From: Matthew Daley <mattjd@gmail.com>
Date: Fri, 1 Nov 2013 00:33:23 +0000 (+1300)
Subject: libvchan: tidy up usages of fcntl in select-type sample application
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~6075
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=098ef0c4d4e0b867e86ddbb9ebc813bb8c2ad617;p=xen.git

libvchan: tidy up usages of fcntl in select-type sample application

Namely, don't overwrite all the other flags when twiddling O_NONBLOCK,
and add basic error handling.

Coverity-ID: 1055041
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
---

diff --git a/tools/libvchan/node-select.c b/tools/libvchan/node-select.c
index 6c6c19eec6..13c58227fd 100644
--- a/tools/libvchan/node-select.c
+++ b/tools/libvchan/node-select.c
@@ -80,6 +80,22 @@ void stdout_wr() {
 	}
 }
 
+static int set_nonblocking(int fd, int nonblocking) {
+	int flags = fcntl(fd, F_GETFL);
+	if (flags == -1)
+		return -1;
+
+	if (nonblocking)
+		flags |= O_NONBLOCK;
+	else
+		flags &= ~O_NONBLOCK;
+
+	if (fcntl(fd, F_SETFL, flags) == -1)
+		return -1;
+
+	return 0;
+}
+
 /**
     Simple libxenvchan application, both client and server.
 	Both sides may write and read, both from the libxenvchan and from 
@@ -105,8 +121,10 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	fcntl(0, F_SETFL, O_NONBLOCK);
-	fcntl(1, F_SETFL, O_NONBLOCK);
+	if (set_nonblocking(0, 1) || set_nonblocking(1, 1)) {
+		perror("set_nonblocking");
+		exit(1);
+	}
 
 	libxenvchan_fd = libxenvchan_fd_for_select(ctrl);
 	for (;;) {
@@ -153,7 +171,10 @@ int main(int argc, char **argv)
 			stdout_wr();
 		}
 		if (!libxenvchan_is_open(ctrl)) {
-			fcntl(1, F_SETFL, 0);
+			if (set_nonblocking(1, 0)) {
+				perror("set_nonblocking");
+				exit(1);
+			}
 			while (outsiz)
 				stdout_wr();
 			return 0;