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
The motivation for this change is to fix linking issues on OSX.
However this only partially fixes linking issues (the uninstrumented
tests and a few others won't succesfully link yet).
This change introduces a struct of function pointers
(``fuzzer::ExternalFuntions``) which when initialised will point to the
optional functions if they are available. Currently these
``LLVMFuzzerInitialize`` and ``LLVMFuzzerCustomMutator`` functions.
Two implementations of ``fuzzer::ExternalFunctions`` constructor are
provided one for Linux and one for OSX.
The OSX implementation uses ``dlsym()`` because the prior implementation
using weak symbols does not work unless the additional flags are passed
to the linker.
The Linux implementation continues to use weak symbols because the
``dlsym()`` approach does not work unless additional flags are passed
to the linker.
Differential Revision: http://reviews.llvm.org/D20741
llvm-svn: 271491
Kostya Serebryany