Use FNV-1A hash to generate unique mutex names

For Windows and MacOSX

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 8cf7ac28b64af4363f7b5fef02be62d0ce6e54bc..112936a3655af1f780eaefdf4ecb1ccac31e27c1 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -2022,6 +2022,80 @@ mdb_env_share_locks(MDB_env *env)
        }
 #endif
 }
+#if defined(_WIN32) || defined(__APPLE__)
+/*
+ * hash_64 - 64 bit Fowler/Noll/Vo-0 FNV-1a hash code
+ *
+ * @(#) $Revision: 5.1 $
+ * @(#) $Id: hash_64a.c,v 5.1 2009/06/30 09:01:38 chongo Exp $
+ * @(#) $Source: /usr/local/src/cmd/fnv/RCS/hash_64a.c,v $
+ *
+ *       http://www.isthe.com/chongo/tech/comp/fnv/index.html
+ *
+ ***
+ *
+ * Please do not copyright this code.  This code is in the public domain.
+ *
+ * LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
+ * EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
+ * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ *
+ * By:
+ *     chongo <Landon Curt Noll> /\oo/\
+ *       http://www.isthe.com/chongo/
+ *
+ * Share and Enjoy!    :-)
+ */
+
+typedef unsigned long long     mdb_hash_t;
+#define MDB_HASH_INIT ((mdb_hash_t)0xcbf29ce484222325ULL)
+
+/** perform a 64 bit Fowler/Noll/Vo FNV-1a hash on a buffer
+ * @param[in] str string to hash
+ * @param[in] hval     initial value for hash
+ * @return 64 bit hash
+ *
+ * NOTE: To use the recommended 64 bit FNV-1a hash, use MDB_HASH_INIT as the
+ *      hval arg on the first call.
+ */
+static inline mdb_hash_t
+mdb_hash_str(char *str, mdb_hash_t hval)
+{
+       unsigned char *s = (unsigned char *)str;        /* unsigned string */
+       /*
+        * FNV-1a hash each octet of the string
+        */
+       while (*s) {
+               /* xor the bottom with the current octet */
+               hval ^= (mdb_hash_t)*s++;
+
+               /* multiply by the 64 bit FNV magic prime mod 2^64 */
+               hval += (hval << 1) + (hval << 4) + (hval << 5) +
+                       (hval << 7) + (hval << 8) + (hval << 40);
+       }
+       /* return our new hash value */
+       return hval;
+}
+
+/** Hash the string and output the hash in hex.
+ * @param[in] str string to hash
+ * @param[out] hexbuf an array of 17 chars to hold the hash
+ */
+static void
+mdb_hash_hex(char *str, char *hexbuf)
+{
+       int i;
+       mdb_hash_t h = mdb_hash_str(str, MDB_HASH_INIT);
+       for (i=0; i<8; i++) {
+               hexbuf += sprintf(hexbuf, "%02x", (unsigned int)h & 0xff);
+               h >>= 8;
+       }
+}
+#endif
 
 /** Open and/or initialize the lock region for the environment.
  * @param[in] env The MDB environment.
@@ -2135,7 +2209,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 #endif
        if (*excl) {
 #ifdef _WIN32
-               char *ptr;
+               char hexbuf[17];
                if (!mdb_sec_inited) {
                        InitializeSecurityDescriptor(&mdb_null_sd,
                                SECURITY_DESCRIPTOR_REVISION);
@@ -2145,22 +2219,14 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                        mdb_all_sa.lpSecurityDescriptor = &mdb_null_sd;
                        mdb_sec_inited = 1;
                }
-               /* FIXME: only using up to 20 characters of the env path here,
-                * probably not enough to assure uniqueness...
-                */
-               sprintf(env->me_txns->mti_rmname, "Global\\MDBr%.20s", lpath);
-               ptr = env->me_txns->mti_rmname + sizeof("Global\\MDBr")-1;
-               while ((ptr = strchr(ptr, '\\')))
-                       *ptr++ = '/';
+               mdb_hash_hex(lpath, hexbuf);
+               sprintf(env->me_txns->mti_rmname, "Global\\MDBr%s", hexbuf);
                env->me_rmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_rmname);
                if (!env->me_rmutex) {
                        rc = ErrCode();
                        goto fail;
                }
-               sprintf(env->me_txns->mti_wmname, "Global\\MDBw%.20s", lpath);
-               ptr = env->me_txns->mti_wmname + sizeof("Global\\MDBw")-1;
-               while ((ptr = strchr(ptr, '\\')))
-                       *ptr++ = '/';
+               sprintf(env->me_txns->mti_wmname, "Global\\MDBw%s", hexbuf);
                env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
                if (!env->me_wmutex) {
                        rc = ErrCode();
@@ -2168,11 +2234,9 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                }
 #else  /* _WIN32 */
 #ifdef __APPLE__
-               char *ptr;
-               sprintf(env->me_txns->mti_rmname, "MDBr%.26s", lpath);
-               ptr = env->me_txns->mti_rmname + sizeof("MDBr")-1;
-               while ((ptr = strchr(ptr, '/')))
-                       *ptr++ = '_';
+               char hexbuf[17];
+               mdb_hash_hex(lpath, hexbuf);
+               sprintf(env->me_txns->mti_rmname, "MDBr%s", hexbuf);
                if (sem_unlink(env->me_txns->mti_rmname)) {
                        rc = ErrCode();
                        if (rc != ENOENT && rc != EINVAL)
@@ -2183,10 +2247,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                        rc = ErrCode();
                        goto fail;
                }
-               sprintf(env->me_txns->mti_wmname, "MDBw%.26s", lpath);
-               ptr = env->me_txns->mti_wmname + sizeof("MDBw")-1;
-               while ((ptr = strchr(ptr, '/')))
-                       *ptr++ = '_';
+               sprintf(env->me_txns->mti_wmname, "MDBw%s", hexbuf);
                if (sem_unlink(env->me_txns->mti_wmname)) {
                        rc = ErrCode();
                        if (rc != ENOENT && rc != EINVAL)