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