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