read/write files not truncated if they already exist

1 files changed, 9 insertions, 1 deletions

diff --git a/mixlib/mix_file.c b/mixlib/mix_file.c
index 6ee88ec..ac623f6 100644
--- a/mixlib/mix_file.c
+++ b/mixlib/mix_file.c
@@ -48,9 +48,17 @@ open_file_(const gchar *name, mix_fmode_t mode)
 {
   mix_file_t *result;
   FILE *file;
+  const gchar *fmode = fmode_to_type_ (mode);
+
+  /* if the read/write file already exists, open in r+ mode */
+  if (mode == mix_io_RDWRT && (file = fopen (name, "r")))
+    {
+      fmode = "r+";
+      fclose (file);
+    }
   
   result = g_new(mix_file_t, 1);
-  file = fopen(name, fmode_to_type_(mode));
+  file = fopen(name, fmode);
   if ( file == NULL ) {
     g_free (result);
     return NULL;