[PATCH] Make sanitizers' interceptors non-weak on FreeBSD

[Viktor Kutuzov]

Hi kcc, samsonov,

Related discussion:
http://docs.freebsd.org/cgi/getmsg.cgi?fetch=16483939+0+current/freebsd-current

http://reviews.llvm.org/D4418

Files:
  lib/interception/interception.h

Index: lib/interception/interception.h
===================================================================
--- lib/interception/interception.h
+++ lib/interception/interception.h
@@ -139,9 +139,19 @@
 # define WRAP(x) __interceptor_ ## x
 # define WRAPPER_NAME(x) "__interceptor_" #x
 # define INTERCEPTOR_ATTRIBUTE __attribute__((visibility("default")))
-# define DECLARE_WRAPPER(ret_type, func, ...) \
-    extern "C" ret_type func(__VA_ARGS__) \
-    __attribute__((weak, alias("__interceptor_" #func), visibility("default")));
+# if defined(__FreeBSD__)
+// FreeBSD's dynamic linker (incompliantly) gives non-weak symbols higher
+// priority than weak ones so weak aliases won't work for indirect calls
+// in position-independent (-fPIC / -fPIE) mode.
+#  define DECLARE_WRAPPER(ret_type, func, ...) \
+     extern "C" ret_type func(__VA_ARGS__) \
+     __attribute__((alias("__interceptor_" #func), visibility("default")));
+# else
+#  define DECLARE_WRAPPER(ret_type, func, ...) \
+     extern "C" ret_type func(__VA_ARGS__) \
+     __attribute__((weak, alias("__interceptor_" #func), \
+       visibility("default")));
+# endif
 #endif
 
 #if !defined(__APPLE__)
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