ITS#7615 use shorter names for semaphores

NetBSD can only handle up to 14 chars, we were using 21. Now
we encode to 15, and for NetBSD truncate the last char.

libraries/liblmdb/mdb.c

@@ -3535,20 +3535,37 @@ mdb_hash_val(MDB_val *val, mdb_hash_t hval)
 	return hval;
 }
 
-/** Hash the string and output the hash in hex.
+/** Hash the string and output the encoded hash.
+ * This uses modified RFC1924 Ascii85 encoding to accommodate systems with
+ * very short name limits. We don't care about the encoding being reversible,
+ * we just want to preserve as many bits of the input as possible in a
+ * small printable string.
  * @param[in] str string to hash
- * @param[out] hexbuf an array of 17 chars to hold the hash
+ * @param[out] encbuf an array of 11 chars to hold the hash
  */
+const static char mdb_a85[]= "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~";
+
 static void
-mdb_hash_hex(MDB_val *val, char *hexbuf)
+mdb_pack85(unsigned long l, char *out)
 {
 	int i;
-	mdb_hash_t h = mdb_hash_val(val, MDB_HASH_INIT);
+
-	for (i=0; i<8; i++) {
+	for (i=0; i<5; i++) {
-		hexbuf += sprintf(hexbuf, "%02x", (unsigned int)h & 0xff);
+		*out++ = mdb_a85[l % 85];
-		h >>= 8;
+		l /= 85;
 	}
 }
+
+static void
+mdb_hash_enc(MDB_val *val, char *encbuf)
+{
+	mdb_hash_t h = mdb_hash_val(val, MDB_HASH_INIT);
+	unsigned long *l = (unsigned long *)&h;
+
+	mdb_pack85(l[0], encbuf);
+	mdb_pack85(l[1], encbuf+5);
+	encbuf[10] = '\0';
+}
 #endif
 
 /** Open and/or initialize the lock region for the environment.
@@ -3661,7 +3678,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 			DWORD nlow;
 		} idbuf;
 		MDB_val val;
-		char hexbuf[17];
+		char encbuf[11];
 
 		if (!mdb_sec_inited) {
 			InitializeSecurityDescriptor(&mdb_null_sd,
@@ -3678,9 +3695,9 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 		idbuf.nlow   = stbuf.nFileIndexLow;
 		val.mv_data = &idbuf;
 		val.mv_size = sizeof(idbuf);
-		mdb_hash_hex(&val, hexbuf);
+		mdb_hash_enc(&val, encbuf);
-		sprintf(env->me_txns->mti_rmname, "Global\\MDBr%s", hexbuf);
+		sprintf(env->me_txns->mti_rmname, "Global\\MDBr%s", encbuf);
-		sprintf(env->me_txns->mti_wmname, "Global\\MDBw%s", hexbuf);
+		sprintf(env->me_txns->mti_wmname, "Global\\MDBw%s", encbuf);
 		env->me_rmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_rmname);
 		if (!env->me_rmutex) goto fail_errno;
 		env->me_wmutex = CreateMutex(&mdb_all_sa, FALSE, env->me_txns->mti_wmname);
@@ -3692,16 +3709,22 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 			ino_t ino;
 		} idbuf;
 		MDB_val val;
-		char hexbuf[17];
+		char encbuf[11];
 
+#if defined(__NetBSD__)
+#define	MDB_SHORT_SEMNAMES	1	/* limited to 14 chars */
+#endif
 		if (fstat(env->me_lfd, &stbuf)) goto fail_errno;
 		idbuf.dev = stbuf.st_dev;
 		idbuf.ino = stbuf.st_ino;
 		val.mv_data = &idbuf;
 		val.mv_size = sizeof(idbuf);
-		mdb_hash_hex(&val, hexbuf);
+		mdb_hash_enc(&val, encbuf);
-		sprintf(env->me_txns->mti_rmname, "/MDBr%s", hexbuf);
+#ifdef MDB_SHORT_SEMNAMES
-		sprintf(env->me_txns->mti_wmname, "/MDBw%s", hexbuf);
+		encbuf[9] = '\0';	/* drop name from 15 chars to 14 chars */
+#endif
+		sprintf(env->me_txns->mti_rmname, "/MDBr%s", encbuf);
+		sprintf(env->me_txns->mti_wmname, "/MDBw%s", encbuf);
 		/* Clean up after a previous run, if needed:  Try to
 		 * remove both semaphores before doing anything else.
 		 */