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//===--- 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/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) {}
virtual ~DataFileStreamer() {
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);
}
};
}
namespace llvm {
DataStreamer *getDataFileStreamer(const std::string &Filename,
std::string *StrError) {
DataFileStreamer *s = new DataFileStreamer();
if (std::error_code e = s->OpenFile(Filename)) {
*StrError = std::string("Could not open ") + Filename + ": " +
e.message() + "\n";
return nullptr;
}
return s;
}
}
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