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 */
81 static int get_key_or_die(const char *config_file)
84 return super_fast_hash((uint8_t *)config_file, strlen(config_file), 0) >> 1;
87 static int mutex_get(key_t key, int flags)
91 DSS_DEBUG_LOG(("getting semaphore 0x%lx\n", (long)key));
92 ret = semget(key, 2, flags);
94 return -ERRNO_TO_DSS_ERROR(errno);
98 static int do_semop(int id, struct sembuf *sops, int num)
102 DSS_DEBUG_LOG(("calling semop\n"));
104 ret = semop(id, sops, num);
107 } while (errno == EINTR);
108 return -ERRNO_TO_DSS_ERROR(errno);
111 static bool mutex_is_locked(int id)
116 DSS_DEBUG_LOG(("trying to lock\n"));
120 sops.sem_flg = SEM_UNDO | IPC_NOWAIT;
122 ret = do_semop(id, &sops, 1);
128 int lock_dss(char *config_file)
131 struct sembuf sops[4];
132 key_t key = get_key_or_die(config_file);
134 ret = mutex_get(key, IPC_CREAT | 0600);
141 sops[0].sem_flg = SEM_UNDO | IPC_NOWAIT;
145 sops[1].sem_flg = SEM_UNDO | IPC_NOWAIT;
149 sops[2].sem_flg = SEM_UNDO | IPC_NOWAIT;
153 sops[3].sem_flg = SEM_UNDO | IPC_NOWAIT;
155 return do_semop(id, sops, 4);
158 int get_dss_pid(char *config_file, pid_t *pid)
161 key_t key = get_key_or_die(config_file);
165 ret = mutex_get(key, 0);
167 return ret == -ERRNO_TO_DSS_ERROR(ENOENT)? -E_NOT_RUNNING : ret;
169 ret = semctl(semid, 1, GETPID);
171 return -E_NOT_RUNNING;
174 return mutex_is_locked(semid)? 1 : -E_NOT_RUNNING;