mem: add memtaint().

[ccan] / ccan / mem / mem.h

diff --git a/ccan/mem/mem.h b/ccan/mem/mem.h
index 1afe508b3a097beefdbf93660165c7146fdb3f25..f2c3d5c7a6f795e2e091df8a545992c6533b50ec 100644 (file)
--- a/ccan/mem/mem.h
+++ b/ccan/mem/mem.h
@@ -149,6 +149,19 @@ static inline bool memeqstr(const void *data, size_t length, const char *string)
        return memeq(data, length, string, strlen(string));
 }
 
+/**
+ * memeqzero - Is a byte array all zeroes?
+ * @data: byte array
+ * @length: length of @data in bytes
+ *
+ * Example:
+ *     if (memeqzero(somebytes, bytes_len)) {
+ *             printf("somebytes == 0!\n");
+ *     }
+ */
+PURE_FUNCTION
+bool memeqzero(const void *data, size_t length);
+
 /**
  * memstarts_str - Does this byte array start with a string prefix?
  * @a: byte array
@@ -200,4 +213,82 @@ static inline bool memends_str(const void *a, size_t al, const char *s)
        return memends(a, al, s, strlen(s));
 }
 
+/**
+ * memoverlaps - Do two memory ranges overlap?
+ * @a: pointer to first memory range
+ * @al: length of first memory range
+ * @b: pointer to second memory range
+ * @al: length of second memory range
+ */
+CONST_FUNCTION
+static inline bool memoverlaps(const void *a_, size_t al,
+                              const void *b_, size_t bl)
+{
+       const char *a = a_;
+       const char *b = b_;
+
+       return (a < (b + bl)) && (b < (a + al));
+}
+
+/*
+ * memswap - Exchange two memory regions
+ * @a: first region
+ * @b: second region
+ * @n: length of the regions
+ *
+ * Undefined results if the two memory regions overlap.
+ */
+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
+
+/**
+ * memtaint - mark a memory region unused
+ * @data: start of region
+ * @len: length in bytes
+ *
+ * This writes an "0xdeadbeef" eyecatcher repeatedly to the memory.
+ * When running under valgrind, it also tells valgrind that the memory is
+ * uninitialized, triggering valgrind errors if it is used for branches
+ * or written out (or passed to memcheck!) in future.
+ *
+ * Example:
+ *     // We'll reuse this buffer later, but be sure we don't access it.
+ *     memtaint(somebytes, bytes_len);
+ */
+void memtaint(void *data, size_t len);
 #endif /* CCAN_MEM_H */