[Libguestfs] [PATCH] daemon: Move the useful 'is_zero' function into common code.

[Richard W.M. Jones]

This is largely a simple refactoring, but it combines another
definition of this function from virt-builder which had a slightly
different prototype.
---
 builder/pxzcat-c.c         | 20 +-------------------
 daemon/daemon.h            | 18 ------------------
 lib/guestfs-internal-all.h | 18 ++++++++++++++++++
 3 files changed, 19 insertions(+), 37 deletions(-)

diff --git a/builder/pxzcat-c.c b/builder/pxzcat-c.c
index 33923b532..ef37849ed 100644
--- a/builder/pxzcat-c.c
+++ b/builder/pxzcat-c.c
@@ -409,24 +409,6 @@ parse_indexes (value filenamev, int fd)
   return combined_index;
 }
 
-/* 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 unsigned char *buffer, size_t size)
-{
-  size_t i;
-
-  for (i = 0; i < size; ++i) {
-    if (buffer[i] != 0)
-      return 0;
-  }
-
-  return 1;
-}
-
 struct global_state {
   /* Current iterator.  Threads update this, but it is protected by a
    * mutex, and each thread takes a copy of it when working on it.
@@ -681,7 +663,7 @@ worker_thread (void *vp)
         /* Don't write if the block is all zero, to preserve output file
          * sparseness.  However we have to update oposition.
          */
-        if (!is_zero (outbuf, wsz)) {
+        if (!is_zero ((char *) outbuf, wsz)) {
           if (xpwrite (global->ofd, outbuf, wsz, oposition) == -1) {
             perror (global->outputfile);
             return &state->status;
diff --git a/daemon/daemon.h b/daemon/daemon.h
index 332e2966a..a317139a5 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -327,24 +327,6 @@ extern void pulse_mode_cancel (void);
  */
 extern void notify_progress_no_ratelimit (uint64_t position, uint64_t total, const struct timeval *now);
 
-/* 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.
  */
diff --git a/lib/guestfs-internal-all.h b/lib/guestfs-internal-all.h
index 0c841ff67..4f7433332 100644
--- a/lib/guestfs-internal-all.h
+++ b/lib/guestfs-internal-all.h
@@ -89,6 +89,24 @@
 #define xdr_uint32_t xdr_u_int32_t
 #endif
 
+/* 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;
+}
+
 /* Macro which compiles the regexp once when the program/library is
  * loaded, and frees it when the library is unloaded.
  */
-- 
2.12.0