1 files changed, 120 insertions, 0 deletions
diff --git a/file_io/unix/flock.c b/file_io/unix/flock.c
new file mode 100644
index 0000000..01e8a63
--- /dev/null
+++ b/file_io/unix/flock.c
@@ -0,0 +1,120 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_arch_file_io.h"
+
+#if APR_HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+#ifdef HAVE_SYS_FILE_H
+#include <sys/file.h>
+#endif
+
+APR_DECLARE(apr_status_t) apr_file_lock(apr_file_t *thefile, int type)
+{
+    int rc;
+
+#if defined(HAVE_FCNTL_H)
+    {
+        struct flock l = { 0 };
+        int fc;
+
+        l.l_whence = SEEK_SET;  /* count l_start from start of file */
+        l.l_start = 0;          /* lock from start of file */
+        l.l_len = 0;            /* lock to end of file */
+        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
+            l.l_type = F_RDLCK;
+        else
+            l.l_type = F_WRLCK;
+
+        fc = (type & APR_FLOCK_NONBLOCK) ? F_SETLK : F_SETLKW;
+
+        /* keep trying if fcntl() gets interrupted (by a signal) */
+        while ((rc = fcntl(thefile->filedes, fc, &l)) < 0 && errno == EINTR)
+            continue;
+
+        if (rc == -1) {
+            /* on some Unix boxes (e.g., Tru64), we get EACCES instead
+             * of EAGAIN; we don't want APR_STATUS_IS_EAGAIN() matching EACCES
+             * since that breaks other things, so fix up the retcode here
+             */
+            if (errno == EACCES) {
+                return EAGAIN;
+            }
+            return errno;
+        }
+    }
+#elif defined(HAVE_SYS_FILE_H)
+    {
+        int ltype;
+
+        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
+            ltype = LOCK_SH;
+        else
+            ltype = LOCK_EX;
+        if ((type & APR_FLOCK_NONBLOCK) != 0)
+            ltype |= LOCK_NB;
+
+        /* keep trying if flock() gets interrupted (by a signal) */
+        while ((rc = flock(thefile->filedes, ltype)) < 0 && errno == EINTR)
+            continue;
+
+        if (rc == -1)
+            return errno;
+    }
+#else
+#error No file locking mechanism is available.
+#endif
+
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_file_unlock(apr_file_t *thefile)
+{
+    int rc;
+
+#if defined(HAVE_FCNTL_H)
+    {
+        struct flock l = { 0 };
+
+        l.l_whence = SEEK_SET;  /* count l_start from start of file */
+        l.l_start = 0;          /* lock from start of file */
+        l.l_len = 0;            /* lock to end of file */
+        l.l_type = F_UNLCK;
+
+        /* keep trying if fcntl() gets interrupted (by a signal) */
+        while ((rc = fcntl(thefile->filedes, F_SETLKW, &l)) < 0
+               && errno == EINTR)
+            continue;
+
+        if (rc == -1)
+            return errno;
+    }
+#elif defined(HAVE_SYS_FILE_H)
+    {
+        /* keep trying if flock() gets interrupted (by a signal) */
+        while ((rc = flock(thefile->filedes, LOCK_UN)) < 0 && errno == EINTR)
+            continue;
+
+        if (rc == -1)
+            return errno;
+    }
+#else
+#error No file locking mechanism is available.
+#endif
+
+    return APR_SUCCESS;
+}