os: FatalError if -displayfd writes fail

When the server is started with the -displayfd option, check to make
sure that the writes succeed and give up running if they don't.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/os/connection.c b/os/connection.c
index 5294e5955..40d9ff39b 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -353,8 +353,10 @@ NotifyParentProcess(void)
 {
 #if !defined(WIN32)
     if (displayfd >= 0) {
-        write(displayfd, display, strlen(display));
-        write(displayfd, "\n", 1);
+        if (write(displayfd, display, strlen(display)) != strlen(display))
+            FatalError("Cannot write display number to fd %d\n", displayfd);
+        if (write(displayfd, "\n", 1) != 1)
+            FatalError("Cannot write display number to fd %d\n", displayfd);
         close(displayfd);
         displayfd = -1;
     }