shared: introduce cmsg_close_all() call

The call iterates through cmsg list and closes all fds passed via
SCM_RIGHTS.

This patch also ensures the call is used wherever appropriate, where we
might get spurious fds sent and we should better close them, then leave
them lying around.

1 files changed, 8 insertions, 6 deletions

diff --git a/src/shutdownd/shutdownd.c b/src/shutdownd/shutdownd.c
index 701882b96d..60a646878e 100644
--- a/src/shutdownd/shutdownd.c
+++ b/src/shutdownd/shutdownd.c
@@ -70,12 +70,7 @@ static int read_packet(int fd, union shutdown_buffer *_b) {
         assert(_b);
 
         n = recvmsg(fd, &msghdr, MSG_DONTWAIT);
-        if (n <= 0) {
-                if (n == 0) {
-                        log_error("Short read");
-                        return -EIO;
-                }
-
+        if (n < 0) {
                 if (errno == EAGAIN || errno == EINTR)
                         return 0;
 
@@ -83,6 +78,13 @@ static int read_packet(int fd, union shutdown_buffer *_b) {
                 return -errno;
         }
 
+        cmsg_close_all(&msghdr);
+
+        if (n == 0) {
+                log_error("Short read");
+                return -EIO;
+        }
+
         if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
             control.cmsghdr.cmsg_level != SOL_SOCKET ||
             control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||