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_environment;
  29
  30 static void save_env(void)
  31 {
  32         int i;
  33         if (saved_environment)
  34                 return;
  35         saved_environment = 1;
  36         orig_cwd = xgetcwd();
  37         for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  38                 orig_env[i] = getenv(env_names[i]);
  39                 if (orig_env[i])
  40                         orig_env[i] = xstrdup(orig_env[i]);
  41         }
  42 }
  43
  44 static void restore_env(void)
  45 {
  46         int i;
  47         if (orig_cwd && chdir(orig_cwd))
  48                 die_errno("could not move to %s", orig_cwd);
  49         free(orig_cwd);
  50         for (i = 0; i < ARRAY_SIZE(env_names); i++) {
  51                 if (orig_env[i])
  52                         setenv(env_names[i], orig_env[i], 1);
  53                 else
  54                         unsetenv(env_names[i]);
  55         }
  56 }
  57
  58 static void commit_pager_choice(void) {
  59         switch (use_pager) {
  60         case 0:
  61                 setenv("GIT_PAGER", "cat", 1);
  62                 break;
  63         case 1:
  64                 setup_pager();
  65                 break;
  66         default:
  67                 break;
  68         }
  69 }
  70
  71 static int handle_options(const char ***argv, int *argc, int *envchanged)
  72 {
  73         const char **orig_argv = *argv;
  74
  75         while (*argc > 0) {
  76                 const char *cmd = (*argv)[0];
  77                 if (cmd[0] != '-')
  78                         break;
  79
  80                 /*
  81                  * For legacy reasons, the "version" and "help"
  82                  * commands can be written with "--" prepended
  83                  * to make them look like flags.
  84                  */
  85                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  86                         break;
  87
  88                 /*
  89                  * Check remaining flags.
  90                  */
  91                 if (skip_prefix(cmd, "--exec-path", &cmd)) {
  92                         if (*cmd == '=')
  93                                 git_set_argv_exec_path(cmd + 1);
  94                         else {
  95                                 puts(git_exec_path());
  96                                 exit(0);
  97                         }
  98                 } else if (!strcmp(cmd, "--html-path")) {
  99                         puts(system_path(GIT_HTML_PATH));
 100                         exit(0);
 101                 } else if (!strcmp(cmd, "--man-path")) {
 102                         puts(system_path(GIT_MAN_PATH));
 103                         exit(0);
 104                 } else if (!strcmp(cmd, "--info-path")) {
 105                         puts(system_path(GIT_INFO_PATH));
 106                         exit(0);
 107                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 108                         use_pager = 1;
 109                 } else if (!strcmp(cmd, "--no-pager")) {
 110                         use_pager = 0;
 111                         if (envchanged)
 112                                 *envchanged = 1;
 113                 } else if (!strcmp(cmd, "--no-replace-objects")) {
 114                         check_replace_refs = 0;
 115                         setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 116                         if (envchanged)
 117                                 *envchanged = 1;
 118                 } else if (!strcmp(cmd, "--git-dir")) {
 119                         if (*argc < 2) {
 120                                 fprintf(stderr, "No directory given for --git-dir.\n" );
 121                                 usage(git_usage_string);
 122                         }
 123                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 124                         if (envchanged)
 125                                 *envchanged = 1;
 126                         (*argv)++;
 127                         (*argc)--;
 128                 } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
 129                         setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
 130                         if (envchanged)
 131                                 *envchanged = 1;
 132                 } else if (!strcmp(cmd, "--namespace")) {
 133                         if (*argc < 2) {
 134                                 fprintf(stderr, "No namespace given for --namespace.\n" );
 135                                 usage(git_usage_string);
 136                         }
 137                         setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 138                         if (envchanged)
 139                                 *envchanged = 1;
 140                         (*argv)++;
 141                         (*argc)--;
 142                 } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
 143                         setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
 144                         if (envchanged)
 145                                 *envchanged = 1;
 146                 } else if (!strcmp(cmd, "--work-tree")) {
 147                         if (*argc < 2) {
 148                                 fprintf(stderr, "No directory given for --work-tree.\n" );
 149                                 usage(git_usage_string);
 150                         }
 151                         setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 152                         if (envchanged)
 153                                 *envchanged = 1;
 154                         (*argv)++;
 155                         (*argc)--;
 156                 } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
 157                         setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
 158                         if (envchanged)
 159                                 *envchanged = 1;
 160                 } else if (!strcmp(cmd, "--bare")) {
 161                         char *cwd = xgetcwd();
 162                         is_bare_repository_cfg = 1;
 163                         setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
 164                         free(cwd);
 165                         setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
 166                         if (envchanged)
 167                                 *envchanged = 1;
 168                 } else if (!strcmp(cmd, "-c")) {
 169                         if (*argc < 2) {
 170                                 fprintf(stderr, "-c expects a configuration string\n" );
 171                                 usage(git_usage_string);
 172                         }
 173                         git_config_push_parameter((*argv)[1]);
 174                         (*argv)++;
 175                         (*argc)--;
 176                 } else if (!strcmp(cmd, "--literal-pathspecs")) {
 177                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
 178                         if (envchanged)
 179                                 *envchanged = 1;
 180                 } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
 181                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
 182                         if (envchanged)
 183                                 *envchanged = 1;
 184                 } else if (!strcmp(cmd, "--glob-pathspecs")) {
 185                         setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 186                         if (envchanged)
 187                                 *envchanged = 1;
 188                 } else if (!strcmp(cmd, "--noglob-pathspecs")) {
 189                         setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
 190                         if (envchanged)
 191                                 *envchanged = 1;
 192                 } else if (!strcmp(cmd, "--icase-pathspecs")) {
 193                         setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
 194                         if (envchanged)
 195                                 *envchanged = 1;
 196                 } else if (!strcmp(cmd, "--shallow-file")) {
 197                         (*argv)++;
 198                         (*argc)--;
 199                         set_alternate_shallow_file((*argv)[0], 1);
 200                         if (envchanged)
 201                                 *envchanged = 1;
 202                 } else if (!strcmp(cmd, "-C")) {
 203                         if (*argc < 2) {
 204                                 fprintf(stderr, "No directory given for -C.\n" );
 205                                 usage(git_usage_string);
 206                         }
 207                         if ((*argv)[1][0]) {
 208                                 if (chdir((*argv)[1]))
 209                                         die_errno("Cannot change to '%s'", (*argv)[1]);
 210                                 if (envchanged)
 211                                         *envchanged = 1;
 212                         }
 213                         (*argv)++;
 214                         (*argc)--;
 215                 } else {
 216                         fprintf(stderr, "Unknown option: %s\n", cmd);
 217                         usage(git_usage_string);
 218                 }
 219
 220                 (*argv)++;
 221                 (*argc)--;
 222         }
 223         return (*argv) - orig_argv;
 224 }
 225
 226 static int handle_alias(int *argcp, const char ***argv)
 227 {
 228         int envchanged = 0, ret = 0, saved_errno = errno;
 229         const char *subdir;
 230         int count, option_count;
 231         const char **new_argv;
 232         const char *alias_command;
 233         char *alias_string;
 234         int unused_nongit;
 235
 236         subdir = setup_git_directory_gently(&unused_nongit);
 237
 238         alias_command = (*argv)[0];
 239         alias_string = alias_lookup(alias_command);
 240         if (alias_string) {
 241                 if (alias_string[0] == '!') {
 242                         struct child_process child = CHILD_PROCESS_INIT;
 243
 244                         commit_pager_choice();
 245
 246                         child.use_shell = 1;
 247                         argv_array_push(&child.args, alias_string + 1);
 248                         argv_array_pushv(&child.args, (*argv) + 1);
 249
 250                         ret = run_command(&child);
 251                         if (ret >= 0)   /* normal exit */
 252                                 exit(ret);
 253
 254                         die_errno("While expanding alias '%s': '%s'",
 255                             alias_command, alias_string + 1);
 256                 }
 257                 count = split_cmdline(alias_string, &new_argv);
 258                 if (count < 0)
 259                         die("Bad alias.%s string: %s", alias_command,
 260                             split_cmdline_strerror(count));
 261                 option_count = handle_options(&new_argv, &count, &envchanged);
 262                 if (envchanged)
 263                         die("alias '%s' changes environment variables\n"
 264                                  "You can use '!git' in the alias to do this.",
 265                                  alias_command);
 266                 memmove(new_argv - option_count, new_argv,
 267                                 count * sizeof(char *));
 268                 new_argv -= option_count;
 269
 270                 if (count < 1)
 271                         die("empty alias for %s", alias_command);
 272
 273                 if (!strcmp(alias_command, new_argv[0]))
 274                         die("recursive alias: %s", alias_command);
 275
 276                 trace_argv_printf(new_argv,
 277                                   "trace: alias expansion: %s =>",
 278                                   alias_command);
 279
 280                 REALLOC_ARRAY(new_argv, count + *argcp);
 281                 /* insert after command name */
 282                 memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 283
 284                 *argv = new_argv;
 285                 *argcp += count - 1;
 286
 287                 ret = 1;
 288         }
 289
 290         if (subdir && chdir(subdir))
 291                 die_errno("Cannot change to '%s'", subdir);
 292
 293         errno = saved_errno;
 294
 295         return ret;
 296 }
 297
 298 #define RUN_SETUP               (1<<0)
 299 #define RUN_SETUP_GENTLY        (1<<1)
 300 #define USE_PAGER               (1<<2)
 301 /*
 302  * require working tree to be present -- anything uses this needs
 303  * RUN_SETUP for reading from the configuration file.
 304  */
 305 #define NEED_WORK_TREE          (1<<3)
 306 #define NO_SETUP                (1<<4)
 307
 308 struct cmd_struct {
 309         const char *cmd;
 310         int (*fn)(int, const char **, const char *);
 311         int option;
 312 };
 313
 314 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 315 {
 316         int status, help;
 317         struct stat st;
 318         const char *prefix;
 319
 320         prefix = NULL;
 321         help = argc == 2 && !strcmp(argv[1], "-h");
 322         if (!help) {
 323                 if (p->option & RUN_SETUP)
 324                         prefix = setup_git_directory();
 325                 else if (p->option & RUN_SETUP_GENTLY) {
 326                         int nongit_ok;
 327                         prefix = setup_git_directory_gently(&nongit_ok);
 328                 }
 329
 330                 if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 331                         use_pager = check_pager_config(p->cmd);
 332                 if (use_pager == -1 && p->option & USE_PAGER)
 333                         use_pager = 1;
 334
 335                 if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 336                     startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 337                         trace_repo_setup(prefix);
 338         }
 339         commit_pager_choice();
 340
 341         if (!help && p->option & NEED_WORK_TREE)
 342                 setup_work_tree();
 343
 344         trace_argv_printf(argv, "trace: built-in: git");
 345
 346         status = p->fn(argc, argv, prefix);
 347         if (status)
 348                 return status;
 349
 350         /* Somebody closed stdout? */
 351         if (fstat(fileno(stdout), &st))
 352                 return 0;
 353         /* Ignore write errors for pipes and sockets.. */
 354         if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 355                 return 0;
 356
 357         /* Check for ENOSPC and EIO errors.. */
 358         if (fflush(stdout))
 359                 die_errno("write failure on standard output");
 360         if (ferror(stdout))
 361                 die("unknown write failure on standard output");
 362         if (fclose(stdout))
 363                 die_errno("close failed on standard output");
 364         return 0;
 365 }
 366
 367 static struct cmd_struct commands[] = {
 368         { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 369         { "am", cmd_am, RUN_SETUP | NEED_WORK_TREE },
 370         { "annotate", cmd_annotate, RUN_SETUP },
 371         { "apply", cmd_apply, RUN_SETUP_GENTLY },
 372         { "archive", cmd_archive },
 373         { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 374         { "blame", cmd_blame, RUN_SETUP },
 375         { "branch", cmd_branch, RUN_SETUP },
 376         { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 377         { "cat-file", cmd_cat_file, RUN_SETUP },
 378         { "check-attr", cmd_check_attr, RUN_SETUP },
 379         { "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 380         { "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 381         { "check-ref-format", cmd_check_ref_format },
 382         { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 383         { "checkout-index", cmd_checkout_index,
 384                 RUN_SETUP | NEED_WORK_TREE},
 385         { "cherry", cmd_cherry, RUN_SETUP },
 386         { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 387         { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 388         { "clone", cmd_clone, NO_SETUP },
 389         { "column", cmd_column, RUN_SETUP_GENTLY },
 390         { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 391         { "commit-tree", cmd_commit_tree, RUN_SETUP },
 392         { "config", cmd_config, RUN_SETUP_GENTLY },
 393         { "count-objects", cmd_count_objects, RUN_SETUP },
 394         { "credential", cmd_credential, RUN_SETUP_GENTLY },
 395         { "describe", cmd_describe, RUN_SETUP },
 396         { "diff", cmd_diff },
 397         { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 398         { "diff-index", cmd_diff_index, RUN_SETUP },
 399         { "diff-tree", cmd_diff_tree, RUN_SETUP },
 400         { "fast-export", cmd_fast_export, RUN_SETUP },
 401         { "fetch", cmd_fetch, RUN_SETUP },
 402         { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 403         { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 404         { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 405         { "format-patch", cmd_format_patch, RUN_SETUP },
 406         { "fsck", cmd_fsck, RUN_SETUP },
 407         { "fsck-objects", cmd_fsck, RUN_SETUP },
 408         { "gc", cmd_gc, RUN_SETUP },
 409         { "get-tar-commit-id", cmd_get_tar_commit_id },
 410         { "grep", cmd_grep, RUN_SETUP_GENTLY },
 411         { "hash-object", cmd_hash_object },
 412         { "help", cmd_help },
 413         { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 414         { "init", cmd_init_db, NO_SETUP },
 415         { "init-db", cmd_init_db, NO_SETUP },
 416         { "interpret-trailers", cmd_interpret_trailers, RUN_SETUP_GENTLY },
 417         { "log", cmd_log, RUN_SETUP },
 418         { "ls-files", cmd_ls_files, RUN_SETUP },
 419         { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 420         { "ls-tree", cmd_ls_tree, RUN_SETUP },
 421         { "mailinfo", cmd_mailinfo },
 422         { "mailsplit", cmd_mailsplit },
 423         { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 424         { "merge-base", cmd_merge_base, RUN_SETUP },
 425         { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 426         { "merge-index", cmd_merge_index, RUN_SETUP },
 427         { "merge-ours", cmd_merge_ours, RUN_SETUP },
 428         { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 429         { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 430         { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 431         { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 432         { "merge-tree", cmd_merge_tree, RUN_SETUP },
 433         { "mktag", cmd_mktag, RUN_SETUP },
 434         { "mktree", cmd_mktree, RUN_SETUP },
 435         { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 436         { "name-rev", cmd_name_rev, RUN_SETUP },
 437         { "notes", cmd_notes, RUN_SETUP },
 438         { "pack-objects", cmd_pack_objects, RUN_SETUP },
 439         { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 440         { "pack-refs", cmd_pack_refs, RUN_SETUP },
 441         { "patch-id", cmd_patch_id },
 442         { "pickaxe", cmd_blame, RUN_SETUP },
 443         { "prune", cmd_prune, RUN_SETUP },
 444         { "prune-packed", cmd_prune_packed, RUN_SETUP },
 445         { "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 446         { "push", cmd_push, RUN_SETUP },
 447         { "read-tree", cmd_read_tree, RUN_SETUP },
 448         { "receive-pack", cmd_receive_pack },
 449         { "reflog", cmd_reflog, RUN_SETUP },
 450         { "remote", cmd_remote, RUN_SETUP },
 451         { "remote-ext", cmd_remote_ext },
 452         { "remote-fd", cmd_remote_fd },
 453         { "repack", cmd_repack, RUN_SETUP },
 454         { "replace", cmd_replace, RUN_SETUP },
 455         { "rerere", cmd_rerere, RUN_SETUP },
 456         { "reset", cmd_reset, RUN_SETUP },
 457         { "rev-list", cmd_rev_list, RUN_SETUP },
 458         { "rev-parse", cmd_rev_parse },
 459         { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 460         { "rm", cmd_rm, RUN_SETUP },
 461         { "send-pack", cmd_send_pack, RUN_SETUP },
 462         { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 463         { "show", cmd_show, RUN_SETUP },
 464         { "show-branch", cmd_show_branch, RUN_SETUP },
 465         { "show-ref", cmd_show_ref, RUN_SETUP },
 466         { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 467         { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 468         { "stripspace", cmd_stripspace },
 469         { "submodule--helper", cmd_submodule__helper, RUN_SETUP },
 470         { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 471         { "tag", cmd_tag, RUN_SETUP },
 472         { "unpack-file", cmd_unpack_file, RUN_SETUP },
 473         { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 474         { "update-index", cmd_update_index, RUN_SETUP },
 475         { "update-ref", cmd_update_ref, RUN_SETUP },
 476         { "update-server-info", cmd_update_server_info, RUN_SETUP },
 477         { "upload-archive", cmd_upload_archive },
 478         { "upload-archive--writer", cmd_upload_archive_writer },
 479         { "var", cmd_var, RUN_SETUP_GENTLY },
 480         { "verify-commit", cmd_verify_commit, RUN_SETUP },
 481         { "verify-pack", cmd_verify_pack },
 482         { "verify-tag", cmd_verify_tag, RUN_SETUP },
 483         { "version", cmd_version },
 484         { "whatchanged", cmd_whatchanged, RUN_SETUP },
 485         { "worktree", cmd_worktree, RUN_SETUP },
 486         { "write-tree", cmd_write_tree, RUN_SETUP },
 487 };
 488
 489 static struct cmd_struct *get_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 p;
 496         }
 497         return NULL;
 498 }
 499
 500 int is_builtin(const char *s)
 501 {
 502         return !!get_builtin(s);
 503 }
 504
 505 #ifdef STRIP_EXTENSION
 506 static void strip_extension(const char **argv)
 507 {
 508         size_t len;
 509
 510         if (strip_suffix(argv[0], STRIP_EXTENSION, &len))
 511                 argv[0] = xmemdupz(argv[0], len);
 512 }
 513 #else
 514 #define strip_extension(cmd)
 515 #endif
 516
 517 static void handle_builtin(int argc, const char **argv)
 518 {
 519         const char *cmd;
 520         struct cmd_struct *builtin;
 521
 522         strip_extension(argv);
 523         cmd = argv[0];
 524
 525         /* Turn "git cmd --help" into "git help cmd" */
 526         if (argc > 1 && !strcmp(argv[1], "--help")) {
 527                 argv[1] = argv[0];
 528                 argv[0] = cmd = "help";
 529         }
 530
 531         builtin = get_builtin(cmd);
 532         if (builtin) {
 533                 if (saved_environment && (builtin->option & NO_SETUP))
 534                         restore_env();
 535                 else
 536                         exit(run_builtin(builtin, argc, argv));
 537         }
 538 }
 539
 540 static void execv_dashed_external(const char **argv)
 541 {
 542         struct strbuf cmd = STRBUF_INIT;
 543         const char *tmp;
 544         int status;
 545
 546         if (use_pager == -1)
 547                 use_pager = check_pager_config(argv[0]);
 548         commit_pager_choice();
 549
 550         strbuf_addf(&cmd, "git-%s", argv[0]);
 551
 552         /*
 553          * argv[0] must be the git command, but the argv array
 554          * belongs to the caller, and may be reused in
 555          * subsequent loop iterations. Save argv[0] and
 556          * restore it on error.
 557          */
 558         tmp = argv[0];
 559         argv[0] = cmd.buf;
 560
 561         trace_argv_printf(argv, "trace: exec:");
 562
 563         /*
 564          * if we fail because the command is not found, it is
 565          * OK to return. Otherwise, we just pass along the status code.
 566          */
 567         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
 568         if (status >= 0 || errno != ENOENT)
 569                 exit(status);
 570
 571         argv[0] = tmp;
 572
 573         strbuf_release(&cmd);
 574 }
 575
 576 static int run_argv(int *argcp, const char ***argv)
 577 {
 578         int done_alias = 0;
 579
 580         while (1) {
 581                 /* See if it's a builtin */
 582                 handle_builtin(*argcp, *argv);
 583
 584                 /* .. then try the external ones */
 585                 execv_dashed_external(*argv);
 586
 587                 /* It could be an alias -- this works around the insanity
 588                  * of overriding "git log" with "git show" by having
 589                  * alias.log = show
 590                  */
 591                 if (done_alias)
 592                         break;
 593                 save_env();
 594                 if (!handle_alias(argcp, argv))
 595                         break;
 596                 done_alias = 1;
 597         }
 598
 599         return done_alias;
 600 }
 601
 602 /*
 603  * Many parts of Git have subprograms communicate via pipe, expect the
 604  * upstream of a pipe to die with SIGPIPE when the downstream of a
 605  * pipe does not need to read all that is written.  Some third-party
 606  * programs that ignore or block SIGPIPE for their own reason forget
 607  * to restore SIGPIPE handling to the default before spawning Git and
 608  * break this carefully orchestrated machinery.
 609  *
 610  * Restore the way SIGPIPE is handled to default, which is what we
 611  * expect.
 612  */
 613 static void restore_sigpipe_to_default(void)
 614 {
 615         sigset_t unblock;
 616
 617         sigemptyset(&unblock);
 618         sigaddset(&unblock, SIGPIPE);
 619         sigprocmask(SIG_UNBLOCK, &unblock, NULL);
 620         signal(SIGPIPE, SIG_DFL);
 621 }
 622
 623 int main(int argc, char **av)
 624 {
 625         const char **argv = (const char **) av;
 626         const char *cmd;
 627         int done_help = 0;
 628
 629         startup_info = &git_startup_info;
 630
 631         cmd = git_extract_argv0_path(argv[0]);
 632         if (!cmd)
 633                 cmd = "git-help";
 634
 635         /*
 636          * Always open file descriptors 0/1/2 to avoid clobbering files
 637          * in die().  It also avoids messing up when the pipes are dup'ed
 638          * onto stdin/stdout/stderr in the child processes we spawn.
 639          */
 640         sanitize_stdfds();
 641
 642         restore_sigpipe_to_default();
 643
 644         git_setup_gettext();
 645
 646         trace_command_performance(argv);
 647
 648         /*
 649          * "git-xxxx" is the same as "git xxxx", but we obviously:
 650          *
 651          *  - cannot take flags in between the "git" and the "xxxx".
 652          *  - cannot execute it externally (since it would just do
 653          *    the same thing over again)
 654          *
 655          * So we just directly call the builtin handler, and die if
 656          * that one cannot handle it.
 657          */
 658         if (skip_prefix(cmd, "git-", &cmd)) {
 659                 argv[0] = cmd;
 660                 handle_builtin(argc, argv);
 661                 die("cannot handle %s as a builtin", cmd);
 662         }
 663
 664         /* Look for flags.. */
 665         argv++;
 666         argc--;
 667         handle_options(&argv, &argc, NULL);
 668         if (argc > 0) {
 669                 /* translate --help and --version into commands */
 670                 skip_prefix(argv[0], "--", &argv[0]);
 671         } else {
 672                 /* The user didn't specify a command; give them help */
 673                 commit_pager_choice();
 674                 printf("usage: %s\n\n", git_usage_string);
 675                 list_common_cmds_help();
 676                 printf("\n%s\n", _(git_more_info_string));
 677                 exit(1);
 678         }
 679         cmd = argv[0];
 680
 681         /*
 682          * We use PATH to find git commands, but we prepend some higher
 683          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 684          * environment, and the $(gitexecdir) from the Makefile at build
 685          * time.
 686          */
 687         setup_path();
 688
 689         while (1) {
 690                 int was_alias = run_argv(&argc, &argv);
 691                 if (errno != ENOENT)
 692                         break;
 693                 if (was_alias) {
 694                         fprintf(stderr, "Expansion of alias '%s' failed; "
 695                                 "'%s' is not a git command\n",
 696                                 cmd, argv[0]);
 697                         exit(1);
 698                 }
 699                 if (!done_help) {
 700                         cmd = argv[0] = help_unknown_cmd(cmd);
 701                         done_help = 1;
 702                 } else
 703                         break;
 704         }
 705
 706         fprintf(stderr, "Failed to run command '%s': %s\n",
 707                 cmd, strerror(errno));
 708
 709         return 1;
 710 }