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-rw-r--r--src/misc/lockf.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/src/misc/lockf.c b/src/misc/lockf.c
new file mode 100644
index 00000000..d8f82efd
--- /dev/null
+++ b/src/misc/lockf.c
@@ -0,0 +1,33 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "libc.h"
+
+int lockf(int fd, int op, off_t size)
+{
+ struct flock l = {
+ .l_type = F_WRLCK,
+ .l_whence = SEEK_CUR,
+ .l_len = size,
+ };
+ switch (op) {
+ case F_TEST:
+ l.l_type = F_RDLCK;
+ if (fcntl(fd, F_GETLK, &l) < 0)
+ return -1;
+ if (l.l_type == F_UNLCK || l.l_pid == getpid())
+ return 0;
+ errno = EACCES;
+ return -1;
+ case F_ULOCK:
+ l.l_type = F_UNLCK;
+ case F_TLOCK:
+ return fcntl(fd, F_SETLK, &l);
+ case F_LOCK:
+ return fcntl(fd, F_SETLKW, &l);
+ }
+ errno = EINVAL;
+ return -1;
+}
+
+LFS64(lockf);