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         if (!tmp)
  80                 tmp = getenv("TMP");
  81         if (!tmp)
  82                 tmp = getenv("TEMP");
  83 #endif
  84         if (!tmp)
  85                 tmp = "/tmp";
  86         n = snprintf(path, len, "%s/%s", tmp, template);
  87         if (len <= n) {
  88                 errno = ENAMETOOLONG;
  89                 return -1;
  90         }
  91         return mkstemp(path);
  92 }
  93
  94
  95 int validate_headref(const char *path)
  96 {
  97         struct stat st;
  98         char *buf, buffer[256];
  99         unsigned char sha1[20];
 100         int len, fd;
 101
 102         if (lstat(path, &st) < 0)
 103                 return -1;
 104
 105         /* Make sure it is a "refs/.." symlink */
 106         if (S_ISLNK(st.st_mode)) {
 107                 len = readlink(path, buffer, sizeof(buffer)-1);
 108                 if (len >= 5 && !memcmp("refs/", buffer, 5))
 109                         return 0;
 110                 return -1;
 111         }
 112
 113         /*
 114          * Anything else, just open it and try to see if it is a symbolic ref.
 115          */
 116         fd = open(path, O_RDONLY);
 117         if (fd < 0)
 118                 return -1;
 119         len = read_in_full(fd, buffer, sizeof(buffer)-1);
 120         close(fd);
 121
 122         /*
 123          * Is it a symbolic ref?
 124          */
 125         if (len < 4)
 126                 return -1;
 127         if (!memcmp("ref:", buffer, 4)) {
 128                 buf = buffer + 4;
 129                 len -= 4;
 130                 while (len && isspace(*buf))
 131                         buf++, len--;
 132                 if (len >= 5 && !memcmp("refs/", buf, 5))
 133                         return 0;
 134         }
 135
 136         /*
 137          * Is this a detached HEAD?
 138          */
 139         if (!get_sha1_hex(buffer, sha1))
 140                 return 0;
 141
 142         return -1;
 143 }
 144
 145 #ifndef NO_ETC_PASSWD
 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 #else
 187
 188 static char *user_path(char *buf, char *path, int sz)
 189 {
 190         return getenv("HOME");
 191 }
 192
 193 #endif
 194
 195 /*
 196  * First, one directory to try is determined by the following algorithm.
 197  *
 198  * (0) If "strict" is given, the path is used as given and no DWIM is
 199  *     done. Otherwise:
 200  * (1) "~/path" to mean path under the running user's home directory;
 201  * (2) "~user/path" to mean path under named user's home directory;
 202  * (3) "relative/path" to mean cwd relative directory; or
 203  * (4) "/absolute/path" to mean absolute directory.
 204  *
 205  * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 206  * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 207  * what we try.
 208  *
 209  * Second, we try chdir() to that.  Upon failure, we return NULL.
 210  *
 211  * Then, we try if the current directory is a valid git repository.
 212  * Upon failure, we return NULL.
 213  *
 214  * If all goes well, we return the directory we used to chdir() (but
 215  * before ~user is expanded), avoiding getcwd() resolving symbolic
 216  * links.  User relative paths are also returned as they are given,
 217  * except DWIM suffixing.
 218  */
 219 char *enter_repo(char *path, int strict)
 220 {
 221         static char used_path[PATH_MAX];
 222         static char validated_path[PATH_MAX];
 223
 224         if (!path)
 225                 return NULL;
 226
 227         if (!strict) {
 228                 static const char *suffix[] = {
 229                         ".git/.git", "/.git", ".git", "", NULL,
 230                 };
 231                 int len = strlen(path);
 232                 int i;
 233                 while ((1 < len) && (path[len-1] == '/')) {
 234                         path[len-1] = 0;
 235                         len--;
 236                 }
 237                 if (PATH_MAX <= len)
 238                         return NULL;
 239                 if (path[0] == '~') {
 240                         if (!user_path(used_path, path, PATH_MAX))
 241                                 return NULL;
 242                         strcpy(validated_path, path);
 243                         path = used_path;
 244                 }
 245                 else if (PATH_MAX - 10 < len)
 246                         return NULL;
 247                 else {
 248                         path = strcpy(used_path, path);
 249                         strcpy(validated_path, path);
 250                 }
 251                 len = strlen(path);
 252                 for (i = 0; suffix[i]; i++) {
 253                         strcpy(path + len, suffix[i]);
 254                         if (!access(path, F_OK)) {
 255                                 strcat(validated_path, suffix[i]);
 256                                 break;
 257                         }
 258                 }
 259                 if (!suffix[i] || chdir(path))
 260                         return NULL;
 261                 path = validated_path;
 262         }
 263         else if (chdir(path))
 264                 return NULL;
 265
 266         if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 267             validate_headref("HEAD") == 0) {
 268                 set_git_dir(".");
 269                 check_repository_format();
 270                 return path;
 271         }
 272
 273         return NULL;
 274 }
 275
 276 int adjust_shared_perm(const char *path)
 277 {
 278         struct stat st;
 279         int mode;
 280
 281         if (!shared_repository)
 282                 return 0;
 283         if (lstat(path, &st) < 0)
 284                 return -1;
 285         mode = st.st_mode;
 286         if (mode & S_IRUSR)
 287                 mode |= (shared_repository == PERM_GROUP
 288                          ? S_IRGRP
 289                          : (shared_repository == PERM_EVERYBODY
 290                             ? (S_IRGRP|S_IROTH)
 291                             : 0));
 292
 293         if (mode & S_IWUSR)
 294                 mode |= S_IWGRP;
 295
 296         if (mode & S_IXUSR)
 297                 mode |= (shared_repository == PERM_GROUP
 298                          ? S_IXGRP
 299                          : (shared_repository == PERM_EVERYBODY
 300                             ? (S_IXGRP|S_IXOTH)
 301                             : 0));
 302         if (S_ISDIR(mode))
 303                 mode |= S_ISGID;
 304         if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
 305                 return -2;
 306         return 0;
 307 }
 308
 309 /* We allow "recursive" symbolic links. Only within reason, though. */
 310 #define MAXDEPTH 5
 311
 312 const char *make_absolute_path(const char *path)
 313 {
 314         static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
 315         char cwd[1024] = "";
 316         int buf_index = 1, len;
 317
 318         int depth = MAXDEPTH;
 319         char *last_elem = NULL;
 320         struct stat st;
 321
 322         if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 323                 die ("Too long path: %.*s", 60, path);
 324
 325         while (depth--) {
 326                 if (stat(buf, &st) || !S_ISDIR(st.st_mode)) {
 327                         char *last_slash = strrchr(buf, '/');
 328                         if (last_slash) {
 329                                 *last_slash = '\0';
 330                                 last_elem = xstrdup(last_slash + 1);
 331                         } else
 332                                 last_elem = xstrdup(buf);
 333                 }
 334
 335                 if (*buf) {
 336                         if (!*cwd && !getcwd(cwd, sizeof(cwd)))
 337                                 die ("Could not get current working directory");
 338
 339                         if (chdir(buf))
 340                                 die ("Could not switch to '%s'", buf);
 341                 }
 342                 if (!getcwd(buf, PATH_MAX))
 343                         die ("Could not get current working directory");
 344
 345                 if (last_elem) {
 346                         int len = strlen(buf);
 347                         if (len + strlen(last_elem) + 2 > PATH_MAX)
 348                                 die ("Too long path name: '%s/%s'",
 349                                                 buf, last_elem);
 350                         buf[len] = '/';
 351                         strcpy(buf + len + 1, last_elem);
 352                         free(last_elem);
 353                         last_elem = NULL;
 354                 }
 355
 356                 if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
 357                         len = readlink(buf, next_buf, PATH_MAX);
 358                         if (len < 0)
 359                                 die ("Invalid symlink: %s", buf);
 360                         next_buf[len] = '\0';
 361                         buf = next_buf;
 362                         buf_index = 1 - buf_index;
 363                         next_buf = bufs[buf_index];
 364                 } else
 365                         break;
 366         }
 367
 368         if (*cwd && chdir(cwd))
 369                 die ("Could not change back to '%s'", cwd);
 370
 371         return buf;
 372 }