X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=sig.c;h=fe7fcede927b574391ce0cf4ee8e5035916d4fd1;hp=d2d7e3b59076a0c2899d53730bda9aad929f6bc6;hb=HEAD;hpb=8daf8f3836e745ba07f1aa01252279588574c95a

diff --git a/sig.c b/sig.c
index d2d7e3b..fe7fced 100644
--- a/sig.c
+++ b/sig.c
@@ -1,8 +1,4 @@
-/*
- * Copyright (C) 2004-2010 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* SPDX-License-Identifier: GPL-2.0 */
 
 #include <string.h>
 #include <errno.h>
@@ -64,12 +60,27 @@ err_out:
 	exit(EXIT_FAILURE);
 }
 
-/*
- * just write one integer to signal pipe
- */
+/* Write the signal number to the signal pipe, abort on errors. */
 static void generic_signal_handler(int s)
 {
-	write(signal_pipe[1], &s, sizeof(int));
+	/*
+	 * Signal handlers that make system calls must save a copy of errno on
+	 * entry to the handler and restore it on exit, to prevent the
+	 * possibility of overwriting a errno value that had previously been
+	 * set in the main program.
+	 */
+	int save_errno = errno;
+	ssize_t ret = write(signal_pipe[1], &s, sizeof(int));
+
+	if (ret == sizeof(int)) {
+		errno = save_errno;
+		return;
+	}
+	if (ret < 0)
+		DSS_EMERG_LOG(("%s\n", strerror(errno)));
+	else
+		DSS_EMERG_LOG(("short write to signal pipe\n"));
+	exit(EXIT_FAILURE);
 }
 
 /**