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278 lines
9.2 KiB
C++
278 lines
9.2 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/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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if (MustDeleteBuffer)
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free((void*)BufferStart);
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}
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/// initCopyOf - Initialize this source buffer with a copy of the specified
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/// memory range. We make the copy so that we can null terminate it
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/// successfully.
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void MemoryBuffer::initCopyOf(const char *BufStart, const char *BufEnd) {
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size_t Size = BufEnd-BufStart;
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BufferStart = (char *)malloc(Size+1);
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BufferEnd = BufferStart+Size;
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memcpy(const_cast<char*>(BufferStart), BufStart, Size);
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*const_cast<char*>(BufferEnd) = 0; // Null terminate buffer.
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MustDeleteBuffer = true;
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}
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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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MustDeleteBuffer = false;
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}
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//===----------------------------------------------------------------------===//
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// MemoryBufferMem implementation.
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//===----------------------------------------------------------------------===//
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namespace {
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class MemoryBufferMem : public MemoryBuffer {
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std::string FileID;
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public:
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MemoryBufferMem(const char *Start, const char *End, StringRef FID,
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bool Copy = false)
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: FileID(FID) {
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if (!Copy)
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init(Start, End);
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else
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initCopyOf(Start, End);
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}
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virtual const char *getBufferIdentifier() const {
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return FileID.c_str();
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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(const char *StartPtr,
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const char *EndPtr,
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const char *BufferName) {
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return new MemoryBufferMem(StartPtr, EndPtr, 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(const char *StartPtr,
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const char *EndPtr,
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const char *BufferName) {
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return new MemoryBufferMem(StartPtr, EndPtr, BufferName, true);
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}
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/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
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/// that 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::getNewUninitMemBuffer(size_t Size,
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StringRef BufferName) {
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char *Buf = (char *)malloc(Size+1);
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if (!Buf) return 0;
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Buf[Size] = 0;
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MemoryBufferMem *SB = new MemoryBufferMem(Buf, Buf+Size, BufferName);
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// The memory for this buffer is owned by the MemoryBuffer.
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SB->MustDeleteBuffer = true;
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return SB;
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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,
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const char *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+1);
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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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if (Filename == "-")
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return getSTDIN();
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return getFile(Filename, ErrStr, FileSize);
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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 MemoryBuffer {
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std::string Filename;
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public:
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MemoryBufferMMapFile(StringRef filename, const char *Pages, uint64_t Size)
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: Filename(filename) {
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init(Pages, Pages+Size);
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}
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virtual const char *getBufferIdentifier() const {
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return Filename.c_str();
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}
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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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}
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MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
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int64_t FileSize) {
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int OpenFlags = 0;
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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.str().c_str(), O_RDONLY|OpenFlags);
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if (FD == -1) {
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if (ErrStr) *ErrStr = strerror(errno);
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return 0;
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}
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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) {
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struct stat FileInfo;
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// TODO: This should use fstat64 when available.
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if (fstat(FD, &FileInfo) == -1) {
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if (ErrStr) *ErrStr = strerror(errno);
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::close(FD);
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return 0;
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}
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FileSize = FileInfo.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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// Close the file descriptor, now that the whole file is in memory.
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::close(FD);
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return new MemoryBufferMMapFile(Filename, Pages, FileSize);
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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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::close(FD);
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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 > 0) {
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BytesLeft -= NumRead;
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BufPtr += NumRead;
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} else if (NumRead == -1 && errno == EINTR) {
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// try again
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} else {
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// error reading.
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if (ErrStr) *ErrStr = strerror(errno);
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close(FD);
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return 0;
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}
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}
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close(FD);
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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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namespace {
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class STDINBufferFile : public MemoryBuffer {
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public:
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virtual const char *getBufferIdentifier() const {
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return "<stdin>";
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}
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};
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}
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MemoryBuffer *MemoryBuffer::getSTDIN() {
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char Buffer[4096*4];
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std::vector<char> FileData;
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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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size_t ReadBytes;
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do {
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ReadBytes = fread(Buffer, sizeof(char), sizeof(Buffer), stdin);
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FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
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} while (ReadBytes == sizeof(Buffer));
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FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
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size_t Size = FileData.size();
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MemoryBuffer *B = new STDINBufferFile();
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B->initCopyOf(&FileData[0], &FileData[Size-1]);
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return B;
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}
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