[llvm-mc-fuzzer] Use LLVMFuzzerInitialize() instead of a custom main() and FuzzerDriver()

Reviewers: kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D20201

llvm-svn: 269405

llvm/tools/llvm-mc-fuzzer/CMakeLists.txt

@@ -13,6 +13,6 @@ if( LLVM_USE_SANITIZE_COVERAGE )
   add_llvm_tool(llvm-mc-fuzzer 
                 llvm-mc-fuzzer.cpp)
   target_link_libraries(llvm-mc-fuzzer
-                        LLVMFuzzerNoMain
+                        LLVMFuzzer
                         )
 endif()

llvm/tools/llvm-mc-fuzzer/llvm-mc-fuzzer.cpp

@@ -57,9 +57,10 @@ static cl::list<std::string>
 std::string FeaturesStr;
 
 static cl::list<std::string>
-    FuzzerArgv("fuzzer-args", cl::Positional,
+    FuzzerArgs("fuzzer-args", cl::Positional,
                cl::desc("Options to pass to the fuzzer"), cl::ZeroOrMore,
                cl::PositionalEatsArgs);
+static std::vector<char *> ModifiedArgv;
 
 int DisassembleOneInput(const uint8_t *Data, size_t Size) {
   char AssemblyText[AssemblyTextBufSize];
@@ -87,7 +88,17 @@ int DisassembleOneInput(const uint8_t *Data, size_t Size) {
   return 0;
 }
 
-int main(int argc, char **argv) {
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  if (Action == AC_Assemble)
+    errs() << "error: -assemble is not implemented\n";
+  else if (Action == AC_Disassemble)
+    return DisassembleOneInput(Data, Size);
+
+  llvm_unreachable("Unknown action");
+  return 0;
+}
+
+int LLVMFuzzerInitialize(int *argc, char ***argv) {
   // The command line is unusual compared to other fuzzers due to the need to
   // specify the target. Options like -triple, -mcpu, and -mattr work like
   // their counterparts in llvm-mc, while -fuzzer-args collects options for the
@@ -111,11 +122,29 @@ int main(int argc, char **argv) {
   // individual instructions that test unique paths. Without this constraint,
   // there will be considerable redundancy in the corpus.
 
+  char **OriginalArgv = *argv;
+
   LLVMInitializeAllTargetInfos();
   LLVMInitializeAllTargetMCs();
   LLVMInitializeAllDisassemblers();
 
-  cl::ParseCommandLineOptions(argc, argv);
+  cl::ParseCommandLineOptions(*argc, OriginalArgv);
+
+  // Rebuild the argv without the arguments llvm-mc-fuzzer consumed so that
+  // the driver can parse its arguments.
+  //
+  // FuzzerArgs cannot provide the non-const pointer that OriginalArgv needs.
+  // Re-use the strings from OriginalArgv instead of copying FuzzerArg to a
+  // non-const buffer to avoid the need to clean up when the fuzzer terminates.
+  ModifiedArgv.push_back(OriginalArgv[0]);
+  for (const auto &FuzzerArg : FuzzerArgs) {
+    for (int i = 1; i < *argc; ++i) {
+      if (FuzzerArg == OriginalArgv[i])
+        ModifiedArgv.push_back(OriginalArgv[i]);
+    }
+  }
+  *argc = ModifiedArgv.size();
+  *argv = ModifiedArgv.data();
 
   // Package up features to be passed to target/subtarget
   // We have to pass it via a global since the callback doesn't
@@ -127,11 +156,5 @@ int main(int argc, char **argv) {
     FeaturesStr = Features.getString();
   }
 
-  if (Action == AC_Assemble)
-    errs() << "error: -assemble is not implemented\n";
-  else if (Action == AC_Disassemble)
-    return fuzzer::FuzzerDriver(argc, argv, DisassembleOneInput);
-
-  llvm_unreachable("Unknown action");
-  return 1;
+  return 0;
 }