git.con commit symbolic-ref -d: do not allow removal of HEAD (12cfa79)
   1#include "builtin.h"
   2#include "exec_cmd.h"
   3#include "help.h"
   4#include "run-command.h"
   5
   6const char git_usage_string[] =
   7        "git [--version] [--help] [-C <path>] [-c name=value]\n"
   8        "           [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
   9        "           [-p | --paginate | --no-pager] [--no-replace-objects] [--bare]\n"
  10        "           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
  11        "           <command> [<args>]";
  12
  13const char git_more_info_string[] =
  14        N_("'git help -a' and 'git help -g' list available subcommands and some\n"
  15           "concept guides. See 'git help <command>' or 'git help <concept>'\n"
  16           "to read about a specific subcommand or concept.");
  17
  18static int use_pager = -1;
  19static char *orig_cwd;
  20static const char *env_names[] = {
  21        GIT_DIR_ENVIRONMENT,
  22        GIT_WORK_TREE_ENVIRONMENT,
  23        GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
  24        GIT_PREFIX_ENVIRONMENT
  25};
  26static char *orig_env[4];
  27static int save_restore_env_balance;
  28
  29static void save_env_before_alias(void)
  30{
  31        int i;
  32
  33        assert(save_restore_env_balance == 0);
  34        save_restore_env_balance = 1;
  35        orig_cwd = xgetcwd();
  36        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  37                orig_env[i] = getenv(env_names[i]);
  38                if (orig_env[i])
  39                        orig_env[i] = xstrdup(orig_env[i]);
  40        }
  41}
  42
  43static void restore_env(int external_alias)
  44{
  45        int i;
  46
  47        assert(save_restore_env_balance == 1);
  48        save_restore_env_balance = 0;
  49        if (!external_alias && orig_cwd && chdir(orig_cwd))
  50                die_errno("could not move to %s", orig_cwd);
  51        free(orig_cwd);
  52        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  53                if (external_alias &&
  54                    !strcmp(env_names[i], GIT_PREFIX_ENVIRONMENT))
  55                        continue;
  56                if (orig_env[i]) {
  57                        setenv(env_names[i], orig_env[i], 1);
  58                        free(orig_env[i]);
  59                } else {
  60                        unsetenv(env_names[i]);
  61                }
  62        }
  63}
  64
  65static void commit_pager_choice(void) {
  66        switch (use_pager) {
  67        case 0:
  68                setenv("GIT_PAGER", "cat", 1);
  69                break;
  70        case 1:
  71                setup_pager();
  72                break;
  73        default:
  74                break;
  75        }
  76}
  77
  78static int handle_options(const char ***argv, int *argc, int *envchanged)
  79{
  80        const char **orig_argv = *argv;
  81
  82        while (*argc > 0) {
  83                const char *cmd = (*argv)[0];
  84                if (cmd[0] != '-')
  85                        break;
  86
  87                /*
  88                 * For legacy reasons, the "version" and "help"
  89                 * commands can be written with "--" prepended
  90                 * to make them look like flags.
  91                 */
  92                if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  93                        break;
  94
  95                /*
  96                 * Check remaining flags.
  97                 */
  98                if (skip_prefix(cmd, "--exec-path", &cmd)) {
  99                        if (*cmd == '=')
 100                                git_set_argv_exec_path(cmd + 1);
 101                        else {
 102                                puts(git_exec_path());
 103                                exit(0);
 104                        }
 105                } else if (!strcmp(cmd, "--html-path")) {
 106                        puts(system_path(GIT_HTML_PATH));
 107                        exit(0);
 108                } else if (!strcmp(cmd, "--man-path")) {
 109                        puts(system_path(GIT_MAN_PATH));
 110                        exit(0);
 111                } else if (!strcmp(cmd, "--info-path")) {
 112                        puts(system_path(GIT_INFO_PATH));
 113                        exit(0);
 114                } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 115                        use_pager = 1;
 116                } else if (!strcmp(cmd, "--no-pager")) {
 117                        use_pager = 0;
 118                        if (envchanged)
 119                                *envchanged = 1;
 120                } else if (!strcmp(cmd, "--no-replace-objects")) {
 121                        check_replace_refs = 0;
 122                        setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 123                        if (envchanged)
 124                                *envchanged = 1;
 125                } else if (!strcmp(cmd, "--git-dir")) {
 126                        if (*argc < 2) {
 127                                fprintf(stderr, "No directory given for --git-dir.\n" );
 128                                usage(git_usage_string);
 129                        }
 130                        setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 131                        if (envchanged)
 132                                *envchanged = 1;
 133                        (*argv)++;
 134                        (*argc)--;
 135                } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
 136                        setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
 137                        if (envchanged)
 138                                *envchanged = 1;
 139                } else if (!strcmp(cmd, "--namespace")) {
 140                        if (*argc < 2) {
 141                                fprintf(stderr, "No namespace given for --namespace.\n" );
 142                                usage(git_usage_string);
 143                        }
 144                        setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 145                        if (envchanged)
 146                                *envchanged = 1;
 147                        (*argv)++;
 148                        (*argc)--;
 149                } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
 150                        setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
 151                        if (envchanged)
 152                                *envchanged = 1;
 153                } else if (!strcmp(cmd, "--work-tree")) {
 154                        if (*argc < 2) {
 155                                fprintf(stderr, "No directory given for --work-tree.\n" );
 156                                usage(git_usage_string);
 157                        }
 158                        setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 159                        if (envchanged)
 160                                *envchanged = 1;
 161                        (*argv)++;
 162                        (*argc)--;
 163                } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
 164                        setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
 165                        if (envchanged)
 166                                *envchanged = 1;
 167                } else if (!strcmp(cmd, "--bare")) {
 168                        char *cwd = xgetcwd();
 169                        is_bare_repository_cfg = 1;
 170                        setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
 171                        free(cwd);
 172                        setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 173                        if (envchanged)
 174                                *envchanged = 1;
 175                } else if (!strcmp(cmd, "-c")) {
 176                        if (*argc < 2) {
 177                                fprintf(stderr, "-c expects a configuration string\n" );
 178                                usage(git_usage_string);
 179                        }
 180                        git_config_push_parameter((*argv)[1]);
 181                        (*argv)++;
 182                        (*argc)--;
 183                } else if (!strcmp(cmd, "--literal-pathspecs")) {
 184                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 185                        if (envchanged)
 186                                *envchanged = 1;
 187                } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 188                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 189                        if (envchanged)
 190                                *envchanged = 1;
 191                } else if (!strcmp(cmd, "--glob-pathspecs")) {
 192                        setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 193                        if (envchanged)
 194                                *envchanged = 1;
 195                } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 196                        setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 197                        if (envchanged)
 198                                *envchanged = 1;
 199                } else if (!strcmp(cmd, "--icase-pathspecs")) {
 200                        setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 201                        if (envchanged)
 202                                *envchanged = 1;
 203                } else if (!strcmp(cmd, "--shallow-file")) {
 204                        (*argv)++;
 205                        (*argc)--;
 206                        set_alternate_shallow_file((*argv)[0], 1);
 207                        if (envchanged)
 208                                *envchanged = 1;
 209                } else if (!strcmp(cmd, "-C")) {
 210                        if (*argc < 2) {
 211                                fprintf(stderr, "No directory given for -C.\n" );
 212                                usage(git_usage_string);
 213                        }
 214                        if ((*argv)[1][0]) {
 215                                if (chdir((*argv)[1]))
 216                                        die_errno("Cannot change to '%s'", (*argv)[1]);
 217                                if (envchanged)
 218                                        *envchanged = 1;
 219                        }
 220                        (*argv)++;
 221                        (*argc)--;
 222                } else {
 223                        fprintf(stderr, "Unknown option: %s\n", cmd);
 224                        usage(git_usage_string);
 225                }
 226
 227                (*argv)++;
 228                (*argc)--;
 229        }
 230        return (*argv) - orig_argv;
 231}
 232
 233static int handle_alias(int *argcp, const char ***argv)
 234{
 235        int envchanged = 0, ret = 0, saved_errno = errno;
 236        int count, option_count;
 237        const char **new_argv;
 238        const char *alias_command;
 239        char *alias_string;
 240        int unused_nongit;
 241
 242        save_env_before_alias();
 243        setup_git_directory_gently(&unused_nongit);
 244
 245        alias_command = (*argv)[0];
 246        alias_string = alias_lookup(alias_command);
 247        if (alias_string) {
 248                if (alias_string[0] == '!') {
 249                        struct child_process child = CHILD_PROCESS_INIT;
 250
 251                        commit_pager_choice();
 252                        restore_env(1);
 253
 254                        child.use_shell = 1;
 255                        argv_array_push(&child.args, alias_string + 1);
 256                        argv_array_pushv(&child.args, (*argv) + 1);
 257
 258                        ret = run_command(&child);
 259                        if (ret >= 0)   /* normal exit */
 260                                exit(ret);
 261
 262                        die_errno("While expanding alias '%s': '%s'",
 263                            alias_command, alias_string + 1);
 264                }
 265                count = split_cmdline(alias_string, &new_argv);
 266                if (count < 0)
 267                        die("Bad alias.%s string: %s", alias_command,
 268                            split_cmdline_strerror(count));
 269                option_count = handle_options(&new_argv, &count, &envchanged);
 270                if (envchanged)
 271                        die("alias '%s' changes environment variables\n"
 272                                 "You can use '!git' in the alias to do this.",
 273                                 alias_command);
 274                memmove(new_argv - option_count, new_argv,
 275                                count * sizeof(char *));
 276                new_argv -= option_count;
 277
 278                if (count < 1)
 279                        die("empty alias for %s", alias_command);
 280
 281                if (!strcmp(alias_command, new_argv[0]))
 282                        die("recursive alias: %s", alias_command);
 283
 284                trace_argv_printf(new_argv,
 285                                  "trace: alias expansion: %s =>",
 286                                  alias_command);
 287
 288                REALLOC_ARRAY(new_argv, count + *argcp);
 289                /* insert after command name */
 290                memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 291
 292                *argv = new_argv;
 293                *argcp += count - 1;
 294
 295                ret = 1;
 296        }
 297
 298        restore_env(0);
 299
 300        errno = saved_errno;
 301
 302        return ret;
 303}
 304
 305#define RUN_SETUP               (1<<0)
 306#define RUN_SETUP_GENTLY        (1<<1)
 307#define USE_PAGER               (1<<2)
 308/*
 309 * require working tree to be present -- anything uses this needs
 310 * RUN_SETUP for reading from the configuration file.
 311 */
 312#define NEED_WORK_TREE          (1<<3)
 313
 314struct cmd_struct {
 315        const char *cmd;
 316        int (*fn)(int, const char **, const char *);
 317        int option;
 318};
 319
 320static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 321{
 322        int status, help;
 323        struct stat st;
 324        const char *prefix;
 325
 326        prefix = NULL;
 327        help = argc == 2 && !strcmp(argv[1], "-h");
 328        if (!help) {
 329                if (p->option & RUN_SETUP)
 330                        prefix = setup_git_directory();
 331                else if (p->option & RUN_SETUP_GENTLY) {
 332                        int nongit_ok;
 333                        prefix = setup_git_directory_gently(&nongit_ok);
 334                }
 335
 336                if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 337                        use_pager = check_pager_config(p->cmd);
 338                if (use_pager == -1 && p->option & USE_PAGER)
 339                        use_pager = 1;
 340
 341                if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 342                    startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 343                        trace_repo_setup(prefix);
 344        }
 345        commit_pager_choice();
 346
 347        if (!help && p->option & NEED_WORK_TREE)
 348                setup_work_tree();
 349
 350        trace_argv_printf(argv, "trace: built-in: git");
 351
 352        status = p->fn(argc, argv, prefix);
 353        if (status)
 354                return status;
 355
 356        /* Somebody closed stdout? */
 357        if (fstat(fileno(stdout), &st))
 358                return 0;
 359        /* Ignore write errors for pipes and sockets.. */
 360        if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 361                return 0;
 362
 363        /* Check for ENOSPC and EIO errors.. */
 364        if (fflush(stdout))
 365                die_errno("write failure on standard output");
 366        if (ferror(stdout))
 367                die("unknown write failure on standard output");
 368        if (fclose(stdout))
 369                die_errno("close failed on standard output");
 370        return 0;
 371}
 372
 373static struct cmd_struct commands[] = {
 374        { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 375        { "am", cmd_am, RUN_SETUP | NEED_WORK_TREE },
 376        { "annotate", cmd_annotate, RUN_SETUP },
 377        { "apply", cmd_apply, RUN_SETUP_GENTLY },
 378        { "archive", cmd_archive },
 379        { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 380        { "blame", cmd_blame, RUN_SETUP },
 381        { "branch", cmd_branch, RUN_SETUP },
 382        { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 383        { "cat-file", cmd_cat_file, RUN_SETUP },
 384        { "check-attr", cmd_check_attr, RUN_SETUP },
 385        { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 386        { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 387        { "check-ref-format", cmd_check_ref_format },
 388        { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 389        { "checkout-index", cmd_checkout_index,
 390                RUN_SETUP | NEED_WORK_TREE},
 391        { "cherry", cmd_cherry, RUN_SETUP },
 392        { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 393        { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 394        { "clone", cmd_clone },
 395        { "column", cmd_column, RUN_SETUP_GENTLY },
 396        { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 397        { "commit-tree", cmd_commit_tree, RUN_SETUP },
 398        { "config", cmd_config, RUN_SETUP_GENTLY },
 399        { "count-objects", cmd_count_objects, RUN_SETUP },
 400        { "credential", cmd_credential, RUN_SETUP_GENTLY },
 401        { "describe", cmd_describe, RUN_SETUP },
 402        { "diff", cmd_diff },
 403        { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 404        { "diff-index", cmd_diff_index, RUN_SETUP },
 405        { "diff-tree", cmd_diff_tree, RUN_SETUP },
 406        { "fast-export", cmd_fast_export, RUN_SETUP },
 407        { "fetch", cmd_fetch, RUN_SETUP },
 408        { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 409        { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 410        { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 411        { "format-patch", cmd_format_patch, RUN_SETUP },
 412        { "fsck", cmd_fsck, RUN_SETUP },
 413        { "fsck-objects", cmd_fsck, RUN_SETUP },
 414        { "gc", cmd_gc, RUN_SETUP },
 415        { "get-tar-commit-id", cmd_get_tar_commit_id },
 416        { "grep", cmd_grep, RUN_SETUP_GENTLY },
 417        { "hash-object", cmd_hash_object },
 418        { "help", cmd_help },
 419        { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 420        { "init", cmd_init_db },
 421        { "init-db", cmd_init_db },
 422        { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP_GENTLY },
 423        { "log", cmd_log, RUN_SETUP },
 424        { "ls-files", cmd_ls_files, RUN_SETUP },
 425        { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 426        { "ls-tree", cmd_ls_tree, RUN_SETUP },
 427        { "mailinfo", cmd_mailinfo },
 428        { "mailsplit", cmd_mailsplit },
 429        { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 430        { "merge-base", cmd_merge_base, RUN_SETUP },
 431        { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 432        { "merge-index", cmd_merge_index, RUN_SETUP },
 433        { "merge-ours", cmd_merge_ours, RUN_SETUP },
 434        { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 435        { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 436        { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 437        { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 438        { "merge-tree", cmd_merge_tree, RUN_SETUP },
 439        { "mktag", cmd_mktag, RUN_SETUP },
 440        { "mktree", cmd_mktree, RUN_SETUP },
 441        { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 442        { "name-rev", cmd_name_rev, RUN_SETUP },
 443        { "notes", cmd_notes, RUN_SETUP },
 444        { "pack-objects", cmd_pack_objects, RUN_SETUP },
 445        { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 446        { "pack-refs", cmd_pack_refs, RUN_SETUP },
 447        { "patch-id", cmd_patch_id },
 448        { "pickaxe", cmd_blame, RUN_SETUP },
 449        { "prune", cmd_prune, RUN_SETUP },
 450        { "prune-packed", cmd_prune_packed, RUN_SETUP },
 451        { "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 452        { "push", cmd_push, RUN_SETUP },
 453        { "read-tree", cmd_read_tree, RUN_SETUP },
 454        { "receive-pack", cmd_receive_pack },
 455        { "reflog", cmd_reflog, RUN_SETUP },
 456        { "remote", cmd_remote, RUN_SETUP },
 457        { "remote-ext", cmd_remote_ext },
 458        { "remote-fd", cmd_remote_fd },
 459        { "repack", cmd_repack, RUN_SETUP },
 460        { "replace", cmd_replace, RUN_SETUP },
 461        { "rerere", cmd_rerere, RUN_SETUP },
 462        { "reset", cmd_reset, RUN_SETUP },
 463        { "rev-list", cmd_rev_list, RUN_SETUP },
 464        { "rev-parse", cmd_rev_parse },
 465        { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 466        { "rm", cmd_rm, RUN_SETUP },
 467        { "send-pack", cmd_send_pack, RUN_SETUP },
 468        { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 469        { "show", cmd_show, RUN_SETUP },
 470        { "show-branch", cmd_show_branch, RUN_SETUP },
 471        { "show-ref", cmd_show_ref, RUN_SETUP },
 472        { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 473        { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 474        { "stripspace", cmd_stripspace },
 475        { "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 476        { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 477        { "tag", cmd_tag, RUN_SETUP },
 478        { "unpack-file", cmd_unpack_file, RUN_SETUP },
 479        { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 480        { "update-index", cmd_update_index, RUN_SETUP },
 481        { "update-ref", cmd_update_ref, RUN_SETUP },
 482        { "update-server-info", cmd_update_server_info, RUN_SETUP },
 483        { "upload-archive", cmd_upload_archive },
 484        { "upload-archive--writer", cmd_upload_archive_writer },
 485        { "var", cmd_var, RUN_SETUP_GENTLY },
 486        { "verify-commit", cmd_verify_commit, RUN_SETUP },
 487        { "verify-pack", cmd_verify_pack },
 488        { "verify-tag", cmd_verify_tag, RUN_SETUP },
 489        { "version", cmd_version },
 490        { "whatchanged", cmd_whatchanged, RUN_SETUP },
 491        { "worktree", cmd_worktree, RUN_SETUP },
 492        { "write-tree", cmd_write_tree, RUN_SETUP },
 493};
 494
 495static struct cmd_struct *get_builtin(const char *s)
 496{
 497        int i;
 498        for (i = 0; i < ARRAY_SIZE(commands); i++) {
 499                struct cmd_struct *p = commands + i;
 500                if (!strcmp(s, p->cmd))
 501                        return p;
 502        }
 503        return NULL;
 504}
 505
 506int is_builtin(const char *s)
 507{
 508        return !!get_builtin(s);
 509}
 510
 511#ifdef STRIP_EXTENSION
 512static void strip_extension(const char **argv)
 513{
 514        size_t len;
 515
 516        if (strip_suffix(argv[0], STRIP_EXTENSION, &len))
 517                argv[0] = xmemdupz(argv[0], len);
 518}
 519#else
 520#define strip_extension(cmd)
 521#endif
 522
 523static void handle_builtin(int argc, const char **argv)
 524{
 525        const char *cmd;
 526        struct cmd_struct *builtin;
 527
 528        strip_extension(argv);
 529        cmd = argv[0];
 530
 531        /* Turn "git cmd --help" into "git help cmd" */
 532        if (argc > 1 && !strcmp(argv[1], "--help")) {
 533                argv[1] = argv[0];
 534                argv[0] = cmd = "help";
 535        }
 536
 537        builtin = get_builtin(cmd);
 538        if (builtin)
 539                exit(run_builtin(builtin, argc, argv));
 540}
 541
 542static void execv_dashed_external(const char **argv)
 543{
 544        struct strbuf cmd = STRBUF_INIT;
 545        const char *tmp;
 546        int status;
 547
 548        if (use_pager == -1)
 549                use_pager = check_pager_config(argv[0]);
 550        commit_pager_choice();
 551
 552        strbuf_addf(&cmd, "git-%s", argv[0]);
 553
 554        /*
 555         * argv[0] must be the git command, but the argv array
 556         * belongs to the caller, and may be reused in
 557         * subsequent loop iterations. Save argv[0] and
 558         * restore it on error.
 559         */
 560        tmp = argv[0];
 561        argv[0] = cmd.buf;
 562
 563        trace_argv_printf(argv, "trace: exec:");
 564
 565        /*
 566         * if we fail because the command is not found, it is
 567         * OK to return. Otherwise, we just pass along the status code.
 568         */
 569        status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 570        if (status >= 0 || errno != ENOENT)
 571                exit(status);
 572
 573        argv[0] = tmp;
 574
 575        strbuf_release(&cmd);
 576}
 577
 578static int run_argv(int *argcp, const char ***argv)
 579{
 580        int done_alias = 0;
 581
 582        while (1) {
 583                /*
 584                 * If we tried alias and futzed with our environment,
 585                 * it no longer is safe to invoke builtins directly in
 586                 * general.  We have to spawn them as dashed externals.
 587                 *
 588                 * NEEDSWORK: if we can figure out cases
 589                 * where it is safe to do, we can avoid spawning a new
 590                 * process.
 591                 */
 592                if (!done_alias)
 593                        handle_builtin(*argcp, *argv);
 594
 595                /* .. then try the external ones */
 596                execv_dashed_external(*argv);
 597
 598                /* It could be an alias -- this works around the insanity
 599                 * of overriding "git log" with "git show" by having
 600                 * alias.log = show
 601                 */
 602                if (done_alias)
 603                        break;
 604                if (!handle_alias(argcp, argv))
 605                        break;
 606                done_alias = 1;
 607        }
 608
 609        return done_alias;
 610}
 611
 612/*
 613 * Many parts of Git have subprograms communicate via pipe, expect the
 614 * upstream of a pipe to die with SIGPIPE when the downstream of a
 615 * pipe does not need to read all that is written.  Some third-party
 616 * programs that ignore or block SIGPIPE for their own reason forget
 617 * to restore SIGPIPE handling to the default before spawning Git and
 618 * break this carefully orchestrated machinery.
 619 *
 620 * Restore the way SIGPIPE is handled to default, which is what we
 621 * expect.
 622 */
 623static void restore_sigpipe_to_default(void)
 624{
 625        sigset_t unblock;
 626
 627        sigemptyset(&unblock);
 628        sigaddset(&unblock, SIGPIPE);
 629        sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 630        signal(SIGPIPE, SIG_DFL);
 631}
 632
 633int main(int argc, char **av)
 634{
 635        const char **argv = (const char **) av;
 636        const char *cmd;
 637        int done_help = 0;
 638
 639        cmd = git_extract_argv0_path(argv[0]);
 640        if (!cmd)
 641                cmd = "git-help";
 642
 643        /*
 644         * Always open file descriptors 0/1/2 to avoid clobbering files
 645         * in die().  It also avoids messing up when the pipes are dup'ed
 646         * onto stdin/stdout/stderr in the child processes we spawn.
 647         */
 648        sanitize_stdfds();
 649
 650        restore_sigpipe_to_default();
 651
 652        git_setup_gettext();
 653
 654        trace_command_performance(argv);
 655
 656        /*
 657         * "git-xxxx" is the same as "git xxxx", but we obviously:
 658         *
 659         *  - cannot take flags in between the "git" and the "xxxx".
 660         *  - cannot execute it externally (since it would just do
 661         *    the same thing over again)
 662         *
 663         * So we just directly call the builtin handler, and die if
 664         * that one cannot handle it.
 665         */
 666        if (skip_prefix(cmd, "git-", &cmd)) {
 667                argv[0] = cmd;
 668                handle_builtin(argc, argv);
 669                die("cannot handle %s as a builtin", cmd);
 670        }
 671
 672        /* Look for flags.. */
 673        argv++;
 674        argc--;
 675        handle_options(&argv, &argc, NULL);
 676        if (argc > 0) {
 677                /* translate --help and --version into commands */
 678                skip_prefix(argv[0], "--", &argv[0]);
 679        } else {
 680                /* The user didn't specify a command; give them help */
 681                commit_pager_choice();
 682                printf("usage: %s\n\n", git_usage_string);
 683                list_common_cmds_help();
 684                printf("\n%s\n", _(git_more_info_string));
 685                exit(1);
 686        }
 687        cmd = argv[0];
 688
 689        /*
 690         * We use PATH to find git commands, but we prepend some higher
 691         * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 692         * environment, and the $(gitexecdir) from the Makefile at build
 693         * time.
 694         */
 695        setup_path();
 696
 697        while (1) {
 698                int was_alias = run_argv(&argc, &argv);
 699                if (errno != ENOENT)
 700                        break;
 701                if (was_alias) {
 702                        fprintf(stderr, "Expansion of alias '%s' failed; "
 703                                "'%s' is not a git command\n",
 704                                cmd, argv[0]);
 705                        exit(1);
 706                }
 707                if (!done_help) {
 708                        cmd = argv[0] = help_unknown_cmd(cmd);
 709                        done_help = 1;
 710                } else
 711                        break;
 712        }
 713
 714        fprintf(stderr, "Failed to run command '%s': %s\n",
 715                cmd, strerror(errno));
 716
 717        return 1;
 718}