1 /* SPDX-License-Identifier: GPL-2.0 */
17 #include <sys/param.h>
20 #include "gcc-compat.h"
23 #include "gcc-compat.h"
27 #if (defined(__GNUC__) && defined(__i386__))
28 #define get16bits(d) (*((const uint16_t *) (d)))
30 #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
31 +(uint32_t)(((const uint8_t *)(d))[0]) )
35 * SuperFastHash, by Paul Hsieh.
36 * https://www.azillionmonkeys.com/qed/hash.html
38 static uint32_t super_fast_hash(const uint8_t *data, uint32_t len, uint32_t hash)
45 for (;len > 0; len--) {
46 hash += get16bits (data);
47 tmp = (get16bits (data+2) << 11) ^ hash;
48 hash = (hash << 16) ^ tmp;
49 data += 2*sizeof (uint16_t);
53 /* Handle end cases */
56 hash += get16bits (data);
58 hash ^= data[sizeof (uint16_t)] << 18;
62 hash += get16bits (data);
71 /* Force "avalanching" of final 127 bits */
82 * Return the canonical absolute name of a given file name.
84 * Slightly modified version of glibc's realpath, Copyright (C)
85 * 1996-2002,2004,2005,2006,2008 Free Software Foundation, Inc.
87 * A canonical name does not contain any `.', `..' components nor any repeated
88 * path separators ('/') or symlinks. All path components must exist. The
89 * result is malloc'd and must be freed by the caller.
91 static int dss_realpath(const char *name, char **resolved_path)
93 char *rpath = NULL, *dest, *extra_buf = NULL;
94 const char *start, *end, *rpath_limit;
96 int ret, num_links = 0;
98 if (name[0] == '\0') {
100 * As per Single Unix Specification V2 we must return an error
101 * if the name argument points to an empty string.
103 ret = -ERRNO_TO_DSS_ERROR(ENOENT);
110 * From realpath(3): Asking pathconf(3) does not really help, since on
111 * the one hand POSIX warns that the result of pathconf(3) may be
112 * huge and unsuitable for mallocing memory. And on the other hand
113 * pathconf(3) may return -1 to signify that PATH_MAX is not bounded.
115 path_max = pathconf(name, _PC_PATH_MAX);
116 if (path_max <= 0 || path_max >= 4096)
119 rpath = dss_malloc(path_max);
120 rpath_limit = rpath + path_max;
122 if (name[0] != '/') {
123 if (!getcwd(rpath, path_max)) {
124 ret = -ERRNO_TO_DSS_ERROR(errno);
127 dest = memchr(rpath, '\0', path_max);
133 for (start = end = name; *start; start = end) {
137 /* Skip sequence of multiple path-separators. */
138 while (*start == '/')
141 /* Find end of path component. */
142 for (end = start; *end && *end != '/'; ++end)
145 if (end - start == 0)
147 else if (end - start == 1 && start[0] == '.')
149 else if (end - start == 2 && start[0] == '.' && start[1] == '.') {
150 /* Back up to previous component, ignore if at root already. */
151 if (dest > rpath + 1)
152 while ((--dest)[-1] != '/') ;
159 if (dest + (end - start) >= rpath_limit) {
160 ptrdiff_t dest_offset = dest - rpath;
162 new_size = rpath_limit - rpath;
163 if (end - start + 1 > path_max)
164 new_size += end - start + 1;
166 new_size += path_max;
167 rpath = dss_realloc(rpath, new_size);
168 rpath_limit = rpath + new_size;
169 dest = rpath + dest_offset;
172 memcpy(dest, start, end - start);
176 if (stat(rpath, &st) < 0) {
177 ret = -ERRNO_TO_DSS_ERROR(errno);
181 if (S_ISLNK(st.st_mode)) {
182 char *buf = alloca(path_max);
185 if (++num_links > MAXSYMLINKS) {
186 ret = -ERRNO_TO_DSS_ERROR(ELOOP);
190 n = readlink(rpath, buf, path_max - 1);
192 ret = -ERRNO_TO_DSS_ERROR(errno);
198 extra_buf = alloca(path_max);
201 if ((long int) (n + len) >= path_max) {
202 ret = -ERRNO_TO_DSS_ERROR(ENAMETOOLONG);
206 /* Careful here, end may be a pointer into extra_buf... */
207 memmove(&extra_buf[n], end, len + 1);
208 end = memcpy(extra_buf, buf, n);
210 if (buf[0] == '/') /* It's an absolute symlink */
212 else /* Back up to previous component, ignore if at root already: */
213 if (dest > rpath + 1)
214 while ((--dest)[-1] != '/')
216 } else if (!S_ISDIR(st.st_mode) && *end != '\0') {
217 ret = -ERRNO_TO_DSS_ERROR(ENOTDIR);
222 if (dest > rpath + 1 && dest[-1] == '/')
225 *resolved_path = rpath;
229 *resolved_path = NULL;
233 static int get_key_or_die(const char *config_file)
240 if (stat(config_file, &statbuf) == 0) {
241 ret = dss_realpath(config_file, &rpath);
243 DSS_EMERG_LOG(("could not resolve path %s: %s\n", config_file,
244 dss_strerror(-ret)));
247 DSS_DEBUG_LOG(("resolved path: %s\n", rpath));
250 * This happens if the user did not specify a config file, and
251 * the default config file does not exist. Another (unlikely)
252 * possibility is that the config file was removed between
253 * startup and this call. We don't care about these corner
254 * cases too much and just use the unresolved path in this
257 rpath = dss_strdup(config_file);
258 ret = super_fast_hash((uint8_t *)rpath, strlen(rpath), 0) >> 1;
263 static int mutex_get(key_t key, int flags)
267 DSS_DEBUG_LOG(("getting semaphore 0x%lx\n", (long)key));
268 ret = semget(key, 2, flags);
270 return -ERRNO_TO_DSS_ERROR(errno);
274 static int do_semop(int id, struct sembuf *sops, int num)
278 DSS_DEBUG_LOG(("calling semop\n"));
280 ret = semop(id, sops, num);
283 } while (errno == EINTR);
284 return -ERRNO_TO_DSS_ERROR(errno);
287 static bool mutex_is_locked(int id)
292 DSS_DEBUG_LOG(("trying to lock\n"));
296 sops.sem_flg = SEM_UNDO | IPC_NOWAIT;
298 ret = do_semop(id, &sops, 1);
304 int lock_dss(char *config_file)
307 struct sembuf sops[4];
308 key_t key = get_key_or_die(config_file);
310 ret = mutex_get(key, IPC_CREAT | 0600);
317 sops[0].sem_flg = SEM_UNDO | IPC_NOWAIT;
321 sops[1].sem_flg = SEM_UNDO | IPC_NOWAIT;
325 sops[2].sem_flg = SEM_UNDO | IPC_NOWAIT;
329 sops[3].sem_flg = SEM_UNDO | IPC_NOWAIT;
331 return do_semop(id, sops, 4);
334 int get_dss_pid(char *config_file, pid_t *pid)
337 key_t key = get_key_or_die(config_file);
341 ret = mutex_get(key, 0);
343 return ret == -ERRNO_TO_DSS_ERROR(ENOENT)? -E_NOT_RUNNING : ret;
345 ret = semctl(semid, 1, GETPID);
347 return -E_NOT_RUNNING;
350 return mutex_is_locked(semid)? 1 : -E_NOT_RUNNING;