[LibFuzzer] Declare and use sanitizer functions in ``fuzzer::ExternalFunctions``

This fixes linking problems on OSX.

Unfortunately it turns out we need to use an instance of the
``fuzzer::ExternalFunctions`` object in several places so this
commit also replaces all instances with a single global instance.

It also turns out initializing a global ``fuzzer::ExternalFunctions``
before main is entered (i.e. letting the object be initialised by the
global initializers) is not safe (on OSX the call to ``Printf()`` in the
CTOR crashes if it is called from a global initializer) so we instead
have a global ``fuzzer::ExternalFunctions*`` and initialize it inside
``FuzzerDriver()``.

Multiple unit tests depend also depend on the
``fuzzer::ExternalFunctions*`` global so a ``main()`` function has been
added that initializes it before running any tests.

Differential Revision: http://reviews.llvm.org/D20943

llvm-svn: 272072

1 files changed, 3 insertions, 6 deletions

diff --git a/llvm/lib/Fuzzer/FuzzerIO.cpp b/llvm/lib/Fuzzer/FuzzerIO.cpp
index 171b188eab5..0e0c4e989cc 100644
--- a/llvm/lib/Fuzzer/FuzzerIO.cpp
+++ b/llvm/lib/Fuzzer/FuzzerIO.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 // IO functions.
 //===----------------------------------------------------------------------===//
+#include "FuzzerExtFunctions.h"
 #include "FuzzerInternal.h"
 #include <iterator>
 #include <fstream>
@@ -18,10 +19,6 @@
 #include <cstdarg>
 #include <cstdio>
 
-extern "C" {
-__attribute__((weak)) void __sanitizer_set_report_fd(void *);
-}
-
 namespace fuzzer {
 
 static FILE *OutputFile = stderr;
@@ -126,8 +123,8 @@ void DupAndCloseStderr() {
     FILE *NewOutputFile = fdopen(OutputFd, "w");
     if (NewOutputFile) {
       OutputFile = NewOutputFile;
-      if (__sanitizer_set_report_fd)
-        __sanitizer_set_report_fd(reinterpret_cast<void*>(OutputFd));
+      if (EF->__sanitizer_set_report_fd)
+        EF->__sanitizer_set_report_fd(reinterpret_cast<void *>(OutputFd));
       close(2);
     }
   }