");
 777                 fprintf(stderr, "Found a possible merge resolution "
 778                                 "for the submodule:\n");
 779                 print_commit((struct commit *) merges.objects[0].item);
 780                 fprintf(stderr,
 781                         "If this is correct simply add it to the index "
 782                         "for example\n"
 783                         "by using:\n\n"
 784                         "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 785                         "which will accept this suggestion.\n",
 786                         sha1_to_hex(merges.objects[0].item->sha1), path);
 787                 break;
 788
 789         default:
 790                 MERGE_WARNING(path, "multiple merges found");
 791                 for (i = 0; i < merges.nr; i++)
 792                         print_commit((struct commit *) merges.objects[i].item);
 793         }
 794
 795         free(merges.objects);
 796         return 0;
 797 }