Merge branch 'jc/makefile-redirection-stderr' into maint
[git] / 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 int use_pager = -1;
19 static char *orig_cwd;
20 static const char *env_names[] = {
21         GIT_DIR_ENVIRONMENT,
22         GIT_WORK_TREE_ENVIRONMENT,
23         GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
24         GIT_PREFIX_ENVIRONMENT
25 };
26 static char *orig_env[4];
27 static int save_restore_env_balance;
28
29 static void save_env_before_alias(void)
30 {
31         int i;
32
33         assert(save_restore_env_balance == 0);
34         save_restore_env_balance = 1;
35         orig_cwd = xgetcwd();
36         for (i = 0; i < ARRAY_SIZE(env_names); i++) {
37                 orig_env[i] = getenv(env_names[i]);
38                 if (orig_env[i])
39                         orig_env[i] = xstrdup(orig_env[i]);
40         }
41 }
42
43 static void restore_env(int external_alias)
44 {
45         int i;
46
47         assert(save_restore_env_balance == 1);
48         save_restore_env_balance = 0;
49         if (!external_alias && orig_cwd && chdir(orig_cwd))
50                 die_errno("could not move to %s", orig_cwd);
51         free(orig_cwd);
52         for (i = 0; i < ARRAY_SIZE(env_names); i++) {
53                 if (external_alias &&
54                     !strcmp(env_names[i], GIT_PREFIX_ENVIRONMENT))
55                         continue;
56                 if (orig_env[i]) {
57                         setenv(env_names[i], orig_env[i], 1);
58                         free(orig_env[i]);
59                 } else {
60                         unsetenv(env_names[i]);
61                 }
62         }
63 }
64
65 static void commit_pager_choice(void) {
66         switch (use_pager) {
67         case 0:
68                 setenv("GIT_PAGER", "cat", 1);
69                 break;
70         case 1:
71                 setup_pager();
72                 break;
73         default:
74                 break;
75         }
76 }
77
78 static int handle_options(const char ***argv, int *argc, int *envchanged)
79 {
80         const char **orig_argv = *argv;
81
82         while (*argc > 0) {
83                 const char *cmd = (*argv)[0];
84                 if (cmd[0] != '-')
85                         break;
86
87                 /*
88                  * For legacy reasons, the "version" and "help"
89                  * commands can be written with "--" prepended
90                  * to make them look like flags.
91                  */
92                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
93                         break;
94
95                 /*
96                  * Check remaining flags.
97                  */
98                 if (skip_prefix(cmd, "--exec-path", &cmd)) {
99                         if (*cmd == '=')
100                                 git_set_argv_exec_path(cmd + 1);
101                         else {
102                                 puts(git_exec_path());
103                                 exit(0);
104                         }
105                 } else if (!strcmp(cmd, "--html-path")) {
106                         puts(system_path(GIT_HTML_PATH));
107                         exit(0);
108                 } else if (!strcmp(cmd, "--man-path")) {
109                         puts(system_path(GIT_MAN_PATH));
110                         exit(0);
111                 } else if (!strcmp(cmd, "--info-path")) {
112                         puts(system_path(GIT_INFO_PATH));
113                         exit(0);
114                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
115                         use_pager = 1;
116                 } else if (!strcmp(cmd, "--no-pager")) {
117                         use_pager = 0;
118                         if (envchanged)
119                                 *envchanged = 1;
120                 } else if (!strcmp(cmd, "--no-replace-objects")) {
121                         check_replace_refs = 0;
122                         setenv(NO_REPLACE_OBJECTS_ENVIRONMENT, "1", 1);
123                         if (envchanged)
124                                 *envchanged = 1;
125                 } else if (!strcmp(cmd, "--git-dir")) {
126                         if (*argc < 2) {
127                                 fprintf(stderr, "No directory given for --git-dir.\n" );
128                                 usage(git_usage_string);
129                         }
130                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
131                         if (envchanged)
132                                 *envchanged = 1;
133                         (*argv)++;
134                         (*argc)--;
135                 } else if (skip_prefix(cmd, "--git-dir=", &cmd)) {
136                         setenv(GIT_DIR_ENVIRONMENT, cmd, 1);
137                         if (envchanged)
138                                 *envchanged = 1;
139                 } else if (!strcmp(cmd, "--namespace")) {
140                         if (*argc < 2) {
141                                 fprintf(stderr, "No namespace given for --namespace.\n" );
142                                 usage(git_usage_string);
143                         }
144                         setenv(GIT_NAMESPACE_ENVIRONMENT, (*argv)[1], 1);
145                         if (envchanged)
146                                 *envchanged = 1;
147                         (*argv)++;
148                         (*argc)--;
149                 } else if (skip_prefix(cmd, "--namespace=", &cmd)) {
150                         setenv(GIT_NAMESPACE_ENVIRONMENT, cmd, 1);
151                         if (envchanged)
152                                 *envchanged = 1;
153                 } else if (!strcmp(cmd, "--work-tree")) {
154                         if (*argc < 2) {
155                                 fprintf(stderr, "No directory given for --work-tree.\n" );
156                                 usage(git_usage_string);
157                         }
158                         setenv(GIT_WORK_TREE_ENVIRONMENT, (*argv)[1], 1);
159                         if (envchanged)
160                                 *envchanged = 1;
161                         (*argv)++;
162                         (*argc)--;
163                 } else if (skip_prefix(cmd, "--work-tree=", &cmd)) {
164                         setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
165                         if (envchanged)
166                                 *envchanged = 1;
167                 } else if (!strcmp(cmd, "--bare")) {
168                         char *cwd = xgetcwd();
169                         is_bare_repository_cfg = 1;
170                         setenv(GIT_DIR_ENVIRONMENT, cwd, 0);
171                         free(cwd);
172                         setenv(GIT_IMPLICIT_WORK_TREE_ENVIRONMENT, "0", 1);
173                         if (envchanged)
174                                 *envchanged = 1;
175                 } else if (!strcmp(cmd, "-c")) {
176                         if (*argc < 2) {
177                                 fprintf(stderr, "-c expects a configuration string\n" );
178                                 usage(git_usage_string);
179                         }
180                         git_config_push_parameter((*argv)[1]);
181                         (*argv)++;
182                         (*argc)--;
183                 } else if (!strcmp(cmd, "--literal-pathspecs")) {
184                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "1", 1);
185                         if (envchanged)
186                                 *envchanged = 1;
187                 } else if (!strcmp(cmd, "--no-literal-pathspecs")) {
188                         setenv(GIT_LITERAL_PATHSPECS_ENVIRONMENT, "0", 1);
189                         if (envchanged)
190                                 *envchanged = 1;
191                 } else if (!strcmp(cmd, "--glob-pathspecs")) {
192                         setenv(GIT_GLOB_PATHSPECS_ENVIRONMENT, "1", 1);
193                         if (envchanged)
194                                 *envchanged = 1;
195                 } else if (!strcmp(cmd, "--noglob-pathspecs")) {
196                         setenv(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, "1", 1);
197                         if (envchanged)
198                                 *envchanged = 1;
199                 } else if (!strcmp(cmd, "--icase-pathspecs")) {
200                         setenv(GIT_ICASE_PATHSPECS_ENVIRONMENT, "1", 1);
201                         if (envchanged)
202                                 *envchanged = 1;
203                 } else if (!strcmp(cmd, "--shallow-file")) {
204                         (*argv)++;
205                         (*argc)--;
206                         set_alternate_shallow_file((*argv)[0], 1);
207                         if (envchanged)
208                                 *envchanged = 1;
209                 } else if (!strcmp(cmd, "-C")) {
210                         if (*argc < 2) {
211                                 fprintf(stderr, "No directory given for -C.\n" );
212                                 usage(git_usage_string);
213                         }
214                         if ((*argv)[1][0]) {
215                                 if (chdir((*argv)[1]))
216                                         die_errno("Cannot change to '%s'", (*argv)[1]);
217                                 if (envchanged)
218                                         *envchanged = 1;
219                         }
220                         (*argv)++;
221                         (*argc)--;
222                 } else {
223                         fprintf(stderr, "Unknown option: %s\n", cmd);
224                         usage(git_usage_string);
225                 }
226
227                 (*argv)++;
228                 (*argc)--;
229         }
230         return (*argv) - orig_argv;
231 }
232
233 static int handle_alias(int *argcp, const char ***argv)
234 {
235         int envchanged = 0, ret = 0, saved_errno = errno;
236         int count, option_count;
237         const char **new_argv;
238         const char *alias_command;
239         char *alias_string;
240         int unused_nongit;
241
242         save_env_before_alias();
243         setup_git_directory_gently(&unused_nongit);
244
245         alias_command = (*argv)[0];
246         alias_string = alias_lookup(alias_command);
247         if (alias_string) {
248                 if (alias_string[0] == '!') {
249                         struct child_process child = CHILD_PROCESS_INIT;
250
251                         commit_pager_choice();
252                         restore_env(1);
253
254                         child.use_shell = 1;
255                         argv_array_push(&child.args, alias_string + 1);
256                         argv_array_pushv(&child.args, (*argv) + 1);
257
258                         ret = run_command(&child);
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 #ifdef STRIP_EXTENSION
512 static void strip_extension(const char **argv)
513 {
514         size_t len;
515
516         if (strip_suffix(argv[0], STRIP_EXTENSION, &len))
517                 argv[0] = xmemdupz(argv[0], len);
518 }
519 #else
520 #define strip_extension(cmd)
521 #endif
522
523 static void handle_builtin(int argc, const char **argv)
524 {
525         const char *cmd;
526         struct cmd_struct *builtin;
527
528         strip_extension(argv);
529         cmd = argv[0];
530
531         /* Turn "git cmd --help" into "git help cmd" */
532         if (argc > 1 && !strcmp(argv[1], "--help")) {
533                 argv[1] = argv[0];
534                 argv[0] = cmd = "help";
535         }
536
537         builtin = get_builtin(cmd);
538         if (builtin)
539                 exit(run_builtin(builtin, argc, argv));
540 }
541
542 static void execv_dashed_external(const char **argv)
543 {
544         struct strbuf cmd = STRBUF_INIT;
545         const char *tmp;
546         int status;
547
548         if (use_pager == -1)
549                 use_pager = check_pager_config(argv[0]);
550         commit_pager_choice();
551
552         strbuf_addf(&cmd, "git-%s", argv[0]);
553
554         /*
555          * argv[0] must be the git command, but the argv array
556          * belongs to the caller, and may be reused in
557          * subsequent loop iterations. Save argv[0] and
558          * restore it on error.
559          */
560         tmp = argv[0];
561         argv[0] = cmd.buf;
562
563         trace_argv_printf(argv, "trace: exec:");
564
565         /*
566          * if we fail because the command is not found, it is
567          * OK to return. Otherwise, we just pass along the status code.
568          */
569         status = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE | RUN_CLEAN_ON_EXIT);
570         if (status >= 0 || errno != ENOENT)
571                 exit(status);
572
573         argv[0] = tmp;
574
575         strbuf_release(&cmd);
576 }
577
578 static int run_argv(int *argcp, const char ***argv)
579 {
580         int done_alias = 0;
581
582         while (1) {
583                 /*
584                  * If we tried alias and futzed with our environment,
585                  * it no longer is safe to invoke builtins directly in
586                  * general.  We have to spawn them as dashed externals.
587                  *
588                  * NEEDSWORK: if we can figure out cases
589                  * where it is safe to do, we can avoid spawning a new
590                  * process.
591                  */
592                 if (!done_alias)
593                         handle_builtin(*argcp, *argv);
594
595                 /* .. then try the external ones */
596                 execv_dashed_external(*argv);
597
598                 /* It could be an alias -- this works around the insanity
599                  * of overriding "git log" with "git show" by having
600                  * alias.log = show
601                  */
602                 if (done_alias)
603                         break;
604                 if (!handle_alias(argcp, argv))
605                         break;
606                 done_alias = 1;
607         }
608
609         return done_alias;
610 }
611
612 /*
613  * Many parts of Git have subprograms communicate via pipe, expect the
614  * upstream of a pipe to die with SIGPIPE when the downstream of a
615  * pipe does not need to read all that is written.  Some third-party
616  * programs that ignore or block SIGPIPE for their own reason forget
617  * to restore SIGPIPE handling to the default before spawning Git and
618  * break this carefully orchestrated machinery.
619  *
620  * Restore the way SIGPIPE is handled to default, which is what we
621  * expect.
622  */
623 static void restore_sigpipe_to_default(void)
624 {
625         sigset_t unblock;
626
627         sigemptyset(&unblock);
628         sigaddset(&unblock, SIGPIPE);
629         sigprocmask(SIG_UNBLOCK, &unblock, NULL);
630         signal(SIGPIPE, SIG_DFL);
631 }
632
633 int main(int argc, char **av)
634 {
635         const char **argv = (const char **) av;
636         const char *cmd;
637         int done_help = 0;
638
639         cmd = git_extract_argv0_path(argv[0]);
640         if (!cmd)
641                 cmd = "git-help";
642
643         /*
644          * Always open file descriptors 0/1/2 to avoid clobbering files
645          * in die().  It also avoids messing up when the pipes are dup'ed
646          * onto stdin/stdout/stderr in the child processes we spawn.
647          */
648         sanitize_stdfds();
649
650         restore_sigpipe_to_default();
651
652         git_setup_gettext();
653
654         trace_command_performance(argv);
655
656         /*
657          * "git-xxxx" is the same as "git xxxx", but we obviously:
658          *
659          *  - cannot take flags in between the "git" and the "xxxx".
660          *  - cannot execute it externally (since it would just do
661          *    the same thing over again)
662          *
663          * So we just directly call the builtin handler, and die if
664          * that one cannot handle it.
665          */
666         if (skip_prefix(cmd, "git-", &cmd)) {
667                 argv[0] = cmd;
668                 handle_builtin(argc, argv);
669                 die("cannot handle %s as a builtin", cmd);
670         }
671
672         /* Look for flags.. */
673         argv++;
674         argc--;
675         handle_options(&argv, &argc, NULL);
676         if (argc > 0) {
677                 /* translate --help and --version into commands */
678                 skip_prefix(argv[0], "--", &argv[0]);
679         } else {
680                 /* The user didn't specify a command; give them help */
681                 commit_pager_choice();
682                 printf("usage: %s\n\n", git_usage_string);
683                 list_common_cmds_help();
684                 printf("\n%s\n", _(git_more_info_string));
685                 exit(1);
686         }
687         cmd = argv[0];
688
689         /*
690          * We use PATH to find git commands, but we prepend some higher
691          * precedence paths: the "--exec-path" option, the GIT_EXEC_PATH
692          * environment, and the $(gitexecdir) from the Makefile at build
693          * time.
694          */
695         setup_path();
696
697         while (1) {
698                 int was_alias = run_argv(&argc, &argv);
699                 if (errno != ENOENT)
700                         break;
701                 if (was_alias) {
702                         fprintf(stderr, "Expansion of alias '%s' failed; "
703                                 "'%s' is not a git command\n",
704                                 cmd, argv[0]);
705                         exit(1);
706                 }
707                 if (!done_help) {
708                         cmd = argv[0] = help_unknown_cmd(cmd);
709                         done_help = 1;
710                 } else
711                         break;
712         }
713
714         fprintf(stderr, "Failed to run command '%s': %s\n",
715                 cmd, strerror(errno));
716
717         return 1;
718 }