Merge pull request #11031 from poettering/gcc-attr-cleanup

various gcc attribute clean-ups

src/basic/hashmap.c

@@ -276,7 +276,7 @@ static const struct hashmap_type_info hashmap_type_info[_HASHMAP_TYPE_MAX] = {
 };
 
 #if VALGRIND
-__attribute__((destructor)) static void cleanup_pools(void) {
+_destructor_ static void cleanup_pools(void) {
         _cleanup_free_ char *t = NULL;
         int r;
 

src/basic/macro.h

@@ -8,27 +8,31 @@
 #include <sys/sysmacros.h>
 #include <sys/types.h>
 
-#define _printf_(a, b) __attribute__ ((__format__(printf, a, b)))
+#define _printf_(a, b) __attribute__((__format__(printf, a, b)))
 #ifdef __clang__
 #  define _alloc_(...)
 #else
-#  define _alloc_(...) __attribute__ ((__alloc_size__(__VA_ARGS__)))
+#  define _alloc_(...) __attribute__((__alloc_size__(__VA_ARGS__)))
 #endif
-#define _sentinel_ __attribute__ ((__sentinel__))
-#define _unused_ __attribute__ ((__unused__))
-#define _destructor_ __attribute__ ((__destructor__))
-#define _pure_ __attribute__ ((__pure__))
-#define _const_ __attribute__ ((__const__))
-#define _deprecated_ __attribute__ ((__deprecated__))
-#define _packed_ __attribute__ ((__packed__))
-#define _malloc_ __attribute__ ((__malloc__))
-#define _weak_ __attribute__ ((__weak__))
+#define _sentinel_ __attribute__((__sentinel__))
+#define _section_(x) __attribute__((__section__(x)))
+#define _used_ __attribute__((__used__))
+#define _unused_ __attribute__((__unused__))
+#define _destructor_ __attribute__((__destructor__))
+#define _pure_ __attribute__((__pure__))
+#define _const_ __attribute__((__const__))
+#define _deprecated_ __attribute__((__deprecated__))
+#define _packed_ __attribute__((__packed__))
+#define _malloc_ __attribute__((__malloc__))
+#define _weak_ __attribute__((__weak__))
 #define _likely_(x) (__builtin_expect(!!(x), 1))
 #define _unlikely_(x) (__builtin_expect(!!(x), 0))
-#define _public_ __attribute__ ((__visibility__("default")))
-#define _hidden_ __attribute__ ((__visibility__("hidden")))
+#define _public_ __attribute__((__visibility__("default")))
+#define _hidden_ __attribute__((__visibility__("hidden")))
 #define _weakref_(x) __attribute__((__weakref__(#x)))
+#define _align_(x) __attribute__((__aligned__(x)))
 #define _alignas_(x) __attribute__((__aligned__(__alignof(x))))
+#define _alignptr_ __attribute__((__aligned__(sizeof(void*))))
 #define _cleanup_(x) __attribute__((__cleanup__(x)))
 #if __GNUC__ >= 7
 #define _fallthrough_ __attribute__((__fallthrough__))
@@ -56,6 +60,29 @@
 #  endif
 #endif
 
+#if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
+#  ifdef __SANITIZE_ADDRESS__
+#      define HAS_FEATURE_ADDRESS_SANITIZER 1
+#  elif defined(__has_feature)
+#    if __has_feature(address_sanitizer)
+#      define HAS_FEATURE_ADDRESS_SANITIZER 1
+#    endif
+#  endif
+#  if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
+#    define HAS_FEATURE_ADDRESS_SANITIZER 0
+#  endif
+#endif
+
+/* Note: on GCC "no_sanitize_address" is a function attribute only, on llvm it may also be applied to global
+ * variables. We define a specific macro which knows this. Note that on GCC we don't need this decorator so much, since
+ * our primary usecase for this attribute is registration structures placed in named ELF sections which shall not be
+ * padded, but GCC doesn't pad those anyway if AddressSanitizer is enabled. */
+#if HAS_FEATURE_ADDRESS_SANITIZER && defined(__clang__)
+#define _variable_no_sanitize_address_ __attribute__((__no_sanitize_address__))
+#else
+#define _variable_no_sanitize_address_
+#endif
+
 /* Temporarily disable some warnings */
 #define DISABLE_WARNING_FORMAT_NONLITERAL                               \
         _Pragma("GCC diagnostic push");                                 \

src/basic/process-util.c

@@ -1172,7 +1172,7 @@ void reset_cached_pid(void) {
  * headers. __register_atfork() is mostly equivalent to pthread_atfork(), but doesn't require us to link against
  * libpthread, as it is part of glibc anyway. */
 extern int __register_atfork(void (*prepare) (void), void (*parent) (void), void (*child) (void), void *dso_handle);
-extern void* __dso_handle __attribute__ ((__weak__));
+extern void* __dso_handle _weak_;
 
 pid_t getpid_cached(void) {
         static bool installed = false;

src/basic/static-destruct.h

@@ -22,10 +22,14 @@ typedef struct StaticDestructor {
                 typeof(variable) *q = p;                                \
                 func(q);                                                \
         }                                                               \
-        /* The actual destructor structure */                           \
-        __attribute__ ((__section__("SYSTEMD_STATIC_DESTRUCT")))        \
-        __attribute__ ((__aligned__(__BIGGEST_ALIGNMENT__)))            \
-        __attribute__ ((__used__))                                      \
+        /* The actual destructor structure we place in a special section to find it */ \
+        _section_("SYSTEMD_STATIC_DESTRUCT")                            \
+        /* We pick pointer alignment, since that is apparently what gcc does for static variables */ \
+        _alignptr_                                                      \
+        /* Make sure this is not dropped from the image because not explicitly referenced */ \
+        _used_                                                          \
+        /* Make sure that AddressSanitizer doesn't pad this variable: we want everything in this section packed next to each other so that we can enumerate it. */ \
+        _variable_no_sanitize_address_                                  \
         static const StaticDestructor UNIQ_T(static_destructor_entry, uq) = { \
                 .data = &(variable),                                    \
                 .destroy = UNIQ_T(static_destructor_wrapper, uq),       \
@@ -33,8 +37,8 @@ typedef struct StaticDestructor {
 
 /* Beginning and end of our section listing the destructors. We define these as weak as we want this to work even if
  * there's not a single destructor is defined in which case the section will be missing. */
-extern const struct StaticDestructor __attribute__((__weak__)) __start_SYSTEMD_STATIC_DESTRUCT[];
-extern const struct StaticDestructor __attribute__((__weak__)) __stop_SYSTEMD_STATIC_DESTRUCT[];
+extern const struct StaticDestructor _weak_ __start_SYSTEMD_STATIC_DESTRUCT[];
+extern const struct StaticDestructor _weak_ __stop_SYSTEMD_STATIC_DESTRUCT[];
 
 /* The function to destroy everything. (Note that this must be static inline, as it's key that it remains in the same
  * linking unit as the variables we want to destroy. */
@@ -44,9 +48,9 @@ static inline void static_destruct(void) {
         if (!__start_SYSTEMD_STATIC_DESTRUCT)
                 return;
 
-        d = ALIGN_TO_PTR(__start_SYSTEMD_STATIC_DESTRUCT, __BIGGEST_ALIGNMENT__);
+        d = ALIGN_TO_PTR(__start_SYSTEMD_STATIC_DESTRUCT, sizeof(void*));
         while (d < __stop_SYSTEMD_STATIC_DESTRUCT) {
                 d->destroy(d->data);
-                d = ALIGN_TO_PTR(d + 1, __BIGGEST_ALIGNMENT__);
+                d = ALIGN_TO_PTR(d + 1, sizeof(void*));
         }
 }

src/basic/util.h

@@ -173,7 +173,7 @@ static inline void _reset_errno_(int *saved_errno) {
 }
 
 #define PROTECT_ERRNO                                                   \
-        _cleanup_(_reset_errno_) __attribute__((__unused__)) int _saved_errno_ = errno
+        _cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno
 
 static inline int negative_errno(void) {
         /* This helper should be used to shut up gcc if you know 'errno' is