util: buffer: Add virBufferStrcatVArgs

Split out the worker loop into a separate function and export it.
Reviewed-by: NEric Blake <eblake@redhat.com>

src/libvirt_private.syms

@@ -1345,6 +1345,7 @@ virBufferFreeAndReset;
 virBufferGetIndent;
 virBufferSetIndent;
 virBufferStrcat;
+virBufferStrcatVArgs;
 virBufferTrim;
 virBufferURIEncodeString;
 virBufferUse;

src/util/virbuffer.c

@@ -830,6 +830,26 @@ virBufferEscapeShell(virBufferPtr buf, const char *str)
     VIR_FREE(escaped);
 }
 
+/**
+ * virBufferStrcatVArgs:
+ * @buf: the buffer to append to
+ * @ap: variable argument structure
+ *
+ * See virBufferStrcat.
+ */
+void
+virBufferStrcatVArgs(virBufferPtr buf,
+                     va_list ap)
+{
+    char *str;
+
+    if (buf->error)
+        return;
+
+    while ((str = va_arg(ap, char *)) != NULL)
+        virBufferAdd(buf, str, -1);
+}
+
 /**
  * virBufferStrcat:
  * @buf: the buffer to append to
@@ -842,14 +862,9 @@ void
 virBufferStrcat(virBufferPtr buf, ...)
 {
     va_list ap;
-    char *str;
-
-    if (buf->error)
-        return;
 
     va_start(ap, buf);
-    while ((str = va_arg(ap, char *)) != NULL)
-        virBufferAdd(buf, str, -1);
+    virBufferStrcatVArgs(buf, ap);
     va_end(ap);
 }
 

src/util/virbuffer.h

@@ -80,6 +80,8 @@ void virBufferVasprintf(virBufferPtr buf, const char *format, va_list ap)
   ATTRIBUTE_FMT_PRINTF(2, 0);
 void virBufferStrcat(virBufferPtr buf, ...)
   ATTRIBUTE_SENTINEL;
+void virBufferStrcatVArgs(virBufferPtr buf, va_list ap);
+
 void virBufferEscape(virBufferPtr buf, char escape, const char *toescape,
                      const char *format, const char *str);
 void virBufferEscapeN(virBufferPtr buf, const char *format,