[libvirt] [PATCH] add sentinel attribute

[Paolo Bonzini]

This patch adds a (macro-wrapped) sentinel attribute to functions
that take a NULL-terminated variable argument list.  This is a nice
debugging aid.

* src/internal.h (ATTRIBUTE_SENTINEL): New.
* src/util/buf.c (virBufferStrcat): Use it.
* src/util/ebtables.c (ebtablesAddRemoveRule): Use it.
* src/util/iptables.c (iptableAddRemoveRule: Use it.
* src/util/qparams.h (new_qparam_set, append_qparams): Use it.
---
 src/internal.h      |   11 +++++++++++
 src/util/buf.h      |    3 ++-
 src/util/ebtables.c |    2 +-
 src/util/iptables.c |    2 +-
 src/util/qparams.h  |    6 ++++--
 5 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/internal.h b/src/internal.h
index bd1cfe6..09c19ea 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -93,6 +93,17 @@
 #endif
 
 /**
+ * ATTRIBUTE_SENTINEL:
+ *
+ * Macro to check for NULL-terminated varargs lists
+ */
+#ifndef ATTRIBUTE_SENTINEL
+#if __GNUC_PREREQ (4, 0)
+#define ATTRIBUTE_SENTINEL __attribute__((__sentinel__))
+#endif
+#endif
+
+/**
  * ATTRIBUTE_FMT_PRINTF
  *
  * Macro used to check printf like functions, if compiling
diff --git a/src/util/buf.h b/src/util/buf.h
index 7d31cb2..94ee8a3 100644
--- a/src/util/buf.h
+++ b/src/util/buf.h
@@ -41,7 +41,8 @@ void virBufferAdd(const virBufferPtr buf, const char *str, int len);
 void virBufferAddChar(const virBufferPtr buf, char c);
 void virBufferVSprintf(const virBufferPtr buf, const char *format, ...)
   ATTRIBUTE_FMT_PRINTF(2, 3);
-void virBufferStrcat(const virBufferPtr buf, ...);
+void virBufferStrcat(const virBufferPtr buf, ...)
+  ATTRIBUTE_SENTINEL;
 void virBufferEscapeString(const virBufferPtr buf, const char *format, const char *str);
 void virBufferURIEncodeString (const virBufferPtr buf, const char *str);
 
diff --git a/src/util/ebtables.c b/src/util/ebtables.c
index 60427d7..20f3342 100644
--- a/src/util/ebtables.c
+++ b/src/util/ebtables.c
@@ -175,7 +175,7 @@ ebtRulesNew(const char *table,
     return NULL;
 }
 
-static int
+static int ATTRIBUTE_SENTINEL
 ebtablesAddRemoveRule(ebtRules *rules, int action, const char *arg, ...)
 {
     va_list args;
diff --git a/src/util/iptables.c b/src/util/iptables.c
index 4562800..284f3c0 100644
--- a/src/util/iptables.c
+++ b/src/util/iptables.c
@@ -382,7 +382,7 @@ iptRulesNew(const char *table,
     return NULL;
 }
 
-static int
+static int ATTRIBUTE_SENTINEL
 iptablesAddRemoveRule(iptRules *rules, int action, const char *arg, ...)
 {
     va_list args;
diff --git a/src/util/qparams.h b/src/util/qparams.h
index 1a92048..a2f5aa2 100644
--- a/src/util/qparams.h
+++ b/src/util/qparams.h
@@ -38,10 +38,12 @@ struct qparam_set {
 };
 
 /* New parameter set. */
-extern struct qparam_set *new_qparam_set (int init_alloc, ...);
+extern struct qparam_set *new_qparam_set (int init_alloc, ...)
+    ATTRIBUTE_SENTINEL;
 
 /* Appending parameters. */
-extern int append_qparams (struct qparam_set *ps, ...);
+extern int append_qparams (struct qparam_set *ps, ...)
+    ATTRIBUTE_SENTINEL;
 extern int append_qparam (struct qparam_set *ps,
                           const char *name, const char *value);
 
-- 
1.6.2.5