Use _builtin_uaddll_overflow/_builtin_uaddl_overflow when available,
abstracting the type to use it with uint64_t.
Otherwise fallback to the implementation as added in
67466f2 ("Prevent
offset + size overflow.").
This also adds the tests for this new helper in the testsuite.
CC_CHECK_FUNC_BUILTIN([__builtin_clz])
CC_CHECK_FUNC_BUILTIN([__builtin_types_compatible_p])
+CC_CHECK_FUNC_BUILTIN([__builtin_uaddl_overflow], [ ], [ ])
+CC_CHECK_FUNC_BUILTIN([__builtin_uaddll_overflow], [ ], [ ])
# dietlibc doesn't have st.st_mtim struct member
AC_CHECK_MEMBERS([struct stat.st_mtim], [], [], [#include <sys/stat.h>])
m4_case([$1],
[__builtin_clz], [$1(0)],
[__builtin_types_compatible_p], [$1(int, int)],
+ [__builtin_uaddl_overflow], [$1(0UL, 0UL, (void*)0)],
+ [__builtin_uaddll_overflow], [$1(0ULL, 0ULL, (void*)0)],
[__builtin_expect], [$1(0, 0)]
)])],
[cc_cv_have_$1=yes],
#pragma once
+#include <inttypes.h>
#include <limits.h>
#include <stdbool.h>
#include <stdlib.h>
free(*(void**) p);
}
#define _cleanup_free_ _cleanup_(freep)
+
+static inline bool addu64_overflow(uint64_t a, uint64_t b, uint64_t *res)
+{
+#if (HAVE___BUILTIN_UADDL_OVERFLOW && HAVE___BUILTIN_UADDLL_OVERFLOW)
+#if __SIZEOF_LONG__ == 8
+ return __builtin_uaddl_overflow(a, b, res);
+#elif __SIZEOF_LONG_LONG__ == 8
+ return __builtin_uaddll_overflow(a, b, res);
+#else
+#error "sizeof(long long) != 8"
+#endif
+#endif
+ *res = a + b;
+ return ULLONG_MAX - a < b;
+}
},
});
+static int test_addu64_overflow(const struct test *t)
+{
+ uint64_t res;
+ bool overflow;
+
+ overflow = addu64_overflow(UINT64_MAX - 1, 1, &res);
+ assert_return(!overflow, EXIT_FAILURE);
+ assert_return(res == UINT64_MAX, EXIT_FAILURE);
+
+ overflow = addu64_overflow(UINT64_MAX, 1, &res);
+ assert_return(overflow, EXIT_FAILURE);
+
+ return EXIT_SUCCESS;
+}
+DEFINE_TEST(test_addu64_overflow,
+ .description = "check implementation of addu4_overflow()",
+ .need_spawn = false,
+ );
+
TESTSUITE_MAIN();