Andrew's git / gitweb.git / git.c
?
git.con commit apply: reject a hunk that does not do anything (ad6e8ed)
   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' list 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;
  23static char *orig_cwd;
  24static const char *env_names[] = {
  25        GIT_DIR_ENVIRONMENT,
  26        GIT_WORK_TREE_ENVIRONMENT,
  27        GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
  28        GIT_PREFIX_ENVIRONMENT
  29};
  30static char *orig_env[4];
  31static int saved_environment;
  32
  33static void save_env(void)
  34{
  35        int i;
  36        if (saved_environment)
  37                return;
  38        saved_environment = 1;
  39        orig_cwd = xgetcwd();
  40        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  41                orig_env[i] = getenv(env_names[i]);
  42                if (orig_env[i])
  43                        orig_env[i] = xstrdup(orig_env[i]);
  44        }
  45}
  46
  47static void restore_env(void)
  48{
  49        int i;
  50        if (orig_cwd && chdir(orig_cwd))
  51                die_errno("could not move to %s", orig_cwd);
  52        free(orig_cwd);
  53        for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  54                if (orig_env[i])
  55                        setenv(env_names[i], orig_env[i], 1);
  56                else
  57                        unsetenv(env_names[i]);
  58        }
  59}
  60
  61static void commit_pager_choice(void) {
  62        switch (use_pager) {
  63        case 0:
  64                setenv("GIT_PAGER", "cat", 1);
  65                break;
  66        case 1:
  67                setup_pager();
  68                break;
  69        default:
  70                break;
  71        }
  72}
  73
  74static int handle_options(const char ***argv, int *argc, int *envchanged)
  75{
  76        const char **orig_argv = *argv;
  77
  78        while (*argc > 0) {
  79                const char *cmd = (*argv)[0];
  80                if (cmd[0] != '-')
  81                        break;
  82
  83                /*
  84                 * For legacy reasons, the "version" and "help"
  85                 * commands can be written with "--" prepended
  86                 * to make them look like flags.
  87                 */
  88                if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  89                        break;
  90
  91                /*
  92                 * Check remaining flags.
  93                 */
  94                if (skip_prefix(cmd, "--exec-path", &cmd)) {
  95                        if (*cmd == '=')
  96                                git_set_argv_exec_path(cmd + 1);
  97                        else {
  98                                puts(git_exec_path());
  99                                exit(0);
 100                        }
 101                } else if (!strcmp(cmd, "--html-path")) {
 102                        puts(system_path(GIT_HTML_PATH));
 103                        exit(0);
 104                } else if (!strcmp(cmd, "--man-path")) {
 105                        puts(system_path(GIT_MAN_PATH));
 106                        exit(0);
 107                } else if (!strcmp(cmd, "--info-path")) {
 108                        puts(system_path(GIT_INFO_PATH));
 109                        exit(0);
 110                } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 111                        use_pager = 1;
 112                } else if (!strcmp(cmd, "--no-pager")) {
 113                        use_pager = 0;
 114                        if (envchanged)
 115                                *envchanged = 1;
 116                } else if (!strcmp(cmd, "--no-replace-objects")) {
 117                        check_replace_refs = 0;
 118                        setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 119                        if (envchanged)
 120                                *envchanged = 1;
 121                } else if (!strcmp(cmd, "--git-dir")) {
 122                        if (*argc < 2) {
 123                                fprintf(stderr, "No directory given for --git-dir.\n" );
 124                                usage(git_usage_string);
 125                        }
 126                        setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 127                        if (envchanged)
 128                                *envchanged = 1;
 129                        (*argv)++;
 130                        (*argc)--;
 131                } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
 132                        setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
 133                        if (envchanged)
 134                                *envchanged = 1;
 135                } else if (!strcmp(cmd, "--namespace")) {
 136                        if (*argc < 2) {
 137                                fprintf(stderr, "No namespace given for --namespace.\n" );
 138                                usage(git_usage_string);
 139                        }
 140                        setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 141                        if (envchanged)
 142                                *envchanged = 1;
 143                        (*argv)++;
 144                        (*argc)--;
 145                } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
 146                        setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
 147                        if (envchanged)
 148                                *envchanged = 1;
 149                } else if (!strcmp(cmd, "--work-tree")) {
 150                        if (*argc < 2) {
 151                                fprintf(stderr, "No directory given for --work-tree.\n" );
 152                                usage(git_usage_string);
 153                        }
 154                        setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 155                        if (envchanged)
 156                                *envchanged = 1;
 157                        (*argv)++;
 158                        (*argc)--;
 159                } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
 160                        setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
 161                        if (envchanged)
 162                                *envchanged = 1;
 163                } else if (!strcmp(cmd, "--bare")) {
 164                        char *cwd = xgetcwd();
 165                        is_bare_repository_cfg = 1;
 166                        setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
 167                        free(cwd);
 168                        setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 169                        if (envchanged)
 170                                *envchanged = 1;
 171                } else if (!strcmp(cmd, "-c")) {
 172                        if (*argc < 2) {
 173                                fprintf(stderr, "-c expects a configuration string\n" );
 174                                usage(git_usage_string);
 175                        }
 176                        git_config_push_parameter((*argv)[1]);
 177                        (*argv)++;
 178                        (*argc)--;
 179                } else if (!strcmp(cmd, "--literal-pathspecs")) {
 180                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 181                        if (envchanged)
 182                                *envchanged = 1;
 183                } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 184                        setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 185                        if (envchanged)
 186                                *envchanged = 1;
 187                } else if (!strcmp(cmd, "--glob-pathspecs")) {
 188                        setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 189                        if (envchanged)
 190                                *envchanged = 1;
 191                } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 192                        setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 193                        if (envchanged)
 194                                *envchanged = 1;
 195                } else if (!strcmp(cmd, "--icase-pathspecs")) {
 196                        setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 197                        if (envchanged)
 198                                *envchanged = 1;
 199                } else if (!strcmp(cmd, "--shallow-file")) {
 200                        (*argv)++;
 201                        (*argc)--;
 202                        set_alternate_shallow_file((*argv)[0], 1);
 203                        if (envchanged)
 204                                *envchanged = 1;
 205                } else if (!strcmp(cmd, "-C")) {
 206                        if (*argc < 2) {
 207                                fprintf(stderr, "No directory given for -C.\n" );
 208                                usage(git_usage_string);
 209                        }
 210                        if (chdir((*argv)[1]))
 211                                die_errno("Cannot change to '%s'", (*argv)[1]);
 212                        if (envchanged)
 213                                *envchanged = 1;
 214                        (*argv)++;
 215                        (*argc)--;
 216                } else {
 217                        fprintf(stderr, "Unknown option: %s\n", cmd);
 218                        usage(git_usage_string);
 219                }
 220
 221                (*argv)++;
 222                (*argc)--;
 223        }
 224        return (*argv) - orig_argv;
 225}
 226
 227static int handle_alias(int *argcp, const char ***argv)
 228{
 229        int envchanged = 0, ret = 0, saved_errno = errno;
 230        const char *subdir;
 231        int count, option_count;
 232        const char **new_argv;
 233        const char *alias_command;
 234        char *alias_string;
 235        int unused_nongit;
 236
 237        subdir = setup_git_directory_gently(&unused_nongit);
 238
 239        alias_command = (*argv)[0];
 240        alias_string = alias_lookup(alias_command);
 241        if (alias_string) {
 242                if (alias_string[0] == '!') {
 243                        const char **alias_argv;
 244                        int argc = *argcp, i;
 245
 246                        commit_pager_choice();
 247
 248                        /* build alias_argv */
 249                        alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 250                        alias_argv[0] = alias_string + 1;
 251                        for (i = 1; i < argc; ++i)
 252                                alias_argv[i] = (*argv)[i];
 253                        alias_argv[argc] = NULL;
 254
 255                        ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 256                        if (ret >= 0)   /* normal exit */
 257                                exit(ret);
 258
 259                        die_errno("While expanding alias '%s': '%s'",
 260                            alias_command, alias_string + 1);
 261                }
 262                count = split_cmdline(alias_string, &new_argv);
 263                if (count < 0)
 264                        die("Bad alias.%s string: %s", alias_command,
 265                            split_cmdline_strerror(count));
 266                option_count = handle_options(&new_argv, &count, &envchanged);
 267                if (envchanged)
 268                        die("alias '%s' changes environment variables\n"
 269                                 "You can use '!git' in the alias to do this.",
 270                                 alias_command);
 271                memmove(new_argv - option_count, new_argv,
 272                                count * sizeof(char *));
 273                new_argv -= option_count;
 274
 275                if (count < 1)
 276                        die("empty alias for %s", alias_command);
 277
 278                if (!strcmp(alias_command, new_argv[0]))
 279                        die("recursive alias: %s", alias_command);
 280
 281                trace_argv_printf(new_argv,
 282                                  "trace: alias expansion: %s =>",
 283                                  alias_command);
 284
 285                REALLOC_ARRAY(new_argv, count + *argcp);
 286                /* insert after command name */
 287                memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 288
 289                *argv = new_argv;
 290                *argcp += count - 1;
 291
 292                ret = 1;
 293        }
 294
 295        if (subdir && chdir(subdir))
 296                die_errno("Cannot change to '%s'", subdir);
 297
 298        errno = saved_errno;
 299
 300        return ret;
 301}
 302
 303#define RUN_SETUP               (1<<0)
 304#define RUN_SETUP_GENTLY        (1<<1)
 305#define USE_PAGER               (1<<2)
 306/*
 307 * require working tree to be present -- anything uses this needs
 308 * RUN_SETUP for reading from the configuration file.
 309 */
 310#define NEED_WORK_TREE          (1<<3)
 311#define NO_SETUP                (1<<4)
 312
 313struct cmd_struct {
 314        const char *cmd;
 315        int (*fn)(int, const char **, const char *);
 316        int option;
 317};
 318
 319static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 320{
 321        int status, help;
 322        struct stat st;
 323        const char *prefix;
 324
 325        prefix = NULL;
 326        help = argc == 2 && !strcmp(argv[1], "-h");
 327        if (!help) {
 328                if (p->option & RUN_SETUP)
 329                        prefix = setup_git_directory();
 330                else if (p->option & RUN_SETUP_GENTLY) {
 331                        int nongit_ok;
 332                        prefix = setup_git_directory_gently(&nongit_ok);
 333                }
 334
 335                if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 336                        use_pager = check_pager_config(p->cmd);
 337                if (use_pager == -1 && p->option & USE_PAGER)
 338                        use_pager = 1;
 339
 340                if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 341                    startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 342                        trace_repo_setup(prefix);
 343        }
 344        commit_pager_choice();
 345
 346        if (!help && p->option & NEED_WORK_TREE)
 347                setup_work_tree();
 348
 349        trace_argv_printf(argv, "trace: built-in: git");
 350
 351        status = p->fn(argc, argv, prefix);
 352        if (status)
 353                return status;
 354
 355        /* Somebody closed stdout? */
 356        if (fstat(fileno(stdout), &st))
 357                return 0;
 358        /* Ignore write errors for pipes and sockets.. */
 359        if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 360                return 0;
 361
 362        /* Check for ENOSPC and EIO errors.. */
 363        if (fflush(stdout))
 364                die_errno("write failure on standard output");
 365        if (ferror(stdout))
 366                die("unknown write failure on standard output");
 367        if (fclose(stdout))
 368                die_errno("close failed on standard output");
 369        return 0;
 370}
 371
 372static struct cmd_struct commands[] = {
 373        { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 374        { "annotate", cmd_annotate, RUN_SETUP },
 375        { "apply", cmd_apply, RUN_SETUP_GENTLY },
 376        { "archive", cmd_archive },
 377        { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 378        { "blame", cmd_blame, RUN_SETUP },
 379        { "branch", cmd_branch, RUN_SETUP },
 380        { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 381        { "cat-file", cmd_cat_file, RUN_SETUP },
 382        { "check-attr", cmd_check_attr, RUN_SETUP },
 383        { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 384        { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 385        { "check-ref-format", cmd_check_ref_format },
 386        { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 387        { "checkout-index", cmd_checkout_index,
 388                RUN_SETUP | NEED_WORK_TREE},
 389        { "cherry", cmd_cherry, RUN_SETUP },
 390        { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 391        { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 392        { "clone", cmd_clone, NO_SETUP },
 393        { "column", cmd_column, RUN_SETUP_GENTLY },
 394        { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 395        { "commit-tree", cmd_commit_tree, RUN_SETUP },
 396        { "config", cmd_config, RUN_SETUP_GENTLY },
 397        { "count-objects", cmd_count_objects, RUN_SETUP },
 398        { "credential", cmd_credential, RUN_SETUP_GENTLY },
 399        { "describe", cmd_describe, RUN_SETUP },
 400        { "diff", cmd_diff },
 401        { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 402        { "diff-index", cmd_diff_index, RUN_SETUP },
 403        { "diff-tree", cmd_diff_tree, RUN_SETUP },
 404        { "fast-export", cmd_fast_export, RUN_SETUP },
 405        { "fetch", cmd_fetch, RUN_SETUP },
 406        { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 407        { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 408        { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 409        { "format-patch", cmd_format_patch, RUN_SETUP },
 410        { "fsck", cmd_fsck, RUN_SETUP },
 411        { "fsck-objects", cmd_fsck, RUN_SETUP },
 412        { "gc", cmd_gc, RUN_SETUP },
 413        { "get-tar-commit-id", cmd_get_tar_commit_id },
 414        { "grep", cmd_grep, RUN_SETUP_GENTLY },
 415        { "hash-object", cmd_hash_object },
 416        { "help", cmd_help },
 417        { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 418        { "init", cmd_init_db, NO_SETUP },
 419        { "init-db", cmd_init_db, NO_SETUP },
 420        { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP },
 421        { "log", cmd_log, RUN_SETUP },
 422        { "ls-files", cmd_ls_files, RUN_SETUP },
 423        { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 424        { "ls-tree", cmd_ls_tree, RUN_SETUP },
 425        { "mailinfo", cmd_mailinfo },
 426        { "mailsplit", cmd_mailsplit },
 427        { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 428        { "merge-base", cmd_merge_base, RUN_SETUP },
 429        { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 430        { "merge-index", cmd_merge_index, RUN_SETUP },
 431        { "merge-ours", cmd_merge_ours, RUN_SETUP },
 432        { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 433        { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 434        { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 435        { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 436        { "merge-tree", cmd_merge_tree, RUN_SETUP },
 437        { "mktag", cmd_mktag, RUN_SETUP },
 438        { "mktree", cmd_mktree, RUN_SETUP },
 439        { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 440        { "name-rev", cmd_name_rev, RUN_SETUP },
 441        { "notes", cmd_notes, RUN_SETUP },
 442        { "pack-objects", cmd_pack_objects, RUN_SETUP },
 443        { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 444        { "pack-refs", cmd_pack_refs, RUN_SETUP },
 445        { "patch-id", cmd_patch_id },
 446        { "pickaxe", cmd_blame, RUN_SETUP },
 447        { "prune", cmd_prune, RUN_SETUP },
 448        { "prune-packed", cmd_prune_packed, RUN_SETUP },
 449        { "push", cmd_push, RUN_SETUP },
 450        { "read-tree", cmd_read_tree, RUN_SETUP },
 451        { "receive-pack", cmd_receive_pack },
 452        { "reflog", cmd_reflog, RUN_SETUP },
 453        { "remote", cmd_remote, RUN_SETUP },
 454        { "remote-ext", cmd_remote_ext },
 455        { "remote-fd", cmd_remote_fd },
 456        { "repack", cmd_repack, RUN_SETUP },
 457        { "replace", cmd_replace, RUN_SETUP },
 458        { "rerere", cmd_rerere, RUN_SETUP },
 459        { "reset", cmd_reset, RUN_SETUP },
 460        { "rev-list", cmd_rev_list, RUN_SETUP },
 461        { "rev-parse", cmd_rev_parse },
 462        { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 463        { "rm", cmd_rm, RUN_SETUP },
 464        { "send-pack", cmd_send_pack, RUN_SETUP },
 465        { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 466        { "show", cmd_show, RUN_SETUP },
 467        { "show-branch", cmd_show_branch, RUN_SETUP },
 468        { "show-ref", cmd_show_ref, RUN_SETUP },
 469        { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 470        { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 471        { "stripspace", cmd_stripspace },
 472        { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 473        { "tag", cmd_tag, RUN_SETUP },
 474        { "unpack-file", cmd_unpack_file, RUN_SETUP },
 475        { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 476        { "update-index", cmd_update_index, RUN_SETUP },
 477        { "update-ref", cmd_update_ref, RUN_SETUP },
 478        { "update-server-info", cmd_update_server_info, RUN_SETUP },
 479        { "upload-archive", cmd_upload_archive },
 480        { "upload-archive--writer", cmd_upload_archive_writer },
 481        { "var", cmd_var, RUN_SETUP_GENTLY },
 482        { "verify-commit", cmd_verify_commit, RUN_SETUP },
 483        { "verify-pack", cmd_verify_pack },
 484        { "verify-tag", cmd_verify_tag, RUN_SETUP },
 485        { "version", cmd_version },
 486        { "whatchanged", cmd_whatchanged, RUN_SETUP },
 487        { "write-tree", cmd_write_tree, RUN_SETUP },
 488};
 489
 490int is_builtin(const char *s)
 491{
 492        int i;
 493        for (i = 0; i < ARRAY_SIZE(commands); i++) {
 494                struct cmd_struct *p = commands+i;
 495                if (!strcmp(s, p->cmd))
 496                        return 1;
 497        }
 498        return 0;
 499}
 500
 501static void handle_builtin(int argc, const char **argv)
 502{
 503        const char *cmd = argv[0];
 504        int i;
 505        static const char ext[] = STRIP_EXTENSION;
 506
 507        if (sizeof(ext) > 1) {
 508                i = strlen(argv[0]) - strlen(ext);
 509                if (i > 0 && !strcmp(argv[0] + i, ext)) {
 510                        char *argv0 = xstrdup(argv[0]);
 511                        argv[0] = cmd = argv0;
 512                        argv0[i] = '\0';
 513                }
 514        }
 515
 516        /* Turn "git cmd --help" into "git help cmd" */
 517        if (argc > 1 && !strcmp(argv[1], "--help")) {
 518                argv[1] = argv[0];
 519                argv[0] = cmd = "help";
 520        }
 521
 522        for (i = 0; i < ARRAY_SIZE(commands); i++) {
 523                struct cmd_struct *p = commands+i;
 524                if (strcmp(p->cmd, cmd))
 525                        continue;
 526                if (saved_environment && (p->option & NO_SETUP)) {
 527                        restore_env();
 528                        break;
 529                }
 530                exit(run_builtin(p, 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}