Fix last commit.

Add flag MDB_ENV_ACTIVE instead of using the state of me_lfd.
Require MDB_RDONLY for MDB_ROFS.  Swap reader/writer mutex lock.

diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
index 9bfe2f8..b39fbfb 100644 (file)
--- a/libraries/libmdb/mdb.c
+++ b/libraries/libmdb/mdb.c
@@ -915,6 +915,8 @@ struct MDB_env {
 #define        MDB_FATAL_ERROR 0x80000000U
        /** Read-only Filesystem. Allow read access, no locking. */
 #define        MDB_ROFS        0x40000000U
+       /** Some fields are initialized. */
+#define        MDB_ENV_ACTIVE  0x20000000U
        uint32_t        me_flags;               /**< @ref mdb_env */
        unsigned int    me_psize;       /**< size of a page, from #GET_PAGESIZE */
        unsigned int    me_maxreaders;  /**< size of the reader table */
@@ -2583,14 +2585,13 @@ mdb_env_get_maxreaders(MDB_env *env, unsigned int *readers)
 /** Further setup required for opening an MDB environment
  */
 static int
-mdb_env_open2(MDB_env *env, unsigned int flags)
+mdb_env_open2(MDB_env *env)
 {
+       unsigned int flags = env->me_flags;
        int i, newenv = 0, prot;
        MDB_meta meta;
        MDB_page *p;
 
-       env->me_flags |= flags;
-
        memset(&meta, 0, sizeof(meta));
 
        if ((i = mdb_env_read_header(env, &meta)) != 0) {
@@ -2931,7 +2932,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS,
                FILE_ATTRIBUTE_NORMAL, NULL)) == INVALID_HANDLE_VALUE) {
                rc = ErrCode();
-               if (rc == ERROR_WRITE_PROTECT) {
+               if (rc == ERROR_WRITE_PROTECT && (env->me_flags & MDB_RDONLY)) {
                        env->me_flags |= MDB_ROFS;
                        return MDB_SUCCESS;
                }
@@ -2949,7 +2950,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
                int fdflags;
                if ((env->me_lfd = open(lpath, O_RDWR|O_CREAT, mode)) == -1) {
                        rc = ErrCode();
-                       if (rc == EROFS) {
+                       if (rc == EROFS && (env->me_flags & MDB_RDONLY)) {
                                env->me_flags |= MDB_ROFS;
                                return MDB_SUCCESS;
                        }
@@ -2962,7 +2963,7 @@ mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
 #else /* O_CLOEXEC on Linux: Open file and set FD_CLOEXEC atomically */
        if ((env->me_lfd = open(lpath, O_RDWR|O_CREAT|O_CLOEXEC, mode)) == -1) {
                rc = ErrCode();
-               if (rc == EROFS) {
+               if (rc == EROFS && (env->me_flags & MDB_RDONLY)) {
                        env->me_flags |= MDB_ROFS;
                        return MDB_SUCCESS;
                }
@@ -3154,15 +3155,15 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
                sprintf(dpath, "%s" DATANAME, path);
        }
 
-       env->me_flags = 0;
+       /* silently ignore WRITEMAP if we're only getting read access */
+       if (F_ISSET(flags, MDB_RDONLY|MDB_WRITEMAP))
+               flags ^= MDB_WRITEMAP;
+       env->me_flags = flags |= MDB_ENV_ACTIVE;
+
        rc = mdb_env_setup_locks(env, lpath, mode, &excl);
        if (rc)
                goto leave;
 
-       /* silently ignore WRITEMAP if we're only getting read access */
-       if (F_ISSET(flags, MDB_RDONLY) && F_ISSET(flags, MDB_WRITEMAP))
-               flags ^= MDB_WRITEMAP;
-
 #ifdef _WIN32
        if (F_ISSET(flags, MDB_RDONLY)) {
                oflags = GENERIC_READ;
@@ -3187,7 +3188,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
                goto leave;
        }
 
-       if ((rc = mdb_env_open2(env, flags)) == MDB_SUCCESS) {
+       if ((rc = mdb_env_open2(env)) == MDB_SUCCESS) {
                if (flags & (MDB_RDONLY|MDB_NOSYNC|MDB_NOMETASYNC|MDB_WRITEMAP)) {
                        env->me_mfd = env->me_fd;
                } else {
@@ -3242,7 +3243,7 @@ mdb_env_close0(MDB_env *env, int excl)
 {
        int i;
 
-       if (env->me_lfd == INVALID_HANDLE_VALUE) /* 1st field to get inited */
+       if (!(env->me_flags & MDB_ENV_ACTIVE))
                return;
 
        free(env->me_dbflags);
@@ -3303,9 +3304,11 @@ mdb_env_close0(MDB_env *env, int excl)
 #endif
                munmap((void *)env->me_txns, (env->me_maxreaders-1)*sizeof(MDB_reader)+sizeof(MDB_txninfo));
        }
-       close(env->me_lfd);
+       if (env->me_lfd != INVALID_HANDLE_VALUE) {
+               close(env->me_lfd);
+       }
 
-       env->me_lfd = INVALID_HANDLE_VALUE;     /* Mark env as reset */
+       env->me_flags &= ~MDB_ENV_ACTIVE;
 }
 
 int
@@ -3357,13 +3360,25 @@ mdb_env_copy(MDB_env *env, const char *path)
        }
 #endif
 
-       /* Temporarily block writers until we snapshot the meta pages */
-       LOCK_MUTEX_W(env);
-
+       /* Do the lock/unlock of the reader mutex before starting the
+        * write txn.  Otherwise other read txns could block writers.
+        */
        rc = mdb_txn_begin(env, NULL, MDB_RDONLY, &txn);
-       if (rc) {
-               UNLOCK_MUTEX_W(env);
+       if (rc)
                goto leave;
+
+       if (!(env->me_flags & MDB_ROFS)) {
+               /* We must start the actual read txn after blocking writers */
+               mdb_txn_reset0(txn);
+
+               /* Temporarily block writers until we snapshot the meta pages */
+               LOCK_MUTEX_W(env);
+
+               rc = mdb_txn_renew0(txn);
+               if (rc) {
+                       UNLOCK_MUTEX_W(env);
+                       goto leave;
+               }
        }
 
        wsize = env->me_psize * 2;
@@ -3377,7 +3392,8 @@ mdb_env_copy(MDB_env *env, const char *path)
        rc = write(newfd, env->me_map, wsize);
        rc = (rc == (int)wsize) ? MDB_SUCCESS : ErrCode();
 #endif
-       UNLOCK_MUTEX_W(env);
+       if (! (env->me_flags & MDB_ROFS))
+               UNLOCK_MUTEX_W(env);
 
        if (rc)
                goto leave;