git.c

   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
   9 const 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
  16 const 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
  21 static struct startup_info git_startup_info;
  22 static int use_pager = -1;
  23 static char *orig_cwd;
  24 static const char *env_names[] = {
  25         GIT_DIR_ENVIRONMENT,
  26         GIT_WORK_TREE_ENVIRONMENT,
  27         GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
  28         GIT_PREFIX_ENVIRONMENT
  29 };
  30 static char *orig_env[4];
  31 static int saved_environment;
  32
  33 static 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
  47 static 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
  61 static 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
  74 static 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
 227 static 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
 313 struct cmd_struct {
 314         const char *cmd;
 315         int (*fn)(int, const char **, const char *);
 316         int option;
 317 };
 318
 319 static 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
 372 static 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         { "log", cmd_log, RUN_SETUP },
 421         { "ls-files", cmd_ls_files, RUN_SETUP },
 422         { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 423         { "ls-tree", cmd_ls_tree, RUN_SETUP },
 424         { "mailinfo", cmd_mailinfo },
 425         { "mailsplit", cmd_mailsplit },
 426         { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 427         { "merge-base", cmd_merge_base, RUN_SETUP },
 428         { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 429         { "merge-index", cmd_merge_index, RUN_SETUP },
 430         { "merge-ours", cmd_merge_ours, RUN_SETUP },
 431         { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 432         { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 433         { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 434         { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 435         { "merge-tree", cmd_merge_tree, RUN_SETUP },
 436         { "mktag", cmd_mktag, RUN_SETUP },
 437         { "mktree", cmd_mktree, RUN_SETUP },
 438         { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 439         { "name-rev", cmd_name_rev, RUN_SETUP },
 440         { "notes", cmd_notes, RUN_SETUP },
 441         { "pack-objects", cmd_pack_objects, RUN_SETUP },
 442         { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 443         { "pack-refs", cmd_pack_refs, RUN_SETUP },
 444         { "patch-id", cmd_patch_id },
 445         { "pickaxe", cmd_blame, RUN_SETUP },
 446         { "prune", cmd_prune, RUN_SETUP },
 447         { "prune-packed", cmd_prune_packed, RUN_SETUP },
 448         { "push", cmd_push, RUN_SETUP },
 449         { "read-tree", cmd_read_tree, RUN_SETUP },
 450         { "receive-pack", cmd_receive_pack },
 451         { "reflog", cmd_reflog, RUN_SETUP },
 452         { "remote", cmd_remote, RUN_SETUP },
 453         { "remote-ext", cmd_remote_ext },
 454         { "remote-fd", cmd_remote_fd },
 455         { "repack", cmd_repack, RUN_SETUP },
 456         { "replace", cmd_replace, RUN_SETUP },
 457         { "rerere", cmd_rerere, RUN_SETUP },
 458         { "reset", cmd_reset, RUN_SETUP },
 459         { "rev-list", cmd_rev_list, RUN_SETUP },
 460         { "rev-parse", cmd_rev_parse },
 461         { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 462         { "rm", cmd_rm, RUN_SETUP },
 463         { "send-pack", cmd_send_pack, RUN_SETUP },
 464         { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 465         { "show", cmd_show, RUN_SETUP },
 466         { "show-branch", cmd_show_branch, RUN_SETUP },
 467         { "show-ref", cmd_show_ref, RUN_SETUP },
 468         { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 469         { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 470         { "stripspace", cmd_stripspace },
 471         { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 472         { "tag", cmd_tag, RUN_SETUP },
 473         { "unpack-file", cmd_unpack_file, RUN_SETUP },
 474         { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 475         { "update-index", cmd_update_index, RUN_SETUP },
 476         { "update-ref", cmd_update_ref, RUN_SETUP },
 477         { "update-server-info", cmd_update_server_info, RUN_SETUP },
 478         { "upload-archive", cmd_upload_archive },
 479         { "upload-archive--writer", cmd_upload_archive_writer },
 480         { "var", cmd_var, RUN_SETUP_GENTLY },
 481         { "verify-commit", cmd_verify_commit, RUN_SETUP },
 482         { "verify-pack", cmd_verify_pack },
 483         { "verify-tag", cmd_verify_tag, RUN_SETUP },
 484         { "version", cmd_version },
 485         { "whatchanged", cmd_whatchanged, RUN_SETUP },
 486         { "write-tree", cmd_write_tree, RUN_SETUP },
 487 };
 488
 489 int is_builtin(const char *s)
 490 {
 491         int i;
 492         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 493                 struct cmd_struct *p = commands+i;
 494                 if (!strcmp(s, p->cmd))
 495                         return 1;
 496         }
 497         return 0;
 498 }
 499
 500 static void handle_builtin(int argc, const char **argv)
 501 {
 502         const char *cmd = argv[0];
 503         int i;
 504         static const char ext[] = STRIP_EXTENSION;
 505
 506         if (sizeof(ext) > 1) {
 507                 i = strlen(argv[0]) - strlen(ext);
 508                 if (i > 0 && !strcmp(argv[0] + i, ext)) {
 509                         char *argv0 = xstrdup(argv[0]);
 510                         argv[0] = cmd = argv0;
 511                         argv0[i] = '\0';
 512                 }
 513         }
 514
 515         /* Turn "git cmd --help" into "git help cmd" */
 516         if (argc > 1 && !strcmp(argv[1], "--help")) {
 517                 argv[1] = argv[0];
 518                 argv[0] = cmd = "help";
 519         }
 520
 521         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 522                 struct cmd_struct *p = commands+i;
 523                 if (strcmp(p->cmd, cmd))
 524                         continue;
 525                 if (saved_environment && (p->option & NO_SETUP)) {
 526                         restore_env();
 527                         break;
 528                 }
 529                 exit(run_builtin(p, argc, argv));
 530         }
 531 }
 532
 533 static void execv_dashed_external(const char **argv)
 534 {
 535         struct strbuf cmd = STRBUF_INIT;
 536         const char *tmp;
 537         int status;
 538
 539         if (use_pager == -1)
 540                 use_pager = check_pager_config(argv[0]);
 541         commit_pager_choice();
 542
 543         strbuf_addf(&cmd, "git-%s", argv[0]);
 544
 545         /*
 546          * argv[0] must be the git command, but the argv array
 547          * belongs to the caller, and may be reused in
 548          * subsequent loop iterations. Save argv[0] and
 549          * restore it on error.
 550          */
 551         tmp = argv[0];
 552         argv[0] = cmd.buf;
 553
 554         trace_argv_printf(argv, "trace: exec:");
 555
 556         /*
 557          * if we fail because the command is not found, it is
 558          * OK to return. Otherwise, we just pass along the status code.
 559          */
 560         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 561         if (status >= 0 || errno != ENOENT)
 562                 exit(status);
 563
 564         argv[0] = tmp;
 565
 566         strbuf_release(&cmd);
 567 }
 568
 569 static int run_argv(int *argcp, const char ***argv)
 570 {
 571         int done_alias = 0;
 572
 573         while (1) {
 574                 /* See if it's a builtin */
 575                 handle_builtin(*argcp, *argv);
 576
 577                 /* .. then try the external ones */
 578                 execv_dashed_external(*argv);
 579
 580                 /* It could be an alias -- this works around the insanity
 581                  * of overriding "git log" with "git show" by having
 582                  * alias.log = show
 583                  */
 584                 if (done_alias)
 585                         break;
 586                 save_env();
 587                 if (!handle_alias(argcp, argv))
 588                         break;
 589                 done_alias = 1;
 590         }
 591
 592         return done_alias;
 593 }
 594
 595 /*
 596  * Many parts of Git have subprograms communicate via pipe, expect the
 597  * upstream of a pipe to die with SIGPIPE when the downstream of a
 598  * pipe does not need to read all that is written.  Some third-party
 599  * programs that ignore or block SIGPIPE for their own reason forget
 600  * to restore SIGPIPE handling to the default before spawning Git and
 601  * break this carefully orchestrated machinery.
 602  *
 603  * Restore the way SIGPIPE is handled to default, which is what we
 604  * expect.
 605  */
 606 static void restore_sigpipe_to_default(void)
 607 {
 608         sigset_t unblock;
 609
 610         sigemptyset(&unblock);
 611         sigaddset(&unblock, SIGPIPE);
 612         sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 613         signal(SIGPIPE, SIG_DFL);
 614 }
 615
 616 int main(int argc, char **av)
 617 {
 618         const char **argv = (const char **) av;
 619         const char *cmd;
 620
 621         startup_info = &git_startup_info;
 622
 623         cmd = git_extract_argv0_path(argv[0]);
 624         if (!cmd)
 625                 cmd = "git-help";
 626
 627         /*
 628          * Always open file descriptors 0/1/2 to avoid clobbering files
 629          * in die().  It also avoids messing up when the pipes are dup'ed
 630          * onto stdin/stdout/stderr in the child processes we spawn.
 631          */
 632         sanitize_stdfds();
 633
 634         restore_sigpipe_to_default();
 635
 636         git_setup_gettext();
 637
 638         trace_command_performance(argv);
 639
 640         /*
 641          * "git-xxxx" is the same as "git xxxx", but we obviously:
 642          *
 643          *  - cannot take flags in between the "git" and the "xxxx".
 644          *  - cannot execute it externally (since it would just do
 645          *    the same thing over again)
 646          *
 647          * So we just directly call the builtin handler, and die if
 648          * that one cannot handle it.
 649          */
 650         if (skip_prefix(cmd, "git-", &cmd)) {
 651                 argv[0] = cmd;
 652                 handle_builtin(argc, argv);
 653                 die("cannot handle %s as a builtin", cmd);
 654         }
 655
 656         /* Look for flags.. */
 657         argv++;
 658         argc--;
 659         handle_options(&argv, &argc, NULL);
 660         if (argc > 0) {
 661                 /* translate --help and --version into commands */
 662                 skip_prefix(argv[0], "--", &argv[0]);
 663         } else {
 664                 /* The user didn't specify a command; give them help */
 665                 commit_pager_choice();
 666                 printf("usage: %s\n\n", git_usage_string);
 667                 list_common_cmds_help();
 668                 printf("\n%s\n", _(git_more_info_string));
 669                 exit(1);
 670         }
 671         cmd = argv[0];
 672
 673         /*
 674          * We use PATH to find git commands, but we prepend some higher
 675          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 676          * environment, and the $(gitexecdir) from the Makefile at build
 677          * time.
 678          */
 679         setup_path();
 680
 681         while (1) {
 682                 static int done_help = 0;
 683                 static int was_alias = 0;
 684                 was_alias = run_argv(&argc, &argv);
 685                 if (errno != ENOENT)
 686                         break;
 687                 if (was_alias) {
 688                         fprintf(stderr, "Expansion of alias '%s' failed; "
 689                                 "'%s' is not a git command\n",
 690                                 cmd, argv[0]);
 691                         exit(1);
 692                 }
 693                 if (!done_help) {
 694                         cmd = argv[0] = help_unknown_cmd(cmd);
 695                         done_help = 1;
 696                 } else
 697                         break;
 698         }
 699
 700         fprintf(stderr, "Failed to run command '%s': %s\n",
 701                 cmd, strerror(errno));
 702
 703         return 1;
 704 }