Automatically clean up passed file descriptorsfd-passing

Close unreported received file descriptors at socket close time.
Allow applications to request that sent descriptors be closed after
being passed.

Signed-off-by: Keith Packard <keithp@keithp.com>

4 files changed, 31 insertions, 11 deletions

diff --git a/Xtrans.c b/Xtrans.c
index 1d52435..8a398f2 100644
--- a/Xtrans.c
+++ b/Xtrans.c
@@ -887,9 +887,9 @@ TRANS(Writev) (XtransConnInfo ciptr, struct iovec *buf, int size)
 }
 
 int
-TRANS(SendFd) (XtransConnInfo ciptr, int fd)
+TRANS(SendFd) (XtransConnInfo ciptr, int fd, int do_close)
 {
-        return ciptr->transptr->SendFd(ciptr, fd);
+    return ciptr->transptr->SendFd(ciptr, fd, do_close);
 }
 
 int
diff --git a/Xtrans.h b/Xtrans.h
index ccc9c4d..36cfc1d 100644
--- a/Xtrans.h
+++ b/Xtrans.h
@@ -358,7 +358,7 @@ int TRANS(Writev)(
     int			/* size */
 );
 
-int TRANS(SendFd) (XtransConnInfo ciptr, int fd);
+int TRANS(SendFd) (XtransConnInfo ciptr, int fd, int do_close);
 
 int TRANS(RecvFd) (XtransConnInfo ciptr);
 
diff --git a/Xtransint.h b/Xtransint.h
index ae1f1e0..dd886db 100644
--- a/Xtransint.h
+++ b/Xtransint.h
@@ -130,6 +130,7 @@ from The Open Group.
 struct _XtransConnFd {
     struct _XtransConnFd   *next;
     int                    fd;
+    int                    do_close;
 };
 
 #endif
@@ -290,7 +291,8 @@ typedef struct _Xtransport {
 
     int (*SendFd)(
 	XtransConnInfo,		/* connection */
-        int                     /* fd */
+        int,                    /* fd */
+        int                     /* do_close */
     );
 
     int (*RecvFd)(
diff --git a/Xtranssock.c b/Xtranssock.c
index b8563bd..23150b2 100644
--- a/Xtranssock.c
+++ b/Xtranssock.c
@@ -2100,7 +2100,7 @@ TRANS(SocketBytesReadable) (XtransConnInfo ciptr, BytesReadable_t *pend)
 #if XTRANS_SEND_FDS
 
 static void
-appendFd(struct _XtransConnFd **prev, int fd)
+appendFd(struct _XtransConnFd **prev, int fd, int do_close)
 {
     struct _XtransConnFd *cf, *new;
 
@@ -2112,6 +2112,7 @@ appendFd(struct _XtransConnFd **prev, int fd)
     }
     new->next = 0;
     new->fd = fd;
+    new->do_close = do_close;
     /* search to end of list */
     for (; (cf = *prev); prev = &(cf->next));
     *prev = new;
@@ -2133,17 +2134,28 @@ removeFd(struct _XtransConnFd **prev)
 }
 
 static void
-discardFd(struct _XtransConnFd **prev, struct _XtransConnFd *upto)
+discardFd(struct _XtransConnFd **prev, struct _XtransConnFd *upto, int do_close)
 {
     struct _XtransConnFd *cf, *next;
 
     for (cf = *prev; cf != upto; cf = next) {
         next = cf->next;
+        if (do_close || cf->do_close)
+            close(cf->fd);
         free(cf);
     }
     *prev = upto;
 }
 
+static void
+cleanupFds(XtransConnInfo ciptr)
+{
+    /* Clean up the send list but don't close the fds */
+    discardFd(&ciptr->send_fds, NULL, 0);
+    /* Clean up the recv list and *do* close the fds */
+    discardFd(&ciptr->recv_fds, NULL, 1);
+}
+
 static int
 nFd(struct _XtransConnFd **prev)
 {
@@ -2163,9 +2175,9 @@ TRANS(SocketRecvFd) (XtransConnInfo ciptr)
 }
 
 static int
-TRANS(SocketSendFd) (XtransConnInfo ciptr, int fd)
+TRANS(SocketSendFd) (XtransConnInfo ciptr, int fd, int do_close)
 {
-    appendFd(&ciptr->send_fds, fd);
+    appendFd(&ciptr->send_fds, fd, do_close);
     return 0;
 }
 
@@ -2177,7 +2189,7 @@ TRANS(SocketRecvFdInvalid)(XtransConnInfo ciptr)
 }
 
 static int
-TRANS(SocketSendFdInvalid)(XtransConnInfo ciptr, int fd)
+TRANS(SocketSendFdInvalid)(XtransConnInfo ciptr, int fd, int do_close)
 {
     errno = EINVAL;
     return -1;
@@ -2244,7 +2256,7 @@ TRANS(SocketRead) (XtransConnInfo ciptr, char *buf, int size)
                 int *fd = (int *) CMSG_DATA(&pass.cmsghdr);
                 int i;
                 for (i = 0; i < nfd; i++)
-                    appendFd(&ciptr->recv_fds, fd[i]);
+                    appendFd(&ciptr->recv_fds, fd[i], 0);
             }
         }
         return size;
@@ -2292,7 +2304,7 @@ TRANS(SocketWritev) (XtransConnInfo ciptr, struct iovec *buf, int size)
         init_msg_send(&msg, buf, size, &pass, nfd);
         i = sendmsg(ciptr->fd, &msg, 0);
         if (i > 0)
-            discardFd(&ciptr->send_fds, cf);
+            discardFd(&ciptr->send_fds, cf, 0);
         return i;
     }
 #endif
@@ -2382,6 +2394,9 @@ TRANS(SocketUNIXClose) (XtransConnInfo ciptr)
 
     prmsg (2,"SocketUNIXClose(%p,%d)\n", ciptr, ciptr->fd);
 
+#if XTRANS_SEND_FDS
+    cleanupFds(ciptr);
+#endif
     ret = close(ciptr->fd);
 
     if (ciptr->flags
@@ -2410,6 +2425,9 @@ TRANS(SocketUNIXCloseForCloning) (XtransConnInfo ciptr)
     prmsg (2,"SocketUNIXCloseForCloning(%p,%d)\n",
 	ciptr, ciptr->fd);
 
+#if XTRANS_SEND_FDS
+    cleanupFds(ciptr);
+#endif
     ret = close(ciptr->fd);
 
     return ret;