[libfuzzer] speeding up corpus load
llvm-svn: 263591
diff --git a/llvm/lib/Fuzzer/FuzzerIO.cpp b/llvm/lib/Fuzzer/FuzzerIO.cpp
index 3fa6721..be7759f 100644
--- a/llvm/lib/Fuzzer/FuzzerIO.cpp
+++ b/llvm/lib/Fuzzer/FuzzerIO.cpp
@@ -61,14 +61,16 @@
Printf("No such directory: %s; exiting\n", Path.c_str());
exit(1);
}
- if (MaxSize) {
- Unit Res(MaxSize);
- T.read(reinterpret_cast<char*>(Res.data()), MaxSize);
- Res.resize(T.gcount());
- return Res;
- }
- return Unit((std::istreambuf_iterator<char>(T)),
- std::istreambuf_iterator<char>());
+
+ T.seekg(0, T.end);
+ size_t FileLen = T.tellg();
+ if (MaxSize)
+ FileLen = std::min(FileLen, MaxSize);
+
+ T.seekg(0, T.beg);
+ Unit Res(FileLen);
+ T.read(reinterpret_cast<char *>(Res.data()), FileLen);
+ return Res;
}
std::string FileToString(const std::string &Path) {