user-manual: add "quick start" as chapter 1
[git] / git.c
1 #include "builtin.h"
2 #include "exec_cmd.h"
3 #include "cache.h"
4 #include "quote.h"
5
6 const char git_usage_string[] =
7         "git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate] [--bare] [--git-dir=GIT_DIR] [--help] COMMAND [ARGS]";
8
9 static void prepend_to_path(const char *dir, int len)
10 {
11         const char *old_path = getenv("PATH");
12         char *path;
13         int path_len = len;
14
15         if (!old_path)
16                 old_path = "/usr/local/bin:/usr/bin:/bin";
17
18         path_len = len + strlen(old_path) + 1;
19
20         path = xmalloc(path_len + 1);
21
22         memcpy(path, dir, len);
23         path[len] = ':';
24         memcpy(path + len + 1, old_path, path_len - len);
25
26         setenv("PATH", path, 1);
27
28         free(path);
29 }
30
31 static int handle_options(const char*** argv, int* argc)
32 {
33         int handled = 0;
34
35         while (*argc > 0) {
36                 const char *cmd = (*argv)[0];
37                 if (cmd[0] != '-')
38                         break;
39
40                 /*
41                  * For legacy reasons, the "version" and "help"
42                  * commands can be written with "--" prepended
43                  * to make them look like flags.
44                  */
45                 if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
46                         break;
47
48                 /*
49                  * Check remaining flags.
50                  */
51                 if (!strncmp(cmd, "--exec-path", 11)) {
52                         cmd += 11;
53                         if (*cmd == '=')
54                                 git_set_exec_path(cmd + 1);
55                         else {
56                                 puts(git_exec_path());
57                                 exit(0);
58                         }
59                 } else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
60                         setup_pager();
61                 } else if (!strcmp(cmd, "--git-dir")) {
62                         if (*argc < 2) {
63                                 fprintf(stderr, "No directory given for --git-dir.\n" );
64                                 usage(git_usage_string);
65                         }
66                         setenv(GIT_DIR_ENVIRONMENT, (*argv)[1], 1);
67                         (*argv)++;
68                         (*argc)--;
69                 } else if (!strncmp(cmd, "--git-dir=", 10)) {
70                         setenv(GIT_DIR_ENVIRONMENT, cmd + 10, 1);
71                 } else if (!strcmp(cmd, "--bare")) {
72                         static char git_dir[PATH_MAX+1];
73                         setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 1);
74                 } else {
75                         fprintf(stderr, "Unknown option: %s\n", cmd);
76                         usage(git_usage_string);
77                 }
78
79                 (*argv)++;
80                 (*argc)--;
81                 handled++;
82         }
83         return handled;
84 }
85
86 static const char *alias_command;
87 static char *alias_string;
88
89 static int git_alias_config(const char *var, const char *value)
90 {
91         if (!strncmp(var, "alias.", 6) && !strcmp(var + 6, alias_command)) {
92                 alias_string = xstrdup(value);
93         }
94         return 0;
95 }
96
97 static int split_cmdline(char *cmdline, const char ***argv)
98 {
99         int src, dst, count = 0, size = 16;
100         char quoted = 0;
101
102         *argv = malloc(sizeof(char*) * size);
103
104         /* split alias_string */
105         (*argv)[count++] = cmdline;
106         for (src = dst = 0; cmdline[src];) {
107                 char c = cmdline[src];
108                 if (!quoted && isspace(c)) {
109                         cmdline[dst++] = 0;
110                         while (cmdline[++src]
111                                         && isspace(cmdline[src]))
112                                 ; /* skip */
113                         if (count >= size) {
114                                 size += 16;
115                                 *argv = xrealloc(*argv, sizeof(char*) * size);
116                         }
117                         (*argv)[count++] = cmdline + dst;
118                 } else if(!quoted && (c == '\'' || c == '"')) {
119                         quoted = c;
120                         src++;
121                 } else if (c == quoted) {
122                         quoted = 0;
123                         src++;
124                 } else {
125                         if (c == '\\' && quoted != '\'') {
126                                 src++;
127                                 c = cmdline[src];
128                                 if (!c) {
129                                         free(*argv);
130                                         *argv = NULL;
131                                         return error("cmdline ends with \\");
132                                 }
133                         }
134                         cmdline[dst++] = c;
135                         src++;
136                 }
137         }
138
139         cmdline[dst] = 0;
140
141         if (quoted) {
142                 free(*argv);
143                 *argv = NULL;
144                 return error("unclosed quote");
145         }
146
147         return count;
148 }
149
150 static int handle_alias(int *argcp, const char ***argv)
151 {
152         int nongit = 0, ret = 0, saved_errno = errno;
153         const char *subdir;
154         int count, option_count;
155         const char** new_argv;
156
157         subdir = setup_git_directory_gently(&nongit);
158
159         alias_command = (*argv)[0];
160         git_config(git_alias_config);
161         if (alias_string) {
162                 count = split_cmdline(alias_string, &new_argv);
163                 option_count = handle_options(&new_argv, &count);
164                 memmove(new_argv - option_count, new_argv,
165                                 count * sizeof(char *));
166                 new_argv -= option_count;
167
168                 if (count < 1)
169                         die("empty alias for %s", alias_command);
170
171                 if (!strcmp(alias_command, new_argv[0]))
172                         die("recursive alias: %s", alias_command);
173
174                 trace_argv_printf(new_argv, count,
175                                   "trace: alias expansion: %s =>",
176                                   alias_command);
177
178                 new_argv = xrealloc(new_argv, sizeof(char*) *
179                                     (count + *argcp + 1));
180                 /* insert after command name */
181                 memcpy(new_argv + count, *argv + 1, sizeof(char*) * *argcp);
182                 new_argv[count+*argcp] = NULL;
183
184                 *argv = new_argv;
185                 *argcp += count - 1;
186
187                 ret = 1;
188         }
189
190         if (subdir)
191                 chdir(subdir);
192
193         errno = saved_errno;
194
195         return ret;
196 }
197
198 const char git_version_string[] = GIT_VERSION;
199
200 #define RUN_SETUP       (1<<0)
201 #define USE_PAGER       (1<<1)
202 /*
203  * require working tree to be present -- anything uses this needs
204  * RUN_SETUP for reading from the configuration file.
205  */
206 #define NOT_BARE        (1<<2)
207
208 static void handle_internal_command(int argc, const char **argv, char **envp)
209 {
210         const char *cmd = argv[0];
211         static struct cmd_struct {
212                 const char *cmd;
213                 int (*fn)(int, const char **, const char *);
214                 int option;
215         } commands[] = {
216                 { "add", cmd_add, RUN_SETUP | NOT_BARE },
217                 { "annotate", cmd_annotate, },
218                 { "apply", cmd_apply },
219                 { "archive", cmd_archive },
220                 { "blame", cmd_blame, RUN_SETUP | USE_PAGER },
221                 { "branch", cmd_branch, RUN_SETUP },
222                 { "cat-file", cmd_cat_file, RUN_SETUP },
223                 { "checkout-index", cmd_checkout_index, RUN_SETUP },
224                 { "check-ref-format", cmd_check_ref_format },
225                 { "cherry", cmd_cherry, RUN_SETUP },
226                 { "commit-tree", cmd_commit_tree, RUN_SETUP },
227                 { "count-objects", cmd_count_objects, RUN_SETUP },
228                 { "describe", cmd_describe, RUN_SETUP },
229                 { "diff", cmd_diff, RUN_SETUP | USE_PAGER },
230                 { "diff-files", cmd_diff_files, RUN_SETUP },
231                 { "diff-index", cmd_diff_index, RUN_SETUP },
232                 { "diff-stages", cmd_diff_stages, RUN_SETUP },
233                 { "diff-tree", cmd_diff_tree, RUN_SETUP },
234                 { "fmt-merge-msg", cmd_fmt_merge_msg, RUN_SETUP },
235                 { "for-each-ref", cmd_for_each_ref, RUN_SETUP },
236                 { "format-patch", cmd_format_patch, RUN_SETUP },
237                 { "get-tar-commit-id", cmd_get_tar_commit_id },
238                 { "grep", cmd_grep, RUN_SETUP },
239                 { "help", cmd_help },
240                 { "init", cmd_init_db },
241                 { "init-db", cmd_init_db },
242                 { "log", cmd_log, RUN_SETUP | USE_PAGER },
243                 { "ls-files", cmd_ls_files, RUN_SETUP },
244                 { "ls-tree", cmd_ls_tree, RUN_SETUP },
245                 { "mailinfo", cmd_mailinfo },
246                 { "mailsplit", cmd_mailsplit },
247                 { "merge-file", cmd_merge_file },
248                 { "mv", cmd_mv, RUN_SETUP | NOT_BARE },
249                 { "name-rev", cmd_name_rev, RUN_SETUP },
250                 { "pack-objects", cmd_pack_objects, RUN_SETUP },
251                 { "pickaxe", cmd_blame, RUN_SETUP | USE_PAGER },
252                 { "prune", cmd_prune, RUN_SETUP },
253                 { "prune-packed", cmd_prune_packed, RUN_SETUP },
254                 { "push", cmd_push, RUN_SETUP },
255                 { "read-tree", cmd_read_tree, RUN_SETUP },
256                 { "reflog", cmd_reflog, RUN_SETUP },
257                 { "repo-config", cmd_repo_config },
258                 { "rerere", cmd_rerere, RUN_SETUP },
259                 { "rev-list", cmd_rev_list, RUN_SETUP },
260                 { "rev-parse", cmd_rev_parse, RUN_SETUP },
261                 { "rm", cmd_rm, RUN_SETUP | NOT_BARE },
262                 { "runstatus", cmd_runstatus, RUN_SETUP | NOT_BARE },
263                 { "shortlog", cmd_shortlog, RUN_SETUP | USE_PAGER },
264                 { "show-branch", cmd_show_branch, RUN_SETUP },
265                 { "show", cmd_show, RUN_SETUP | USE_PAGER },
266                 { "stripspace", cmd_stripspace },
267                 { "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
268                 { "tar-tree", cmd_tar_tree },
269                 { "unpack-objects", cmd_unpack_objects, RUN_SETUP },
270                 { "update-index", cmd_update_index, RUN_SETUP },
271                 { "update-ref", cmd_update_ref, RUN_SETUP },
272                 { "upload-archive", cmd_upload_archive },
273                 { "version", cmd_version },
274                 { "whatchanged", cmd_whatchanged, RUN_SETUP | USE_PAGER },
275                 { "write-tree", cmd_write_tree, RUN_SETUP },
276                 { "verify-pack", cmd_verify_pack },
277                 { "show-ref", cmd_show_ref, RUN_SETUP },
278                 { "pack-refs", cmd_pack_refs, RUN_SETUP },
279         };
280         int i;
281
282         /* Turn "git cmd --help" into "git help cmd" */
283         if (argc > 1 && !strcmp(argv[1], "--help")) {
284                 argv[1] = argv[0];
285                 argv[0] = cmd = "help";
286         }
287
288         for (i = 0; i < ARRAY_SIZE(commands); i++) {
289                 struct cmd_struct *p = commands+i;
290                 const char *prefix;
291                 if (strcmp(p->cmd, cmd))
292                         continue;
293
294                 prefix = NULL;
295                 if (p->option & RUN_SETUP)
296                         prefix = setup_git_directory();
297                 if (p->option & USE_PAGER)
298                         setup_pager();
299                 if ((p->option & NOT_BARE) && is_bare_repository())
300                         die("%s cannot be used in a bare git directory", cmd);
301                 trace_argv_printf(argv, argc, "trace: built-in: git");
302
303                 exit(p->fn(argc, argv, prefix));
304         }
305 }
306
307 int main(int argc, const char **argv, char **envp)
308 {
309         const char *cmd = argv[0] ? argv[0] : "git-help";
310         char *slash = strrchr(cmd, '/');
311         const char *exec_path = NULL;
312         int done_alias = 0;
313
314         /*
315          * Take the basename of argv[0] as the command
316          * name, and the dirname as the default exec_path
317          * if it's an absolute path and we don't have
318          * anything better.
319          */
320         if (slash) {
321                 *slash++ = 0;
322                 if (*cmd == '/')
323                         exec_path = cmd;
324                 cmd = slash;
325         }
326
327         /*
328          * "git-xxxx" is the same as "git xxxx", but we obviously:
329          *
330          *  - cannot take flags in between the "git" and the "xxxx".
331          *  - cannot execute it externally (since it would just do
332          *    the same thing over again)
333          *
334          * So we just directly call the internal command handler, and
335          * die if that one cannot handle it.
336          */
337         if (!strncmp(cmd, "git-", 4)) {
338                 cmd += 4;
339                 argv[0] = cmd;
340                 handle_internal_command(argc, argv, envp);
341                 die("cannot handle %s internally", cmd);
342         }
343
344         /* Look for flags.. */
345         argv++;
346         argc--;
347         handle_options(&argv, &argc);
348         if (argc > 0) {
349                 if (!strncmp(argv[0], "--", 2))
350                         argv[0] += 2;
351         } else {
352                 /* Default command: "help" */
353                 argv[0] = "help";
354                 argc = 1;
355         }
356         cmd = argv[0];
357
358         /*
359          * We search for git commands in the following order:
360          *  - git_exec_path()
361          *  - the path of the "git" command if we could find it
362          *    in $0
363          *  - the regular PATH.
364          */
365         if (exec_path)
366                 prepend_to_path(exec_path, strlen(exec_path));
367         exec_path = git_exec_path();
368         prepend_to_path(exec_path, strlen(exec_path));
369
370         while (1) {
371                 /* See if it's an internal command */
372                 handle_internal_command(argc, argv, envp);
373
374                 /* .. then try the external ones */
375                 execv_git_cmd(argv);
376
377                 /* It could be an alias -- this works around the insanity
378                  * of overriding "git log" with "git show" by having
379                  * alias.log = show
380                  */
381                 if (done_alias || !handle_alias(&argc, &argv))
382                         break;
383                 done_alias = 1;
384         }
385
386         if (errno == ENOENT)
387                 help_unknown_cmd(cmd);
388
389         fprintf(stderr, "Failed to run command '%s': %s\n",
390                 cmd, strerror(errno));
391
392         return 1;
393 }