?alloc: do not return NULL when asked for zero bytes
[git.git] / git.c
1 #include <stdio.h>
2 #include <sys/types.h>
3 #include <sys/stat.h>
4 #include <dirent.h>
5 #include <unistd.h>
6 #include <stdlib.h>
7 #include <string.h>
8 #include <errno.h>
9 #include <limits.h>
10 #include <stdarg.h>
11 #include <sys/ioctl.h>
12 #include "git-compat-util.h"
13
14 #ifndef PATH_MAX
15 # define PATH_MAX 4096
16 #endif
17
18 static const char git_usage[] =
19         "Usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--help] COMMAND [ ARGS ]";
20
21 /* most gui terms set COLUMNS (although some don't export it) */
22 static int term_columns(void)
23 {
24         char *col_string = getenv("COLUMNS");
25         int n_cols = 0;
26
27         if (col_string && (n_cols = atoi(col_string)) > 0)
28                 return n_cols;
29
30 #ifdef TIOCGWINSZ
31         {
32                 struct winsize ws;
33                 if (!ioctl(1, TIOCGWINSZ, &ws)) {
34                         if (ws.ws_col)
35                                 return ws.ws_col;
36                 }
37         }
38 #endif
39
40         return 80;
41 }
42
43 static void oom(void)
44 {
45         fprintf(stderr, "git: out of memory\n");
46         exit(1);
47 }
48
49 static inline void mput_char(char c, unsigned int num)
50 {
51         while(num--)
52                 putchar(c);
53 }
54
55 static struct cmdname {
56         size_t len;
57         char name[1];
58 } **cmdname;
59 static int cmdname_alloc, cmdname_cnt;
60
61 static void add_cmdname(const char *name, int len)
62 {
63         struct cmdname *ent;
64         if (cmdname_alloc <= cmdname_cnt) {
65                 cmdname_alloc = cmdname_alloc + 200;
66                 cmdname = realloc(cmdname, cmdname_alloc * sizeof(*cmdname));
67                 if (!cmdname)
68                         oom();
69         }
70         ent = malloc(sizeof(*ent) + len);
71         if (!ent)
72                 oom();
73         ent->len = len;
74         memcpy(ent->name, name, len);
75         ent->name[len] = 0;
76         cmdname[cmdname_cnt++] = ent;
77 }
78
79 static int cmdname_compare(const void *a_, const void *b_)
80 {
81         struct cmdname *a = *(struct cmdname **)a_;
82         struct cmdname *b = *(struct cmdname **)b_;
83         return strcmp(a->name, b->name);
84 }
85
86 static void pretty_print_string_list(struct cmdname **cmdname, int longest)
87 {
88         int cols = 1, rows;
89         int space = longest + 1; /* min 1 SP between words */
90         int max_cols = term_columns() - 1; /* don't print *on* the edge */
91         int i, j;
92
93         if (space < max_cols)
94                 cols = max_cols / space;
95         rows = (cmdname_cnt + cols - 1) / cols;
96
97         qsort(cmdname, cmdname_cnt, sizeof(*cmdname), cmdname_compare);
98
99         for (i = 0; i < rows; i++) {
100                 printf("  ");
101
102                 for (j = 0; j < cols; j++) {
103                         int n = j * rows + i;
104                         int size = space;
105                         if (n >= cmdname_cnt)
106                                 break;
107                         if (j == cols-1 || n + rows >= cmdname_cnt)
108                                 size = 1;
109                         printf("%-*s", size, cmdname[n]->name);
110                 }
111                 putchar('\n');
112         }
113 }
114
115 static void list_commands(const char *exec_path, const char *pattern)
116 {
117         unsigned int longest = 0;
118         char path[PATH_MAX];
119         int dirlen;
120         DIR *dir = opendir(exec_path);
121         struct dirent *de;
122
123         if (!dir) {
124                 fprintf(stderr, "git: '%s': %s\n", exec_path, strerror(errno));
125                 exit(1);
126         }
127
128         dirlen = strlen(exec_path);
129         if (PATH_MAX - 20 < dirlen) {
130                 fprintf(stderr, "git: insanely long exec-path '%s'\n",
131                         exec_path);
132                 exit(1);
133         }
134
135         memcpy(path, exec_path, dirlen);
136         path[dirlen++] = '/';
137
138         while ((de = readdir(dir)) != NULL) {
139                 struct stat st;
140                 int entlen;
141
142                 if (strncmp(de->d_name, "git-", 4))
143                         continue;
144                 strcpy(path+dirlen, de->d_name);
145                 if (stat(path, &st) || /* stat, not lstat */
146                     !S_ISREG(st.st_mode) ||
147                     !(st.st_mode & S_IXUSR))
148                         continue;
149
150                 entlen = strlen(de->d_name);
151                 if (4 < entlen && !strcmp(de->d_name + entlen - 4, ".exe"))
152                         entlen -= 4;
153
154                 if (longest < entlen)
155                         longest = entlen;
156
157                 add_cmdname(de->d_name + 4, entlen-4);
158         }
159         closedir(dir);
160
161         printf("git commands available in '%s'\n", exec_path);
162         printf("----------------------------");
163         mput_char('-', strlen(exec_path));
164         putchar('\n');
165         pretty_print_string_list(cmdname, longest - 4);
166         putchar('\n');
167 }
168
169 #ifdef __GNUC__
170 static void cmd_usage(const char *exec_path, const char *fmt, ...)
171         __attribute__((__format__(__printf__, 2, 3), __noreturn__));
172 #endif
173 static void cmd_usage(const char *exec_path, const char *fmt, ...)
174 {
175         if (fmt) {
176                 va_list ap;
177
178                 va_start(ap, fmt);
179                 printf("git: ");
180                 vprintf(fmt, ap);
181                 va_end(ap);
182                 putchar('\n');
183         }
184         else
185                 puts(git_usage);
186
187         putchar('\n');
188
189         if(exec_path)
190                 list_commands(exec_path, "git-*");
191
192         exit(1);
193 }
194
195 static void prepend_to_path(const char *dir, int len)
196 {
197         char *path, *old_path = getenv("PATH");
198         int path_len = len;
199
200         if (!old_path)
201                 old_path = "/usr/local/bin:/usr/bin:/bin";
202
203         path_len = len + strlen(old_path) + 1;
204
205         path = malloc(path_len + 1);
206
207         memcpy(path, dir, len);
208         path[len] = ':';
209         memcpy(path + len + 1, old_path, path_len - len);
210
211         setenv("PATH", path, 1);
212 }
213
214 static void show_man_page(char *git_cmd)
215 {
216         char *page;
217
218         if (!strncmp(git_cmd, "git", 3))
219                 page = git_cmd;
220         else {
221                 int page_len = strlen(git_cmd) + 4;
222
223                 page = malloc(page_len + 1);
224                 strcpy(page, "git-");
225                 strcpy(page + 4, git_cmd);
226                 page[page_len] = 0;
227         }
228
229         execlp("man", "man", page, NULL);
230 }
231
232 int main(int argc, char **argv, char **envp)
233 {
234         char git_command[PATH_MAX + 1];
235         char wd[PATH_MAX + 1];
236         int i, len, show_help = 0;
237         char *exec_path = getenv("GIT_EXEC_PATH");
238
239         getcwd(wd, PATH_MAX);
240
241         if (!exec_path)
242                 exec_path = GIT_EXEC_PATH;
243
244         for (i = 1; i < argc; i++) {
245                 char *arg = argv[i];
246
247                 if (strncmp(arg, "--", 2))
248                         break;
249
250                 arg += 2;
251
252                 if (!strncmp(arg, "exec-path", 9)) {
253                         arg += 9;
254                         if (*arg == '=')
255                                 exec_path = arg + 1;
256                         else {
257                                 puts(exec_path);
258                                 exit(0);
259                         }
260                 }
261                 else if (!strcmp(arg, "version")) {
262                         printf("git version %s\n", GIT_VERSION);
263                         exit(0);
264                 }
265                 else if (!strcmp(arg, "help"))
266                         show_help = 1;
267                 else if (!show_help)
268                         cmd_usage(NULL, NULL);
269         }
270
271         if (i >= argc || show_help) {
272                 if (i >= argc)
273                         cmd_usage(exec_path, NULL);
274
275                 show_man_page(argv[i]);
276         }
277
278         if (*exec_path != '/') {
279                 if (!getcwd(git_command, sizeof(git_command))) {
280                         fprintf(stderr,
281                                 "git: cannot determine current directory\n");
282                         exit(1);
283                 }
284                 len = strlen(git_command);
285
286                 /* Trivial cleanup */
287                 while (!strncmp(exec_path, "./", 2)) {
288                         exec_path += 2;
289                         while (*exec_path == '/')
290                                 exec_path++;
291                 }
292                 snprintf(git_command + len, sizeof(git_command) - len,
293                          "/%s", exec_path);
294         }
295         else
296                 strcpy(git_command, exec_path);
297         len = strlen(git_command);
298         prepend_to_path(git_command, len);
299
300         len += snprintf(git_command + len, sizeof(git_command) - len,
301                         "/git-%s", argv[i]);
302         if (sizeof(git_command) <= len) {
303                 fprintf(stderr, "git: command name given is too long.\n");
304                 exit(1);
305         }
306
307         /* execve() can only ever return if it fails */
308         execve(git_command, &argv[i], envp);
309
310         if (errno == ENOENT)
311                 cmd_usage(exec_path, "'%s' is not a git-command", argv[i]);
312
313         fprintf(stderr, "Failed to run command '%s': %s\n",
314                 git_command, strerror(errno));
315
316         return 1;
317 }