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