1//===--- llvm/Support/DataStream.cpp - Lazy streamed data -----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements DataStreamer, which fetches bytes of Data from 11// a stream source. It provides support for streaming (lazy reading) of 12// bitcode. An example implementation of streaming from a file or stdin 13// is included. 14// 15//===----------------------------------------------------------------------===// 16 17#include "llvm/Support/DataStream.h" 18#include "llvm/ADT/Statistic.h" 19#include "llvm/Support/FileSystem.h" 20#include "llvm/Support/Program.h" 21#include <cerrno> 22#include <cstdio> 23#include <string> 24#include <system_error> 25#if !defined(_MSC_VER) && !defined(__MINGW32__) 26#include <unistd.h> 27#else 28#include <io.h> 29#endif 30using namespace llvm; 31 32#define DEBUG_TYPE "Data-stream" 33 34// Interface goals: 35// * StreamableMemoryObject doesn't care about complexities like using 36// threads/async callbacks to actually overlap download+compile 37// * Don't want to duplicate Data in memory 38// * Don't need to know total Data len in advance 39// Non-goals: 40// StreamableMemoryObject already has random access so this interface only does 41// in-order streaming (no arbitrary seeking, else we'd have to buffer all the 42// Data here in addition to MemoryObject). This also means that if we want 43// to be able to to free Data, BitstreamBytes/BitcodeReader will implement it 44 45STATISTIC(NumStreamFetches, "Number of calls to Data stream fetch"); 46 47namespace llvm { 48DataStreamer::~DataStreamer() {} 49} 50 51namespace { 52 53// Very simple stream backed by a file. Mostly useful for stdin and debugging; 54// actual file access is probably still best done with mmap. 55class DataFileStreamer : public DataStreamer { 56 int Fd; 57public: 58 DataFileStreamer() : Fd(0) {} 59 virtual ~DataFileStreamer() { 60 close(Fd); 61 } 62 size_t GetBytes(unsigned char *buf, size_t len) override { 63 NumStreamFetches++; 64 return read(Fd, buf, len); 65 } 66 67 std::error_code OpenFile(const std::string &Filename) { 68 if (Filename == "-") { 69 Fd = 0; 70 sys::ChangeStdinToBinary(); 71 return std::error_code(); 72 } 73 74 return sys::fs::openFileForRead(Filename, Fd); 75 } 76}; 77 78} 79 80namespace llvm { 81DataStreamer *getDataFileStreamer(const std::string &Filename, 82 std::string *StrError) { 83 DataFileStreamer *s = new DataFileStreamer(); 84 if (std::error_code e = s->OpenFile(Filename)) { 85 *StrError = std::string("Could not open ") + Filename + ": " + 86 e.message() + "\n"; 87 return nullptr; 88 } 89 return s; 90} 91 92} 93