*) Add functions for file-level locking/unlocking.

*) Add test program for the new functions.


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@60811 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 151 insertions, 0 deletions

diff --git a/file_io/unix/Makefile.in b/file_io/unix/Makefile.in
index 05254e350..d437f0157 100644
--- a/file_io/unix/Makefile.in
+++ b/file_io/unix/Makefile.in
@@ -14,6 +14,7 @@ OBJS=dir.o \
 	fileacc.o \
 	filedup.o \
 	filestat.o \
+	flock.o \
 	fullrw.o \
 	open.o \
 	pipe.o \
diff --git a/file_io/unix/flock.c b/file_io/unix/flock.c
new file mode 100644
index 000000000..ecd7f7ae4
--- /dev/null
+++ b/file_io/unix/flock.c
@@ -0,0 +1,150 @@
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2000 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" must
+ *    not be used to endorse or promote products derived from this
+ *    software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    nor may "Apache" appear in their name, without prior written
+ *    permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+#include "fileio.h"
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+#ifdef HAVE_SYS_FILE_H
+#include <sys/file.h>
+#endif
+
+apr_status_t apr_lock_file(apr_file_t *thefile, int type)
+{
+    int rc;
+
+#if defined(HAVE_FCNTL_H)
+    {
+        struct flock l = { 0 };
+        int fc;
+
+        l.l_whence = SEEK_SET;  /* lock from current point */
+        l.l_start = 0;          /* begin lock at this offset */
+        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)
+            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_status_t apr_unlock_file(apr_file_t *thefile)
+{
+    int rc;
+
+#if defined(HAVE_FCNTL_H)
+    {
+        struct flock l = { 0 };
+
+        l.l_whence = SEEK_SET;  /* lock from current point */
+        l.l_start = 0;          /* begin lock at this offset */
+        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;
+}