Merge topic branch t/realpath into pu

[dss.git] / ipc.c

diff --git a/ipc.c b/ipc.c
index 0f295a9d2e6fc34b600d38594d5bd219afd08ccf..e6ec79e062cf2543f8159d6bcf390cdb872438c6 100644 (file)
--- a/ipc.c
+++ b/ipc.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
 #include <sys/wait.h>
 #include <stdio.h>
 #include <inttypes.h>
@@ -22,22 +24,58 @@
 #include "err.h"
 #include "ipc.h"
 
-static key_t 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
+ */
+uint32_t super_fast_hash(const uint8_t *data, uint32_t len, uint32_t hash)
 {
-       key_t ret;
-
-       assert(config_file);
-       ret = ftok(config_file, 'D');
-       if (ret >= 0)
-               return ret;
-       /*
-        * 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.
-        */
-       return 0x0D55; /* no magic, this number just looks a bit like DSS */
+       uint32_t tmp;
+       int rem = len & 3;
+
+       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;
 }
 
 static int mutex_get(key_t key, int flags)
@@ -81,11 +119,10 @@ static bool mutex_is_locked(int id)
        return false;
 }
 
-int lock_dss(char *config_file)
+int lock_dss(uint32_t key)
 {
        int ret, id;
        struct sembuf sops[4];
-       key_t key = get_key(config_file);
 
        ret = mutex_get(key, IPC_CREAT | 0600);
        if (ret < 0)
@@ -111,10 +148,9 @@ int lock_dss(char *config_file)
        return do_semop(id, sops, 4);
 }
 
-int get_dss_pid(char *config_file, pid_t *pid)
+int get_dss_pid(uint32_t key, pid_t *pid)
 {
        int ret, semid;
-       key_t key = get_key(config_file);
 
        if (pid)
                *pid = 0;