<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Sep 1, 2017 at 12:50 PM, Justin Bogner <span dir="ltr"><<a href="mailto:mail@justinbogner.com" target="_blank">mail@justinbogner.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">Kostya Serebryany <<a href="mailto:kcc@google.com">kcc@google.com</a>> writes:<br>
> Can we reuse lib/fuzzer/standalone/<wbr>StandaloneFuzzTargetMain.c for this<br>
> purpose?<br>
<br>
</span>Given that this was moved to compiler-rt, I don't think so. We really<br>
want to be able to test these things when we only have an LLVM checkout.<br>
<br>
If we did find a way to make this practical we'd have to make<br>
StandaloneFuzzTargetMain's argument handling a bit more robust.<br>
<span class=""><br>
> Also, it's possible to link against libFuzzer w/o using the coverage<br>
> instrumentation.<br>
<br>
</span>Fair enough, but does that give us any real advantage over wiring up a<br>
dummy main? </blockquote><div><br></div><div>Less code. :) </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This way we can build these targets with any compiler<br>
regardless of whether it supports libFuzzer, so anyone building anywhere<br>
should see problems before it gets to the bots.<br></blockquote><div><br></div><div>That's a valid point. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb"><div class="h5"><br>
> On Fri, Sep 1, 2017 at 10:02 AM, Justin Bogner via llvm-commits <<br>
> <a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<br>
><br>
>> Author: bogner<br>
>> Date: Fri Sep 1 10:02:22 2017<br>
>> New Revision: 312338<br>
>><br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project?rev=312338&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project?rev=312338&view=rev</a><br>
>> Log:<br>
>> llvm-isel-fuzzer: Make buildable and testable without libFuzzer<br>
>><br>
>> This adds a dummy main so we can build and run the llvm-isel-fuzzer<br>
>> functionality when we aren't building LLVM with coverage. The approach<br>
>> here should serve as a template to stop in-tree fuzzers from<br>
>> bitrotting (See <a href="http://llvm.org/pr34314" rel="noreferrer" target="_blank">llvm.org/pr34314</a>).<br>
>><br>
>> Note that I'll probably move most of the logic in DummyISelFuzzer's<br>
>> `main` to a library so it's easy to reuse it in other fuzz targets,<br>
>> but I'm planning on doing that in a follow up that also consolidates<br>
>> argument handling in our LLVMFuzzerInitialize implementations.<br>
>><br>
>> Added:<br>
>> llvm/trunk/tools/llvm-isel-<wbr>fuzzer/DummyISelFuzzer.cpp<br>
>> Modified:<br>
>> llvm/trunk/cmake/modules/<wbr>AddLLVM.cmake<br>
>> llvm/trunk/tools/llvm-isel-<wbr>fuzzer/CMakeLists.txt<br>
>><br>
>> Modified: llvm/trunk/cmake/modules/<wbr>AddLLVM.cmake<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/llvm/trunk/cmake/</a><br>
>> modules/AddLLVM.cmake?rev=<wbr>312338&r1=312337&r2=312338&<wbr>view=diff<br>
>> ==============================<wbr>==============================<br>
>> ==================<br>
>> --- llvm/trunk/cmake/modules/<wbr>AddLLVM.cmake (original)<br>
>> +++ llvm/trunk/cmake/modules/<wbr>AddLLVM.cmake Fri Sep 1 10:02:22 2017<br>
>> @@ -893,11 +893,15 @@ macro(add_llvm_utility name)<br>
>> endmacro(add_llvm_utility name)<br>
>><br>
>> macro(add_llvm_fuzzer name)<br>
>> + cmake_parse_arguments(ARG "" "DUMMY_MAIN" "" ${ARGN})<br>
>> if( LLVM_USE_SANITIZE_COVERAGE )<br>
>> set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=fuzzer")<br>
>> - add_llvm_executable(${name} ${ARGN})<br>
>> + add_llvm_executable(${name} ${ARG_UNPARSED_ARGUMENTS})<br>
>> set_target_properties(${name} PROPERTIES FOLDER "Fuzzers")<br>
>> - endif()<br>
>> + elseif( ARG_DUMMY_MAIN )<br>
>> + add_llvm_executable(${name} ${ARG_DUMMY_MAIN}<br>
>> ${ARG_UNPARSED_ARGUMENTS})<br>
>> + set_target_properties(${name} PROPERTIES FOLDER "Fuzzers")<br>
>> +endif()<br>
>> endmacro()<br>
>><br>
>> macro(add_llvm_target target_name)<br>
>><br>
>> Modified: llvm/trunk/tools/llvm-isel-<wbr>fuzzer/CMakeLists.txt<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/llvm/trunk/tools/llvm-</a><br>
>> isel-fuzzer/CMakeLists.txt?<wbr>rev=312338&r1=312337&r2=<wbr>312338&view=diff<br>
>> ==============================<wbr>==============================<br>
>> ==================<br>
>> --- llvm/trunk/tools/llvm-isel-<wbr>fuzzer/CMakeLists.txt (original)<br>
>> +++ llvm/trunk/tools/llvm-isel-<wbr>fuzzer/CMakeLists.txt Fri Sep 1 10:02:22<br>
>> 2017<br>
>> @@ -12,4 +12,5 @@ set(LLVM_LINK_COMPONENTS<br>
>> Support<br>
>> Target<br>
>> )<br>
>> -add_llvm_fuzzer(llvm-isel-<wbr>fuzzer llvm-isel-fuzzer.cpp)<br>
>> +add_llvm_fuzzer(llvm-isel-<wbr>fuzzer llvm-isel-fuzzer.cpp<br>
>> + DUMMY_MAIN DummyISelFuzzer.cpp)<br>
>><br>
>> Added: llvm/trunk/tools/llvm-isel-<wbr>fuzzer/DummyISelFuzzer.cpp<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/llvm/trunk/tools/llvm-</a><br>
>> isel-fuzzer/DummyISelFuzzer.<wbr>cpp?rev=312338&view=auto<br>
>> ==============================<wbr>==============================<br>
>> ==================<br>
>> --- llvm/trunk/tools/llvm-isel-<wbr>fuzzer/DummyISelFuzzer.cpp (added)<br>
>> +++ llvm/trunk/tools/llvm-isel-<wbr>fuzzer/DummyISelFuzzer.cpp Fri Sep 1<br>
>> 10:02:22 2017<br>
>> @@ -0,0 +1,56 @@<br>
>> +//===--- DummyFuzzerMain.cpp - Entry point to sanity check the fuzzer<br>
>> -----===//<br>
>> +//<br>
>> +// The LLVM Compiler Infrastructure<br>
>> +//<br>
>> +// This file is distributed under the University of Illinois Open Source<br>
>> +// License. See LICENSE.TXT for details.<br>
>> +//<br>
>> +//===------------------------<wbr>------------------------------<br>
>> ----------------===//<br>
>> +//<br>
>> +// Implementation of main so we can build and test without linking<br>
>> libFuzzer.<br>
>> +//<br>
>> +//===------------------------<wbr>------------------------------<br>
>> ----------------===//<br>
>> +<br>
>> +#include "llvm/ADT/StringRef.h"<br>
>> +#include "llvm/Support/Compiler.h"<br>
>> +#include "llvm/Support/Error.h"<br>
>> +#include "llvm/Support/MemoryBuffer.h"<br>
>> +#include "llvm/Support/raw_ostream.h"<br>
>> +<br>
>> +using namespace llvm;<br>
>> +<br>
>> +extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);<br>
>> +extern "C" LLVM_ATTRIBUTE_WEAK int LLVMFuzzerInitialize(int *argc,<br>
>> + char ***argv) {<br>
>> + return 0;<br>
>> +}<br>
>> +<br>
>> +int main(int argc, char *argv[]) {<br>
>> + errs() << "*** This tool was not linked to libFuzzer.\n"<br>
>> + << "*** No fuzzing will be performed.\n";<br>
>> + if (int RC = LLVMFuzzerInitialize(&argc, &argv)) {<br>
>> + errs() << "Initialization failed\n";<br>
>> + return RC;<br>
>> + }<br>
>> +<br>
>> + for (int I = 1; I < argc; ++I) {<br>
>> + StringRef Arg(argv[I]);<br>
>> + if (Arg.startswith("-")) {<br>
>> + if (Arg.equals("-ignore_<wbr>remaining_args=1"))<br>
>> + break;<br>
>> + continue;<br>
>> + }<br>
>> +<br>
>> + auto BufOrErr = MemoryBuffer::getFile(Arg, /*FileSize-*/ -1,<br>
>> + /*RequiresNullTerminator=*/<br>
>> false);<br>
>> + if (std::error_code EC = BufOrErr.getError()) {<br>
>> + errs() << "Error reading file: " << Arg << ": " << EC.message() <<<br>
>> "\n";<br>
>> + return 1;<br>
>> + }<br>
>> + std::unique_ptr<MemoryBuffer> Buf = std::move(BufOrErr.get());<br>
>> + errs() << "Running: " << Arg << " (" << Buf->getBufferSize() << "<br>
>> bytes)\n";<br>
>> + LLVMFuzzerTestOneInput(<br>
>> + reinterpret_cast<const uint8_t *>(Buf->getBufferStart()),<br>
>> + Buf->getBufferSize());<br>
>> + }<br>
>> +}<br>
>><br>
>><br>
>> ______________________________<wbr>_________________<br>
>> llvm-commits mailing list<br>
>> <a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a><br>
>> <a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" rel="noreferrer" target="_blank">http://lists.llvm.org/cgi-bin/<wbr>mailman/listinfo/llvm-commits</a><br>
>><br>
</div></div></blockquote></div><br></div></div>