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 (!strcmp(arg, "help")) {
 248                         show_help = 1;
 249                         continue;
 250                 }
 251
 252                 if (strncmp(arg, "--", 2))
 253                         break;
 254
 255                 arg += 2;
 256
 257                 if (!strncmp(arg, "exec-path", 9)) {
 258                         arg += 9;
 259                         if (*arg == '=')
 260                                 exec_path = arg + 1;
 261                         else {
 262                                 puts(exec_path);
 263                                 exit(0);
 264                         }
 265                 }
 266                 else if (!strcmp(arg, "version")) {
 267                         printf("git version %s\n", GIT_VERSION);
 268                         exit(0);
 269                 }
 270                 else if (!strcmp(arg, "help"))
 271                         show_help = 1;
 272                 else if (!show_help)
 273                         cmd_usage(NULL, NULL);
 274         }
 275
 276         if (i >= argc || show_help) {
 277                 if (i >= argc)
 278                         cmd_usage(exec_path, NULL);
 279
 280                 show_man_page(argv[i]);
 281         }
 282
 283         if (*exec_path != '/') {
 284                 if (!getcwd(git_command, sizeof(git_command))) {
 285                         fprintf(stderr,
 286                                 "git: cannot determine current directory\n");
 287                         exit(1);
 288                 }
 289                 len = strlen(git_command);
 290
 291                 /* Trivial cleanup */
 292                 while (!strncmp(exec_path, "./", 2)) {
 293                         exec_path += 2;
 294                         while (*exec_path == '/')
 295                                 exec_path++;
 296                 }
 297                 snprintf(git_command + len, sizeof(git_command) - len,
 298                          "/%s", exec_path);
 299         }
 300         else
 301                 strcpy(git_command, exec_path);
 302         len = strlen(git_command);
 303         prepend_to_path(git_command, len);
 304
 305         len += snprintf(git_command + len, sizeof(git_command) - len,
 306                         "/git-%s", argv[i]);
 307         if (sizeof(git_command) <= len) {
 308                 fprintf(stderr, "git: command name given is too long.\n");
 309                 exit(1);
 310         }
 311
 312         /* execve() can only ever return if it fails */
 313         execve(git_command, &argv[i], envp);
 314
 315         if (errno == ENOENT)
 316                 cmd_usage(exec_path, "'%s' is not a git-command", argv[i]);
 317
 318         fprintf(stderr, "Failed to run command '%s': %s\n",
 319                 git_command, strerror(errno));
 320
 321         return 1;
 322 }