path.c

   1 /*
   2  * I'm tired of doing "vsnprintf()" etc just to open a
   3  * file, so here's a "return static buffer with printf"
   4  * interface for paths.
   5  *
   6  * It's obviously not thread-safe. Sue me. But it's quite
   7  * useful for doing things like
   8  *
   9  *   f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
  10  *
  11  * which is what it's designed for.
  12  */
  13 #include "cache.h"
  14
  15 static char bad_path[] = "/bad-path/";
  16
  17 static char *get_pathname(void)
  18 {
  19         static char pathname_array[4][PATH_MAX];
  20         static int index;
  21         return pathname_array[3 & ++index];
  22 }
  23
  24 static char *cleanup_path(char *path)
  25 {
  26         /* Clean it up */
  27         if (!memcmp(path, "./", 2)) {
  28                 path += 2;
  29                 while (*path == '/')
  30                         path++;
  31         }
  32         return path;
  33 }
  34
  35 char *mkpath(const char *fmt, ...)
  36 {
  37         va_list args;
  38         unsigned len;
  39         char *pathname = get_pathname();
  40
  41         va_start(args, fmt);
  42         len = vsnprintf(pathname, PATH_MAX, fmt, args);
  43         va_end(args);
  44         if (len >= PATH_MAX)
  45                 return bad_path;
  46         return cleanup_path(pathname);
  47 }
  48
  49 char *git_path(const char *fmt, ...)
  50 {
  51         const char *git_dir = get_git_dir();
  52         char *pathname = get_pathname();
  53         va_list args;
  54         unsigned len;
  55
  56         len = strlen(git_dir);
  57         if (len > PATH_MAX-100)
  58                 return bad_path;
  59         memcpy(pathname, git_dir, len);
  60         if (len && git_dir[len-1] != '/')
  61                 pathname[len++] = '/';
  62         va_start(args, fmt);
  63         len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
  64         va_end(args);
  65         if (len >= PATH_MAX)
  66                 return bad_path;
  67         return cleanup_path(pathname);
  68 }
  69
  70
  71 /* git_mkstemp() - create tmp file honoring TMPDIR variable */
  72 int git_mkstemp(char *path, size_t len, const char *template)
  73 {
  74         const char *tmp;
  75         size_t n;
  76
  77         tmp = getenv("TMPDIR");
  78 #ifdef __MINGW32__
  79         /* on Windows it is TMP and TEMP */
  80         if (!tmp)
  81             tmp = getenv("TMP");
  82         if (!tmp)
  83             tmp = getenv("TEMP");
  84 #endif
  85         if (!tmp)
  86                 tmp = "/tmp";
  87         n = snprintf(path, len, "%s/%s", tmp, template);
  88         if (len <= n) {
  89                 errno = ENAMETOOLONG;
  90                 return -1;
  91         }
  92         return mkstemp(path);
  93 }
  94
  95
  96 int validate_headref(const char *path)
  97 {
  98         struct stat st;
  99         char *buf, buffer[256];
 100         unsigned char sha1[20];
 101         int fd;
 102         ssize_t len;
 103
 104         if (lstat(path, &st) < 0)
 105                 return -1;
 106
 107         /* Make sure it is a "refs/.." symlink */
 108         if (S_ISLNK(st.st_mode)) {
 109                 len = readlink(path, buffer, sizeof(buffer)-1);
 110                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 111                         return 0;
 112                 return -1;
 113         }
 114
 115         /*
 116          * Anything else, just open it and try to see if it is a symbolic ref.
 117          */
 118         fd = open(path, O_RDONLY);
 119         if (fd < 0)
 120                 return -1;
 121         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 122         close(fd);
 123
 124         /*
 125          * Is it a symbolic ref?
 126          */
 127         if (len < 4)
 128                 return -1;
 129         if (!memcmp("ref:", buffer, 4)) {
 130                 buf = buffer + 4;
 131                 len -= 4;
 132                 while (len && isspace(*buf))
 133                         buf++, len--;
 134                 if (len >= 5 && !memcmp("refs/", buf, 5))
 135                         return 0;
 136         }
 137
 138         /*
 139          * Is this a detached HEAD?
 140          */
 141         if (!get_sha1_hex(buffer, sha1))
 142                 return 0;
 143
 144         return -1;
 145 }
 146
 147 static char *user_path(char *buf, char *path, int sz)
 148 {
 149         struct passwd *pw;
 150         char *slash;
 151         int len, baselen;
 152
 153         if (!path || path[0] != '~')
 154                 return NULL;
 155         path++;
 156         slash = strchr(path, '/');
 157         if (path[0] == '/' || !path[0]) {
 158                 pw = getpwuid(getuid());
 159         }
 160         else {
 161                 if (slash) {
 162                         *slash = 0;
 163                         pw = getpwnam(path);
 164                         *slash = '/';
 165                 }
 166                 else
 167                         pw = getpwnam(path);
 168         }
 169         if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
 170                 return NULL;
 171         baselen = strlen(pw->pw_dir);
 172         memcpy(buf, pw->pw_dir, baselen);
 173         while ((1 < baselen) && (buf[baselen-1] == '/')) {
 174                 buf[baselen-1] = 0;
 175                 baselen--;
 176         }
 177         if (slash && slash[1]) {
 178                 len = strlen(slash);
 179                 if (sz <= baselen + len)
 180                         return NULL;
 181                 memcpy(buf + baselen, slash, len + 1);
 182         }
 183         return buf;
 184 }
 185
 186 /*
 187  * First, one directory to try is determined by the following algorithm.
 188  *
 189  * (0) If "strict" is given, the path is used as given and no DWIM is
 190  *     done. Otherwise:
 191  * (1) "~/path" to mean path under the running user's home directory;
 192  * (2) "~user/path" to mean path under named user's home directory;
 193  * (3) "relative/path" to mean cwd relative directory; or
 194  * (4) "/absolute/path" to mean absolute directory.
 195  *
 196  * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 197  * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 198  * what we try.
 199  *
 200  * Second, we try chdir() to that.  Upon failure, we return NULL.
 201  *
 202  * Then, we try if the current directory is a valid git repository.
 203  * Upon failure, we return NULL.
 204  *
 205  * If all goes well, we return the directory we used to chdir() (but
 206  * before ~user is expanded), avoiding getcwd() resolving symbolic
 207  * links.  User relative paths are also returned as they are given,
 208  * except DWIM suffixing.
 209  */
 210 char *enter_repo(char *path, int strict)
 211 {
 212         static char used_path[PATH_MAX];
 213         static char validated_path[PATH_MAX];
 214
 215         if (!path)
 216                 return NULL;
 217
 218         if (!strict) {
 219                 static const char *suffix[] = {
 220                         ".git/.git", "/.git", ".git", "", NULL,
 221                 };
 222                 int len = strlen(path);
 223                 int i;
 224                 while ((1 < len) && (path[len-1] == '/')) {
 225                         path[len-1] = 0;
 226                         len--;
 227                 }
 228                 if (PATH_MAX <= len)
 229                         return NULL;
 230                 if (path[0] == '~') {
 231                         if (!user_path(used_path, path, PATH_MAX))
 232                                 return NULL;
 233                         strcpy(validated_path, path);
 234                         path = used_path;
 235                 }
 236                 else if (PATH_MAX - 10 < len)
 237                         return NULL;
 238                 else {
 239                         path = strcpy(used_path, path);
 240                         strcpy(validated_path, path);
 241                 }
 242                 len = strlen(path);
 243                 for (i = 0; suffix[i]; i++) {
 244                         strcpy(path + len, suffix[i]);
 245                         if (!access(path, F_OK)) {
 246                                 strcat(validated_path, suffix[i]);
 247                                 break;
 248                         }
 249                 }
 250                 if (!suffix[i] || chdir(path))
 251                         return NULL;
 252                 path = validated_path;
 253         }
 254         else if (chdir(path))
 255                 return NULL;
 256
 257         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 258             validate_headref("HEAD") == 0) {
 259                 setenv(GIT_DIR_ENVIRONMENT, ".", 1);
 260                 check_repository_format();
 261                 return path;
 262         }
 263
 264         return NULL;
 265 }
 266
 267 int adjust_shared_perm(const char *path)
 268 {
 269         struct stat st;
 270         int mode;
 271
 272         if (!shared_repository)
 273                 return 0;
 274         if (lstat(path, &st) < 0)
 275                 return -1;
 276         mode = st.st_mode;
 277
 278         if (shared_repository) {
 279                 int tweak = shared_repository;
 280                 if (!(mode & S_IWUSR))
 281                         tweak &= ~0222;
 282                 mode = (mode & ~0777) | tweak;
 283         } else {
 284                 /* Preserve old PERM_UMASK behaviour */
 285                 if (mode & S_IWUSR)
 286                         mode |= S_IWGRP;
 287         }
 288
 289         if (S_ISDIR(mode)) {
 290                 mode |= FORCE_DIR_SET_GID;
 291
 292                 /* Copy read bits to execute bits */
 293                 mode |= (shared_repository & 0444) >> 2;
 294         }
 295
 296         if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
 297                 return -2;
 298         return 0;
 299 }
 300
 301 /* We allow "recursive" symbolic links. Only within reason, though. */
 302 #define MAXDEPTH 5
 303
 304 const char *make_absolute_path(const char *path)
 305 {
 306         static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
 307         char cwd[1024] = "";
 308         int buf_index = 1, len;
 309
 310         int depth = MAXDEPTH;
 311         char *last_elem = NULL;
 312         struct stat st;
 313
 314         if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 315                 die ("Too long path: %.*s", 60, path);
 316
 317         while (depth--) {
 318                 if (stat(buf, &st) || !S_ISDIR(st.st_mode)) {
 319                         char *last_slash = strrchr(buf, '/');
 320                         if (last_slash) {
 321                                 *last_slash = '\0';
 322                                 last_elem = xstrdup(last_slash + 1);
 323                         } else {
 324                                 last_elem = xstrdup(buf);
 325                                 *buf = '\0';
 326                         }
 327                 }
 328
 329                 if (*buf) {
 330                         if (!*cwd && !getcwd(cwd, sizeof(cwd)))
 331                                 die ("Could not get current working directory");
 332
 333                         if (chdir(buf))
 334                                 die ("Could not switch to '%s'", buf);
 335                 }
 336                 if (!getcwd(buf, PATH_MAX))
 337                         die ("Could not get current working directory");
 338
 339                 if (last_elem) {
 340                         int len = strlen(buf);
 341                         if (len + strlen(last_elem) + 2 > PATH_MAX)
 342                                 die ("Too long path name: '%s/%s'",
 343                                                 buf, last_elem);
 344                         buf[len] = '/';
 345                         strcpy(buf + len + 1, last_elem);
 346                         free(last_elem);
 347                         last_elem = NULL;
 348                 }
 349
 350                 if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
 351                         len = readlink(buf, next_buf, PATH_MAX);
 352                         if (len < 0)
 353                                 die ("Invalid symlink: %s", buf);
 354                         next_buf[len] = '\0';
 355                         buf = next_buf;
 356                         buf_index = 1 - buf_index;
 357                         next_buf = bufs[buf_index];
 358                 } else
 359                         break;
 360         }
 361
 362         if (*cwd && chdir(cwd))
 363                 die ("Could not change back to '%s'", cwd);
 364
 365         return buf;
 366 }
 367
 368 char *make_native_separator(char* path) {
 369 #ifdef __MINGW32__
 370         char* c;
 371         for (c = path; *c; c++) {
 372                 if (*c == '/')
 373                         *c = '\\';
 374         }
 375         return path;
 376 #else
 377         return path;
 378 #endif
 379 }