daemon: Move useful is_zero function to header file.

[libguestfs.git] / daemon / daemon.h

diff --git a/daemon/daemon.h b/daemon/daemon.h
index 40a087d..b4f99a8 100644 (file)
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -36,7 +36,7 @@ extern int verbose;
 extern int autosync_umount;
 
 extern const char *sysroot;
-extern int sysroot_len;
+extern size_t sysroot_len;
 
 extern char *sysroot_path (const char *path);
 
@@ -191,6 +191,24 @@ extern void pulse_mode_start (void);
 extern void pulse_mode_end (void);
 extern void pulse_mode_cancel (void);
 
+/* Return true iff the buffer is all zero bytes.
+ *
+ * Note that gcc is smart enough to optimize this properly:
+ * http://stackoverflow.com/questions/1493936/faster-means-of-checking-for-an-empty-buffer-in-c/1493989#1493989
+ */
+static inline int
+is_zero (const char *buffer, size_t size)
+{
+  size_t i;
+
+  for (i = 0; i < size; ++i) {
+    if (buffer[i] != 0)
+      return 0;
+  }
+
+  return 1;
+}
+
 /* Helper for functions that need a root filesystem mounted.
  * NB. Cannot be used for FileIn functions.
  */