Implement POSIX lockf.
This has been requested a few times over the years. This is basically
a very late rebase of https://android-review.googlesource.com/45470
which was abandoned years ago. One addition is that this version has
_FILE_OFFSET_BITS=64 support.
POSIX puts this in <unistd.h>. glibc also has it in <fcntl.h>.
Bug: http://b/13077650
Change-Id: I5862b1dc326e326c01ad92438ecc1578d19ba739
diff --git a/libc/bionic/lockf.cpp b/libc/bionic/lockf.cpp
new file mode 100644
index 0000000..1510b3d
--- /dev/null
+++ b/libc/bionic/lockf.cpp
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS 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
+ * COPYRIGHT OWNER OR 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.
+ */
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+
+int lockf64(int fd, int cmd, off64_t length) {
+ // Translate POSIX lockf into fcntl.
+ struct flock fl;
+ memset(&fl, 0, sizeof(fl));
+ fl.l_whence = SEEK_CUR;
+ fl.l_start = 0;
+ fl.l_len = length;
+
+ if (cmd == F_ULOCK) {
+ fl.l_type = F_UNLCK;
+ cmd = F_SETLK64;
+ return fcntl(fd, F_SETLK64, &fl);
+ }
+
+ if (cmd == F_LOCK) {
+ fl.l_type = F_WRLCK;
+ return fcntl(fd, F_SETLKW64, &fl);
+ }
+
+ if (cmd == F_TLOCK) {
+ fl.l_type = F_WRLCK;
+ return fcntl(fd, F_SETLK64, &fl);
+ }
+
+ if (cmd == F_TEST) {
+ fl.l_type = F_RDLCK;
+ if (fcntl(fd, F_GETLK64, &fl) == -1) return -1;
+ if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) return 0;
+ errno = EACCES;
+ return -1;
+ }
+
+ errno = EINVAL;
+ return -1;
+}
+
+int lockf(int fd, int cmd, off_t length) {
+ return lockf64(fd, cmd, length);
+}