submodule.con commit refactor argv_array into generic code (c1189ca)
   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#include "argv-array.h"
  13
  14static struct string_list config_name_for_path;
  15static struct string_list config_fetch_recurse_submodules_for_name;
  16static struct string_list config_ignore_for_name;
  17static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
  18static struct string_list changed_submodule_paths;
  19static int initialized_fetch_ref_tips;
  20static struct sha1_array ref_tips_before_fetch;
  21static struct sha1_array ref_tips_after_fetch;
  22
  23/*
  24 * The following flag is set if the .gitmodules file is unmerged. We then
  25 * disable recursion for all submodules where .git/config doesn't have a
  26 * matching config entry because we can't guess what might be configured in
  27 * .gitmodules unless the user resolves the conflict. When a command line
  28 * option is given (which always overrides configuration) this flag will be
  29 * ignored.
  30 */
  31static int gitmodules_is_unmerged;
  32
  33static int add_submodule_odb(const char *path)
  34{
  35        struct strbuf objects_directory = STRBUF_INIT;
  36        struct alternate_object_database *alt_odb;
  37        int ret = 0;
  38        const char *git_dir;
  39
  40        strbuf_addf(&objects_directory, "%s/.git", path);
  41        git_dir = read_gitfile_gently(objects_directory.buf);
  42        if (git_dir) {
  43                strbuf_reset(&objects_directory);
  44                strbuf_addstr(&objects_directory, git_dir);
  45        }
  46        strbuf_addstr(&objects_directory, "/objects/");
  47        if (!is_directory(objects_directory.buf)) {
  48                ret = -1;
  49                goto done;
  50        }
  51        /* avoid adding it twice */
  52        for (alt_odb = alt_odb_list; alt_odb; alt_odb = alt_odb->next)
  53                if (alt_odb->name - alt_odb->base == objects_directory.len &&
  54                                !strncmp(alt_odb->base, objects_directory.buf,
  55                                        objects_directory.len))
  56                        goto done;
  57
  58        alt_odb = xmalloc(objects_directory.len + 42 + sizeof(*alt_odb));
  59        alt_odb->next = alt_odb_list;
  60        strcpy(alt_odb->base, objects_directory.buf);
  61        alt_odb->name = alt_odb->base + objects_directory.len;
  62        alt_odb->name[2] = '/';
  63        alt_odb->name[40] = '\0';
  64        alt_odb->name[41] = '\0';
  65        alt_odb_list = alt_odb;
  66        prepare_alt_odb();
  67done:
  68        strbuf_release(&objects_directory);
  69        return ret;
  70}
  71
  72void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
  73                                             const char *path)
  74{
  75        struct string_list_item *path_option, *ignore_option;
  76        path_option = unsorted_string_list_lookup(&config_name_for_path, path);
  77        if (path_option) {
  78                ignore_option = unsorted_string_list_lookup(&config_ignore_for_name, path_option->util);
  79                if (ignore_option)
  80                        handle_ignore_submodules_arg(diffopt, ignore_option->util);
  81                else if (gitmodules_is_unmerged)
  82                        DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
  83        }
  84}
  85
  86int submodule_config(const char *var, const char *value, void *cb)
  87{
  88        if (!prefixcmp(var, "submodule."))
  89                return parse_submodule_config_option(var, value);
  90        else if (!strcmp(var, "fetch.recursesubmodules")) {
  91                config_fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(var, value);
  92                return 0;
  93        }
  94        return 0;
  95}
  96
  97void gitmodules_config(void)
  98{
  99        const char *work_tree = get_git_work_tree();
 100        if (work_tree) {
 101                struct strbuf gitmodules_path = STRBUF_INIT;
 102                int pos;
 103                strbuf_addstr(&gitmodules_path, work_tree);
 104                strbuf_addstr(&gitmodules_path, "/.gitmodules");
 105                if (read_cache() < 0)
 106                        die("index file corrupt");
 107                pos = cache_name_pos(".gitmodules", 11);
 108                if (pos < 0) { /* .gitmodules not found or isn't merged */
 109                        pos = -1 - pos;
 110                        if (active_nr > pos) {  /* there is a .gitmodules */
 111                                const struct cache_entry *ce = active_cache[pos];
 112                                if (ce_namelen(ce) == 11 &&
 113                                    !memcmp(ce->name, ".gitmodules", 11))
 114                                        gitmodules_is_unmerged = 1;
 115                        }
 116                }
 117
 118                if (!gitmodules_is_unmerged)
 119                        git_config_from_file(submodule_config, gitmodules_path.buf, NULL);
 120                strbuf_release(&gitmodules_path);
 121        }
 122}
 123
 124int parse_submodule_config_option(const char *var, const char *value)
 125{
 126        int len;
 127        struct string_list_item *config;
 128        struct strbuf submodname = STRBUF_INIT;
 129
 130        var += 10;              /* Skip "submodule." */
 131
 132        len = strlen(var);
 133        if ((len > 5) && !strcmp(var + len - 5, ".path")) {
 134                strbuf_add(&submodname, var, len - 5);
 135                config = unsorted_string_list_lookup(&config_name_for_path, value);
 136                if (config)
 137                        free(config->util);
 138                else
 139                        config = string_list_append(&config_name_for_path, xstrdup(value));
 140                config->util = strbuf_detach(&submodname, NULL);
 141                strbuf_release(&submodname);
 142        } else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
 143                strbuf_add(&submodname, var, len - 23);
 144                config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
 145                if (!config)
 146                        config = string_list_append(&config_fetch_recurse_submodules_for_name,
 147                                                    strbuf_detach(&submodname, NULL));
 148                config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
 149                strbuf_release(&submodname);
 150        } else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
 151                if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 152                    strcmp(value, "all") && strcmp(value, "none")) {
 153                        warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 154                        return 0;
 155                }
 156
 157                strbuf_add(&submodname, var, len - 7);
 158                config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
 159                if (config)
 160                        free(config->util);
 161                else
 162                        config = string_list_append(&config_ignore_for_name,
 163                                                    strbuf_detach(&submodname, NULL));
 164                strbuf_release(&submodname);
 165                config->util = xstrdup(value);
 166                return 0;
 167        }
 168        return 0;
 169}
 170
 171void handle_ignore_submodules_arg(struct diff_options *diffopt,
 172                                  const char *arg)
 173{
 174        DIFF_OPT_CLR(diffopt, IGNORE_SUBMODULES);
 175        DIFF_OPT_CLR(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 176        DIFF_OPT_CLR(diffopt, IGNORE_DIRTY_SUBMODULES);
 177
 178        if (!strcmp(arg, "all"))
 179                DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
 180        else if (!strcmp(arg, "untracked"))
 181                DIFF_OPT_SET(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
 182        else if (!strcmp(arg, "dirty"))
 183                DIFF_OPT_SET(diffopt, IGNORE_DIRTY_SUBMODULES);
 184        else if (strcmp(arg, "none"))
 185                die("bad --ignore-submodules argument: %s", arg);
 186}
 187
 188static int prepare_submodule_summary(struct rev_info *rev, const char *path,
 189                struct commit *left, struct commit *right,
 190                int *fast_forward, int *fast_backward)
 191{
 192        struct commit_list *merge_bases, *list;
 193
 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        return prepare_revision_walk(rev);
 214}
 215
 216static void print_submodule_summary(struct rev_info *rev, FILE *f,
 217                const char *del, const char *add, const char *reset)
 218{
 219        static const char format[] = "  %m %s";
 220        struct strbuf sb = STRBUF_INIT;
 221        struct commit *commit;
 222
 223        while ((commit = get_revision(rev))) {
 224                struct pretty_print_context ctx = {0};
 225                ctx.date_mode = rev->date_mode;
 226                strbuf_setlen(&sb, 0);
 227                if (commit->object.flags & SYMMETRIC_LEFT) {
 228                        if (del)
 229                                strbuf_addstr(&sb, del);
 230                }
 231                else if (add)
 232                        strbuf_addstr(&sb, add);
 233                format_commit_message(commit, format, &sb, &ctx);
 234                if (reset)
 235                        strbuf_addstr(&sb, reset);
 236                strbuf_addch(&sb, '\n');
 237                fprintf(f, "%s", sb.buf);
 238        }
 239        strbuf_release(&sb);
 240}
 241
 242int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
 243{
 244        switch (git_config_maybe_bool(opt, arg)) {
 245        case 1:
 246                return RECURSE_SUBMODULES_ON;
 247        case 0:
 248                return RECURSE_SUBMODULES_OFF;
 249        default:
 250                if (!strcmp(arg, "on-demand"))
 251                        return RECURSE_SUBMODULES_ON_DEMAND;
 252                die("bad %s argument: %s", opt, arg);
 253        }
 254}
 255
 256void show_submodule_summary(FILE *f, const char *path,
 257                unsigned char one[20], unsigned char two[20],
 258                unsigned dirty_submodule,
 259                const char *del, const char *add, const char *reset)
 260{
 261        struct rev_info rev;
 262        struct commit *left = left, *right = right;
 263        const char *message = NULL;
 264        struct strbuf sb = STRBUF_INIT;
 265        int fast_forward = 0, fast_backward = 0;
 266
 267        if (is_null_sha1(two))
 268                message = "(submodule deleted)";
 269        else if (add_submodule_odb(path))
 270                message = "(not checked out)";
 271        else if (is_null_sha1(one))
 272                message = "(new submodule)";
 273        else if (!(left = lookup_commit_reference(one)) ||
 274                 !(right = lookup_commit_reference(two)))
 275                message = "(commits not present)";
 276
 277        if (!message &&
 278            prepare_submodule_summary(&rev, path, left, right,
 279                                        &fast_forward, &fast_backward))
 280                message = "(revision walker failed)";
 281
 282        if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
 283                fprintf(f, "Submodule %s contains untracked content\n", path);
 284        if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 285                fprintf(f, "Submodule %s contains modified content\n", path);
 286
 287        if (!hashcmp(one, two)) {
 288                strbuf_release(&sb);
 289                return;
 290        }
 291
 292        strbuf_addf(&sb, "Submodule %s %s..", path,
 293                        find_unique_abbrev(one, DEFAULT_ABBREV));
 294        if (!fast_backward && !fast_forward)
 295                strbuf_addch(&sb, '.');
 296        strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
 297        if (message)
 298                strbuf_addf(&sb, " %s\n", message);
 299        else
 300                strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
 301        fwrite(sb.buf, sb.len, 1, f);
 302
 303        if (!message) {
 304                print_submodule_summary(&rev, f, del, add, reset);
 305                clear_commit_marks(left, ~0);
 306                clear_commit_marks(right, ~0);
 307        }
 308
 309        strbuf_release(&sb);
 310}
 311
 312void set_config_fetch_recurse_submodules(int value)
 313{
 314        config_fetch_recurse_submodules = value;
 315}
 316
 317static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
 318{
 319        int is_present = 0;
 320        if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
 321                /* Even if the submodule is checked out and the commit is
 322                 * present, make sure it is reachable from a ref. */
 323                struct child_process cp;
 324                const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
 325                struct strbuf buf = STRBUF_INIT;
 326
 327                argv[3] = sha1_to_hex(sha1);
 328                memset(&cp, 0, sizeof(cp));
 329                cp.argv = argv;
 330                cp.env = local_repo_env;
 331                cp.git_cmd = 1;
 332                cp.no_stdin = 1;
 333                cp.out = -1;
 334                cp.dir = path;
 335                if (!run_command(&cp) && !strbuf_read(&buf, cp.out, 1024))
 336                        is_present = 1;
 337
 338                close(cp.out);
 339                strbuf_release(&buf);
 340        }
 341        return is_present;
 342}
 343
 344static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 345                                         struct diff_options *options,
 346                                         void *data)
 347{
 348        int i;
 349        for (i = 0; i < q->nr; i++) {
 350                struct diff_filepair *p = q->queue[i];
 351                if (!S_ISGITLINK(p->two->mode))
 352                        continue;
 353
 354                if (S_ISGITLINK(p->one->mode)) {
 355                        /* NEEDSWORK: We should honor the name configured in
 356                         * the .gitmodules file of the commit we are examining
 357                         * here to be able to correctly follow submodules
 358                         * being moved around. */
 359                        struct string_list_item *path;
 360                        path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
 361                        if (!path && !is_submodule_commit_present(p->two->path, p->two->sha1))
 362                                string_list_append(&changed_submodule_paths, xstrdup(p->two->path));
 363                } else {
 364                        /* Submodule is new or was moved here */
 365                        /* NEEDSWORK: When the .git directories of submodules
 366                         * live inside the superprojects .git directory some
 367                         * day we should fetch new submodules directly into
 368                         * that location too when config or options request
 369                         * that so they can be checked out from there. */
 370                        continue;
 371                }
 372        }
 373}
 374
 375static int add_sha1_to_array(const char *ref, const unsigned char *sha1,
 376                             int flags, void *data)
 377{
 378        sha1_array_append(data, sha1);
 379        return 0;
 380}
 381
 382void check_for_new_submodule_commits(unsigned char new_sha1[20])
 383{
 384        if (!initialized_fetch_ref_tips) {
 385                for_each_ref(add_sha1_to_array, &ref_tips_before_fetch);
 386                initialized_fetch_ref_tips = 1;
 387        }
 388
 389        sha1_array_append(&ref_tips_after_fetch, new_sha1);
 390}
 391
 392static void add_sha1_to_argv(const unsigned char sha1[20], void *data)
 393{
 394        argv_array_push(data, sha1_to_hex(sha1));
 395}
 396
 397static void calculate_changed_submodule_paths(void)
 398{
 399        struct rev_info rev;
 400        struct commit *commit;
 401        struct argv_array argv = ARGV_ARRAY_INIT;
 402
 403        init_revisions(&rev, NULL);
 404        argv_array_push(&argv, "--"); /* argv[0] program name */
 405        sha1_array_for_each_unique(&ref_tips_after_fetch,
 406                                   add_sha1_to_argv, &argv);
 407        argv_array_push(&argv, "--not");
 408        sha1_array_for_each_unique(&ref_tips_before_fetch,
 409                                   add_sha1_to_argv, &argv);
 410        setup_revisions(argv.argc, argv.argv, &rev, NULL);
 411        if (prepare_revision_walk(&rev))
 412                die("revision walk setup failed");
 413
 414        /*
 415         * Collect all submodules (whether checked out or not) for which new
 416         * commits have been recorded upstream in "changed_submodule_paths".
 417         */
 418        while ((commit = get_revision(&rev))) {
 419                struct commit_list *parent = commit->parents;
 420                while (parent) {
 421                        struct diff_options diff_opts;
 422                        diff_setup(&diff_opts);
 423                        diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
 424                        diff_opts.format_callback = submodule_collect_changed_cb;
 425                        if (diff_setup_done(&diff_opts) < 0)
 426                                die("diff_setup_done failed");
 427                        diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
 428                        diffcore_std(&diff_opts);
 429                        diff_flush(&diff_opts);
 430                        parent = parent->next;
 431                }
 432        }
 433
 434        argv_array_clear(&argv);
 435        sha1_array_clear(&ref_tips_before_fetch);
 436        sha1_array_clear(&ref_tips_after_fetch);
 437        initialized_fetch_ref_tips = 0;
 438}
 439
 440int fetch_populated_submodules(int num_options, const char **options,
 441                               const char *prefix, int command_line_option,
 442                               int quiet)
 443{
 444        int i, result = 0, argc = 0, default_argc;
 445        struct child_process cp;
 446        const char **argv;
 447        struct string_list_item *name_for_path;
 448        const char *work_tree = get_git_work_tree();
 449        if (!work_tree)
 450                goto out;
 451
 452        if (!the_index.initialized)
 453                if (read_cache() < 0)
 454                        die("index file corrupt");
 455
 456        /* 6: "fetch" (options) --recurse-submodules-default default "--submodule-prefix" prefix NULL */
 457        argv = xcalloc(num_options + 6, sizeof(const char *));
 458        argv[argc++] = "fetch";
 459        for (i = 0; i < num_options; i++)
 460                argv[argc++] = options[i];
 461        argv[argc++] = "--recurse-submodules-default";
 462        default_argc = argc++;
 463        argv[argc++] = "--submodule-prefix";
 464
 465        memset(&cp, 0, sizeof(cp));
 466        cp.argv = argv;
 467        cp.env = local_repo_env;
 468        cp.git_cmd = 1;
 469        cp.no_stdin = 1;
 470
 471        calculate_changed_submodule_paths();
 472
 473        for (i = 0; i < active_nr; i++) {
 474                struct strbuf submodule_path = STRBUF_INIT;
 475                struct strbuf submodule_git_dir = STRBUF_INIT;
 476                struct strbuf submodule_prefix = STRBUF_INIT;
 477                struct cache_entry *ce = active_cache[i];
 478                const char *git_dir, *name, *default_argv;
 479
 480                if (!S_ISGITLINK(ce->ce_mode))
 481                        continue;
 482
 483                name = ce->name;
 484                name_for_path = unsorted_string_list_lookup(&config_name_for_path, ce->name);
 485                if (name_for_path)
 486                        name = name_for_path->util;
 487
 488                default_argv = "yes";
 489                if (command_line_option == RECURSE_SUBMODULES_DEFAULT) {
 490                        struct string_list_item *fetch_recurse_submodules_option;
 491                        fetch_recurse_submodules_option = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name);
 492                        if (fetch_recurse_submodules_option) {
 493                                if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_OFF)
 494                                        continue;
 495                                if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_ON_DEMAND) {
 496                                        if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 497                                                continue;
 498                                        default_argv = "on-demand";
 499                                }
 500                        } else {
 501                                if ((config_fetch_recurse_submodules == RECURSE_SUBMODULES_OFF) ||
 502                                    gitmodules_is_unmerged)
 503                                        continue;
 504                                if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) {
 505                                        if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 506                                                continue;
 507                                        default_argv = "on-demand";
 508                                }
 509                        }
 510                } else if (command_line_option == RECURSE_SUBMODULES_ON_DEMAND) {
 511                        if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
 512                                continue;
 513                        default_argv = "on-demand";
 514                }
 515
 516                strbuf_addf(&submodule_path, "%s/%s", work_tree, ce->name);
 517                strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
 518                strbuf_addf(&submodule_prefix, "%s%s/", prefix, ce->name);
 519                git_dir = read_gitfile_gently(submodule_git_dir.buf);
 520                if (!git_dir)
 521                        git_dir = submodule_git_dir.buf;
 522                if (is_directory(git_dir)) {
 523                        if (!quiet)
 524                                printf("Fetching submodule %s%s\n", prefix, ce->name);
 525                        cp.dir = submodule_path.buf;
 526                        argv[default_argc] = default_argv;
 527                        argv[argc] = submodule_prefix.buf;
 528                        if (run_command(&cp))
 529                                result = 1;
 530                }
 531                strbuf_release(&submodule_path);
 532                strbuf_release(&submodule_git_dir);
 533                strbuf_release(&submodule_prefix);
 534        }
 535        free(argv);
 536out:
 537        string_list_clear(&changed_submodule_paths, 1);
 538        return result;
 539}
 540
 541unsigned is_submodule_modified(const char *path, int ignore_untracked)
 542{
 543        ssize_t len;
 544        struct child_process cp;
 545        const char *argv[] = {
 546                "status",
 547                "--porcelain",
 548                NULL,
 549                NULL,
 550        };
 551        struct strbuf buf = STRBUF_INIT;
 552        unsigned dirty_submodule = 0;
 553        const char *line, *next_line;
 554        const char *git_dir;
 555
 556        strbuf_addf(&buf, "%s/.git", path);
 557        git_dir = read_gitfile_gently(buf.buf);
 558        if (!git_dir)
 559                git_dir = buf.buf;
 560        if (!is_directory(git_dir)) {
 561                strbuf_release(&buf);
 562                /* The submodule is not checked out, so it is not modified */
 563                return 0;
 564
 565        }
 566        strbuf_reset(&buf);
 567
 568        if (ignore_untracked)
 569                argv[2] = "-uno";
 570
 571        memset(&cp, 0, sizeof(cp));
 572        cp.argv = argv;
 573        cp.env = local_repo_env;
 574        cp.git_cmd = 1;
 575        cp.no_stdin = 1;
 576        cp.out = -1;
 577        cp.dir = path;
 578        if (start_command(&cp))
 579                die("Could not run git status --porcelain");
 580
 581        len = strbuf_read(&buf, cp.out, 1024);
 582        line = buf.buf;
 583        while (len > 2) {
 584                if ((line[0] == '?') && (line[1] == '?')) {
 585                        dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
 586                        if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
 587                                break;
 588                } else {
 589                        dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
 590                        if (ignore_untracked ||
 591                            (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
 592                                break;
 593                }
 594                next_line = strchr(line, '\n');
 595                if (!next_line)
 596                        break;
 597                next_line++;
 598                len -= (next_line - line);
 599                line = next_line;
 600        }
 601        close(cp.out);
 602
 603        if (finish_command(&cp))
 604                die("git status --porcelain failed");
 605
 606        strbuf_release(&buf);
 607        return dirty_submodule;
 608}
 609
 610static int find_first_merges(struct object_array *result, const char *path,
 611                struct commit *a, struct commit *b)
 612{
 613        int i, j;
 614        struct object_array merges;
 615        struct commit *commit;
 616        int contains_another;
 617
 618        char merged_revision[42];
 619        const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 620                                   "--all", merged_revision, NULL };
 621        struct rev_info revs;
 622        struct setup_revision_opt rev_opts;
 623
 624        memset(&merges, 0, sizeof(merges));
 625        memset(result, 0, sizeof(struct object_array));
 626        memset(&rev_opts, 0, sizeof(rev_opts));
 627
 628        /* get all revisions that merge commit a */
 629        snprintf(merged_revision, sizeof(merged_revision), "^%s",
 630                        sha1_to_hex(a->object.sha1));
 631        init_revisions(&revs, NULL);
 632        rev_opts.submodule = path;
 633        setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);
 634
 635        /* save all revisions from the above list that contain b */
 636        if (prepare_revision_walk(&revs))
 637                die("revision walk setup failed");
 638        while ((commit = get_revision(&revs)) != NULL) {
 639                struct object *o = &(commit->object);
 640                if (in_merge_bases(b, &commit, 1))
 641                        add_object_array(o, NULL, &merges);
 642        }
 643
 644        /* Now we've got all merges that contain a and b. Prune all
 645         * merges that contain another found merge and save them in
 646         * result.
 647         */
 648        for (i = 0; i < merges.nr; i++) {
 649                struct commit *m1 = (struct commit *) merges.objects[i].item;
 650
 651                contains_another = 0;
 652                for (j = 0; j < merges.nr; j++) {
 653                        struct commit *m2 = (struct commit *) merges.objects[j].item;
 654                        if (i != j && in_merge_bases(m2, &m1, 1)) {
 655                                contains_another = 1;
 656                                break;
 657                        }
 658                }
 659
 660                if (!contains_another)
 661                        add_object_array(merges.objects[i].item,
 662                                         merges.objects[i].name, result);
 663        }
 664
 665        free(merges.objects);
 666        return result->nr;
 667}
 668
 669static void print_commit(struct commit *commit)
 670{
 671        struct strbuf sb = STRBUF_INIT;
 672        struct pretty_print_context ctx = {0};
 673        ctx.date_mode = DATE_NORMAL;
 674        format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 675        fprintf(stderr, "%s\n", sb.buf);
 676        strbuf_release(&sb);
 677}
 678
 679#define MERGE_WARNING(path, msg) \
 680        warning("Failed to merge submodule %s (%s)", path, msg);
 681
 682int merge_submodule(unsigned char result[20], const char *path,
 683                    const unsigned char base[20], const unsigned char a[20],
 684                    const unsigned char b[20])
 685{
 686        struct commit *commit_base, *commit_a, *commit_b;
 687        int parent_count;
 688        struct object_array merges;
 689
 690        int i;
 691
 692        /* store a in result in case we fail */
 693        hashcpy(result, a);
 694
 695        /* we can not handle deletion conflicts */
 696        if (is_null_sha1(base))
 697                return 0;
 698        if (is_null_sha1(a))
 699                return 0;
 700        if (is_null_sha1(b))
 701                return 0;
 702
 703        if (add_submodule_odb(path)) {
 704                MERGE_WARNING(path, "not checked out");
 705                return 0;
 706        }
 707
 708        if (!(commit_base = lookup_commit_reference(base)) ||
 709            !(commit_a = lookup_commit_reference(a)) ||
 710            !(commit_b = lookup_commit_reference(b))) {
 711                MERGE_WARNING(path, "commits not present");
 712                return 0;
 713        }
 714
 715        /* check whether both changes are forward */
 716        if (!in_merge_bases(commit_base, &commit_a, 1) ||
 717            !in_merge_bases(commit_base, &commit_b, 1)) {
 718                MERGE_WARNING(path, "commits don't follow merge-base");
 719                return 0;
 720        }
 721
 722        /* Case #1: a is contained in b or vice versa */
 723        if (in_merge_bases(commit_a, &commit_b, 1)) {
 724                hashcpy(result, b);
 725                return 1;
 726        }
 727        if (in_merge_bases(commit_b, &commit_a, 1)) {
 728                hashcpy(result, a);
 729                return 1;
 730        }
 731
 732        /*
 733         * Case #2: There are one or more merges that contain a and b in
 734         * the submodule. If there is only one, then present it as a
 735         * suggestion to the user, but leave it marked unmerged so the
 736         * user needs to confirm the resolution.
 737         */
 738
 739        /* find commit which merges them */
 740        parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 741        switch (parent_count) {
 742        case 0:
 743                MERGE_WARNING(path, "merge following commits not found");
 744                break;
 745
 746        case 1:
 747                MERGE_WARNING(path, "not fast-forward");
 748                fprintf(stderr, "Found a possible merge resolution "
 749                                "for the submodule:\n");
 750                print_commit((struct commit *) merges.objects[0].item);
 751                fprintf(stderr,
 752                        "If this is correct simply add it to the index "
 753                        "for example\n"
 754                        "by using:\n\n"
 755                        "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 756                        "which will accept this suggestion.\n",
 757                        sha1_to_hex(merges.objects[0].item->sha1), path);
 758                break;
 759
 760        default:
 761                MERGE_WARNING(path, "multiple merges found");
 762                for (i = 0; i < merges.nr; i++)
 763                        print_commit((struct commit *) merges.objects[i].item);
 764        }
 765
 766        free(merges.objects);
 767        return 0;
 768}