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298 lines
10 KiB
C++
298 lines
10 KiB
C++
//===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the MemoryBuffer interface.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/ADT/OwningPtr.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/System/Errno.h"
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#include "llvm/System/Path.h"
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#include "llvm/System/Process.h"
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#include "llvm/System/Program.h"
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#include <cassert>
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#include <cstdio>
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#include <cstring>
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#include <cerrno>
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#include <sys/types.h>
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#include <sys/stat.h>
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#if !defined(_MSC_VER) && !defined(__MINGW32__)
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#include <unistd.h>
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#include <sys/uio.h>
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#else
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#include <io.h>
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#endif
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#include <fcntl.h>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// MemoryBuffer implementation itself.
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//===----------------------------------------------------------------------===//
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MemoryBuffer::~MemoryBuffer() { }
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/// init - Initialize this MemoryBuffer as a reference to externally allocated
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/// memory, memory that we know is already null terminated.
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void MemoryBuffer::init(const char *BufStart, const char *BufEnd) {
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assert(BufEnd[0] == 0 && "Buffer is not null terminated!");
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BufferStart = BufStart;
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BufferEnd = BufEnd;
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}
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//===----------------------------------------------------------------------===//
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// MemoryBufferMem implementation.
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//===----------------------------------------------------------------------===//
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/// CopyStringRef - Copies contents of a StringRef into a block of memory and
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/// null-terminates it.
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static void CopyStringRef(char *Memory, StringRef Data) {
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memcpy(Memory, Data.data(), Data.size());
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Memory[Data.size()] = 0; // Null terminate string.
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}
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/// GetNamedBuffer - Allocates a new MemoryBuffer with Name copied after it.
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template <typename T>
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static T* GetNamedBuffer(StringRef Buffer, StringRef Name) {
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char *Mem = static_cast<char*>(operator new(sizeof(T) + Name.size() + 1));
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CopyStringRef(Mem + sizeof(T), Name);
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return new (Mem) T(Buffer);
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}
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namespace {
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/// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
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class MemoryBufferMem : public MemoryBuffer {
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public:
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MemoryBufferMem(StringRef InputData) {
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init(InputData.begin(), InputData.end());
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}
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virtual const char *getBufferIdentifier() const {
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// The name is stored after the class itself.
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return reinterpret_cast<const char*>(this + 1);
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}
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};
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}
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/// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
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/// that EndPtr[0] must be a null byte and be accessible!
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MemoryBuffer *MemoryBuffer::getMemBuffer(StringRef InputData,
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StringRef BufferName) {
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return GetNamedBuffer<MemoryBufferMem>(InputData, BufferName);
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}
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/// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
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/// copying the contents and taking ownership of it. This has no requirements
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/// on EndPtr[0].
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MemoryBuffer *MemoryBuffer::getMemBufferCopy(StringRef InputData,
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StringRef BufferName) {
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MemoryBuffer *Buf = getNewUninitMemBuffer(InputData.size(), BufferName);
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if (!Buf) return 0;
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memcpy(const_cast<char*>(Buf->getBufferStart()), InputData.data(),
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InputData.size());
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return Buf;
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}
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/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
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/// that is not initialized. Note that the caller should initialize the
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/// memory allocated by this method. The memory is owned by the MemoryBuffer
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/// object.
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MemoryBuffer *MemoryBuffer::getNewUninitMemBuffer(size_t Size,
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StringRef BufferName) {
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// Allocate space for the MemoryBuffer, the data and the name. It is important
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// that MemoryBuffer and data are aligned so PointerIntPair works with them.
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size_t AlignedStringLen =
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RoundUpToAlignment(sizeof(MemoryBufferMem) + BufferName.size() + 1,
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sizeof(void*)); // TODO: Is sizeof(void*) enough?
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size_t RealLen = AlignedStringLen + Size + 1;
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char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
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if (!Mem) return 0;
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// The name is stored after the class itself.
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CopyStringRef(Mem + sizeof(MemoryBufferMem), BufferName);
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// The buffer begins after the name and must be aligned.
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char *Buf = Mem + AlignedStringLen;
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Buf[Size] = 0; // Null terminate buffer.
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return new (Mem) MemoryBufferMem(StringRef(Buf, Size));
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}
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/// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
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/// is completely initialized to zeros. Note that the caller should
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/// initialize the memory allocated by this method. The memory is owned by
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/// the MemoryBuffer object.
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MemoryBuffer *MemoryBuffer::getNewMemBuffer(size_t Size, StringRef BufferName) {
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MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
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if (!SB) return 0;
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memset(const_cast<char*>(SB->getBufferStart()), 0, Size);
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return SB;
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}
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/// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
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/// if the Filename is "-". If an error occurs, this returns null and fills
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/// in *ErrStr with a reason. If stdin is empty, this API (unlike getSTDIN)
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/// returns an empty buffer.
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MemoryBuffer *MemoryBuffer::getFileOrSTDIN(StringRef Filename,
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std::string *ErrStr,
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int64_t FileSize,
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struct stat *FileInfo) {
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if (Filename == "-")
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return getSTDIN(ErrStr);
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return getFile(Filename, ErrStr, FileSize, FileInfo);
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}
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MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *Filename,
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std::string *ErrStr,
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int64_t FileSize,
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struct stat *FileInfo) {
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if (strcmp(Filename, "-") == 0)
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return getSTDIN(ErrStr);
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return getFile(Filename, ErrStr, FileSize, FileInfo);
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}
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//===----------------------------------------------------------------------===//
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// MemoryBuffer::getFile implementation.
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//===----------------------------------------------------------------------===//
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namespace {
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/// MemoryBufferMMapFile - This represents a file that was mapped in with the
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/// sys::Path::MapInFilePages method. When destroyed, it calls the
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/// sys::Path::UnMapFilePages method.
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class MemoryBufferMMapFile : public MemoryBufferMem {
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public:
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MemoryBufferMMapFile(StringRef Buffer)
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: MemoryBufferMem(Buffer) { }
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~MemoryBufferMMapFile() {
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sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
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}
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};
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/// FileCloser - RAII object to make sure an FD gets closed properly.
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class FileCloser {
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int FD;
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public:
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explicit FileCloser(int FD) : FD(FD) {}
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~FileCloser() { ::close(FD); }
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};
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}
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MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
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int64_t FileSize, struct stat *FileInfo) {
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SmallString<256> PathBuf(Filename.begin(), Filename.end());
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return MemoryBuffer::getFile(PathBuf.c_str(), ErrStr, FileSize, FileInfo);
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}
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MemoryBuffer *MemoryBuffer::getFile(const char *Filename, std::string *ErrStr,
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int64_t FileSize, struct stat *FileInfo) {
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int OpenFlags = O_RDONLY;
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#ifdef O_BINARY
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OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
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#endif
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int FD = ::open(Filename, OpenFlags);
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if (FD == -1) {
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if (ErrStr) *ErrStr = sys::StrError();
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return 0;
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}
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FileCloser FC(FD); // Close FD on return.
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// If we don't know the file size, use fstat to find out. fstat on an open
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// file descriptor is cheaper than stat on a random path.
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if (FileSize == -1 || FileInfo) {
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struct stat MyFileInfo;
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struct stat *FileInfoPtr = FileInfo? FileInfo : &MyFileInfo;
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// TODO: This should use fstat64 when available.
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if (fstat(FD, FileInfoPtr) == -1) {
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if (ErrStr) *ErrStr = sys::StrError();
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return 0;
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}
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FileSize = FileInfoPtr->st_size;
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}
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// If the file is large, try to use mmap to read it in. We don't use mmap
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// for small files, because this can severely fragment our address space. Also
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// don't try to map files that are exactly a multiple of the system page size,
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// as the file would not have the required null terminator.
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//
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// FIXME: Can we just mmap an extra page in the latter case?
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if (FileSize >= 4096*4 &&
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(FileSize & (sys::Process::GetPageSize()-1)) != 0) {
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if (const char *Pages = sys::Path::MapInFilePages(FD, FileSize)) {
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return GetNamedBuffer<MemoryBufferMMapFile>(StringRef(Pages, FileSize),
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Filename);
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}
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}
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MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
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if (!Buf) {
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// Failed to create a buffer.
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if (ErrStr) *ErrStr = "could not allocate buffer";
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return 0;
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}
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OwningPtr<MemoryBuffer> SB(Buf);
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char *BufPtr = const_cast<char*>(SB->getBufferStart());
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size_t BytesLeft = FileSize;
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while (BytesLeft) {
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ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
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if (NumRead == -1) {
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if (errno == EINTR)
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continue;
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// Error while reading.
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if (ErrStr) *ErrStr = sys::StrError();
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return 0;
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} else if (NumRead == 0) {
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// We hit EOF early, truncate and terminate buffer.
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Buf->BufferEnd = BufPtr;
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*BufPtr = 0;
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return SB.take();
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}
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BytesLeft -= NumRead;
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BufPtr += NumRead;
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}
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return SB.take();
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}
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//===----------------------------------------------------------------------===//
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// MemoryBuffer::getSTDIN implementation.
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//===----------------------------------------------------------------------===//
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MemoryBuffer *MemoryBuffer::getSTDIN(std::string *ErrStr) {
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// Read in all of the data from stdin, we cannot mmap stdin.
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//
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// FIXME: That isn't necessarily true, we should try to mmap stdin and
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// fallback if it fails.
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sys::Program::ChangeStdinToBinary();
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const ssize_t ChunkSize = 4096*4;
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SmallString<ChunkSize> Buffer;
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ssize_t ReadBytes;
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// Read into Buffer until we hit EOF.
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do {
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Buffer.reserve(Buffer.size() + ChunkSize);
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ReadBytes = read(0, Buffer.end(), ChunkSize);
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if (ReadBytes == -1) {
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if (errno == EINTR) continue;
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if (ErrStr) *ErrStr = sys::StrError();
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return 0;
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}
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Buffer.set_size(Buffer.size() + ReadBytes);
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} while (ReadBytes != 0);
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return getMemBufferCopy(Buffer, "<stdin>");
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}
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