inet: fix: possible unaligned access in packed structure (inet/inet6)

[lttng-tools.git] / src / common / macros.h

diff --git a/src/common/macros.h b/src/common/macros.h
index 8ae6535d0de57ed1878bf42b98d37163fadccb49..36ec04b745738d59090f2de5825ba230060b9fa4 100644 (file)
--- a/src/common/macros.h
+++ b/src/common/macros.h
@@ -20,6 +20,7 @@
 #define _MACROS_H
 
 #include <stdlib.h>
+#include <stddef.h>
 #include <string.h>
 #include <common/compat/string.h>
 
@@ -58,12 +59,20 @@ void *zmalloc(size_t len)
 #define ARRAY_SIZE(array)   (sizeof(array) / (sizeof((array)[0])))
 #endif
 
+#ifndef container_of
+#define container_of(ptr, type, member)                                        \
+       ({                                                              \
+               const typeof(((type *)NULL)->member) * __ptr = (ptr);   \
+               (type *)((char *)__ptr - offsetof(type, member));       \
+       })
+#endif
+
 #ifndef max
 #define max(a, b) ((a) > (b) ? (a) : (b))
 #endif
 
 #ifndef max_t
-#define max_t(type, a, b)      ((type) max(a, b))
+#define max_t(type, a, b)      max((type) a, (type) b)
 #endif
 
 #ifndef min
@@ -74,12 +83,26 @@ void *zmalloc(size_t len)
 #define LTTNG_PACKED __attribute__((__packed__))
 #endif
 
-#ifndef LTTNG_HIDDEN
+/*
+ * LTTNG_HIDDEN: set the hidden attribute for internal functions
+ * On Windows, symbols are local unless explicitly exported,
+ * see https://gcc.gnu.org/wiki/Visibility
+ */
+#if defined(_WIN32) || defined(__CYGWIN__)
+#define LTTNG_HIDDEN
+#else
 #define LTTNG_HIDDEN __attribute__((visibility("hidden")))
 #endif
 
 #define member_sizeof(type, field)     sizeof(((type *) 0)->field)
 
+/*
+ * Get an aligned pointer to a value. This is meant
+ * as a helper to pass an aligned pointer to a member in a packed structure
+ * to a function.
+ */
+#define ALIGNED_CONST_PTR(value) (((const typeof(value) []) { value }))
+
 /*
  * lttng_strncpy returns 0 on success, or nonzero on failure.
  * It checks that the @src string fits into @dst_len before performing