Andrew's git / gitweb.git / git.c
?
git.con commit reflog_expire(): never update a reference to null_sha1 (423c688)
   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 struct startup_info git_startup_info;
  19static int use_pager = -1;
  20static char *orig_cwd;
  21static const char *env_names[] = {
  22        GIT_DIR_ENVIRONMENT,
  23        GIT_WORK_TREE_ENVIRONMENT,
  24        GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
  25        GIT_PREFIX_ENVIRONMENT
  26};
  27static char *orig_env[4];
  28static int saved_environment;
  29
  30static void save_env(void)
  31{
  32        int i;
  33        if (saved_environment)
  34                return;
  35        saved_environment = 1;
  36        orig_cwd = xgetcwd();
  37        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  38                orig_env[i] = getenv(env_names[i]);
  39                if (orig_env[i])
  40                        orig_env[i] = xstrdup(orig_env[i]);
  41        }
  42}
  43
  44static void restore_env(void)
  45{
  46        int i;
  47        if (orig_cwd && chdir(orig_cwd))
  48                die_errno("could not move to %s", orig_cwd);
  49        free(orig_cwd);
  50        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  51                if (orig_env[i])
  52                        setenv(env_names[i], orig_env[i], 1);
  53                else
  54                        unsetenv(env_names[i]);
  55        }
  56}
  57
  58static void commit_pager_choice(void) {
  59        switch (use_pager) {
  60        case 0:
  61                setenv("GIT_PAGER", "cat", 1);
  62                break;
  63        case 1:
  64                setup_pager();
  65                break;
  66        default:
  67                break;
  68        }
  69}
  70
  71static int handle_options(const char ***argv, int *argc, int *envchanged)
  72{
  73        const char **orig_argv = *argv;
  74
  75        while (*argc > 0) {
  76                const char *cmd = (*argv)[0];
  77                if (cmd[0] != '-')
  78                        break;
  79
  80                /*
  81                 * For legacy reasons, the "version" and "help"
  82                 * commands can be written with "--" prepended
  83                 * to make them look like flags.
  84                 */
  85                if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  86                        break;
  87
  88                /*
  89                 * Check remaining flags.
  90                 */
  91                if (skip_prefix(cmd, "--exec-path", &cmd)) {
  92                        if (*cmd == '=')
  93                                git_set_argv_exec_path(cmd + 1);
  94                        else {
  95                                puts(git_exec_path());
  96                                exit(0);
  97                        }
  98                } else if (!strcmp(cmd, "--html-path")) {
  99                        puts(system_path(GIT_HTML_PATH));
 100                        exit(0);
 101                } else if (!strcmp(cmd, "--man-path")) {
 102                        puts(system_path(GIT_MAN_PATH));
 103                        exit(0);
 104                } else if (!strcmp(cmd, "--info-path")) {
 105                        puts(system_path(GIT_INFO_PATH));
 106                        exit(0);
 107                } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 108                        use_pager = 1;
 109                } else if (!strcmp(cmd, "--no-pager")) {
 110                        use_pager = 0;
 111                        if (envchanged)
 112                                *envchanged = 1;
 113                } else if (!strcmp(cmd, "--no-replace-objects")) {
 114                        check_replace_refs = 0;
 115                        setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 116                        if (envchanged)
 117                                *envchanged = 1;
 118                } else if (!strcmp(cmd, "--git-dir")) {
 119                        if (*argc < 2) {
 120                                fprintf(stderr, "No directory given for --git-dir.\n" );
 121                                usage(git_usage_string);
 122                        }
 123                        setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 124                        if (envchanged)
 125                                *envchanged = 1;
 126                        (*argv)++;
 127                        (*argc)--;
 128                } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
 129                        setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
 130                        if (envchanged)
 131                                *envchanged = 1;
 132                } else if (!strcmp(cmd, "--namespace")) {
 133                        if (*argc < 2) {
 134                                fprintf(stderr, "No namespace given for --namespace.\n" );
 135                                usage(git_usage_string);
 136                        }
 137                        setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 138                        if (envchanged)
 139                                *envchanged = 1;
 140                        (*argv)++;
 141                        (*argc)--;
 142                } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
 143                        setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
 144                        if (envchanged)
 145                                *envchanged = 1;
 146                } else if (!strcmp(cmd, "--work-tree")) {
 147                        if (*argc < 2) {
 148                                fprintf(stderr, "No directory given for --work-tree.\n" );
 149                                usage(git_usage_string);
 150                        }
 151                        setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 152                        if (envchanged)
 153                                *envchanged = 1;
 154                        (*argv)++;
 155                        (*argc)--;
 156                } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
 157                        setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
 158                        if (envchanged)
 159                                *envchanged = 1;
 160                } else if (!strcmp(cmd, "--bare")) {
 161                        char *cwd = xgetcwd();
 162                        is_bare_repository_cfg = 1;
 163                        setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
 164                        free(cwd);
 165                        setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 166                        if (envchanged)
 167                                *envchanged = 1;
 168                } else if (!strcmp(cmd, "-c")) {
 169                        if (*argc < 2) {
 170                                fprintf(stderr, "-c expects a configuration string\n" );
 171                                usage(git_usage_string);
 172                        }
 173                        git_config_push_parameter((*argv)[1]);
 174                        (*argv)++;
 175                        (*argc)--;
 176                } else if (!strcmp(cmd, "--literal-pathspecs")) {
 177                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 178                        if (envchanged)
 179                                *envchanged = 1;
 180                } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 181                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 182                        if (envchanged)
 183                                *envchanged = 1;
 184                } else if (!strcmp(cmd, "--glob-pathspecs")) {
 185                        setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 186                        if (envchanged)
 187                                *envchanged = 1;
 188                } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 189                        setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 190                        if (envchanged)
 191                                *envchanged = 1;
 192                } else if (!strcmp(cmd, "--icase-pathspecs")) {
 193                        setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 194                        if (envchanged)
 195                                *envchanged = 1;
 196                } else if (!strcmp(cmd, "--shallow-file")) {
 197                        (*argv)++;
 198                        (*argc)--;
 199                        set_alternate_shallow_file((*argv)[0], 1);
 200                        if (envchanged)
 201                                *envchanged = 1;
 202                } else if (!strcmp(cmd, "-C")) {
 203                        if (*argc < 2) {
 204                                fprintf(stderr, "No directory given for -C.\n" );
 205                                usage(git_usage_string);
 206                        }
 207                        if (chdir((*argv)[1]))
 208                                die_errno("Cannot change to '%s'", (*argv)[1]);
 209                        if (envchanged)
 210                                *envchanged = 1;
 211                        (*argv)++;
 212                        (*argc)--;
 213                } else {
 214                        fprintf(stderr, "Unknown option: %s\n", cmd);
 215                        usage(git_usage_string);
 216                }
 217
 218                (*argv)++;
 219                (*argc)--;
 220        }
 221        return (*argv) - orig_argv;
 222}
 223
 224static int handle_alias(int *argcp, const char ***argv)
 225{
 226        int envchanged = 0, ret = 0, saved_errno = errno;
 227        const char *subdir;
 228        int count, option_count;
 229        const char **new_argv;
 230        const char *alias_command;
 231        char *alias_string;
 232        int unused_nongit;
 233
 234        subdir = setup_git_directory_gently(&unused_nongit);
 235
 236        alias_command = (*argv)[0];
 237        alias_string = alias_lookup(alias_command);
 238        if (alias_string) {
 239                if (alias_string[0] == '!') {
 240                        const char **alias_argv;
 241                        int argc = *argcp, i;
 242
 243                        commit_pager_choice();
 244
 245                        /* build alias_argv */
 246                        alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 247                        alias_argv[0] = alias_string + 1;
 248                        for (i = 1; i < argc; ++i)
 249                                alias_argv[i] = (*argv)[i];
 250                        alias_argv[argc] = NULL;
 251
 252                        ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 253                        if (ret >= 0)   /* normal exit */
 254                                exit(ret);
 255
 256                        die_errno("While expanding alias '%s': '%s'",
 257                            alias_command, alias_string + 1);
 258                }
 259                count = split_cmdline(alias_string, &new_argv);
 260                if (count < 0)
 261                        die("Bad alias.%s string: %s", alias_command,
 262                            split_cmdline_strerror(count));
 263                option_count = handle_options(&new_argv, &count, &envchanged);
 264                if (envchanged)
 265                        die("alias '%s' changes environment variables\n"
 266                                 "You can use '!git' in the alias to do this.",
 267                                 alias_command);
 268                memmove(new_argv - option_count, new_argv,
 269                                count * sizeof(char *));
 270                new_argv -= option_count;
 271
 272                if (count < 1)
 273                        die("empty alias for %s", alias_command);
 274
 275                if (!strcmp(alias_command, new_argv[0]))
 276                        die("recursive alias: %s", alias_command);
 277
 278                trace_argv_printf(new_argv,
 279                                  "trace: alias expansion: %s =>",
 280                                  alias_command);
 281
 282                REALLOC_ARRAY(new_argv, count + *argcp);
 283                /* insert after command name */
 284                memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 285
 286                *argv = new_argv;
 287                *argcp += count - 1;
 288
 289                ret = 1;
 290        }
 291
 292        if (subdir && chdir(subdir))
 293                die_errno("Cannot change to '%s'", subdir);
 294
 295        errno = saved_errno;
 296
 297        return ret;
 298}
 299
 300#define RUN_SETUP               (1<<0)
 301#define RUN_SETUP_GENTLY        (1<<1)
 302#define USE_PAGER               (1<<2)
 303/*
 304 * require working tree to be present -- anything uses this needs
 305 * RUN_SETUP for reading from the configuration file.
 306 */
 307#define NEED_WORK_TREE          (1<<3)
 308#define NO_SETUP                (1<<4)
 309
 310struct cmd_struct {
 311        const char *cmd;
 312        int (*fn)(int, const char **, const char *);
 313        int option;
 314};
 315
 316static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 317{
 318        int status, help;
 319        struct stat st;
 320        const char *prefix;
 321
 322        prefix = NULL;
 323        help = argc == 2 && !strcmp(argv[1], "-h");
 324        if (!help) {
 325                if (p->option & RUN_SETUP)
 326                        prefix = setup_git_directory();
 327                else if (p->option & RUN_SETUP_GENTLY) {
 328                        int nongit_ok;
 329                        prefix = setup_git_directory_gently(&nongit_ok);
 330                }
 331
 332                if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 333                        use_pager = check_pager_config(p->cmd);
 334                if (use_pager == -1 && p->option & USE_PAGER)
 335                        use_pager = 1;
 336
 337                if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 338                    startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 339                        trace_repo_setup(prefix);
 340        }
 341        commit_pager_choice();
 342
 343        if (!help && p->option & NEED_WORK_TREE)
 344                setup_work_tree();
 345
 346        trace_argv_printf(argv, "trace: built-in: git");
 347
 348        status = p->fn(argc, argv, prefix);
 349        if (status)
 350                return status;
 351
 352        /* Somebody closed stdout? */
 353        if (fstat(fileno(stdout), &st))
 354                return 0;
 355        /* Ignore write errors for pipes and sockets.. */
 356        if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 357                return 0;
 358
 359        /* Check for ENOSPC and EIO errors.. */
 360        if (fflush(stdout))
 361                die_errno("write failure on standard output");
 362        if (ferror(stdout))
 363                die("unknown write failure on standard output");
 364        if (fclose(stdout))
 365                die_errno("close failed on standard output");
 366        return 0;
 367}
 368
 369static struct cmd_struct commands[] = {
 370        { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 371        { "annotate", cmd_annotate, RUN_SETUP },
 372        { "apply", cmd_apply, RUN_SETUP_GENTLY },
 373        { "archive", cmd_archive },
 374        { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 375        { "blame", cmd_blame, RUN_SETUP },
 376        { "branch", cmd_branch, RUN_SETUP },
 377        { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 378        { "cat-file", cmd_cat_file, RUN_SETUP },
 379        { "check-attr", cmd_check_attr, RUN_SETUP },
 380        { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 381        { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 382        { "check-ref-format", cmd_check_ref_format },
 383        { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 384        { "checkout-index", cmd_checkout_index,
 385                RUN_SETUP | NEED_WORK_TREE},
 386        { "cherry", cmd_cherry, RUN_SETUP },
 387        { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 388        { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 389        { "clone", cmd_clone, NO_SETUP },
 390        { "column", cmd_column, RUN_SETUP_GENTLY },
 391        { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 392        { "commit-tree", cmd_commit_tree, RUN_SETUP },
 393        { "config", cmd_config, RUN_SETUP_GENTLY },
 394        { "count-objects", cmd_count_objects, RUN_SETUP },
 395        { "credential", cmd_credential, RUN_SETUP_GENTLY },
 396        { "describe", cmd_describe, RUN_SETUP },
 397        { "diff", cmd_diff },
 398        { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 399        { "diff-index", cmd_diff_index, RUN_SETUP },
 400        { "diff-tree", cmd_diff_tree, RUN_SETUP },
 401        { "fast-export", cmd_fast_export, RUN_SETUP },
 402        { "fetch", cmd_fetch, RUN_SETUP },
 403        { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 404        { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 405        { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 406        { "format-patch", cmd_format_patch, RUN_SETUP },
 407        { "fsck", cmd_fsck, RUN_SETUP },
 408        { "fsck-objects", cmd_fsck, RUN_SETUP },
 409        { "gc", cmd_gc, RUN_SETUP },
 410        { "get-tar-commit-id", cmd_get_tar_commit_id },
 411        { "grep", cmd_grep, RUN_SETUP_GENTLY },
 412        { "hash-object", cmd_hash_object },
 413        { "help", cmd_help },
 414        { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 415        { "init", cmd_init_db, NO_SETUP },
 416        { "init-db", cmd_init_db, NO_SETUP },
 417        { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP },
 418        { "log", cmd_log, RUN_SETUP },
 419        { "ls-files", cmd_ls_files, RUN_SETUP },
 420        { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 421        { "ls-tree", cmd_ls_tree, RUN_SETUP },
 422        { "mailinfo", cmd_mailinfo },
 423        { "mailsplit", cmd_mailsplit },
 424        { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 425        { "merge-base", cmd_merge_base, RUN_SETUP },
 426        { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 427        { "merge-index", cmd_merge_index, RUN_SETUP },
 428        { "merge-ours", cmd_merge_ours, RUN_SETUP },
 429        { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 430        { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 431        { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 432        { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 433        { "merge-tree", cmd_merge_tree, RUN_SETUP },
 434        { "mktag", cmd_mktag, RUN_SETUP },
 435        { "mktree", cmd_mktree, RUN_SETUP },
 436        { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 437        { "name-rev", cmd_name_rev, RUN_SETUP },
 438        { "notes", cmd_notes, RUN_SETUP },
 439        { "pack-objects", cmd_pack_objects, RUN_SETUP },
 440        { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 441        { "pack-refs", cmd_pack_refs, RUN_SETUP },
 442        { "patch-id", cmd_patch_id },
 443        { "pickaxe", cmd_blame, RUN_SETUP },
 444        { "prune", cmd_prune, RUN_SETUP },
 445        { "prune-packed", cmd_prune_packed, RUN_SETUP },
 446        { "push", cmd_push, RUN_SETUP },
 447        { "read-tree", cmd_read_tree, RUN_SETUP },
 448        { "receive-pack", cmd_receive_pack },
 449        { "reflog", cmd_reflog, RUN_SETUP },
 450        { "remote", cmd_remote, RUN_SETUP },
 451        { "remote-ext", cmd_remote_ext },
 452        { "remote-fd", cmd_remote_fd },
 453        { "repack", cmd_repack, RUN_SETUP },
 454        { "replace", cmd_replace, RUN_SETUP },
 455        { "rerere", cmd_rerere, RUN_SETUP },
 456        { "reset", cmd_reset, RUN_SETUP },
 457        { "rev-list", cmd_rev_list, RUN_SETUP },
 458        { "rev-parse", cmd_rev_parse },
 459        { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 460        { "rm", cmd_rm, RUN_SETUP },
 461        { "send-pack", cmd_send_pack, RUN_SETUP },
 462        { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 463        { "show", cmd_show, RUN_SETUP },
 464        { "show-branch", cmd_show_branch, RUN_SETUP },
 465        { "show-ref", cmd_show_ref, RUN_SETUP },
 466        { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 467        { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 468        { "stripspace", cmd_stripspace },
 469        { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 470        { "tag", cmd_tag, RUN_SETUP },
 471        { "unpack-file", cmd_unpack_file, RUN_SETUP },
 472        { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 473        { "update-index", cmd_update_index, RUN_SETUP },
 474        { "update-ref", cmd_update_ref, RUN_SETUP },
 475        { "update-server-info", cmd_update_server_info, RUN_SETUP },
 476        { "upload-archive", cmd_upload_archive },
 477        { "upload-archive--writer", cmd_upload_archive_writer },
 478        { "var", cmd_var, RUN_SETUP_GENTLY },
 479        { "verify-commit", cmd_verify_commit, RUN_SETUP },
 480        { "verify-pack", cmd_verify_pack },
 481        { "verify-tag", cmd_verify_tag, RUN_SETUP },
 482        { "version", cmd_version },
 483        { "whatchanged", cmd_whatchanged, RUN_SETUP },
 484        { "write-tree", cmd_write_tree, RUN_SETUP },
 485};
 486
 487static struct cmd_struct *get_builtin(const char *s)
 488{
 489        int i;
 490        for (i = 0; i < ARRAY_SIZE(commands); i++) {
 491                struct cmd_struct *p = commands + i;
 492                if (!strcmp(s, p->cmd))
 493                        return p;
 494        }
 495        return NULL;
 496}
 497
 498int is_builtin(const char *s)
 499{
 500        return !!get_builtin(s);
 501}
 502
 503static void handle_builtin(int argc, const char **argv)
 504{
 505        const char *cmd = argv[0];
 506        int i;
 507        static const char ext[] = STRIP_EXTENSION;
 508        struct cmd_struct *builtin;
 509
 510        if (sizeof(ext) > 1) {
 511                i = strlen(argv[0]) - strlen(ext);
 512                if (i > 0 && !strcmp(argv[0] + i, ext)) {
 513                        char *argv0 = xstrdup(argv[0]);
 514                        argv[0] = cmd = argv0;
 515                        argv0[i] = '\0';
 516                }
 517        }
 518
 519        /* Turn "git cmd --help" into "git help cmd" */
 520        if (argc > 1 && !strcmp(argv[1], "--help")) {
 521                argv[1] = argv[0];
 522                argv[0] = cmd = "help";
 523        }
 524
 525        builtin = get_builtin(cmd);
 526        if (builtin) {
 527                if (saved_environment && (builtin->option & NO_SETUP))
 528                        restore_env();
 529                else
 530                        exit(run_builtin(builtin, argc, argv));
 531        }
 532}
 533
 534static void execv_dashed_external(const char **argv)
 535{
 536        struct strbuf cmd = STRBUF_INIT;
 537        const char *tmp;
 538        int status;
 539
 540        if (use_pager == -1)
 541                use_pager = check_pager_config(argv[0]);
 542        commit_pager_choice();
 543
 544        strbuf_addf(&cmd, "git-%s", argv[0]);
 545
 546        /*
 547         * argv[0] must be the git command, but the argv array
 548         * belongs to the caller, and may be reused in
 549         * subsequent loop iterations. Save argv[0] and
 550         * restore it on error.
 551         */
 552        tmp = argv[0];
 553        argv[0] = cmd.buf;
 554
 555        trace_argv_printf(argv, "trace: exec:");
 556
 557        /*
 558         * if we fail because the command is not found, it is
 559         * OK to return. Otherwise, we just pass along the status code.
 560         */
 561        status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 562        if (status >= 0 || errno != ENOENT)
 563                exit(status);
 564
 565        argv[0] = tmp;
 566
 567        strbuf_release(&cmd);
 568}
 569
 570static int run_argv(int *argcp, const char ***argv)
 571{
 572        int done_alias = 0;
 573
 574        while (1) {
 575                /* See if it's a builtin */
 576                handle_builtin(*argcp, *argv);
 577
 578                /* .. then try the external ones */
 579                execv_dashed_external(*argv);
 580
 581                /* It could be an alias -- this works around the insanity
 582                 * of overriding "git log" with "git show" by having
 583                 * alias.log = show
 584                 */
 585                if (done_alias)
 586                        break;
 587                save_env();
 588                if (!handle_alias(argcp, argv))
 589                        break;
 590                done_alias = 1;
 591        }
 592
 593        return done_alias;
 594}
 595
 596/*
 597 * Many parts of Git have subprograms communicate via pipe, expect the
 598 * upstream of a pipe to die with SIGPIPE when the downstream of a
 599 * pipe does not need to read all that is written.  Some third-party
 600 * programs that ignore or block SIGPIPE for their own reason forget
 601 * to restore SIGPIPE handling to the default before spawning Git and
 602 * break this carefully orchestrated machinery.
 603 *
 604 * Restore the way SIGPIPE is handled to default, which is what we
 605 * expect.
 606 */
 607static void restore_sigpipe_to_default(void)
 608{
 609        sigset_t unblock;
 610
 611        sigemptyset(&unblock);
 612        sigaddset(&unblock, SIGPIPE);
 613        sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 614        signal(SIGPIPE, SIG_DFL);
 615}
 616
 617int main(int argc, char **av)
 618{
 619        const char **argv = (const char **) av;
 620        const char *cmd;
 621
 622        startup_info = &git_startup_info;
 623
 624        cmd = git_extract_argv0_path(argv[0]);
 625        if (!cmd)
 626                cmd = "git-help";
 627
 628        /*
 629         * Always open file descriptors 0/1/2 to avoid clobbering files
 630         * in die().  It also avoids messing up when the pipes are dup'ed
 631         * onto stdin/stdout/stderr in the child processes we spawn.
 632         */
 633        sanitize_stdfds();
 634
 635        restore_sigpipe_to_default();
 636
 637        git_setup_gettext();
 638
 639        trace_command_performance(argv);
 640
 641        /*
 642         * "git-xxxx" is the same as "git xxxx", but we obviously:
 643         *
 644         *  - cannot take flags in between the "git" and the "xxxx".
 645         *  - cannot execute it externally (since it would just do
 646         *    the same thing over again)
 647         *
 648         * So we just directly call the builtin handler, and die if
 649         * that one cannot handle it.
 650         */
 651        if (skip_prefix(cmd, "git-", &cmd)) {
 652                argv[0] = cmd;
 653                handle_builtin(argc, argv);
 654                die("cannot handle %s as a builtin", cmd);
 655        }
 656
 657        /* Look for flags.. */
 658        argv++;
 659        argc--;
 660        handle_options(&argv, &argc, NULL);
 661        if (argc > 0) {
 662                /* translate --help and --version into commands */
 663                skip_prefix(argv[0], "--", &argv[0]);
 664        } else {
 665                /* The user didn't specify a command; give them help */
 666                commit_pager_choice();
 667                printf("usage: %s\n\n", git_usage_string);
 668                list_common_cmds_help();
 669                printf("\n%s\n", _(git_more_info_string));
 670                exit(1);
 671        }
 672        cmd = argv[0];
 673
 674        /*
 675         * We use PATH to find git commands, but we prepend some higher
 676         * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 677         * environment, and the $(gitexecdir) from the Makefile at build
 678         * time.
 679         */
 680        setup_path();
 681
 682        while (1) {
 683                static int done_help = 0;
 684                static int was_alias = 0;
 685                was_alias = run_argv(&argc, &argv);
 686                if (errno != ENOENT)
 687                        break;
 688                if (was_alias) {
 689                        fprintf(stderr, "Expansion of alias '%s' failed; "
 690                                "'%s' is not a git command\n",
 691                                cmd, argv[0]);
 692                        exit(1);
 693                }
 694                if (!done_help) {
 695                        cmd = argv[0] = help_unknown_cmd(cmd);
 696                        done_help = 1;
 697                } else
 698                        break;
 699        }
 700
 701        fprintf(stderr, "Failed to run command '%s': %s\n",
 702                cmd, strerror(errno));
 703
 704        return 1;
 705}