From e8d1e7304feb9318a841ad4a7d5a8773271ab814 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Thu, 24 Sep 2015 11:49:40 +0930
Subject: [PATCH 1/1] mem: add memcheck() for valgrind.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 ccan/mem/mem.h                        | 35 +++++++++++++++++++++++++++
 ccan/mem/test/api-memcheck.c          | 28 +++++++++++++++++++++
 ccan/mem/test/compile_fail-memcheck.c | 23 ++++++++++++++++++
 3 files changed, 86 insertions(+)
 create mode 100644 ccan/mem/test/api-memcheck.c
 create mode 100644 ccan/mem/test/compile_fail-memcheck.c

diff --git a/ccan/mem/mem.h b/ccan/mem/mem.h
index dd66cc62..68a4aa3c 100644
--- a/ccan/mem/mem.h
+++ b/ccan/mem/mem.h
@@ -227,4 +227,39 @@ static inline bool memoverlaps(const void *a_, size_t al,
  */
 void memswap(void *a, void *b, size_t n);
 
+#if HAVE_VALGRIND_MEMCHECK_H
+#include <valgrind/memcheck.h>
+static inline void *memcheck_(const void *data, size_t len)
+{
+	VALGRIND_CHECK_MEM_IS_DEFINED(data, len);
+	return (void *)data;
+}
+#else
+static inline void *memcheck_(const void *data, size_t len)
+{
+	return (void *)data;
+}
+#endif
+
+#if HAVE_TYPEOF
+/**
+ * memcheck - check that a memory region is initialized
+ * @data: start of region
+ * @len: length in bytes
+ *
+ * When running under valgrind, this causes an error to be printed
+ * if the entire region is not defined.  Otherwise valgrind only
+ * reports an error when an undefined value is used for a branch, or
+ * written out.
+ *
+ * Example:
+ *	// Search for space, but make sure it's all initialized.
+ *	if (memchr(memcheck(somebytes, bytes_len), ' ', bytes_len)) {
+ *		printf("space was found!\n");
+ *	}
+ */
+#define memcheck(data, len) ((__typeof__((data)+0))memcheck_((data), (len)))
+#else
+#define memcheck(data, len) memcheck_((data), (len))
+#endif
 #endif /* CCAN_MEM_H */
diff --git a/ccan/mem/test/api-memcheck.c b/ccan/mem/test/api-memcheck.c
new file mode 100644
index 00000000..ca8a111c
--- /dev/null
+++ b/ccan/mem/test/api-memcheck.c
@@ -0,0 +1,28 @@
+#include "config.h"
+
+#include <assert.h>
+
+#include <ccan/mem/mem.h>
+#include <ccan/tap/tap.h>
+
+int main(void)
+{
+	char haystack[] = "abcd\0efgh";
+	char *p;
+	const char *pc;
+
+	/* This is how many tests you plan to run */
+	plan_tests(4);
+
+	p = memcheck(haystack, sizeof(haystack));
+	ok1(p == haystack);
+	pc = memcheck(haystack, sizeof(haystack));
+	ok1(pc == haystack);
+	p = memcheck(p, sizeof(haystack));
+	ok1(p == haystack);
+	pc = memcheck(pc, sizeof(haystack));
+	ok1(pc == haystack);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}
diff --git a/ccan/mem/test/compile_fail-memcheck.c b/ccan/mem/test/compile_fail-memcheck.c
new file mode 100644
index 00000000..32620f10
--- /dev/null
+++ b/ccan/mem/test/compile_fail-memcheck.c
@@ -0,0 +1,23 @@
+#include "config.h"
+
+#include <assert.h>
+#include <ccan/mem/mem.h>
+
+int main(void)
+{
+	const char *haystack = "abcd\0efgh";
+	char *p;
+
+#ifdef FAIL
+#if !HAVE_TYPEOF
+#error "Can't fail without typeof"
+#else
+	/* Should catch const discard errors. */
+	p = memcheck(haystack, sizeof(haystack));
+#endif
+#else
+	p = memcheck((char *)haystack, sizeof(haystack));
+#endif
+
+	return p == haystack ? 0 : 1;
+}
-- 
2.39.2