Wrap O_DSYNC in MDB_DSYNC.

If O_DSYNC is not defined, that may be due to poor compiler options.
We could fall back to the less efficient O_SYNC, but it seems better
to let the user learn of the problem and give better compiler options.

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 3de7e1d71bb06fb365697880fb76825a08f6761b..84c448226772592bc2dfd487ddba684287e7a479 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -55,6 +55,14 @@ typedef ULONG                pgno_t;
 
 #include "midl.h"
 
+/* Note: If O_DSYNC is undefined but exists in /usr/include,
+ * preferably set some compiler flag to get the definition.
+ * Otherwise compile with the less efficient -DMDB_DSYNC=O_SYNC.
+ */
+#ifndef MDB_DSYNC
+# define MDB_DSYNC     O_DSYNC
+#endif
+
 #ifndef DEBUG
 #define DEBUG 1
 #endif
@@ -1407,7 +1415,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
        if ((rc = mdb_env_open2(env, flags)) == MDB_SUCCESS) {
                /* synchronous fd for meta writes */
                if (!(flags & (MDB_RDONLY|MDB_NOSYNC)))
-                       oflags |= O_DSYNC;
+                       oflags |= MDB_DSYNC;
                if ((env->me_mfd = open(dpath, oflags, mode)) == -1) {
                        rc = errno;
                        goto leave;