file_utils: add open_at_same()

[mirror_lxc.git] / src / lxc / file_utils.c

diff --git a/src/lxc/file_utils.c b/src/lxc/file_utils.c
index 13a87055275185f1932abfd30be83abdd48a2476..a361d188e7baf9e2e6f8610227ae169686e67611 100644 (file)
--- a/src/lxc/file_utils.c
+++ b/src/lxc/file_utils.c
@@ -670,6 +670,21 @@ int open_at(int dfd, const char *path, unsigned int o_flags,
        return move_fd(fd);
 }
 
+int open_at_same(int fd_same, int dfd, const char *path, unsigned int o_flags,
+                unsigned int resolve_flags, mode_t mode)
+{
+       __do_close int fd = -EBADF;
+
+       fd = open_at(dfd, path, o_flags, resolve_flags, mode);
+       if (fd < 0)
+               return -errno;
+
+       if (!same_file_lax(fd_same, fd))
+               return ret_errno(EINVAL);
+
+       return move_fd(fd);
+}
+
 int fd_make_nonblocking(int fd)
 {
        int flags;