From 4e259dbbba565c6f874ead9a8974175ffc6a2bb8 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Fri, 3 Apr 2020 15:05:14 +0200
Subject: [PATCH] fix #6153

---
 src/include/gnunet_common.h  | 18 ++++++++++++++----
 src/util/common_allocation.c | 20 ++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/include/gnunet_common.h b/src/include/gnunet_common.h
index 6e185c314..6d9652a16 100644
--- a/src/include/gnunet_common.h
+++ b/src/include/gnunet_common.h
@@ -1098,6 +1098,19 @@ GNUNET_ntoh_double (double d);
   })
 
 
+/**
+ * Check that memory in @a a is all zeros. @a a must be a pointer.
+ *
+ * @param a pointer to @a n bytes which should be tested for the
+ *          entire memory being zero'ed out.
+ * @param n number of bytes in @a to be tested
+ * @return 0 if a is zero, non-zero otherwise
+ */
+int
+GNUNET_is_zero_ (const void *a,
+                 size_t n);
+
+
 /**
  * Check that memory in @a a is all zeros. @a a must be a pointer.
  *
@@ -1106,10 +1119,7 @@ GNUNET_ntoh_double (double d);
  * @return 0 if a is zero, non-zero otherwise
  */
 #define GNUNET_is_zero(a)           \
-  ({                                \
-    static const typeof (*a) _z;    \
-    memcmp ((a), &_z, sizeof(_z)); \
-  })
+  GNUNET_is_zero_ (a, sizeof (a))
 
 
 /**
diff --git a/src/util/common_allocation.c b/src/util/common_allocation.c
index 35c557000..5945fdcde 100644
--- a/src/util/common_allocation.c
+++ b/src/util/common_allocation.c
@@ -533,4 +533,24 @@ GNUNET_copy_message (const struct GNUNET_MessageHeader *msg)
 }
 
 
+/**
+ * Check that memory in @a a is all zeros. @a a must be a pointer.
+ *
+ * @param a pointer to @a n bytes which should be tested for the
+ *          entire memory being zero'ed out.
+ * @param n number of bytes in @a to be tested
+ * @return 0 if a is zero, non-zero otherwise
+ */
+int
+GNUNET_is_zero_ (const void *a,
+                 size_t n)
+{
+  const char *b = a;
+  for (size_t i = 0; i < n; i++)
+    if (b[i])
+      return 0;
+  return 1;
+}
+
+
 /* end of common_allocation.c */
-- 
2.25.1