Reland "[NFC][libFuzzer] Prefix TempPath with string showing the work it is doing."

With fix (somehow one hunk is missed).

compiler-rt/lib/fuzzer/FuzzerDriver.cpp

@@ -345,7 +345,7 @@ int CleanseCrashInput(const Vector<std::string> &Args,
   assert(Cmd.hasArgument(InputFilePath));
   Cmd.removeArgument(InputFilePath);
 
-  auto TmpFilePath = TempPath(".repro");
+  auto TmpFilePath = TempPath("CleanseCrashInput", ".repro");
   Cmd.addArgument(TmpFilePath);
   Cmd.setOutputFile(getDevNull());
   Cmd.combineOutAndErr();
@@ -499,7 +499,7 @@ void Merge(Fuzzer *F, FuzzingOptions &Options, const Vector<std::string> &Args,
   std::sort(OldCorpus.begin(), OldCorpus.end());
   std::sort(NewCorpus.begin(), NewCorpus.end());
 
-  std::string CFPath = CFPathOrNull ? CFPathOrNull : TempPath(".txt");
+  std::string CFPath = CFPathOrNull ? CFPathOrNull : TempPath("Merge", ".txt");
   Vector<std::string> NewFiles;
   Set<uint32_t> NewFeatures, NewCov;
   CrashResistantMerge(Args, OldCorpus, NewCorpus, &NewFiles, {}, &NewFeatures,

compiler-rt/lib/fuzzer/FuzzerFork.cpp

@@ -297,7 +297,7 @@ void FuzzWithFork(Random &Rand, const FuzzingOptions &Options,
   for (auto &Dir : CorpusDirs)
     GetSizedFilesFromDir(Dir, &SeedFiles);
   std::sort(SeedFiles.begin(), SeedFiles.end());
-  Env.TempDir = TempPath(".dir");
+  Env.TempDir = TempPath("FuzzWithFork", ".dir");
   Env.DFTDir = DirPlusFile(Env.TempDir, "DFT");
   RmDirRecursive(Env.TempDir);  // in case there is a leftover from old runs.
   MkDir(Env.TempDir);

compiler-rt/lib/fuzzer/FuzzerIO.cpp

@@ -151,9 +151,9 @@ void RmDirRecursive(const std::string &Dir) {
       [](const std::string &Path) { RemoveFile(Path); });
 }
 
-std::string TempPath(const char *Extension) {
-  return DirPlusFile(TmpDir(),
-                     "libFuzzerTemp." + std::to_string(GetPid()) + Extension);
+std::string TempPath(const char *Prefix, const char *Extension) {
+  return DirPlusFile(TmpDir(), std::string("libFuzzerTemp.") + Prefix +
+                                   std::to_string(GetPid()) + Extension);
 }
 
 }  // namespace fuzzer

compiler-rt/lib/fuzzer/FuzzerIO.h

@@ -42,7 +42,7 @@ std::string DirName(const std::string &FileName);
 // Returns path to a TmpDir.
 std::string TmpDir();
 
-std::string TempPath(const char *Extension);
+std::string TempPath(const char *Prefix, const char *Extension);
 
 bool IsInterestingCoverageFile(const std::string &FileName);
 

compiler-rt/lib/fuzzer/FuzzerLoop.cpp

@@ -256,7 +256,7 @@ void Fuzzer::ExitCallback() {
 void Fuzzer::MaybeExitGracefully() {
   if (!F->GracefulExitRequested) return;
   Printf("==%lu== INFO: libFuzzer: exiting as requested\n", GetPid());
-  RmDirRecursive(TempPath(".dir"));
+  RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
   F->PrintFinalStats();
   _Exit(0);
 }
@@ -265,7 +265,7 @@ void Fuzzer::InterruptCallback() {
   Printf("==%lu== libFuzzer: run interrupted; exiting\n", GetPid());
   PrintFinalStats();
   ScopedDisableMsanInterceptorChecks S; // RmDirRecursive may call opendir().
-  RmDirRecursive(TempPath(".dir"));
+  RmDirRecursive(TempPath("FuzzWithFork", ".dir"));
   // Stop right now, don't perform any at-exit actions.
   _Exit(Options.InterruptExitCode);
 }