aboutsummaryrefslogtreecommitdiff
path: root/io/lockf.c
diff options
context:
space:
mode:
authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /io/lockf.c
downloadglibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.zip
glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.gz
glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.bz2
initial import
Diffstat (limited to 'io/lockf.c')
-rw-r--r--io/lockf.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/io/lockf.c b/io/lockf.c
new file mode 100644
index 0000000..9166419
--- /dev/null
+++ b/io/lockf.c
@@ -0,0 +1,68 @@
+/* Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+/* lockf is a simplified interface to fcntl's locking facilities. */
+
+int
+lockf (int fd, int cmd, off_t len)
+{
+ struct flock fl;
+
+ switch (cmd)
+ {
+ case F_TEST:
+ /* Test the lock: return 0 if FD is unlocked or locked by this process;
+ return -1, set errno to EACCES, if another process holds the lock. */
+ if (fcntl (fd, F_GETLK, &fl) < 0)
+ return -1;
+ if (fl.l_type == F_UNLCK || fl.l_pid == getpid ())
+ return 0;
+ errno = EACCES;
+ return -1;
+
+ case F_ULOCK:
+ fl.l_type = F_UNLCK;
+ cmd = F_SETLK;
+ break;
+ case F_LOCK:
+ fl.l_type = F_WRLCK;
+ cmd = F_SETLKW;
+ break;
+ case F_TLOCK:
+ fl.l_type = F_WRLCK;
+ cmd = F_SETLK;
+ break;
+
+ default:
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* lockf is always relative to the current file position. */
+ fl.l_whence = SEEK_CUR;
+ fl.l_start = 0;
+
+ fl.l_len = len;
+
+ return fcntl (fd, cmd, &fl);
+}