[PATCH remote-viewer] Fix potential file descriptor leaks found by Coverity.

[Julien Ropé]

The error code returned by virt_viewer_session_open_fd() and virt_viewer_session_channel_open_fd() were not checked. The file descriptor passed to them could then be left opened even if the function failed, causing a leak of resources.

This was reported by a Coverity scan, logged under https://bugzilla.redhat.com/show_bug.cgi?id=1655792

Signed-off-by: Julien Ropé <jrope at redhat.com>
---
 src/virt-viewer-app.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/virt-viewer-app.c b/src/virt-viewer-app.c
index a292ad8..12ee09d 100644
--- a/src/virt-viewer-app.c
+++ b/src/virt-viewer-app.c
@@ -1296,7 +1296,11 @@ virt_viewer_app_channel_open(VirtViewerSession *session,
         return;
     }
 
-    virt_viewer_session_channel_open_fd(session, channel, fd);
+    if (!virt_viewer_session_channel_open_fd(session, channel, fd)) {
+        // in case of error, close the file descriptor to prevent a leak
+        // NOTE: as VNC doesn't support channel_open, this function will always return false for this protocol.
+        close(fd);
+    }
 }
 #else
 static void
@@ -1355,7 +1359,10 @@ virt_viewer_app_default_activate(VirtViewerApp *self, GError **error)
 #endif
 
     if (fd >= 0) {
-        return virt_viewer_session_open_fd(VIRT_VIEWER_SESSION(priv->session), fd);
+        gboolean ret = virt_viewer_session_open_fd(VIRT_VIEWER_SESSION(priv->session), fd);
+        if (!ret)
+            close (fd);
+        return ret ;
     } else if (priv->guri) {
         virt_viewer_app_trace(self, "Opening connection to display at %s", priv->guri);
         return virt_viewer_session_open_uri(VIRT_VIEWER_SESSION(priv->session), priv->guri, error);
-- 
2.24.1