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);
  63         ent->name[len] = 0;
  64         cmdname[cmdname_cnt++] = ent;
  65 }
  66
  67 static int cmdname_compare(const void *a_, const void *b_)
  68 {
  69         struct cmdname *a = *(struct cmdname **)a_;
  70         struct cmdname *b = *(struct cmdname **)b_;
  71         return strcmp(a->name, b->name);
  72 }
  73
  74 static void pretty_print_string_list(struct cmdname **cmdname, int longest)
  75 {
  76         int cols = 1;
  77         int space = longest + 1; /* min 1 SP between words */
  78         int max_cols = term_columns() - 1; /* don't print *on* the edge */
  79         int i;
  80
  81         if (space < max_cols)
  82                 cols = max_cols / space;
  83
  84         qsort(cmdname, cmdname_cnt, sizeof(*cmdname), cmdname_compare);
  85
  86         for (i = 0; i < cmdname_cnt; ) {
  87                 int c;
  88                 printf("  ");
  89
  90                 for (c = cols; c && i < cmdname_cnt; i++) {
  91                         printf("%s", cmdname[i]->name);
  92
  93                         if (--c)
  94                                 mput_char(' ', space - cmdname[i]->len);
  95                 }
  96                 putchar('\n');
  97         }
  98 }
  99
 100 static void list_commands(const char *exec_path, const char *pattern)
 101 {
 102         unsigned int longest = 0;
 103         char path[PATH_MAX];
 104         int dirlen;
 105         DIR *dir = opendir(exec_path);
 106         struct dirent *de;
 107
 108         if (!dir) {
 109                 fprintf(stderr, "git: '%s': %s\n", exec_path, strerror(errno));
 110                 exit(1);
 111         }
 112
 113         dirlen = strlen(exec_path);
 114         if (PATH_MAX - 20 < dirlen) {
 115                 fprintf(stderr, "git: insanely long exec-path '%s'\n",
 116                         exec_path);
 117                 exit(1);
 118         }
 119
 120         memcpy(path, exec_path, dirlen);
 121         path[dirlen++] = '/';
 122
 123         while ((de = readdir(dir)) != NULL) {
 124                 struct stat st;
 125                 int entlen;
 126
 127                 if (strncmp(de->d_name, "git-", 4))
 128                         continue;
 129                 strcpy(path+dirlen, de->d_name);
 130                 if (stat(path, &st) || /* stat, not lstat */
 131                     !S_ISREG(st.st_mode) ||
 132                     !(st.st_mode & S_IXUSR))
 133                         continue;
 134
 135                 entlen = strlen(de->d_name);
 136                 if (4 < entlen && !strcmp(de->d_name + entlen - 4, ".exe"))
 137                         entlen -= 4;
 138
 139                 if (longest < entlen)
 140                         longest = entlen;
 141
 142                 add_cmdname(de->d_name + 4, entlen-4);
 143         }
 144         closedir(dir);
 145
 146         printf("git commands available in '%s'\n", exec_path);
 147         printf("----------------------------");
 148         mput_char('-', strlen(exec_path));
 149         putchar('\n');
 150         pretty_print_string_list(cmdname, longest - 4);
 151         putchar('\n');
 152 }
 153
 154 #ifdef __GNUC__
 155 static void usage(const char *exec_path, const char *fmt, ...)
 156         __attribute__((__format__(__printf__, 2, 3), __noreturn__));
 157 #endif
 158 static void usage(const char *exec_path, const char *fmt, ...)
 159 {
 160         if (fmt) {
 161                 va_list ap;
 162
 163                 va_start(ap, fmt);
 164                 printf("git: ");
 165                 vprintf(fmt, ap);
 166                 va_end(ap);
 167                 putchar('\n');
 168         }
 169         else
 170                 puts(git_usage);
 171
 172         putchar('\n');
 173
 174         if(exec_path)
 175                 list_commands(exec_path, "git-*");
 176
 177         exit(1);
 178 }
 179
 180 static void prepend_to_path(const char *dir, int len)
 181 {
 182         char *path, *old_path = getenv("PATH");
 183         int path_len = len;
 184
 185         if (!old_path)
 186                 old_path = "/usr/local/bin:/usr/bin:/bin";
 187
 188         path_len = len + strlen(old_path) + 1;
 189
 190         path = malloc(path_len + 1);
 191         path[path_len + 1] = '\0';
 192
 193         memcpy(path, dir, len);
 194         path[len] = ':';
 195         memcpy(path + len + 1, old_path, path_len - len);
 196
 197         setenv("PATH", path, 1);
 198 }
 199
 200 static void show_man_page(char *git_cmd)
 201 {
 202         char *page;
 203
 204         if (!strncmp(git_cmd, "git", 3))
 205                 page = git_cmd;
 206         else {
 207                 int page_len = strlen(git_cmd) + 4;
 208
 209                 page = malloc(page_len + 1);
 210                 strcpy(page, "git-");
 211                 strcpy(page + 4, git_cmd);
 212                 page[page_len] = 0;
 213         }
 214
 215         execlp("man", "man", page, NULL);
 216 }
 217
 218 int main(int argc, char **argv, char **envp)
 219 {
 220         char git_command[PATH_MAX + 1];
 221         char wd[PATH_MAX + 1];
 222         int i, len, show_help = 0;
 223         char *exec_path = getenv("GIT_EXEC_PATH");
 224
 225         getcwd(wd, PATH_MAX);
 226
 227         if (!exec_path)
 228                 exec_path = GIT_EXEC_PATH;
 229
 230         for (i = 1; i < argc; i++) {
 231                 char *arg = argv[i];
 232
 233                 if (strncmp(arg, "--", 2))
 234                         break;
 235
 236                 arg += 2;
 237
 238                 if (!strncmp(arg, "exec-path", 9)) {
 239                         arg += 9;
 240                         if (*arg == '=')
 241                                 exec_path = arg + 1;
 242                         else {
 243                                 puts(exec_path);
 244                                 exit(0);
 245                         }
 246                 }
 247                 else if (!strcmp(arg, "version")) {
 248                         printf("git version %s\n", GIT_VERSION);
 249                         exit(0);
 250                 }
 251                 else if (!strcmp(arg, "help"))
 252                         show_help = 1;
 253                 else if (!show_help)
 254                         usage(NULL, NULL);
 255         }
 256
 257         if (i >= argc || show_help) {
 258                 if (i >= argc)
 259                         usage(exec_path, NULL);
 260
 261                 show_man_page(argv[i]);
 262         }
 263
 264         if (*exec_path != '/') {
 265                 if (!getcwd(git_command, sizeof(git_command))) {
 266                         fprintf(stderr,
 267                                 "git: cannot determine current directory");
 268                         exit(1);
 269                 }
 270                 len = strlen(git_command);
 271
 272                 /* Trivial cleanup */
 273                 while (!strncmp(exec_path, "./", 2)) {
 274                         exec_path += 2;
 275                         while (*exec_path == '/')
 276                                 exec_path++;
 277                 }
 278                 snprintf(git_command + len, sizeof(git_command) - len,
 279                          "/%s", exec_path);
 280         }
 281         else
 282                 strcpy(git_command, exec_path);
 283         len = strlen(git_command);
 284         prepend_to_path(git_command, len);
 285
 286         strncat(&git_command[len], "/git-", sizeof(git_command) - len);
 287         len += 5;
 288         strncat(&git_command[len], argv[i], sizeof(git_command) - len);
 289
 290         if (access(git_command, X_OK))
 291                 usage(exec_path, "'%s' is not a git-command", argv[i]);
 292
 293         /* execve() can only ever return if it fails */
 294         execve(git_command, &argv[i], envp);
 295         printf("Failed to run command '%s': %s\n", git_command, strerror(errno));
 296
 297         return 1;
 298 }