They are wrappers of POSIX fcntl "file private locking".
Signed-off-by: Fam Zheng <f...@redhat.com>
---
include/qemu/osdep.h | 2 ++
util/osdep.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 1e3221c..81913a7 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -265,6 +265,8 @@ int qemu_madvise(void *addr, size_t len, int advice);
int qemu_open(const char *name, int flags, ...);
int qemu_close(int fd);
+int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
+int qemu_unlock_fd(int fd, int64_t start, int64_t len);
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
diff --git a/util/osdep.c b/util/osdep.c
index d56d071..9e5d7fa 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -236,6 +236,37 @@ int qemu_close(int fd)
return close(fd);
}
+static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
+{
+#ifdef F_OFD_SETLK
+ struct flock fl = (struct flock) {
+ .l_whence = SEEK_SET,
+ /* Locking byte 1 avoids interfereing with virtlockd. */
+ .l_start = start,
+ .l_len = len,
+ .l_type = fl_type,
+ };
+ if (fcntl(fd, F_OFD_SETLK, &fl) == -1) {
+ return -errno;
+ } else {
+ return 0;
+ }
+#else
+ return -ENOTSUP;
+#endif
+}
+
+int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive)
+{
+
+ return qemu_lock_fcntl(fd, start, len, exclusive ? F_WRLCK : F_RDLCK);
+}
+
+int qemu_unlock_fd(int fd, int64_t start, int64_t len)
+{
+ return qemu_lock_fcntl(fd, start, len, F_UNLCK);
+}
+
/*
* A variant of write(2) which handles partial write.
*
--
2.8.2
