Subzero: Fix build problem against LLVM trunk.

pnacl-llvm/DataStream.cpp

+//===--- llvm/Support/DataStream.cpp - Lazy streamed data -----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements DataStreamer, which fetches bytes of Data from
+// a stream source. It provides support for streaming (lazy reading) of
+// bitcode. An example implementation of streaming from a file or stdin
+// is included.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DataStream.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Program.h"
+#include <string>
+#include <system_error>
+#if !defined(_MSC_VER) && !defined(__MINGW32__)
+#include <unistd.h>
+#else
+#include <io.h>
+#endif
+using namespace llvm;
+
+#define DEBUG_TYPE "Data-stream"
+
+// Interface goals:
+// * StreamingMemoryObject doesn't care about complexities like using
+//   threads/async callbacks to actually overlap download+compile
+// * Don't want to duplicate Data in memory
+// * Don't need to know total Data len in advance
+// Non-goals:
+// StreamingMemoryObject already has random access so this interface only does
+// in-order streaming (no arbitrary seeking, else we'd have to buffer all the
+// Data here in addition to MemoryObject).  This also means that if we want
+// to be able to to free Data, BitstreamBytes/BitcodeReader will implement it
+
+STATISTIC(NumStreamFetches, "Number of calls to Data stream fetch");
+
+namespace llvm {
+DataStreamer::~DataStreamer() {}
+}
+
+namespace {
+
+// Very simple stream backed by a file. Mostly useful for stdin and debugging;
+// actual file access is probably still best done with mmap.
+class DataFileStreamer : public DataStreamer {
+ int Fd;
+public:
+  DataFileStreamer() : Fd(0) {}
+  ~DataFileStreamer() override { close(Fd); }
+  size_t GetBytes(unsigned char *buf, size_t len) override {
+    NumStreamFetches++;
+    return read(Fd, buf, len);
+  }
+
+  std::error_code OpenFile(const std::string &Filename) {
+    if (Filename == "-") {
+      Fd = 0;
+      sys::ChangeStdinToBinary();
+      return std::error_code();
+    }
+
+    return sys::fs::openFileForRead(Filename, Fd);
+  }
+};
+
+}
+
+std::unique_ptr<DataStreamer>
+llvm::getDataFileStreamer(const std::string &Filename, std::string *StrError) {
+  std::unique_ptr<DataFileStreamer> s = make_unique<DataFileStreamer>();
+  if (std::error_code e = s->OpenFile(Filename)) {
+    *StrError = std::string("Could not open ") + Filename + ": " +
+        e.message() + "\n";
+    return nullptr;
+  }
+  return std::move(s);
+}