osdep: add qemu_unlink()

Add a helper function to match qemu_open() which may return files
under the /dev/fdset prefix. Those shouldn't be removed, since it's
only a qemu namespace.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

util/osdep.c

@@ -370,6 +370,21 @@ int qemu_close(int fd)
     return close(fd);
 }
 
+/*
+ * Delete a file from the filesystem, unless the filename is /dev/fdset/...
+ *
+ * Returns: On success, zero is returned.  On error, -1 is returned,
+ * and errno is set appropriately.
+ */
+int qemu_unlink(const char *name)
+{
+    if (g_str_has_prefix(name, "/dev/fdset/")) {
+        return 0;
+    }
+
+    return unlink(name);
+}
+
 /*
  * A variant of write(2) which handles partial write.
  *