[libFuzzer] Portably disassemble and find calls to sanitizer_cov_trace_pc_guard.

Instead of directly using objdump, which is not present on Windows, we consider
different tools depending on the platform.
For Windows, we consider dumpbin and llvm-objdump.

Differential Revision: https://reviews.llvm.org/D28635

llvm-svn: 292739

llvm/lib/Fuzzer/FuzzerTracePC.cpp

@@ -18,6 +18,7 @@
 #include "FuzzerExtFunctions.h"
 #include "FuzzerIO.h"
 #include "FuzzerTracePC.h"
+#include "FuzzerUtil.h"
 #include "FuzzerValueBitMap.h"
 #include <map>
 #include <set>
@@ -141,8 +142,8 @@ void TracePC::PrintCoverage() {
     Printf("MODULE_WITH_COVERAGE: %s\n", ModuleName.c_str());
     // sancov does not yet fully support DSOs.
     // std::string Cmd = "sancov -print-coverage-pcs " + ModuleName;
-    std::string Cmd = "objdump -d " + ModuleName +
-        " | grep 'call.*__sanitizer_cov_trace_pc_guard' | awk -F: '{print $1}'";
+    std::string Cmd = DisassembleCmd(ModuleName) + " | " +
+        SearchRegexCmd("call.*__sanitizer_cov_trace_pc_guard");
     std::string SanCovOutput;
     if (!ExecuteCommandAndReadOutput(Cmd, &SanCovOutput)) {
       Printf("INFO: Command failed: %s\n", Cmd.c_str());
@@ -151,6 +152,10 @@ void TracePC::PrintCoverage() {
     std::istringstream ISS(SanCovOutput);
     std::string S;
     while (std::getline(ISS, S, '\n')) {
+      size_t PcOffsetEnd = S.find(':');
+      if (PcOffsetEnd == std::string::npos)
+        continue;
+      S.resize(PcOffsetEnd);
       uintptr_t PcOffset = std::stol(S, 0, 16);
       if (!std::binary_search(CoveredOffsets.begin(), CoveredOffsets.end(),
                               PcOffset)) {

llvm/lib/Fuzzer/FuzzerUtil.h

@@ -67,6 +67,10 @@ inline std::string CloneArgsWithoutX(const std::vector<std::string> &Args,
   return CloneArgsWithoutX(Args, X, X);
 }
 
+std::string DisassembleCmd(const std::string &FileName);
+
+std::string SearchRegexCmd(const std::string &Regex);
+
 }  // namespace fuzzer
 
 #endif  // LLVM_FUZZER_UTIL_H

llvm/lib/Fuzzer/FuzzerUtilPosix.cpp

@@ -118,6 +118,14 @@ const void *SearchMemory(const void *Data, size_t DataLen, const void *Patt,
   return memmem(Data, DataLen, Patt, PattLen);
 }
 
+std::string DisassembleCmd(const std::string &FileName) {
+  return "objdump -d " + FileName;
+}
+
+std::string SearchRegexCmd(const std::string &Regex) {
+  return "grep '" + Regex + "'";
+}
+
 }  // namespace fuzzer
 
 #endif // LIBFUZZER_POSIX

llvm/lib/Fuzzer/FuzzerUtilWindows.cpp

@@ -178,6 +178,20 @@ const void *SearchMemory(const void *Data, size_t DataLen, const void *Patt,
   return NULL;
 }
 
+std::string DisassembleCmd(const std::string &FileName) {
+  if (ExecuteCommand("dumpbin > nul") == 0)
+    return "dumpbin /disasm " + FileName;
+  if (ExecuteCommand("llvm-objdump > nul") == 0)
+    return "llvm-objdump -d " + FileName;
+  Printf("libFuzzer: couldn't find tool to disassemble (dumpbin, "
+      "llvm-objdump)\n");
+  exit(1);
+}
+
+std::string SearchRegexCmd(const std::string &Regex) {
+  return "findstr /r \"" + Regex + "\"";
+}
+
 } // namespace fuzzer
 
 #endif // LIBFUZZER_WINDOWS