From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 1 Oct 2020 12:13:37 +0000 (+0200)
Subject: virBitmapToString: Properly handle empty bitmaps
X-Git-Tag: v6.9.0-rc1~386
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e2d13d607f23f6a219d50da2a9dfea5e934f4c95;p=thirdparty%2Flibvirt.git

virBitmapToString: Properly handle empty bitmaps

virBitmapNewEmpty() can create a bitmap with 0 length. With such a
bitmap virBitmapToString will return NULL rather than an empty string.
Initialize the buffer to avoid that.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index ed28427736..a999023777 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -345,6 +345,9 @@ virBitmapToString(virBitmapPtr bitmap)
 
     sz = bitmap->map_len;
 
+    /* initialize buffer to return empty string for 0 length bitmap */
+    virBufferAdd(&buf, "", -1);
+
     while (sz--) {
         virBufferAsprintf(&buf, "%0*lx",
                           VIR_BITMAP_BITS_PER_UNIT / 4,