[PATCH] winebuild: Fix a segmentation fault

[James Larrowe]

When 'winebuild' is called with no arguments, the make_c_identifier
function is passed a null pointer, which is dereferenced and causes
a segmentation fault. This patch fixes that issue.

Signed-off-by: James Larrowe <larrowe.semaj11(a)gmail.com>
---
 tools/winebuild/utils.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/winebuild/utils.c b/tools/winebuild/utils.c
index 95da1758c5..a6b1c102fd 100644
--- a/tools/winebuild/utils.c
+++ b/tools/winebuild/utils.c
@@ -816,10 +816,17 @@ char *make_c_identifier( const char *str )
 {
     char *p, buffer[256];
 
-    for (p = buffer; *str && p < buffer+sizeof(buffer)-1; p++, str++)
+    if ( str == NULL )
     {
-        if (isalnum(*str)) *p = *str;
-        else *p = '_';
+        return NULL;
+    }
+    else
+    {
+        for (p = buffer; *str && p < buffer+sizeof(buffer)-1; p++, str++)
+        {
+            if (isalnum(*str)) *p = *str;
+            else *p = '_';
+        }
     }
     *p = 0;
     return xstrdup( buffer );
-- 
2.20.1