git.con commit Documentation/config.txt: describe the structure first and then meaning (ff5507e)
   1#include "builtin.h"
   2#include "cache.h"
   3#include "exec_cmd.h"
   4#include "help.h"
   5#include "quote.h"
   6#include "run-command.h"
   7#include "commit.h"
   8
   9const char git_usage_string[] =
  10        "git [--version] [--help] [-C <path>] [-c name=value]\n"
  11        "           [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
  12        "           [-p|--paginate|--no-pager] [--no-replace-objects] [--bare]\n"
  13        "           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
  14        "           <command> [<args>]";
  15
  16const char git_more_info_string[] =
  17        N_("'git help -a' and 'git help -g' lists available subcommands and some\n"
  18           "concept guides. See 'git help <command>' or 'git help <concept>'\n"
  19           "to read about a specific subcommand or concept.");
  20
  21static struct startup_info git_startup_info;
  22static int use_pager = -1;
  23
  24static void commit_pager_choice(void) {
  25        switch (use_pager) {
  26        case 0:
  27                setenv("GIT_PAGER", "cat", 1);
  28                break;
  29        case 1:
  30                setup_pager();
  31                break;
  32        default:
  33                break;
  34        }
  35}
  36
  37static int handle_options(const char ***argv, int *argc, int *envchanged)
  38{
  39        const char **orig_argv = *argv;
  40
  41        while (*argc > 0) {
  42                const char *cmd = (*argv)[0];
  43                if (cmd[0] != '-')
  44                        break;
  45
  46                /*
  47                 * For legacy reasons, the "version" and "help"
  48                 * commands can be written with "--" prepended
  49                 * to make them look like flags.
  50                 */
  51                if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  52                        break;
  53
  54                /*
  55                 * Check remaining flags.
  56                 */
  57                if (!prefixcmp(cmd, "--exec-path")) {
  58                        cmd += 11;
  59                        if (*cmd == '=')
  60                                git_set_argv_exec_path(cmd + 1);
  61                        else {
  62                                puts(git_exec_path());
  63                                exit(0);
  64                        }
  65                } else if (!strcmp(cmd, "--html-path")) {
  66                        puts(system_path(GIT_HTML_PATH));
  67                        exit(0);
  68                } else if (!strcmp(cmd, "--man-path")) {
  69                        puts(system_path(GIT_MAN_PATH));
  70                        exit(0);
  71                } else if (!strcmp(cmd, "--info-path")) {
  72                        puts(system_path(GIT_INFO_PATH));
  73                        exit(0);
  74                } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
  75                        use_pager = 1;
  76                } else if (!strcmp(cmd, "--no-pager")) {
  77                        use_pager = 0;
  78                        if (envchanged)
  79                                *envchanged = 1;
  80                } else if (!strcmp(cmd, "--no-replace-objects")) {
  81                        read_replace_refs = 0;
  82                        setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
  83                        if (envchanged)
  84                                *envchanged = 1;
  85                } else if (!strcmp(cmd, "--git-dir")) {
  86                        if (*argc < 2) {
  87                                fprintf(stderr, "No directory given for --git-dir.\n" );
  88                                usage(git_usage_string);
  89                        }
  90                        setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
  91                        if (envchanged)
  92                                *envchanged = 1;
  93                        (*argv)++;
  94                        (*argc)--;
  95                } else if (!prefixcmp(cmd, "--git-dir=")) {
  96                        setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
  97                        if (envchanged)
  98                                *envchanged = 1;
  99                } else if (!strcmp(cmd, "--namespace")) {
 100                        if (*argc < 2) {
 101                                fprintf(stderr, "No namespace given for --namespace.\n" );
 102                                usage(git_usage_string);
 103                        }
 104                        setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 105                        if (envchanged)
 106                                *envchanged = 1;
 107                        (*argv)++;
 108                        (*argc)--;
 109                } else if (!prefixcmp(cmd, "--namespace=")) {
 110                        setenv(GIT_NAMESPACE_ENVIRONMENT, cmd + 12, 1);
 111                        if (envchanged)
 112                                *envchanged = 1;
 113                } else if (!strcmp(cmd, "--work-tree")) {
 114                        if (*argc < 2) {
 115                                fprintf(stderr, "No directory given for --work-tree.\n" );
 116                                usage(git_usage_string);
 117                        }
 118                        setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 119                        if (envchanged)
 120                                *envchanged = 1;
 121                        (*argv)++;
 122                        (*argc)--;
 123                } else if (!prefixcmp(cmd, "--work-tree=")) {
 124                        setenv(GIT_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 125                        if (envchanged)
 126                                *envchanged = 1;
 127                } else if (!strcmp(cmd, "--bare")) {
 128                        static char git_dir[PATH_MAX+1];
 129                        is_bare_repository_cfg = 1;
 130                        setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
 131                        setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 132                        if (envchanged)
 133                                *envchanged = 1;
 134                } else if (!strcmp(cmd, "-c")) {
 135                        if (*argc < 2) {
 136                                fprintf(stderr, "-c expects a configuration string\n" );
 137                                usage(git_usage_string);
 138                        }
 139                        git_config_push_parameter((*argv)[1]);
 140                        (*argv)++;
 141                        (*argc)--;
 142                } else if (!strcmp(cmd, "--literal-pathspecs")) {
 143                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 144                        if (envchanged)
 145                                *envchanged = 1;
 146                } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 147                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 148                        if (envchanged)
 149                                *envchanged = 1;
 150                } else if (!strcmp(cmd, "--glob-pathspecs")) {
 151                        setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 152                        if (envchanged)
 153                                *envchanged = 1;
 154                } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 155                        setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 156                        if (envchanged)
 157                                *envchanged = 1;
 158                } else if (!strcmp(cmd, "--icase-pathspecs")) {
 159                        setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 160                        if (envchanged)
 161                                *envchanged = 1;
 162                } else if (!strcmp(cmd, "--shallow-file")) {
 163                        (*argv)++;
 164                        (*argc)--;
 165                        set_alternate_shallow_file((*argv)[0]);
 166                        if (envchanged)
 167                                *envchanged = 1;
 168                } else if (!strcmp(cmd, "-C")) {
 169                        if (*argc < 2) {
 170                                fprintf(stderr, "No directory given for -C.\n" );
 171                                usage(git_usage_string);
 172                        }
 173                        if (chdir((*argv)[1]))
 174                                die_errno("Cannot change to '%s'", (*argv)[1]);
 175                        if (envchanged)
 176                                *envchanged = 1;
 177                        (*argv)++;
 178                        (*argc)--;
 179                } else {
 180                        fprintf(stderr, "Unknown option: %s\n", cmd);
 181                        usage(git_usage_string);
 182                }
 183
 184                (*argv)++;
 185                (*argc)--;
 186        }
 187        return (*argv) - orig_argv;
 188}
 189
 190static int handle_alias(int *argcp, const char ***argv)
 191{
 192        int envchanged = 0, ret = 0, saved_errno = errno;
 193        const char *subdir;
 194        int count, option_count;
 195        const char **new_argv;
 196        const char *alias_command;
 197        char *alias_string;
 198        int unused_nongit;
 199
 200        subdir = setup_git_directory_gently(&unused_nongit);
 201
 202        alias_command = (*argv)[0];
 203        alias_string = alias_lookup(alias_command);
 204        if (alias_string) {
 205                if (alias_string[0] == '!') {
 206                        const char **alias_argv;
 207                        int argc = *argcp, i;
 208
 209                        commit_pager_choice();
 210
 211                        /* build alias_argv */
 212                        alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 213                        alias_argv[0] = alias_string + 1;
 214                        for (i = 1; i < argc; ++i)
 215                                alias_argv[i] = (*argv)[i];
 216                        alias_argv[argc] = NULL;
 217
 218                        ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 219                        if (ret >= 0)   /* normal exit */
 220                                exit(ret);
 221
 222                        die_errno("While expanding alias '%s': '%s'",
 223                            alias_command, alias_string + 1);
 224                }
 225                count = split_cmdline(alias_string, &new_argv);
 226                if (count < 0)
 227                        die("Bad alias.%s string: %s", alias_command,
 228                            split_cmdline_strerror(count));
 229                option_count = handle_options(&new_argv, &count, &envchanged);
 230                if (envchanged)
 231                        die("alias '%s' changes environment variables\n"
 232                                 "You can use '!git' in the alias to do this.",
 233                                 alias_command);
 234                memmove(new_argv - option_count, new_argv,
 235                                count * sizeof(char *));
 236                new_argv -= option_count;
 237
 238                if (count < 1)
 239                        die("empty alias for %s", alias_command);
 240
 241                if (!strcmp(alias_command, new_argv[0]))
 242                        die("recursive alias: %s", alias_command);
 243
 244                trace_argv_printf(new_argv,
 245                                  "trace: alias expansion: %s =>",
 246                                  alias_command);
 247
 248                new_argv = xrealloc(new_argv, sizeof(char *) *
 249                                    (count + *argcp));
 250                /* insert after command name */
 251                memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 252
 253                *argv = new_argv;
 254                *argcp += count - 1;
 255
 256                ret = 1;
 257        }
 258
 259        if (subdir && chdir(subdir))
 260                die_errno("Cannot change to '%s'", subdir);
 261
 262        errno = saved_errno;
 263
 264        return ret;
 265}
 266
 267#define RUN_SETUP               (1<<0)
 268#define RUN_SETUP_GENTLY        (1<<1)
 269#define USE_PAGER               (1<<2)
 270/*
 271 * require working tree to be present -- anything uses this needs
 272 * RUN_SETUP for reading from the configuration file.
 273 */
 274#define NEED_WORK_TREE          (1<<3)
 275
 276struct cmd_struct {
 277        const char *cmd;
 278        int (*fn)(int, const char **, const char *);
 279        int option;
 280};
 281
 282static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 283{
 284        int status, help;
 285        struct stat st;
 286        const char *prefix;
 287
 288        prefix = NULL;
 289        help = argc == 2 && !strcmp(argv[1], "-h");
 290        if (!help) {
 291                if (p->option & RUN_SETUP)
 292                        prefix = setup_git_directory();
 293                if (p->option & RUN_SETUP_GENTLY) {
 294                        int nongit_ok;
 295                        prefix = setup_git_directory_gently(&nongit_ok);
 296                }
 297
 298                if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 299                        use_pager = check_pager_config(p->cmd);
 300                if (use_pager == -1 && p->option & USE_PAGER)
 301                        use_pager = 1;
 302
 303                if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 304                    startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 305                        trace_repo_setup(prefix);
 306        }
 307        commit_pager_choice();
 308
 309        if (!help && p->option & NEED_WORK_TREE)
 310                setup_work_tree();
 311
 312        trace_argv_printf(argv, "trace: built-in: git");
 313
 314        status = p->fn(argc, argv, prefix);
 315        if (status)
 316                return status;
 317
 318        /* Somebody closed stdout? */
 319        if (fstat(fileno(stdout), &st))
 320                return 0;
 321        /* Ignore write errors for pipes and sockets.. */
 322        if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 323                return 0;
 324
 325        /* Check for ENOSPC and EIO errors.. */
 326        if (fflush(stdout))
 327                die_errno("write failure on standard output");
 328        if (ferror(stdout))
 329                die("unknown write failure on standard output");
 330        if (fclose(stdout))
 331                die_errno("close failed on standard output");
 332        return 0;
 333}
 334
 335static void handle_internal_command(int argc, const char **argv)
 336{
 337        const char *cmd = argv[0];
 338        static struct cmd_struct commands[] = {
 339                { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 340                { "annotate", cmd_annotate, RUN_SETUP },
 341                { "apply", cmd_apply, RUN_SETUP_GENTLY },
 342                { "archive", cmd_archive },
 343                { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 344                { "blame", cmd_blame, RUN_SETUP },
 345                { "branch", cmd_branch, RUN_SETUP },
 346                { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 347                { "cat-file", cmd_cat_file, RUN_SETUP },
 348                { "check-attr", cmd_check_attr, RUN_SETUP },
 349                { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 350                { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 351                { "check-ref-format", cmd_check_ref_format },
 352                { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 353                { "checkout-index", cmd_checkout_index,
 354                        RUN_SETUP | NEED_WORK_TREE},
 355                { "cherry", cmd_cherry, RUN_SETUP },
 356                { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 357                { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 358                { "clone", cmd_clone },
 359                { "column", cmd_column, RUN_SETUP_GENTLY },
 360                { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 361                { "commit-tree", cmd_commit_tree, RUN_SETUP },
 362                { "config", cmd_config, RUN_SETUP_GENTLY },
 363                { "count-objects", cmd_count_objects, RUN_SETUP },
 364                { "credential", cmd_credential, RUN_SETUP_GENTLY },
 365                { "describe", cmd_describe, RUN_SETUP },
 366                { "diff", cmd_diff },
 367                { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 368                { "diff-index", cmd_diff_index, RUN_SETUP },
 369                { "diff-tree", cmd_diff_tree, RUN_SETUP },
 370                { "fast-export", cmd_fast_export, RUN_SETUP },
 371                { "fetch", cmd_fetch, RUN_SETUP },
 372                { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 373                { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 374                { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 375                { "format-patch", cmd_format_patch, RUN_SETUP },
 376                { "fsck", cmd_fsck, RUN_SETUP },
 377                { "fsck-objects", cmd_fsck, RUN_SETUP },
 378                { "gc", cmd_gc, RUN_SETUP },
 379                { "get-tar-commit-id", cmd_get_tar_commit_id },
 380                { "grep", cmd_grep, RUN_SETUP_GENTLY },
 381                { "hash-object", cmd_hash_object },
 382                { "help", cmd_help },
 383                { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 384                { "init", cmd_init_db },
 385                { "init-db", cmd_init_db },
 386                { "log", cmd_log, RUN_SETUP },
 387                { "ls-files", cmd_ls_files, RUN_SETUP },
 388                { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 389                { "ls-tree", cmd_ls_tree, RUN_SETUP },
 390                { "mailinfo", cmd_mailinfo },
 391                { "mailsplit", cmd_mailsplit },
 392                { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 393                { "merge-base", cmd_merge_base, RUN_SETUP },
 394                { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 395                { "merge-index", cmd_merge_index, RUN_SETUP },
 396                { "merge-ours", cmd_merge_ours, RUN_SETUP },
 397                { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 398                { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 399                { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 400                { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 401                { "merge-tree", cmd_merge_tree, RUN_SETUP },
 402                { "mktag", cmd_mktag, RUN_SETUP },
 403                { "mktree", cmd_mktree, RUN_SETUP },
 404                { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 405                { "name-rev", cmd_name_rev, RUN_SETUP },
 406                { "notes", cmd_notes, RUN_SETUP },
 407                { "pack-objects", cmd_pack_objects, RUN_SETUP },
 408                { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 409                { "pack-refs", cmd_pack_refs, RUN_SETUP },
 410                { "patch-id", cmd_patch_id },
 411                { "peek-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 412                { "pickaxe", cmd_blame, RUN_SETUP },
 413                { "prune", cmd_prune, RUN_SETUP },
 414                { "prune-packed", cmd_prune_packed, RUN_SETUP },
 415                { "push", cmd_push, RUN_SETUP },
 416                { "read-tree", cmd_read_tree, RUN_SETUP },
 417                { "receive-pack", cmd_receive_pack },
 418                { "reflog", cmd_reflog, RUN_SETUP },
 419                { "remote", cmd_remote, RUN_SETUP },
 420                { "remote-ext", cmd_remote_ext },
 421                { "remote-fd", cmd_remote_fd },
 422                { "repack", cmd_repack, RUN_SETUP },
 423                { "replace", cmd_replace, RUN_SETUP },
 424                { "repo-config", cmd_repo_config, RUN_SETUP_GENTLY },
 425                { "rerere", cmd_rerere, RUN_SETUP },
 426                { "reset", cmd_reset, RUN_SETUP },
 427                { "rev-list", cmd_rev_list, RUN_SETUP },
 428                { "rev-parse", cmd_rev_parse },
 429                { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 430                { "rm", cmd_rm, RUN_SETUP },
 431                { "send-pack", cmd_send_pack, RUN_SETUP },
 432                { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 433                { "show", cmd_show, RUN_SETUP },
 434                { "show-branch", cmd_show_branch, RUN_SETUP },
 435                { "show-ref", cmd_show_ref, RUN_SETUP },
 436                { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 437                { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 438                { "stripspace", cmd_stripspace },
 439                { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 440                { "tag", cmd_tag, RUN_SETUP },
 441                { "tar-tree", cmd_tar_tree },
 442                { "unpack-file", cmd_unpack_file, RUN_SETUP },
 443                { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 444                { "update-index", cmd_update_index, RUN_SETUP },
 445                { "update-ref", cmd_update_ref, RUN_SETUP },
 446                { "update-server-info", cmd_update_server_info, RUN_SETUP },
 447                { "upload-archive", cmd_upload_archive },
 448                { "upload-archive--writer", cmd_upload_archive_writer },
 449                { "var", cmd_var, RUN_SETUP_GENTLY },
 450                { "verify-pack", cmd_verify_pack },
 451                { "verify-tag", cmd_verify_tag, RUN_SETUP },
 452                { "version", cmd_version },
 453                { "whatchanged", cmd_whatchanged, RUN_SETUP },
 454                { "write-tree", cmd_write_tree, RUN_SETUP },
 455        };
 456        int i;
 457        static const char ext[] = STRIP_EXTENSION;
 458
 459        if (sizeof(ext) > 1) {
 460                i = strlen(argv[0]) - strlen(ext);
 461                if (i > 0 && !strcmp(argv[0] + i, ext)) {
 462                        char *argv0 = xstrdup(argv[0]);
 463                        argv[0] = cmd = argv0;
 464                        argv0[i] = '\0';
 465                }
 466        }
 467
 468        /* Turn "git cmd --help" into "git help cmd" */
 469        if (argc > 1 && !strcmp(argv[1], "--help")) {
 470                argv[1] = argv[0];
 471                argv[0] = cmd = "help";
 472        }
 473
 474        for (i = 0; i < ARRAY_SIZE(commands); i++) {
 475                struct cmd_struct *p = commands+i;
 476                if (strcmp(p->cmd, cmd))
 477                        continue;
 478                exit(run_builtin(p, argc, argv));
 479        }
 480}
 481
 482static void execv_dashed_external(const char **argv)
 483{
 484        struct strbuf cmd = STRBUF_INIT;
 485        const char *tmp;
 486        int status;
 487
 488        if (use_pager == -1)
 489                use_pager = check_pager_config(argv[0]);
 490        commit_pager_choice();
 491
 492        strbuf_addf(&cmd, "git-%s", argv[0]);
 493
 494        /*
 495         * argv[0] must be the git command, but the argv array
 496         * belongs to the caller, and may be reused in
 497         * subsequent loop iterations. Save argv[0] and
 498         * restore it on error.
 499         */
 500        tmp = argv[0];
 501        argv[0] = cmd.buf;
 502
 503        trace_argv_printf(argv, "trace: exec:");
 504
 505        /*
 506         * if we fail because the command is not found, it is
 507         * OK to return. Otherwise, we just pass along the status code.
 508         */
 509        status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 510        if (status >= 0 || errno != ENOENT)
 511                exit(status);
 512
 513        argv[0] = tmp;
 514
 515        strbuf_release(&cmd);
 516}
 517
 518static int run_argv(int *argcp, const char ***argv)
 519{
 520        int done_alias = 0;
 521
 522        while (1) {
 523                /* See if it's an internal command */
 524                handle_internal_command(*argcp, *argv);
 525
 526                /* .. then try the external ones */
 527                execv_dashed_external(*argv);
 528
 529                /* It could be an alias -- this works around the insanity
 530                 * of overriding "git log" with "git show" by having
 531                 * alias.log = show
 532                 */
 533                if (done_alias || !handle_alias(argcp, argv))
 534                        break;
 535                done_alias = 1;
 536        }
 537
 538        return done_alias;
 539}
 540
 541
 542int main(int argc, char **av)
 543{
 544        const char **argv = (const char **) av;
 545        const char *cmd;
 546
 547        startup_info = &git_startup_info;
 548
 549        cmd = git_extract_argv0_path(argv[0]);
 550        if (!cmd)
 551                cmd = "git-help";
 552
 553        /*
 554         * Always open file descriptors 0/1/2 to avoid clobbering files
 555         * in die().  It also avoids messing up when the pipes are dup'ed
 556         * onto stdin/stdout/stderr in the child processes we spawn.
 557         */
 558        sanitize_stdfds();
 559
 560        git_setup_gettext();
 561
 562        /*
 563         * "git-xxxx" is the same as "git xxxx", but we obviously:
 564         *
 565         *  - cannot take flags in between the "git" and the "xxxx".
 566         *  - cannot execute it externally (since it would just do
 567         *    the same thing over again)
 568         *
 569         * So we just directly call the internal command handler, and
 570         * die if that one cannot handle it.
 571         */
 572        if (!prefixcmp(cmd, "git-")) {
 573                cmd += 4;
 574                argv[0] = cmd;
 575                handle_internal_command(argc, argv);
 576                die("cannot handle %s internally", cmd);
 577        }
 578
 579        /* Look for flags.. */
 580        argv++;
 581        argc--;
 582        handle_options(&argv, &argc, NULL);
 583        if (argc > 0) {
 584                if (!prefixcmp(argv[0], "--"))
 585                        argv[0] += 2;
 586        } else {
 587                /* The user didn't specify a command; give them help */
 588                commit_pager_choice();
 589                printf("usage: %s\n\n", git_usage_string);
 590                list_common_cmds_help();
 591                printf("\n%s\n", _(git_more_info_string));
 592                exit(1);
 593        }
 594        cmd = argv[0];
 595
 596        /*
 597         * We use PATH to find git commands, but we prepend some higher
 598         * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 599         * environment, and the $(gitexecdir) from the Makefile at build
 600         * time.
 601         */
 602        setup_path();
 603
 604        while (1) {
 605                static int done_help = 0;
 606                static int was_alias = 0;
 607                was_alias = run_argv(&argc, &argv);
 608                if (errno != ENOENT)
 609                        break;
 610                if (was_alias) {
 611                        fprintf(stderr, "Expansion of alias '%s' failed; "
 612                                "'%s' is not a git command\n",
 613                                cmd, argv[0]);
 614                        exit(1);
 615                }
 616                if (!done_help) {
 617                        cmd = argv[0] = help_unknown_cmd(cmd);
 618                        done_help = 1;
 619                } else
 620                        break;
 621        }
 622
 623        fprintf(stderr, "Failed to run command '%s': %s\n",
 624                cmd, strerror(errno));
 625
 626        return 1;
 627}