git.oblomov.eu Git - git/blob - 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 saved_env_before_alias;
  29
  30 static void save_env_before_alias(void)
  31 {
  32         int i;
  33         if (saved_env_before_alias)
  34                 return;
  35         saved_env_before_alias = 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         if (!external_alias && orig_cwd && chdir(orig_cwd))
  48                 die_errno("could not move to %s", orig_cwd);
  49         free(orig_cwd);
  50         for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  51                 if (external_alias &&
  52                     !strcmp(env_names[i], GIT_PREFIX_ENVIRONMENT))
  53                         continue;
  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 ((*argv)[1][0]) {
 211                                 if (chdir((*argv)[1]))
 212                                         die_errno("Cannot change to '%s'", (*argv)[1]);
 213                                 if (envchanged)
 214                                         *envchanged = 1;
 215                         }
 216                         (*argv)++;
 217                         (*argc)--;
 218                 } else {
 219                         fprintf(stderr, "Unknown option: %s\n", cmd);
 220                         usage(git_usage_string);
 221                 }
 222
 223                 (*argv)++;
 224                 (*argc)--;
 225         }
 226         return (*argv) - orig_argv;
 227 }
 228
 229 static int handle_alias(int *argcp, const char ***argv)
 230 {
 231         int envchanged = 0, ret = 0, saved_errno = errno;
 232         int count, option_count;
 233         const char **new_argv;
 234         const char *alias_command;
 235         char *alias_string;
 236         int unused_nongit;
 237
 238         save_env_before_alias();
 239         setup_git_directory_gently(&unused_nongit);
 240
 241         alias_command = (*argv)[0];
 242         alias_string = alias_lookup(alias_command);
 243         if (alias_string) {
 244                 if (alias_string[0] == '!') {
 245                         const char **alias_argv;
 246                         int argc = *argcp, i;
 247
 248                         commit_pager_choice();
 249                         restore_env(1);
 250
 251                         /* build alias_argv */
 252                         alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 253                         alias_argv[0] = alias_string + 1;
 254                         for (i = 1; i < argc; ++i)
 255                                 alias_argv[i] = (*argv)[i];
 256                         alias_argv[argc] = NULL;
 257
 258                         ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 259                         if (ret >= 0)   /* normal exit */
 260                                 exit(ret);
 261
 262                         die_errno("While expanding alias '%s': '%s'",
 263                             alias_command, alias_string + 1);
 264                 }
 265                 count = split_cmdline(alias_string, &new_argv);
 266                 if (count < 0)
 267                         die("Bad alias.%s string: %s", alias_command,
 268                             split_cmdline_strerror(count));
 269                 option_count = handle_options(&new_argv, &count, &envchanged);
 270                 if (envchanged)
 271                         die("alias '%s' changes environment variables\n"
 272                                  "You can use '!git' in the alias to do this.",
 273                                  alias_command);
 274                 memmove(new_argv - option_count, new_argv,
 275                                 count * sizeof(char *));
 276                 new_argv -= option_count;
 277
 278                 if (count < 1)
 279                         die("empty alias for %s", alias_command);
 280
 281                 if (!strcmp(alias_command, new_argv[0]))
 282                         die("recursive alias: %s", alias_command);
 283
 284                 trace_argv_printf(new_argv,
 285                                   "trace: alias expansion: %s =>",
 286                                   alias_command);
 287
 288                 REALLOC_ARRAY(new_argv, count + *argcp);
 289                 /* insert after command name */
 290                 memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 291
 292                 *argv = new_argv;
 293                 *argcp += count - 1;
 294
 295                 ret = 1;
 296         }
 297
 298         restore_env(0);
 299
 300         errno = saved_errno;
 301
 302         return ret;
 303 }
 304
 305 #define RUN_SETUP               (1<<0)
 306 #define RUN_SETUP_GENTLY        (1<<1)
 307 #define USE_PAGER               (1<<2)
 308 /*
 309  * require working tree to be present -- anything uses this needs
 310  * RUN_SETUP for reading from the configuration file.
 311  */
 312 #define NEED_WORK_TREE          (1<<3)
 313
 314 struct cmd_struct {
 315         const char *cmd;
 316         int (*fn)(int, const char **, const char *);
 317         int option;
 318 };
 319
 320 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 321 {
 322         int status, help;
 323         struct stat st;
 324         const char *prefix;
 325
 326         prefix = NULL;
 327         help = argc == 2 && !strcmp(argv[1], "-h");
 328         if (!help) {
 329                 if (p->option & RUN_SETUP)
 330                         prefix = setup_git_directory();
 331                 else if (p->option & RUN_SETUP_GENTLY) {
 332                         int nongit_ok;
 333                         prefix = setup_git_directory_gently(&nongit_ok);
 334                 }
 335
 336                 if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 337                         use_pager = check_pager_config(p->cmd);
 338                 if (use_pager == -1 && p->option & USE_PAGER)
 339                         use_pager = 1;
 340
 341                 if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 342                     startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 343                         trace_repo_setup(prefix);
 344         }
 345         commit_pager_choice();
 346
 347         if (!help && p->option & NEED_WORK_TREE)
 348                 setup_work_tree();
 349
 350         trace_argv_printf(argv, "trace: built-in: git");
 351
 352         status = p->fn(argc, argv, prefix);
 353         if (status)
 354                 return status;
 355
 356         /* Somebody closed stdout? */
 357         if (fstat(fileno(stdout), &st))
 358                 return 0;
 359         /* Ignore write errors for pipes and sockets.. */
 360         if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 361                 return 0;
 362
 363         /* Check for ENOSPC and EIO errors.. */
 364         if (fflush(stdout))
 365                 die_errno("write failure on standard output");
 366         if (ferror(stdout))
 367                 die("unknown write failure on standard output");
 368         if (fclose(stdout))
 369                 die_errno("close failed on standard output");
 370         return 0;
 371 }
 372
 373 static struct cmd_struct commands[] = {
 374         { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 375         { "am", cmd_am, RUN_SETUP | NEED_WORK_TREE },
 376         { "annotate", cmd_annotate, RUN_SETUP },
 377         { "apply", cmd_apply, RUN_SETUP_GENTLY },
 378         { "archive", cmd_archive },
 379         { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 380         { "blame", cmd_blame, RUN_SETUP },
 381         { "branch", cmd_branch, RUN_SETUP },
 382         { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 383         { "cat-file", cmd_cat_file, RUN_SETUP },
 384         { "check-attr", cmd_check_attr, RUN_SETUP },
 385         { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 386         { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 387         { "check-ref-format", cmd_check_ref_format },
 388         { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 389         { "checkout-index", cmd_checkout_index,
 390                 RUN_SETUP | NEED_WORK_TREE},
 391         { "cherry", cmd_cherry, RUN_SETUP },
 392         { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 393         { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 394         { "clone", cmd_clone },
 395         { "column", cmd_column, RUN_SETUP_GENTLY },
 396         { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 397         { "commit-tree", cmd_commit_tree, RUN_SETUP },
 398         { "config", cmd_config, RUN_SETUP_GENTLY },
 399         { "count-objects", cmd_count_objects, RUN_SETUP },
 400         { "credential", cmd_credential, RUN_SETUP_GENTLY },
 401         { "describe", cmd_describe, RUN_SETUP },
 402         { "diff", cmd_diff },
 403         { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 404         { "diff-index", cmd_diff_index, RUN_SETUP },
 405         { "diff-tree", cmd_diff_tree, RUN_SETUP },
 406         { "fast-export", cmd_fast_export, RUN_SETUP },
 407         { "fetch", cmd_fetch, RUN_SETUP },
 408         { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 409         { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 410         { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 411         { "format-patch", cmd_format_patch, RUN_SETUP },
 412         { "fsck", cmd_fsck, RUN_SETUP },
 413         { "fsck-objects", cmd_fsck, RUN_SETUP },
 414         { "gc", cmd_gc, RUN_SETUP },
 415         { "get-tar-commit-id", cmd_get_tar_commit_id },
 416         { "grep", cmd_grep, RUN_SETUP_GENTLY },
 417         { "hash-object", cmd_hash_object },
 418         { "help", cmd_help },
 419         { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 420         { "init", cmd_init_db },
 421         { "init-db", cmd_init_db },
 422         { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP_GENTLY },
 423         { "log", cmd_log, RUN_SETUP },
 424         { "ls-files", cmd_ls_files, RUN_SETUP },
 425         { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 426         { "ls-tree", cmd_ls_tree, RUN_SETUP },
 427         { "mailinfo", cmd_mailinfo },
 428         { "mailsplit", cmd_mailsplit },
 429         { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 430         { "merge-base", cmd_merge_base, RUN_SETUP },
 431         { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 432         { "merge-index", cmd_merge_index, RUN_SETUP },
 433         { "merge-ours", cmd_merge_ours, RUN_SETUP },
 434         { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 435         { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 436         { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 437         { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 438         { "merge-tree", cmd_merge_tree, RUN_SETUP },
 439         { "mktag", cmd_mktag, RUN_SETUP },
 440         { "mktree", cmd_mktree, RUN_SETUP },
 441         { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 442         { "name-rev", cmd_name_rev, RUN_SETUP },
 443         { "notes", cmd_notes, RUN_SETUP },
 444         { "pack-objects", cmd_pack_objects, RUN_SETUP },
 445         { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 446         { "pack-refs", cmd_pack_refs, RUN_SETUP },
 447         { "patch-id", cmd_patch_id },
 448         { "pickaxe", cmd_blame, RUN_SETUP },
 449         { "prune", cmd_prune, RUN_SETUP },
 450         { "prune-packed", cmd_prune_packed, RUN_SETUP },
 451         { "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 452         { "push", cmd_push, RUN_SETUP },
 453         { "read-tree", cmd_read_tree, RUN_SETUP },
 454         { "receive-pack", cmd_receive_pack },
 455         { "reflog", cmd_reflog, RUN_SETUP },
 456         { "remote", cmd_remote, RUN_SETUP },
 457         { "remote-ext", cmd_remote_ext },
 458         { "remote-fd", cmd_remote_fd },
 459         { "repack", cmd_repack, RUN_SETUP },
 460         { "replace", cmd_replace, RUN_SETUP },
 461         { "rerere", cmd_rerere, RUN_SETUP },
 462         { "reset", cmd_reset, RUN_SETUP },
 463         { "rev-list", cmd_rev_list, RUN_SETUP },
 464         { "rev-parse", cmd_rev_parse },
 465         { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 466         { "rm", cmd_rm, RUN_SETUP },
 467         { "send-pack", cmd_send_pack, RUN_SETUP },
 468         { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 469         { "show", cmd_show, RUN_SETUP },
 470         { "show-branch", cmd_show_branch, RUN_SETUP },
 471         { "show-ref", cmd_show_ref, RUN_SETUP },
 472         { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 473         { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 474         { "stripspace", cmd_stripspace },
 475         { "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 476         { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 477         { "tag", cmd_tag, RUN_SETUP },
 478         { "unpack-file", cmd_unpack_file, RUN_SETUP },
 479         { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 480         { "update-index", cmd_update_index, RUN_SETUP },
 481         { "update-ref", cmd_update_ref, RUN_SETUP },
 482         { "update-server-info", cmd_update_server_info, RUN_SETUP },
 483         { "upload-archive", cmd_upload_archive },
 484         { "upload-archive--writer", cmd_upload_archive_writer },
 485         { "var", cmd_var, RUN_SETUP_GENTLY },
 486         { "verify-commit", cmd_verify_commit, RUN_SETUP },
 487         { "verify-pack", cmd_verify_pack },
 488         { "verify-tag", cmd_verify_tag, RUN_SETUP },
 489         { "version", cmd_version },
 490         { "whatchanged", cmd_whatchanged, RUN_SETUP },
 491         { "worktree", cmd_worktree, RUN_SETUP },
 492         { "write-tree", cmd_write_tree, RUN_SETUP },
 493 };
 494
 495 static struct cmd_struct *get_builtin(const char *s)
 496 {
 497         int i;
 498         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 499                 struct cmd_struct *p = commands + i;
 500                 if (!strcmp(s, p->cmd))
 501                         return p;
 502         }
 503         return NULL;
 504 }
 505
 506 int is_builtin(const char *s)
 507 {
 508         return !!get_builtin(s);
 509 }
 510
 511 static void handle_builtin(int argc, const char **argv)
 512 {
 513         const char *cmd = argv[0];
 514         int i;
 515         static const char ext[] = STRIP_EXTENSION;
 516         struct cmd_struct *builtin;
 517
 518         if (sizeof(ext) > 1) {
 519                 i = strlen(argv[0]) - strlen(ext);
 520                 if (i > 0 && !strcmp(argv[0] + i, ext)) {
 521                         char *argv0 = xstrdup(argv[0]);
 522                         argv[0] = cmd = argv0;
 523                         argv0[i] = '\0';
 524                 }
 525         }
 526
 527         /* Turn "git cmd --help" into "git help cmd" */
 528         if (argc > 1 && !strcmp(argv[1], "--help")) {
 529                 argv[1] = argv[0];
 530                 argv[0] = cmd = "help";
 531         }
 532
 533         builtin = get_builtin(cmd);
 534         if (builtin) {
 535                 /*
 536                  * XXX: if we can figure out cases where it is _safe_
 537                  * to do, we can avoid spawning a new process when
 538                  * saved_env_before_alias is true
 539                  * (i.e. setup_git_dir* has been run once)
 540                  */
 541                 if (!saved_env_before_alias)
 542                         exit(run_builtin(builtin, argc, argv));
 543         }
 544 }
 545
 546 static void execv_dashed_external(const char **argv)
 547 {
 548         struct strbuf cmd = STRBUF_INIT;
 549         const char *tmp;
 550         int status;
 551
 552         if (use_pager == -1)
 553                 use_pager = check_pager_config(argv[0]);
 554         commit_pager_choice();
 555
 556         strbuf_addf(&cmd, "git-%s", argv[0]);
 557
 558         /*
 559          * argv[0] must be the git command, but the argv array
 560          * belongs to the caller, and may be reused in
 561          * subsequent loop iterations. Save argv[0] and
 562          * restore it on error.
 563          */
 564         tmp = argv[0];
 565         argv[0] = cmd.buf;
 566
 567         trace_argv_printf(argv, "trace: exec:");
 568
 569         /*
 570          * if we fail because the command is not found, it is
 571          * OK to return. Otherwise, we just pass along the status code.
 572          */
 573         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 574         if (status >= 0 || errno != ENOENT)
 575                 exit(status);
 576
 577         argv[0] = tmp;
 578
 579         strbuf_release(&cmd);
 580 }
 581
 582 static int run_argv(int *argcp, const char ***argv)
 583 {
 584         int done_alias = 0;
 585
 586         while (1) {
 587                 /* See if it's a builtin */
 588                 handle_builtin(*argcp, *argv);
 589
 590                 /* .. then try the external ones */
 591                 execv_dashed_external(*argv);
 592
 593                 /* It could be an alias -- this works around the insanity
 594                  * of overriding "git log" with "git show" by having
 595                  * alias.log = show
 596                  */
 597                 if (done_alias)
 598                         break;
 599                 if (!handle_alias(argcp, argv))
 600                         break;
 601                 done_alias = 1;
 602         }
 603
 604         return done_alias;
 605 }
 606
 607 /*
 608  * Many parts of Git have subprograms communicate via pipe, expect the
 609  * upstream of a pipe to die with SIGPIPE when the downstream of a
 610  * pipe does not need to read all that is written.  Some third-party
 611  * programs that ignore or block SIGPIPE for their own reason forget
 612  * to restore SIGPIPE handling to the default before spawning Git and
 613  * break this carefully orchestrated machinery.
 614  *
 615  * Restore the way SIGPIPE is handled to default, which is what we
 616  * expect.
 617  */
 618 static void restore_sigpipe_to_default(void)
 619 {
 620         sigset_t unblock;
 621
 622         sigemptyset(&unblock);
 623         sigaddset(&unblock, SIGPIPE);
 624         sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 625         signal(SIGPIPE, SIG_DFL);
 626 }
 627
 628 int main(int argc, char **av)
 629 {
 630         const char **argv = (const char **) av;
 631         const char *cmd;
 632         int done_help = 0;
 633
 634         startup_info = &git_startup_info;
 635
 636         cmd = git_extract_argv0_path(argv[0]);
 637         if (!cmd)
 638                 cmd = "git-help";
 639
 640         /*
 641          * Always open file descriptors 0/1/2 to avoid clobbering files
 642          * in die().  It also avoids messing up when the pipes are dup'ed
 643          * onto stdin/stdout/stderr in the child processes we spawn.
 644          */
 645         sanitize_stdfds();
 646
 647         restore_sigpipe_to_default();
 648
 649         git_setup_gettext();
 650
 651         trace_command_performance(argv);
 652
 653         /*
 654          * "git-xxxx" is the same as "git xxxx", but we obviously:
 655          *
 656          *  - cannot take flags in between the "git" and the "xxxx".
 657          *  - cannot execute it externally (since it would just do
 658          *    the same thing over again)
 659          *
 660          * So we just directly call the builtin handler, and die if
 661          * that one cannot handle it.
 662          */
 663         if (skip_prefix(cmd, "git-", &cmd)) {
 664                 argv[0] = cmd;
 665                 handle_builtin(argc, argv);
 666                 die("cannot handle %s as a builtin", cmd);
 667         }
 668
 669         /* Look for flags.. */
 670         argv++;
 671         argc--;
 672         handle_options(&argv, &argc, NULL);
 673         if (argc > 0) {
 674                 /* translate --help and --version into commands */
 675                 skip_prefix(argv[0], "--", &argv[0]);
 676         } else {
 677                 /* The user didn't specify a command; give them help */
 678                 commit_pager_choice();
 679                 printf("usage: %s\n\n", git_usage_string);
 680                 list_common_cmds_help();
 681                 printf("\n%s\n", _(git_more_info_string));
 682                 exit(1);
 683         }
 684         cmd = argv[0];
 685
 686         /*
 687          * We use PATH to find git commands, but we prepend some higher
 688          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 689          * environment, and the $(gitexecdir) from the Makefile at build
 690          * time.
 691          */
 692         setup_path();
 693
 694         while (1) {
 695                 int was_alias = run_argv(&argc, &argv);
 696                 if (errno != ENOENT)
 697                         break;
 698                 if (was_alias) {
 699                         fprintf(stderr, "Expansion of alias '%s' failed; "
 700                                 "'%s' is not a git command\n",
 701                                 cmd, argv[0]);
 702                         exit(1);
 703                 }
 704                 if (!done_help) {
 705                         cmd = argv[0] = help_unknown_cmd(cmd);
 706                         done_help = 1;
 707                 } else
 708                         break;
 709         }
 710
 711         fprintf(stderr, "Failed to run command '%s': %s\n",
 712                 cmd, strerror(errno));
 713
 714         return 1;
 715 }