[lib/Fuzzer] Add SHA1 implementation from public domain.

Summary:
This adds a SHA1 implementation taken from public domain code.
The change is trivial, but as it involves third-party code I'd like
a second pair of eyes before commit.

LibFuzzer can not use SHA1 from openssl because openssl may not be available
and because we may be fuzzing openssl itself.
Using sha1sum via a pipe is too slow.

Test Plan: n/a

Reviewers: chandlerc

Reviewed By: chandlerc

Subscribers: majnemer, llvm-commits

Differential Revision: http://reviews.llvm.org/D9733

llvm-svn: 237400

1 files changed, 9 insertions, 38 deletions

diff --git a/llvm/lib/Fuzzer/FuzzerUtil.cpp b/llvm/lib/Fuzzer/FuzzerUtil.cpp
index 2fb6e05..c4b0afa 100644
--- a/llvm/lib/Fuzzer/FuzzerUtil.cpp
+++ b/llvm/lib/Fuzzer/FuzzerUtil.cpp
@@ -10,6 +10,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "FuzzerInternal.h"
+#include <sstream>
+#include <iomanip>
 #include <iostream>
 #include <sys/time.h>
 #include <cassert>
@@ -35,44 +37,13 @@ void PrintASCII(const Unit &U, const char *PrintAfter) {
   std::cerr << PrintAfter;
 }
 
-// Try to compute a SHA1 sum of this Unit using an external 'sha1sum' command.
-// We can not use the SHA1 function from openssl directly because
-//  a) openssl may not be available,
-//  b) we may be fuzzing openssl itself.
-// This is all very sad, suggestions are welcome.
-static std::string TrySha1(const Unit &in) {
-  char TempPath[] = "/tmp/fuzzer-tmp-XXXXXX";
-  int FD = mkstemp(TempPath);
-  if (FD < 0) return "";
-  ssize_t Written = write(FD, in.data(), in.size());
-  close(FD);
-  if (static_cast<size_t>(Written) != in.size()) return "";
-
-  std::string Cmd = "sha1sum < ";
-  Cmd += TempPath;
-  FILE *F = popen(Cmd.c_str(), "r");
-  if (!F) return "";
-  char Sha1[41];
-  fgets(Sha1, sizeof(Sha1), F);
-  fclose(F);
-
-  unlink(TempPath);
-  return Sha1;
-}
-
-std::string Hash(const Unit &in) {
-  std::string Sha1 = TrySha1(in);
-  if (!Sha1.empty())
-    return Sha1;
-
-  size_t h1 = 0, h2 = 0;
-  for (auto x : in) {
-    h1 += x;
-    h1 *= 5;
-    h2 += x;
-    h2 *= 7;
-  }
-  return std::to_string(h1) + std::to_string(h2);
+std::string Hash(const Unit &U) {
+  uint8_t Hash[kSHA1NumBytes];
+  ComputeSHA1(U.data(), U.size(), Hash);
+  std::stringstream SS;
+  for (int i = 0; i < kSHA1NumBytes; i++)
+    SS << std::hex << std::setfill('0') << std::setw(2) << (unsigned)Hash[i];
+  return SS.str();
 }
 
 static void AlarmHandler(int, siginfo_t *, void *) {