lmdb-test: workaround for MDB_FIXEDMAP to avoid sporadic failures.

Change-Id: I6ba993ff50956d328fd76326c67aa83dff20ce48

mtest5.c

@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -37,6 +44,8 @@ int main(int argc,char * argv[])
 	int *values;
 	char sval[32];
 	char kval[sizeof(int)];
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -52,7 +61,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id5", MDB_CREATE, &dbi) == MDB_SUCCESS)