From a0a6868d90d0f850b337309ad2e1ed19ed0fbb33 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Thu, 17 Jul 2014 03:31:58 +0100
Subject: [PATCH] better error detection in vips_system()

---
 ChangeLog                | 1 +
 libvips/iofuncs/system.c | 5 ++---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 0f463934..1172b87e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,7 @@
 - vips_scale() now does round to nearest to avoid rounding errors
 - improve im_openout() compat macro
 - more vips7 compatibility fixes, thanks steve
+- more robust vips_system()
 
 30/6/14 started 7.40.3
 - fix interlaced thumbnails in vipsthumbnail, thanks lovell
diff --git a/libvips/iofuncs/system.c b/libvips/iofuncs/system.c
index 55df343e..028cc25b 100644
--- a/libvips/iofuncs/system.c
+++ b/libvips/iofuncs/system.c
@@ -177,7 +177,8 @@ vips_system_build( VipsObject *object )
 			memmove( p, p + 1, strlen( p ) );
 
 	if( !g_spawn_command_line_sync( cmd, 
-		&std_output, &std_error, &result, &error ) ) {
+		&std_output, &std_error, &result, &error ) ||
+		result ) {
 		if( error ) {
 			vips_error( class->nickname, "%s", error->message );
 			g_error_free( error );
@@ -202,8 +203,6 @@ vips_system_build( VipsObject *object )
 		return( -1 ); 
 	}
 
-	g_assert( !result ); 
-
 	if( std_error ) {
 		vips__chomp( std_error ); 
 		if( strcmp( std_error, "" ) != 0 )