git.c

   1 #include "builtin.h"
   2 #include "exec_cmd.h"
   3 #include "help.h"
   4 #include "run-command.h"
   5
   6 const 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
  13 const 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
  18 static struct startup_info git_startup_info;
  19 static int use_pager = -1;
  20 static char *orig_cwd;
  21 static const char *env_names[] = {
  22         GIT_DIR_ENVIRONMENT,
  23         GIT_WORK_TREE_ENVIRONMENT,
  24         GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
  25         GIT_PREFIX_ENVIRONMENT
  26 };
  27 static char *orig_env[4];
  28 static int save_restore_env_balance;
  29
  30 static void save_env_before_alias(void)
  31 {
  32         int i;
  33
  34         assert(save_restore_env_balance == 0);
  35         save_restore_env_balance = 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
  44 static void restore_env(int external_alias)
  45 {
  46         int i;
  47
  48         assert(save_restore_env_balance == 1);
  49         save_restore_env_balance = 0;
  50         if (!external_alias && 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 (external_alias &&
  55                     !strcmp(env_names[i], GIT_PREFIX_ENVIRONMENT))
  56                         continue;
  57                 if (orig_env[i]) {
  58                         setenv(env_names[i], orig_env[i], 1);
  59                         free(orig_env[i]);
  60                 } else {
  61                         unsetenv(env_names[i]);
  62                 }
  63         }
  64 }
  65
  66 static void commit_pager_choice(void) {
  67         switch (use_pager) {
  68         case 0:
  69                 setenv("GIT_PAGER", "cat", 1);
  70                 break;
  71         case 1:
  72                 setup_pager();
  73                 break;
  74         default:
  75                 break;
  76         }
  77 }
  78
  79 static int handle_options(const char ***argv, int *argc, int *envchanged)
  80 {
  81         const char **orig_argv = *argv;
  82
  83         while (*argc > 0) {
  84                 const char *cmd = (*argv)[0];
  85                 if (cmd[0] != '-')
  86                         break;
  87
  88                 /*
  89                  * For legacy reasons, the "version" and "help"
  90                  * commands can be written with "--" prepended
  91                  * to make them look like flags.
  92                  */
  93                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  94                         break;
  95
  96                 /*
  97                  * Check remaining flags.
  98                  */
  99                 if (skip_prefix(cmd, "--exec-path", &cmd)) {
 100                         if (*cmd == '=')
 101                                 git_set_argv_exec_path(cmd + 1);
 102                         else {
 103                                 puts(git_exec_path());
 104                                 exit(0);
 105                         }
 106                 } else if (!strcmp(cmd, "--html-path")) {
 107                         puts(system_path(GIT_HTML_PATH));
 108                         exit(0);
 109                 } else if (!strcmp(cmd, "--man-path")) {
 110                         puts(system_path(GIT_MAN_PATH));
 111                         exit(0);
 112                 } else if (!strcmp(cmd, "--info-path")) {
 113                         puts(system_path(GIT_INFO_PATH));
 114                         exit(0);
 115                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 116                         use_pager = 1;
 117                 } else if (!strcmp(cmd, "--no-pager")) {
 118                         use_pager = 0;
 119                         if (envchanged)
 120                                 *envchanged = 1;
 121                 } else if (!strcmp(cmd, "--no-replace-objects")) {
 122                         check_replace_refs = 0;
 123                         setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 124                         if (envchanged)
 125                                 *envchanged = 1;
 126                 } else if (!strcmp(cmd, "--git-dir")) {
 127                         if (*argc < 2) {
 128                                 fprintf(stderr, "No directory given for --git-dir.\n" );
 129                                 usage(git_usage_string);
 130                         }
 131                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 132                         if (envchanged)
 133                                 *envchanged = 1;
 134                         (*argv)++;
 135                         (*argc)--;
 136                 } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
 137                         setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
 138                         if (envchanged)
 139                                 *envchanged = 1;
 140                 } else if (!strcmp(cmd, "--namespace")) {
 141                         if (*argc < 2) {
 142                                 fprintf(stderr, "No namespace given for --namespace.\n" );
 143                                 usage(git_usage_string);
 144                         }
 145                         setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 146                         if (envchanged)
 147                                 *envchanged = 1;
 148                         (*argv)++;
 149                         (*argc)--;
 150                 } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
 151                         setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
 152                         if (envchanged)
 153                                 *envchanged = 1;
 154                 } else if (!strcmp(cmd, "--work-tree")) {
 155                         if (*argc < 2) {
 156                                 fprintf(stderr, "No directory given for --work-tree.\n" );
 157                                 usage(git_usage_string);
 158                         }
 159                         setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 160                         if (envchanged)
 161                                 *envchanged = 1;
 162                         (*argv)++;
 163                         (*argc)--;
 164                 } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
 165                         setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
 166                         if (envchanged)
 167                                 *envchanged = 1;
 168                 } else if (!strcmp(cmd, "--bare")) {
 169                         char *cwd = xgetcwd();
 170                         is_bare_repository_cfg = 1;
 171                         setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
 172                         free(cwd);
 173                         setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 174                         if (envchanged)
 175                                 *envchanged = 1;
 176                 } else if (!strcmp(cmd, "-c")) {
 177                         if (*argc < 2) {
 178                                 fprintf(stderr, "-c expects a configuration string\n" );
 179                                 usage(git_usage_string);
 180                         }
 181                         git_config_push_parameter((*argv)[1]);
 182                         (*argv)++;
 183                         (*argc)--;
 184                 } else if (!strcmp(cmd, "--literal-pathspecs")) {
 185                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 186                         if (envchanged)
 187                                 *envchanged = 1;
 188                 } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 189                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 190                         if (envchanged)
 191                                 *envchanged = 1;
 192                 } else if (!strcmp(cmd, "--glob-pathspecs")) {
 193                         setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 194                         if (envchanged)
 195                                 *envchanged = 1;
 196                 } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 197                         setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 198                         if (envchanged)
 199                                 *envchanged = 1;
 200                 } else if (!strcmp(cmd, "--icase-pathspecs")) {
 201                         setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 202                         if (envchanged)
 203                                 *envchanged = 1;
 204                 } else if (!strcmp(cmd, "--shallow-file")) {
 205                         (*argv)++;
 206                         (*argc)--;
 207                         set_alternate_shallow_file((*argv)[0], 1);
 208                         if (envchanged)
 209                                 *envchanged = 1;
 210                 } else if (!strcmp(cmd, "-C")) {
 211                         if (*argc < 2) {
 212                                 fprintf(stderr, "No directory given for -C.\n" );
 213                                 usage(git_usage_string);
 214                         }
 215                         if ((*argv)[1][0]) {
 216                                 if (chdir((*argv)[1]))
 217                                         die_errno("Cannot change to '%s'", (*argv)[1]);
 218                                 if (envchanged)
 219                                         *envchanged = 1;
 220                         }
 221                         (*argv)++;
 222                         (*argc)--;
 223                 } else {
 224                         fprintf(stderr, "Unknown option: %s\n", cmd);
 225                         usage(git_usage_string);
 226                 }
 227
 228                 (*argv)++;
 229                 (*argc)--;
 230         }
 231         return (*argv) - orig_argv;
 232 }
 233
 234 static int handle_alias(int *argcp, const char ***argv)
 235 {
 236         int envchanged = 0, ret = 0, saved_errno = errno;
 237         int count, option_count;
 238         const char **new_argv;
 239         const char *alias_command;
 240         char *alias_string;
 241         int unused_nongit;
 242
 243         save_env_before_alias();
 244         setup_git_directory_gently(&unused_nongit);
 245
 246         alias_command = (*argv)[0];
 247         alias_string = alias_lookup(alias_command);
 248         if (alias_string) {
 249                 if (alias_string[0] == '!') {
 250                         const char **alias_argv;
 251                         int argc = *argcp, i;
 252
 253                         commit_pager_choice();
 254                         restore_env(1);
 255
 256                         /* build alias_argv */
 257                         alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 258                         alias_argv[0] = alias_string + 1;
 259                         for (i = 1; i < argc; ++i)
 260                                 alias_argv[i] = (*argv)[i];
 261                         alias_argv[argc] = NULL;
 262
 263                         ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 264                         if (ret >= 0)   /* normal exit */
 265                                 exit(ret);
 266
 267                         die_errno("While expanding alias '%s': '%s'",
 268                             alias_command, alias_string + 1);
 269                 }
 270                 count = split_cmdline(alias_string, &new_argv);
 271                 if (count < 0)
 272                         die("Bad alias.%s string: %s", alias_command,
 273                             split_cmdline_strerror(count));
 274                 option_count = handle_options(&new_argv, &count, &envchanged);
 275                 if (envchanged)
 276                         die("alias '%s' changes environment variables\n"
 277                                  "You can use '!git' in the alias to do this.",
 278                                  alias_command);
 279                 memmove(new_argv - option_count, new_argv,
 280                                 count * sizeof(char *));
 281                 new_argv -= option_count;
 282
 283                 if (count < 1)
 284                         die("empty alias for %s", alias_command);
 285
 286                 if (!strcmp(alias_command, new_argv[0]))
 287                         die("recursive alias: %s", alias_command);
 288
 289                 trace_argv_printf(new_argv,
 290                                   "trace: alias expansion: %s =>",
 291                                   alias_command);
 292
 293                 REALLOC_ARRAY(new_argv, count + *argcp);
 294                 /* insert after command name */
 295                 memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 296
 297                 *argv = new_argv;
 298                 *argcp += count - 1;
 299
 300                 ret = 1;
 301         }
 302
 303         restore_env(0);
 304
 305         errno = saved_errno;
 306
 307         return ret;
 308 }
 309
 310 #define RUN_SETUP               (1<<0)
 311 #define RUN_SETUP_GENTLY        (1<<1)
 312 #define USE_PAGER               (1<<2)
 313 /*
 314  * require working tree to be present -- anything uses this needs
 315  * RUN_SETUP for reading from the configuration file.
 316  */
 317 #define NEED_WORK_TREE          (1<<3)
 318
 319 struct cmd_struct {
 320         const char *cmd;
 321         int (*fn)(int, const char **, const char *);
 322         int option;
 323 };
 324
 325 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 326 {
 327         int status, help;
 328         struct stat st;
 329         const char *prefix;
 330
 331         prefix = NULL;
 332         help = argc == 2 && !strcmp(argv[1], "-h");
 333         if (!help) {
 334                 if (p->option & RUN_SETUP)
 335                         prefix = setup_git_directory();
 336                 else if (p->option & RUN_SETUP_GENTLY) {
 337                         int nongit_ok;
 338                         prefix = setup_git_directory_gently(&nongit_ok);
 339                 }
 340
 341                 if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 342                         use_pager = check_pager_config(p->cmd);
 343                 if (use_pager == -1 && p->option & USE_PAGER)
 344                         use_pager = 1;
 345
 346                 if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 347                     startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 348                         trace_repo_setup(prefix);
 349         }
 350         commit_pager_choice();
 351
 352         if (!help && p->option & NEED_WORK_TREE)
 353                 setup_work_tree();
 354
 355         trace_argv_printf(argv, "trace: built-in: git");
 356
 357         status = p->fn(argc, argv, prefix);
 358         if (status)
 359                 return status;
 360
 361         /* Somebody closed stdout? */
 362         if (fstat(fileno(stdout), &st))
 363                 return 0;
 364         /* Ignore write errors for pipes and sockets.. */
 365         if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 366                 return 0;
 367
 368         /* Check for ENOSPC and EIO errors.. */
 369         if (fflush(stdout))
 370                 die_errno("write failure on standard output");
 371         if (ferror(stdout))
 372                 die("unknown write failure on standard output");
 373         if (fclose(stdout))
 374                 die_errno("close failed on standard output");
 375         return 0;
 376 }
 377
 378 static struct cmd_struct commands[] = {
 379         { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 380         { "am", cmd_am, RUN_SETUP | NEED_WORK_TREE },
 381         { "annotate", cmd_annotate, RUN_SETUP },
 382         { "apply", cmd_apply, RUN_SETUP_GENTLY },
 383         { "archive", cmd_archive },
 384         { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 385         { "blame", cmd_blame, RUN_SETUP },
 386         { "branch", cmd_branch, RUN_SETUP },
 387         { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 388         { "cat-file", cmd_cat_file, RUN_SETUP },
 389         { "check-attr", cmd_check_attr, RUN_SETUP },
 390         { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 391         { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 392         { "check-ref-format", cmd_check_ref_format },
 393         { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 394         { "checkout-index", cmd_checkout_index,
 395                 RUN_SETUP | NEED_WORK_TREE},
 396         { "cherry", cmd_cherry, RUN_SETUP },
 397         { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 398         { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 399         { "clone", cmd_clone },
 400         { "column", cmd_column, RUN_SETUP_GENTLY },
 401         { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 402         { "commit-tree", cmd_commit_tree, RUN_SETUP },
 403         { "config", cmd_config, RUN_SETUP_GENTLY },
 404         { "count-objects", cmd_count_objects, RUN_SETUP },
 405         { "credential", cmd_credential, RUN_SETUP_GENTLY },
 406         { "describe", cmd_describe, RUN_SETUP },
 407         { "diff", cmd_diff },
 408         { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 409         { "diff-index", cmd_diff_index, RUN_SETUP },
 410         { "diff-tree", cmd_diff_tree, RUN_SETUP },
 411         { "fast-export", cmd_fast_export, RUN_SETUP },
 412         { "fetch", cmd_fetch, RUN_SETUP },
 413         { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 414         { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 415         { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 416         { "format-patch", cmd_format_patch, RUN_SETUP },
 417         { "fsck", cmd_fsck, RUN_SETUP },
 418         { "fsck-objects", cmd_fsck, RUN_SETUP },
 419         { "gc", cmd_gc, RUN_SETUP },
 420         { "get-tar-commit-id", cmd_get_tar_commit_id },
 421         { "grep", cmd_grep, RUN_SETUP_GENTLY },
 422         { "hash-object", cmd_hash_object },
 423         { "help", cmd_help },
 424         { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 425         { "init", cmd_init_db },
 426         { "init-db", cmd_init_db },
 427         { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP_GENTLY },
 428         { "log", cmd_log, RUN_SETUP },
 429         { "ls-files", cmd_ls_files, RUN_SETUP },
 430         { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 431         { "ls-tree", cmd_ls_tree, RUN_SETUP },
 432         { "mailinfo", cmd_mailinfo },
 433         { "mailsplit", cmd_mailsplit },
 434         { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 435         { "merge-base", cmd_merge_base, RUN_SETUP },
 436         { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 437         { "merge-index", cmd_merge_index, RUN_SETUP },
 438         { "merge-ours", cmd_merge_ours, RUN_SETUP },
 439         { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 440         { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 441         { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 442         { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 443         { "merge-tree", cmd_merge_tree, RUN_SETUP },
 444         { "mktag", cmd_mktag, RUN_SETUP },
 445         { "mktree", cmd_mktree, RUN_SETUP },
 446         { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 447         { "name-rev", cmd_name_rev, RUN_SETUP },
 448         { "notes", cmd_notes, RUN_SETUP },
 449         { "pack-objects", cmd_pack_objects, RUN_SETUP },
 450         { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 451         { "pack-refs", cmd_pack_refs, RUN_SETUP },
 452         { "patch-id", cmd_patch_id },
 453         { "pickaxe", cmd_blame, RUN_SETUP },
 454         { "prune", cmd_prune, RUN_SETUP },
 455         { "prune-packed", cmd_prune_packed, RUN_SETUP },
 456         { "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 457         { "push", cmd_push, RUN_SETUP },
 458         { "read-tree", cmd_read_tree, RUN_SETUP },
 459         { "receive-pack", cmd_receive_pack },
 460         { "reflog", cmd_reflog, RUN_SETUP },
 461         { "remote", cmd_remote, RUN_SETUP },
 462         { "remote-ext", cmd_remote_ext },
 463         { "remote-fd", cmd_remote_fd },
 464         { "repack", cmd_repack, RUN_SETUP },
 465         { "replace", cmd_replace, RUN_SETUP },
 466         { "rerere", cmd_rerere, RUN_SETUP },
 467         { "reset", cmd_reset, RUN_SETUP },
 468         { "rev-list", cmd_rev_list, RUN_SETUP },
 469         { "rev-parse", cmd_rev_parse },
 470         { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 471         { "rm", cmd_rm, RUN_SETUP },
 472         { "send-pack", cmd_send_pack, RUN_SETUP },
 473         { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 474         { "show", cmd_show, RUN_SETUP },
 475         { "show-branch", cmd_show_branch, RUN_SETUP },
 476         { "show-ref", cmd_show_ref, RUN_SETUP },
 477         { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 478         { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 479         { "stripspace", cmd_stripspace },
 480         { "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 481         { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 482         { "tag", cmd_tag, RUN_SETUP },
 483         { "unpack-file", cmd_unpack_file, RUN_SETUP },
 484         { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 485         { "update-index", cmd_update_index, RUN_SETUP },
 486         { "update-ref", cmd_update_ref, RUN_SETUP },
 487         { "update-server-info", cmd_update_server_info, RUN_SETUP },
 488         { "upload-archive", cmd_upload_archive },
 489         { "upload-archive--writer", cmd_upload_archive_writer },
 490         { "var", cmd_var, RUN_SETUP_GENTLY },
 491         { "verify-commit", cmd_verify_commit, RUN_SETUP },
 492         { "verify-pack", cmd_verify_pack },
 493         { "verify-tag", cmd_verify_tag, RUN_SETUP },
 494         { "version", cmd_version },
 495         { "whatchanged", cmd_whatchanged, RUN_SETUP },
 496         { "worktree", cmd_worktree, RUN_SETUP },
 497         { "write-tree", cmd_write_tree, RUN_SETUP },
 498 };
 499
 500 static struct cmd_struct *get_builtin(const char *s)
 501 {
 502         int i;
 503         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 504                 struct cmd_struct *p = commands + i;
 505                 if (!strcmp(s, p->cmd))
 506                         return p;
 507         }
 508         return NULL;
 509 }
 510
 511 int is_builtin(const char *s)
 512 {
 513         return !!get_builtin(s);
 514 }
 515
 516 #ifdef STRIP_EXTENSION
 517 static void strip_extension(const char **argv)
 518 {
 519         size_t len;
 520
 521         if (strip_suffix(argv[0], STRIP_EXTENSION, &len))
 522                 argv[0] = xmemdupz(argv[0], len);
 523 }
 524 #else
 525 #define strip_extension(cmd)
 526 #endif
 527
 528 static void handle_builtin(int argc, const char **argv)
 529 {
 530         const char *cmd;
 531         struct cmd_struct *builtin;
 532
 533         strip_extension(argv);
 534         cmd = argv[0];
 535
 536         /* Turn "git cmd --help" into "git help cmd" */
 537         if (argc > 1 && !strcmp(argv[1], "--help")) {
 538                 argv[1] = argv[0];
 539                 argv[0] = cmd = "help";
 540         }
 541
 542         builtin = get_builtin(cmd);
 543         if (builtin)
 544                 exit(run_builtin(builtin, argc, argv));
 545 }
 546
 547 static void execv_dashed_external(const char **argv)
 548 {
 549         struct strbuf cmd = STRBUF_INIT;
 550         const char *tmp;
 551         int status;
 552
 553         if (use_pager == -1)
 554                 use_pager = check_pager_config(argv[0]);
 555         commit_pager_choice();
 556
 557         strbuf_addf(&cmd, "git-%s", argv[0]);
 558
 559         /*
 560          * argv[0] must be the git command, but the argv array
 561          * belongs to the caller, and may be reused in
 562          * subsequent loop iterations. Save argv[0] and
 563          * restore it on error.
 564          */
 565         tmp = argv[0];
 566         argv[0] = cmd.buf;
 567
 568         trace_argv_printf(argv, "trace: exec:");
 569
 570         /*
 571          * if we fail because the command is not found, it is
 572          * OK to return. Otherwise, we just pass along the status code.
 573          */
 574         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 575         if (status >= 0 || errno != ENOENT)
 576                 exit(status);
 577
 578         argv[0] = tmp;
 579
 580         strbuf_release(&cmd);
 581 }
 582
 583 static int run_argv(int *argcp, const char ***argv)
 584 {
 585         int done_alias = 0;
 586
 587         while (1) {
 588                 /*
 589                  * If we tried alias and futzed with our environment,
 590                  * it no longer is safe to invoke builtins directly in
 591                  * general.  We have to spawn them as dashed externals.
 592                  *
 593                  * NEEDSWORK: if we can figure out cases
 594                  * where it is safe to do, we can avoid spawning a new
 595                  * process.
 596                  */
 597                 if (!done_alias)
 598                         handle_builtin(*argcp, *argv);
 599
 600                 /* .. then try the external ones */
 601                 execv_dashed_external(*argv);
 602
 603                 /* It could be an alias -- this works around the insanity
 604                  * of overriding "git log" with "git show" by having
 605                  * alias.log = show
 606                  */
 607                 if (done_alias)
 608                         break;
 609                 if (!handle_alias(argcp, argv))
 610                         break;
 611                 done_alias = 1;
 612         }
 613
 614         return done_alias;
 615 }
 616
 617 /*
 618  * Many parts of Git have subprograms communicate via pipe, expect the
 619  * upstream of a pipe to die with SIGPIPE when the downstream of a
 620  * pipe does not need to read all that is written.  Some third-party
 621  * programs that ignore or block SIGPIPE for their own reason forget
 622  * to restore SIGPIPE handling to the default before spawning Git and
 623  * break this carefully orchestrated machinery.
 624  *
 625  * Restore the way SIGPIPE is handled to default, which is what we
 626  * expect.
 627  */
 628 static void restore_sigpipe_to_default(void)
 629 {
 630         sigset_t unblock;
 631
 632         sigemptyset(&unblock);
 633         sigaddset(&unblock, SIGPIPE);
 634         sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 635         signal(SIGPIPE, SIG_DFL);
 636 }
 637
 638 int main(int argc, char **av)
 639 {
 640         const char **argv = (const char **) av;
 641         const char *cmd;
 642         int done_help = 0;
 643
 644         startup_info = &git_startup_info;
 645
 646         cmd = git_extract_argv0_path(argv[0]);
 647         if (!cmd)
 648                 cmd = "git-help";
 649
 650         /*
 651          * Always open file descriptors 0/1/2 to avoid clobbering files
 652          * in die().  It also avoids messing up when the pipes are dup'ed
 653          * onto stdin/stdout/stderr in the child processes we spawn.
 654          */
 655         sanitize_stdfds();
 656
 657         restore_sigpipe_to_default();
 658
 659         git_setup_gettext();
 660
 661         trace_command_performance(argv);
 662
 663         /*
 664          * "git-xxxx" is the same as "git xxxx", but we obviously:
 665          *
 666          *  - cannot take flags in between the "git" and the "xxxx".
 667          *  - cannot execute it externally (since it would just do
 668          *    the same thing over again)
 669          *
 670          * So we just directly call the builtin handler, and die if
 671          * that one cannot handle it.
 672          */
 673         if (skip_prefix(cmd, "git-", &cmd)) {
 674                 argv[0] = cmd;
 675                 handle_builtin(argc, argv);
 676                 die("cannot handle %s as a builtin", cmd);
 677         }
 678
 679         /* Look for flags.. */
 680         argv++;
 681         argc--;
 682         handle_options(&argv, &argc, NULL);
 683         if (argc > 0) {
 684                 /* translate --help and --version into commands */
 685                 skip_prefix(argv[0], "--", &argv[0]);
 686         } else {
 687                 /* The user didn't specify a command; give them help */
 688                 commit_pager_choice();
 689                 printf("usage: %s\n\n", git_usage_string);
 690                 list_common_cmds_help();
 691                 printf("\n%s\n", _(git_more_info_string));
 692                 exit(1);
 693         }
 694         cmd = argv[0];
 695
 696         /*
 697          * We use PATH to find git commands, but we prepend some higher
 698          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 699          * environment, and the $(gitexecdir) from the Makefile at build
 700          * time.
 701          */
 702         setup_path();
 703
 704         while (1) {
 705                 int was_alias = run_argv(&argc, &argv);
 706                 if (errno != ENOENT)
 707                         break;
 708                 if (was_alias) {
 709                         fprintf(stderr, "Expansion of alias '%s' failed; "
 710                                 "'%s' is not a git command\n",
 711                                 cmd, argv[0]);
 712                         exit(1);
 713                 }
 714                 if (!done_help) {
 715                         cmd = argv[0] = help_unknown_cmd(cmd);
 716                         done_help = 1;
 717                 } else
 718                         break;
 719         }
 720
 721         fprintf(stderr, "Failed to run command '%s': %s\n",
 722                 cmd, strerror(errno));
 723
 724         return 1;
 725 }