git.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "exec_cmd.h"
   4 #include "help.h"
   5 #include "quote.h"
   6 #include "run-command.h"
   7
   8 const char git_usage_string[] =
   9         "git [--version] [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
  10         "           [-p|--paginate|--no-pager] [--no-replace-objects] [--bare]\n"
  11         "           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
  12         "           [-c name=value] [--help]\n"
  13         "           <command> [<args>]";
  14
  15 const char git_more_info_string[] =
  16         "See 'git help <command>' for more information on a specific command.";
  17
  18 static struct startup_info git_startup_info;
  19 static int use_pager = -1;
  20 struct pager_config {
  21         const char *cmd;
  22         int want;
  23         char *value;
  24 };
  25
  26 static int pager_command_config(const char *var, const char *value, void *data)
  27 {
  28         struct pager_config *c = data;
  29         if (!prefixcmp(var, "pager.") && !strcmp(var + 6, c->cmd)) {
  30                 int b = git_config_maybe_bool(var, value);
  31                 if (b >= 0)
  32                         c->want = b;
  33                 else {
  34                         c->want = 1;
  35                         c->value = xstrdup(value);
  36                 }
  37         }
  38         return 0;
  39 }
  40
  41 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
  42 int check_pager_config(const char *cmd)
  43 {
  44         struct pager_config c;
  45         c.cmd = cmd;
  46         c.want = -1;
  47         c.value = NULL;
  48         git_config(pager_command_config, &c);
  49         if (c.value)
  50                 pager_program = c.value;
  51         return c.want;
  52 }
  53
  54 static void commit_pager_choice(void) {
  55         switch (use_pager) {
  56         case 0:
  57                 setenv("GIT_PAGER", "cat", 1);
  58                 break;
  59         case 1:
  60                 setup_pager();
  61                 break;
  62         default:
  63                 break;
  64         }
  65 }
  66
  67 static int handle_options(const char ***argv, int *argc, int *envchanged)
  68 {
  69         const char **orig_argv = *argv;
  70
  71         while (*argc > 0) {
  72                 const char *cmd = (*argv)[0];
  73                 if (cmd[0] != '-')
  74                         break;
  75
  76                 /*
  77                  * For legacy reasons, the "version" and "help"
  78                  * commands can be written with "--" prepended
  79                  * to make them look like flags.
  80                  */
  81                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
  82                         break;
  83
  84                 /*
  85                  * Check remaining flags.
  86                  */
  87                 if (!prefixcmp(cmd, "--exec-path")) {
  88                         cmd += 11;
  89                         if (*cmd == '=')
  90                                 git_set_argv_exec_path(cmd + 1);
  91                         else {
  92                                 puts(git_exec_path());
  93                                 exit(0);
  94                         }
  95                 } else if (!strcmp(cmd, "--html-path")) {
  96                         puts(system_path(GIT_HTML_PATH));
  97                         exit(0);
  98                 } else if (!strcmp(cmd, "--man-path")) {
  99                         puts(system_path(GIT_MAN_PATH));
 100                         exit(0);
 101                 } else if (!strcmp(cmd, "--info-path")) {
 102                         puts(system_path(GIT_INFO_PATH));
 103                         exit(0);
 104                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 105                         use_pager = 1;
 106                 } else if (!strcmp(cmd, "--no-pager")) {
 107                         use_pager = 0;
 108                         if (envchanged)
 109                                 *envchanged = 1;
 110                 } else if (!strcmp(cmd, "--no-replace-objects")) {
 111                         read_replace_refs = 0;
 112                         setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
 113                         if (envchanged)
 114                                 *envchanged = 1;
 115                 } else if (!strcmp(cmd, "--git-dir")) {
 116                         if (*argc < 2) {
 117                                 fprintf(stderr, "No directory given for --git-dir.\n" );
 118                                 usage(git_usage_string);
 119                         }
 120                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
 121                         if (envchanged)
 122                                 *envchanged = 1;
 123                         (*argv)++;
 124                         (*argc)--;
 125                 } else if (!prefixcmp(cmd, "--git-dir=")) {
 126                         setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
 127                         if (envchanged)
 128                                 *envchanged = 1;
 129                 } else if (!strcmp(cmd, "--namespace")) {
 130                         if (*argc < 2) {
 131                                 fprintf(stderr, "No namespace given for --namespace.\n" );
 132                                 usage(git_usage_string);
 133                         }
 134                         setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
 135                         if (envchanged)
 136                                 *envchanged = 1;
 137                         (*argv)++;
 138                         (*argc)--;
 139                 } else if (!prefixcmp(cmd, "--namespace=")) {
 140                         setenv(GIT_NAMESPACE_ENVIRONMENT, cmd + 12, 1);
 141                         if (envchanged)
 142                                 *envchanged = 1;
 143                 } else if (!strcmp(cmd, "--work-tree")) {
 144                         if (*argc < 2) {
 145                                 fprintf(stderr, "No directory given for --work-tree.\n" );
 146                                 usage(git_usage_string);
 147                         }
 148                         setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
 149                         if (envchanged)
 150                                 *envchanged = 1;
 151                         (*argv)++;
 152                         (*argc)--;
 153                 } else if (!prefixcmp(cmd, "--work-tree=")) {
 154                         setenv(GIT_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
 155                         if (envchanged)
 156                                 *envchanged = 1;
 157                 } else if (!strcmp(cmd, "--bare")) {
 158                         static char git_dir[PATH_MAX+1];
 159                         is_bare_repository_cfg = 1;
 160                         setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
 161                         if (envchanged)
 162                                 *envchanged = 1;
 163                 } else if (!strcmp(cmd, "-c")) {
 164                         if (*argc < 2) {
 165                                 fprintf(stderr, "-c expects a configuration string\n" );
 166                                 usage(git_usage_string);
 167                         }
 168                         git_config_push_parameter((*argv)[1]);
 169                         (*argv)++;
 170                         (*argc)--;
 171                 } else {
 172                         fprintf(stderr, "Unknown option: %s\n", cmd);
 173                         usage(git_usage_string);
 174                 }
 175
 176                 (*argv)++;
 177                 (*argc)--;
 178         }
 179         return (*argv) - orig_argv;
 180 }
 181
 182 static int handle_alias(int *argcp, const char ***argv)
 183 {
 184         int envchanged = 0, ret = 0, saved_errno = errno;
 185         const char *subdir;
 186         int count, option_count;
 187         const char **new_argv;
 188         const char *alias_command;
 189         char *alias_string;
 190         int unused_nongit;
 191
 192         subdir = setup_git_directory_gently(&unused_nongit);
 193
 194         alias_command = (*argv)[0];
 195         alias_string = alias_lookup(alias_command);
 196         if (alias_string) {
 197                 if (alias_string[0] == '!') {
 198                         const char **alias_argv;
 199                         int argc = *argcp, i;
 200
 201                         commit_pager_choice();
 202
 203                         /* build alias_argv */
 204                         alias_argv = xmalloc(sizeof(*alias_argv) * (argc + 1));
 205                         alias_argv[0] = alias_string + 1;
 206                         for (i = 1; i < argc; ++i)
 207                                 alias_argv[i] = (*argv)[i];
 208                         alias_argv[argc] = NULL;
 209
 210                         ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 211                         if (ret >= 0)   /* normal exit */
 212                                 exit(ret);
 213
 214                         die_errno("While expanding alias '%s': '%s'",
 215                             alias_command, alias_string + 1);
 216                 }
 217                 count = split_cmdline(alias_string, &new_argv);
 218                 if (count < 0)
 219                         die("Bad alias.%s string: %s", alias_command,
 220                             split_cmdline_strerror(count));
 221                 option_count = handle_options(&new_argv, &count, &envchanged);
 222                 if (envchanged)
 223                         die("alias '%s' changes environment variables\n"
 224                                  "You can use '!git' in the alias to do this.",
 225                                  alias_command);
 226                 memmove(new_argv - option_count, new_argv,
 227                                 count * sizeof(char *));
 228                 new_argv -= option_count;
 229
 230                 if (count < 1)
 231                         die("empty alias for %s", alias_command);
 232
 233                 if (!strcmp(alias_command, new_argv[0]))
 234                         die("recursive alias: %s", alias_command);
 235
 236                 trace_argv_printf(new_argv,
 237                                   "trace: alias expansion: %s =>",
 238                                   alias_command);
 239
 240                 new_argv = xrealloc(new_argv, sizeof(char *) *
 241                                     (count + *argcp));
 242                 /* insert after command name */
 243                 memcpy(new_argv + count, *argv + 1, sizeof(char *) * *argcp);
 244
 245                 *argv = new_argv;
 246                 *argcp += count - 1;
 247
 248                 ret = 1;
 249         }
 250
 251         if (subdir && chdir(subdir))
 252                 die_errno("Cannot change to '%s'", subdir);
 253
 254         errno = saved_errno;
 255
 256         return ret;
 257 }
 258
 259 const char git_version_string[] = GIT_VERSION;
 260
 261 #define RUN_SETUP               (1<<0)
 262 #define RUN_SETUP_GENTLY        (1<<1)
 263 #define USE_PAGER               (1<<2)
 264 /*
 265  * require working tree to be present -- anything uses this needs
 266  * RUN_SETUP for reading from the configuration file.
 267  */
 268 #define NEED_WORK_TREE          (1<<3)
 269
 270 struct cmd_struct {
 271         const char *cmd;
 272         int (*fn)(int, const char **, const char *);
 273         int option;
 274 };
 275
 276 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 277 {
 278         int status, help;
 279         struct stat st;
 280         const char *prefix;
 281
 282         prefix = NULL;
 283         help = argc == 2 && !strcmp(argv[1], "-h");
 284         if (!help) {
 285                 if (p->option & RUN_SETUP)
 286                         prefix = setup_git_directory();
 287                 if (p->option & RUN_SETUP_GENTLY) {
 288                         int nongit_ok;
 289                         prefix = setup_git_directory_gently(&nongit_ok);
 290                 }
 291
 292                 if (use_pager == -1 && p->option & (RUN_SETUP | RUN_SETUP_GENTLY))
 293                         use_pager = check_pager_config(p->cmd);
 294                 if (use_pager == -1 && p->option & USE_PAGER)
 295                         use_pager = 1;
 296
 297                 if ((p->option & (RUN_SETUP | RUN_SETUP_GENTLY)) &&
 298                     startup_info->have_repository) /* get_git_dir() may set up repo, avoid that */
 299                         trace_repo_setup(prefix);
 300         }
 301         commit_pager_choice();
 302
 303         if (!help && p->option & NEED_WORK_TREE)
 304                 setup_work_tree();
 305
 306         trace_argv_printf(argv, "trace: built-in: git");
 307
 308         status = p->fn(argc, argv, prefix);
 309         if (status)
 310                 return status;
 311
 312         /* Somebody closed stdout? */
 313         if (fstat(fileno(stdout), &st))
 314                 return 0;
 315         /* Ignore write errors for pipes and sockets.. */
 316         if (S_ISFIFO(st.st_mode) || S_ISSOCK(st.st_mode))
 317                 return 0;
 318
 319         /* Check for ENOSPC and EIO errors.. */
 320         if (fflush(stdout))
 321                 die_errno("write failure on standard output");
 322         if (ferror(stdout))
 323                 die("unknown write failure on standard output");
 324         if (fclose(stdout))
 325                 die_errno("close failed on standard output");
 326         return 0;
 327 }
 328
 329 static void handle_internal_command(int argc, const char **argv)
 330 {
 331         const char *cmd = argv[0];
 332         static struct cmd_struct commands[] = {
 333                 { "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 334                 { "annotate", cmd_annotate, RUN_SETUP },
 335                 { "apply", cmd_apply, RUN_SETUP_GENTLY },
 336                 { "archive", cmd_archive },
 337                 { "bisect--helper", cmd_bisect__helper, RUN_SETUP },
 338                 { "blame", cmd_blame, RUN_SETUP },
 339                 { "branch", cmd_branch, RUN_SETUP },
 340                 { "bundle", cmd_bundle, RUN_SETUP_GENTLY },
 341                 { "cat-file", cmd_cat_file, RUN_SETUP },
 342                 { "check-attr", cmd_check_attr, RUN_SETUP },
 343                 { "check-ref-format", cmd_check_ref_format },
 344                 { "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 345                 { "checkout-index", cmd_checkout_index,
 346                         RUN_SETUP | NEED_WORK_TREE},
 347                 { "cherry", cmd_cherry, RUN_SETUP },
 348                 { "cherry-pick", cmd_cherry_pick, RUN_SETUP | NEED_WORK_TREE },
 349                 { "clean", cmd_clean, RUN_SETUP | NEED_WORK_TREE },
 350                 { "clone", cmd_clone },
 351                 { "commit", cmd_commit, RUN_SETUP | NEED_WORK_TREE },
 352                 { "commit-tree", cmd_commit_tree, RUN_SETUP },
 353                 { "config", cmd_config, RUN_SETUP_GENTLY },
 354                 { "count-objects", cmd_count_objects, RUN_SETUP },
 355                 { "describe", cmd_describe, RUN_SETUP },
 356                 { "diff", cmd_diff },
 357                 { "diff-files", cmd_diff_files, RUN_SETUP | NEED_WORK_TREE },
 358                 { "diff-index", cmd_diff_index, RUN_SETUP },
 359                 { "diff-tree", cmd_diff_tree, RUN_SETUP },
 360                 { "fast-export", cmd_fast_export, RUN_SETUP },
 361                 { "fetch", cmd_fetch, RUN_SETUP },
 362                 { "fetch-pack", cmd_fetch_pack, RUN_SETUP },
 363                 { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
 364                 { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
 365                 { "format-patch", cmd_format_patch, RUN_SETUP },
 366                 { "fsck", cmd_fsck, RUN_SETUP },
 367                 { "fsck-objects", cmd_fsck, RUN_SETUP },
 368                 { "gc", cmd_gc, RUN_SETUP },
 369                 { "get-tar-commit-id", cmd_get_tar_commit_id },
 370                 { "grep", cmd_grep, RUN_SETUP_GENTLY },
 371                 { "hash-object", cmd_hash_object },
 372                 { "help", cmd_help },
 373                 { "index-pack", cmd_index_pack, RUN_SETUP_GENTLY },
 374                 { "init", cmd_init_db },
 375                 { "init-db", cmd_init_db },
 376                 { "log", cmd_log, RUN_SETUP },
 377                 { "ls-files", cmd_ls_files, RUN_SETUP },
 378                 { "ls-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 379                 { "ls-tree", cmd_ls_tree, RUN_SETUP },
 380                 { "mailinfo", cmd_mailinfo },
 381                 { "mailsplit", cmd_mailsplit },
 382                 { "merge", cmd_merge, RUN_SETUP | NEED_WORK_TREE },
 383                 { "merge-base", cmd_merge_base, RUN_SETUP },
 384                 { "merge-file", cmd_merge_file, RUN_SETUP_GENTLY },
 385                 { "merge-index", cmd_merge_index, RUN_SETUP },
 386                 { "merge-ours", cmd_merge_ours, RUN_SETUP },
 387                 { "merge-recursive", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 388                 { "merge-recursive-ours", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 389                 { "merge-recursive-theirs", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 390                 { "merge-subtree", cmd_merge_recursive, RUN_SETUP | NEED_WORK_TREE },
 391                 { "merge-tree", cmd_merge_tree, RUN_SETUP },
 392                 { "mktag", cmd_mktag, RUN_SETUP },
 393                 { "mktree", cmd_mktree, RUN_SETUP },
 394                 { "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 395                 { "name-rev", cmd_name_rev, RUN_SETUP },
 396                 { "notes", cmd_notes, RUN_SETUP },
 397                 { "pack-objects", cmd_pack_objects, RUN_SETUP },
 398                 { "pack-redundant", cmd_pack_redundant, RUN_SETUP },
 399                 { "pack-refs", cmd_pack_refs, RUN_SETUP },
 400                 { "patch-id", cmd_patch_id },
 401                 { "peek-remote", cmd_ls_remote, RUN_SETUP_GENTLY },
 402                 { "pickaxe", cmd_blame, RUN_SETUP },
 403                 { "prune", cmd_prune, RUN_SETUP },
 404                 { "prune-packed", cmd_prune_packed, RUN_SETUP },
 405                 { "push", cmd_push, RUN_SETUP },
 406                 { "read-tree", cmd_read_tree, RUN_SETUP },
 407                 { "receive-pack", cmd_receive_pack },
 408                 { "reflog", cmd_reflog, RUN_SETUP },
 409                 { "remote", cmd_remote, RUN_SETUP },
 410                 { "remote-ext", cmd_remote_ext },
 411                 { "remote-fd", cmd_remote_fd },
 412                 { "replace", cmd_replace, RUN_SETUP },
 413                 { "repo-config", cmd_repo_config, RUN_SETUP_GENTLY },
 414                 { "rerere", cmd_rerere, RUN_SETUP },
 415                 { "reset", cmd_reset, RUN_SETUP },
 416                 { "rev-list", cmd_rev_list, RUN_SETUP },
 417                 { "rev-parse", cmd_rev_parse },
 418                 { "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
 419                 { "rm", cmd_rm, RUN_SETUP },
 420                 { "send-pack", cmd_send_pack, RUN_SETUP },
 421                 { "shortlog", cmd_shortlog, RUN_SETUP_GENTLY | USE_PAGER },
 422                 { "show", cmd_show, RUN_SETUP },
 423                 { "show-branch", cmd_show_branch, RUN_SETUP },
 424                 { "show-ref", cmd_show_ref, RUN_SETUP },
 425                 { "stage", cmd_add, RUN_SETUP | NEED_WORK_TREE },
 426                 { "status", cmd_status, RUN_SETUP | NEED_WORK_TREE },
 427                 { "stripspace", cmd_stripspace },
 428                 { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
 429                 { "tag", cmd_tag, RUN_SETUP },
 430                 { "tar-tree", cmd_tar_tree },
 431                 { "unpack-file", cmd_unpack_file, RUN_SETUP },
 432                 { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
 433                 { "update-index", cmd_update_index, RUN_SETUP },
 434                 { "update-ref", cmd_update_ref, RUN_SETUP },
 435                 { "update-server-info", cmd_update_server_info, RUN_SETUP },
 436                 { "upload-archive", cmd_upload_archive },
 437                 { "var", cmd_var, RUN_SETUP_GENTLY },
 438                 { "verify-pack", cmd_verify_pack },
 439                 { "verify-tag", cmd_verify_tag, RUN_SETUP },
 440                 { "version", cmd_version },
 441                 { "whatchanged", cmd_whatchanged, RUN_SETUP },
 442                 { "write-tree", cmd_write_tree, RUN_SETUP },
 443         };
 444         int i;
 445         static const char ext[] = STRIP_EXTENSION;
 446
 447         if (sizeof(ext) > 1) {
 448                 i = strlen(argv[0]) - strlen(ext);
 449                 if (i > 0 && !strcmp(argv[0] + i, ext)) {
 450                         char *argv0 = xstrdup(argv[0]);
 451                         argv[0] = cmd = argv0;
 452                         argv0[i] = '\0';
 453                 }
 454         }
 455
 456         /* Turn "git cmd --help" into "git help cmd" */
 457         if (argc > 1 && !strcmp(argv[1], "--help")) {
 458                 argv[1] = argv[0];
 459                 argv[0] = cmd = "help";
 460         }
 461
 462         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 463                 struct cmd_struct *p = commands+i;
 464                 if (strcmp(p->cmd, cmd))
 465                         continue;
 466                 exit(run_builtin(p, argc, argv));
 467         }
 468 }
 469
 470 static void execv_dashed_external(const char **argv)
 471 {
 472         struct strbuf cmd = STRBUF_INIT;
 473         const char *tmp;
 474         int status;
 475
 476         if (use_pager == -1)
 477                 use_pager = check_pager_config(argv[0]);
 478         commit_pager_choice();
 479
 480         strbuf_addf(&cmd, "git-%s", argv[0]);
 481
 482         /*
 483          * argv[0] must be the git command, but the argv array
 484          * belongs to the caller, and may be reused in
 485          * subsequent loop iterations. Save argv[0] and
 486          * restore it on error.
 487          */
 488         tmp = argv[0];
 489         argv[0] = cmd.buf;
 490
 491         trace_argv_printf(argv, "trace: exec:");
 492
 493         /*
 494          * if we fail because the command is not found, it is
 495          * OK to return. Otherwise, we just pass along the status code.
 496          */
 497         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
 498         if (status >= 0 || errno != ENOENT)
 499                 exit(status);
 500
 501         argv[0] = tmp;
 502
 503         strbuf_release(&cmd);
 504 }
 505
 506 static int run_argv(int *argcp, const char ***argv)
 507 {
 508         int done_alias = 0;
 509
 510         while (1) {
 511                 /* See if it's an internal command */
 512                 handle_internal_command(*argcp, *argv);
 513
 514                 /* .. then try the external ones */
 515                 execv_dashed_external(*argv);
 516
 517                 /* It could be an alias -- this works around the insanity
 518                  * of overriding "git log" with "git show" by having
 519                  * alias.log = show
 520                  */
 521                 if (done_alias || !handle_alias(argcp, argv))
 522                         break;
 523                 done_alias = 1;
 524         }
 525
 526         return done_alias;
 527 }
 528
 529
 530 int main(int argc, const char **argv)
 531 {
 532         const char *cmd;
 533
 534         startup_info = &git_startup_info;
 535
 536         cmd = git_extract_argv0_path(argv[0]);
 537         if (!cmd)
 538                 cmd = "git-help";
 539
 540         /*
 541          * "git-xxxx" is the same as "git xxxx", but we obviously:
 542          *
 543          *  - cannot take flags in between the "git" and the "xxxx".
 544          *  - cannot execute it externally (since it would just do
 545          *    the same thing over again)
 546          *
 547          * So we just directly call the internal command handler, and
 548          * die if that one cannot handle it.
 549          */
 550         if (!prefixcmp(cmd, "git-")) {
 551                 cmd += 4;
 552                 argv[0] = cmd;
 553                 handle_internal_command(argc, argv);
 554                 die("cannot handle %s internally", cmd);
 555         }
 556
 557         /* Look for flags.. */
 558         argv++;
 559         argc--;
 560         handle_options(&argv, &argc, NULL);
 561         if (argc > 0) {
 562                 if (!prefixcmp(argv[0], "--"))
 563                         argv[0] += 2;
 564         } else {
 565                 /* The user didn't specify a command; give them help */
 566                 commit_pager_choice();
 567                 printf("usage: %s\n\n", git_usage_string);
 568                 list_common_cmds_help();
 569                 printf("\n%s\n", git_more_info_string);
 570                 exit(1);
 571         }
 572         cmd = argv[0];
 573
 574         /*
 575          * We use PATH to find git commands, but we prepend some higher
 576          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
 577          * environment, and the $(gitexecdir) from the Makefile at build
 578          * time.
 579          */
 580         setup_path();
 581
 582         while (1) {
 583                 static int done_help = 0;
 584                 static int was_alias = 0;
 585                 was_alias = run_argv(&argc, &argv);
 586                 if (errno != ENOENT)
 587                         break;
 588                 if (was_alias) {
 589                         fprintf(stderr, "Expansion of alias '%s' failed; "
 590                                 "'%s' is not a git command\n",
 591                                 cmd, argv[0]);
 592                         exit(1);
 593                 }
 594                 if (!done_help) {
 595                         cmd = argv[0] = help_unknown_cmd(cmd);
 596                         done_help = 1;
 597                 } else
 598                         break;
 599         }
 600
 601         fprintf(stderr, "Failed to run command '%s': %s\n",
 602                 cmd, strerror(errno));
 603
 604         return 1;
 605 }