X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=ipc.c;h=183c76e9b4ad0b46ee2910207f12626fbb7087ca;hp=723570e60b291811b8de24214159d18423557ee3;hb=5b1c780d1a3e02a6f64242ef5d8c0a2dc71de3ec;hpb=c92370affe722f38a85a41d1b5524e4a102b8f4d

diff --git a/ipc.c b/ipc.c
index 723570e..183c76e 100644
--- a/ipc.c
+++ b/ipc.c
@@ -22,29 +22,247 @@
 #include "err.h"
 #include "ipc.h"
 
-static int get_key(const char *config_file)
+#if (defined(__GNUC__) && defined(__i386__))
+#define get16bits(d) (*((const uint16_t *) (d)))
+#else
+#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+		+(uint32_t)(((const uint8_t *)(d))[0]) )
+#endif
+
+/*
+ * SuperFastHash, by Paul Hsieh.
+ * http://www.azillionmonkeys.com/qed/hash.html
+ */
+static uint32_t super_fast_hash(const uint8_t *data, uint32_t len, uint32_t hash)
 {
-	int ret;
+	uint32_t tmp;
+	int rem = len & 3;
 
-	assert(config_file);
-	ret = ftok(config_file, 'D');
-	if (ret >= 0)
-		return ret;
+	len >>= 2;
+
+	for (;len > 0; len--) {
+		hash  += get16bits (data);
+		tmp    = (get16bits (data+2) << 11) ^ hash;
+		hash   = (hash << 16) ^ tmp;
+		data  += 2*sizeof (uint16_t);
+		hash  += hash >> 11;
+	}
+
+	/* Handle end cases */
+	switch (rem) {
+	case 3:
+		hash += get16bits (data);
+		hash ^= hash << 16;
+		hash ^= data[sizeof (uint16_t)] << 18;
+		hash += hash >> 11;
+		break;
+	case 2:
+		hash += get16bits (data);
+		hash ^= hash << 11;
+		hash += hash >> 17;
+		break;
+	case 1:
+		hash += *data;
+		hash ^= hash << 10;
+		hash += hash >> 1;
+	}
+	/* Force "avalanching" of final 127 bits */
+	hash ^= hash << 3;
+	hash += hash >> 5;
+	hash ^= hash << 4;
+	hash += hash >> 17;
+	hash ^= hash << 25;
+	hash += hash >> 6;
+	return hash;
+}
+
+/*
+ * Return the canonical absolute name of a given file name.
+ *
+ * Slightly modified version of glibc's realpath, Copyright (C)
+ * 1996-2002,2004,2005,2006,2008 Free Software Foundation, Inc.
+ *
+ * A canonical name does not contain any `.', `..' components nor any repeated
+ * path separators ('/') or symlinks. All path components must exist. The
+ * result is malloc'd and must be freed by the caller.
+ */
+static int dss_realpath(const char *name, char **resolved_path)
+{
+	char *rpath = NULL, *dest, *extra_buf = NULL;
+	const char *start, *end, *rpath_limit;
+	long int path_max;
+	int ret, num_links = 0;
+
+	if (name[0] == '\0') {
+		/*
+		 * As per Single Unix Specification V2 we must return an error
+		 * if the name argument points to an empty string.
+		 */
+		ret = -ERRNO_TO_DSS_ERROR(ENOENT);
+		goto error;
+	}
+#ifdef PATH_MAX
+	path_max = PATH_MAX;
+#else
 	/*
-	 * This happens if the user did not specify a config file, and the
-	 * default config file does not exist.  Another (unlikely) possibility
-	 * is that the config file was removed between startup and this call.
-	 * We don't care about these corner cases too much and just return a
-	 * fixed key in this case.
+	 * From realpath(3): Asking pathconf(3) does not really help, since on
+	 * the one hand POSIX warns that the result of pathconf(3) may be
+	 * huge and unsuitable for mallocing memory. And on the other hand
+	 * pathconf(3) may return -1 to signify that PATH_MAX is not bounded.
 	 */
-	return 0x0D55; /* no magic, this number just looks a bit like DSS */
+	path_max = pathconf(name, _PC_PATH_MAX);
+	if (path_max <= 0 || path_max >= 4096)
+		path_max = 4096;
+#endif
+	rpath = dss_malloc(path_max);
+	rpath_limit = rpath + path_max;
+
+	if (name[0] != '/') {
+		if (!getcwd(rpath, path_max)) {
+			ret = -ERRNO_TO_DSS_ERROR(errno);
+			goto error;
+		}
+		dest = memchr(rpath, '\0', path_max);
+	} else {
+		rpath[0] = '/';
+		dest = rpath + 1;
+	}
+
+	for (start = end = name; *start; start = end) {
+		struct stat st;
+		int n;
+
+		/* Skip sequence of multiple path-separators.  */
+		while (*start == '/')
+			++start;
+
+		/* Find end of path component.  */
+		for (end = start; *end && *end != '/'; ++end)
+			/* Nothing.  */ ;
+
+		if (end - start == 0)
+			break;
+		else if (end - start == 1 && start[0] == '.')
+			/* nothing */ ;
+		else if (end - start == 2 && start[0] == '.' && start[1] == '.') {
+			/* Back up to previous component, ignore if at root already.  */
+			if (dest > rpath + 1)
+				while ((--dest)[-1] != '/') ;
+		} else {
+			size_t new_size;
+
+			if (dest[-1] != '/')
+				*dest++ = '/';
+
+			if (dest + (end - start) >= rpath_limit) {
+				ptrdiff_t dest_offset = dest - rpath;
+
+				new_size = rpath_limit - rpath;
+				if (end - start + 1 > path_max)
+					new_size += end - start + 1;
+				else
+					new_size += path_max;
+				rpath = dss_realloc(rpath, new_size);
+				rpath_limit = rpath + new_size;
+				dest = rpath + dest_offset;
+			}
+
+			memcpy(dest, start, end - start);
+			dest += end - start;
+			*dest = '\0';
+
+			if (stat(rpath, &st) < 0) {
+				ret = -ERRNO_TO_DSS_ERROR(errno);
+				goto error;
+			}
+
+			if (S_ISLNK(st.st_mode)) {
+				char *buf = alloca(path_max);
+				size_t len;
+
+				if (++num_links > MAXSYMLINKS) {
+					ret = -ERRNO_TO_DSS_ERROR(ELOOP);
+					goto error;
+				}
+
+				n = readlink(rpath, buf, path_max - 1);
+				if (n < 0) {
+					ret = -ERRNO_TO_DSS_ERROR(errno);
+					goto error;
+				}
+				buf[n] = '\0';
+
+				if (!extra_buf)
+					extra_buf = alloca(path_max);
+
+				len = strlen(end);
+				if ((long int) (n + len) >= path_max) {
+					ret = -ERRNO_TO_DSS_ERROR(ENAMETOOLONG);
+					goto error;
+				}
+
+				/* Careful here, end may be a pointer into extra_buf... */
+				memmove(&extra_buf[n], end, len + 1);
+				name = end = memcpy(extra_buf, buf, n);
+
+				if (buf[0] == '/') /* It's an absolute symlink */
+					dest = rpath + 1;
+				else /* Back up to previous component, ignore if at root already: */
+					if (dest > rpath + 1)
+						while ((--dest)[-1] != '/')
+							; /* nothing */
+			} else if (!S_ISDIR(st.st_mode) && *end != '\0') {
+				ret = -ERRNO_TO_DSS_ERROR(ENOTDIR);
+				goto error;
+			}
+		}
+	}
+	if (dest > rpath + 1 && dest[-1] == '/')
+		--dest;
+	*dest = '\0';
+	*resolved_path = rpath;
+	return 1;
+error:
+	free(rpath);
+	*resolved_path = NULL;
+	return ret;
 }
 
-static int mutex_get(int key, int flags)
+static int get_key_or_die(const char *config_file)
 {
 	int ret;
+	struct stat statbuf;
+	char *rpath;
 
-	DSS_DEBUG_LOG(("getting semaphore 0x%x\n", key));
+	assert(config_file);
+	if (stat(config_file, &statbuf) == 0) {
+		ret = dss_realpath(config_file, &rpath);
+		if (ret < 0) {
+			DSS_EMERG_LOG(("could not resolve path %s: %s\n", config_file,
+				dss_strerror(-ret)));
+			exit(EXIT_FAILURE);
+		}
+		DSS_DEBUG_LOG(("resolved path: %s\n", rpath));
+	} else
+		/*
+		 * This happens if the user did not specify a config file, and
+		 * the default config file does not exist.  Another (unlikely)
+		 * possibility is that the config file was removed between
+		 * startup and this call. We don't care about these corner
+		 * cases too much and just use the unresolved path in this
+		 * case.
+		 */
+		rpath = dss_strdup(config_file);
+	ret = super_fast_hash((uint8_t *)rpath, strlen(rpath), 0) >> 1;
+	free(rpath);
+	return ret;
+}
+
+static int mutex_get(key_t key, int flags)
+{
+	int ret;
+
+	DSS_DEBUG_LOG(("getting semaphore 0x%lx\n", (long)key));
 	ret = semget(key, 2, flags);
 	if (ret < 0)
 		return -ERRNO_TO_DSS_ERROR(errno);
@@ -64,31 +282,6 @@ static int do_semop(int id, struct sembuf *sops, int num)
 	return -ERRNO_TO_DSS_ERROR(errno);
 }
 
-static int mutex_lock(int id)
-{
-	struct sembuf sops[4];
-
-	DSS_DEBUG_LOG(("locking\n"));
-
-	sops[0].sem_num = 0;
-	sops[0].sem_op = 0;
-	sops[0].sem_flg = SEM_UNDO | IPC_NOWAIT;
-
-	sops[1].sem_num = 0;
-	sops[1].sem_op = 1;
-	sops[1].sem_flg = SEM_UNDO | IPC_NOWAIT;
-
-	sops[2].sem_num = 1;
-	sops[2].sem_op = 0;
-	sops[2].sem_flg = SEM_UNDO | IPC_NOWAIT;
-
-	sops[3].sem_num = 1;
-	sops[3].sem_op = 1;
-	sops[3].sem_flg = SEM_UNDO | IPC_NOWAIT;
-
-	return do_semop(id, sops, 4);
-}
-
 static bool mutex_is_locked(int id)
 {
 	struct sembuf sops;
@@ -108,23 +301,44 @@ static bool mutex_is_locked(int id)
 
 int lock_dss(char *config_file)
 {
-	int ret, key = get_key(config_file);
+	int ret, id;
+	struct sembuf sops[4];
+	key_t key = get_key_or_die(config_file);
 
 	ret = mutex_get(key, IPC_CREAT | 0600);
 	if (ret < 0)
 		return ret;
-	return mutex_lock(ret);
+	id = ret;
+
+	sops[0].sem_num = 0;
+	sops[0].sem_op = 0;
+	sops[0].sem_flg = SEM_UNDO | IPC_NOWAIT;
+
+	sops[1].sem_num = 0;
+	sops[1].sem_op = 1;
+	sops[1].sem_flg = SEM_UNDO | IPC_NOWAIT;
+
+	sops[2].sem_num = 1;
+	sops[2].sem_op = 0;
+	sops[2].sem_flg = SEM_UNDO | IPC_NOWAIT;
+
+	sops[3].sem_num = 1;
+	sops[3].sem_op = 1;
+	sops[3].sem_flg = SEM_UNDO | IPC_NOWAIT;
+
+	return do_semop(id, sops, 4);
 }
 
 int get_dss_pid(char *config_file, pid_t *pid)
 {
-	int ret, semid, key = get_key(config_file);
+	int ret, semid;
+	key_t key = get_key_or_die(config_file);
 
 	if (pid)
 		*pid = 0;
 	ret = mutex_get(key, 0);
 	if (ret < 0)
-		return ret;
+		return ret == -ERRNO_TO_DSS_ERROR(ENOENT)? -E_NOT_RUNNING : ret;
 	semid = ret;
 	ret = semctl(semid, 1, GETPID);
 	if (ret < 0)