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293 lines
9.7 KiB
C++
293 lines
9.7 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/System/MappedFile.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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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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delete [] 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 = new char[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, const char *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(unsigned Size,
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const char *BufferName) {
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char *Buf = new char[Size+1];
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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(unsigned Size,
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const char *BufferName) {
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MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
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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(const char *FilenameStart,
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unsigned FnSize,
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std::string *ErrStr,
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int64_t FileSize) {
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if (FnSize != 1 || FilenameStart[0] != '-')
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return getFile(FilenameStart, FnSize, ErrStr, FileSize);
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MemoryBuffer *M = getSTDIN();
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if (M) return M;
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// If stdin was empty, M is null. Cons up an empty memory buffer now.
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const char *EmptyStr = "";
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return MemoryBuffer::getMemBuffer(EmptyStr, EmptyStr, "<stdin>");
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}
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//===----------------------------------------------------------------------===//
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// MemoryBufferMMapFile implementation.
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//===----------------------------------------------------------------------===//
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namespace {
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class MemoryBufferMMapFile : public MemoryBuffer {
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sys::MappedFile File;
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public:
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MemoryBufferMMapFile() {}
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bool open(const sys::Path &Filename, std::string *ErrStr);
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virtual const char *getBufferIdentifier() const {
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return File.path().c_str();
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}
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~MemoryBufferMMapFile();
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};
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}
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bool MemoryBufferMMapFile::open(const sys::Path &Filename,
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std::string *ErrStr) {
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// FIXME: This does an extra stat syscall to figure out the size, but we
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// already know the size!
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bool Failure = File.open(Filename, sys::MappedFile::READ_ACCESS, ErrStr);
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if (Failure) return true;
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if (!File.map(ErrStr))
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return true;
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size_t Size = File.size();
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static unsigned PageSize = sys::Process::GetPageSize();
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assert(((PageSize & (PageSize-1)) == 0) && PageSize &&
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"Page size is not a power of 2!");
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// If this file is not an exact multiple of the system page size (common
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// case), then the OS has zero terminated the buffer for us.
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if ((Size & (PageSize-1))) {
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init(File.charBase(), File.charBase()+Size);
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} else {
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// Otherwise, we allocate a new memory buffer and copy the data over
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initCopyOf(File.charBase(), File.charBase()+Size);
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// No need to keep the file mapped any longer.
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File.unmap();
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}
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return false;
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}
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MemoryBufferMMapFile::~MemoryBufferMMapFile() {
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if (File.isMapped())
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File.unmap();
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}
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//===----------------------------------------------------------------------===//
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// MemoryBuffer::getFile implementation.
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//===----------------------------------------------------------------------===//
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MemoryBuffer *MemoryBuffer::getFile(const char *FilenameStart, unsigned FnSize,
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std::string *ErrStr, int64_t FileSize){
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// FIXME: it would be nice if PathWithStatus didn't copy the filename into a
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// temporary string. :(
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sys::PathWithStatus P(FilenameStart, FnSize);
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#if 1
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MemoryBufferMMapFile *M = new MemoryBufferMMapFile();
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if (!M->open(P, ErrStr))
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return M;
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delete M;
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return 0;
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#else
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// FIXME: We need an efficient and portable method to open a file and then use
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// 'read' to copy the bits out. The unix implementation is below. This is
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// an important optimization for clients that want to open large numbers of
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// small files (using mmap on everything can easily exhaust address space!).
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// If the user didn't specify a filesize, do a stat to find it.
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if (FileSize == -1) {
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const sys::FileStatus *FS = P.getFileStatus();
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if (FS == 0) return 0; // Error stat'ing file.
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FileSize = FS->fileSize;
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}
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// If the file is larger than some threshold, use mmap, otherwise use 'read'.
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if (FileSize >= 4096*4) {
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MemoryBufferMMapFile *M = new MemoryBufferMMapFile();
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if (!M->open(P, ErrStr))
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return M;
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delete M;
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return 0;
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}
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MemoryBuffer *SB = getNewUninitMemBuffer(FileSize, FilenameStart);
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char *BufPtr = const_cast<char*>(SB->getBufferStart());
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int FD = ::open(FilenameStart, O_RDONLY);
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if (FD == -1) {
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delete SB;
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return 0;
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}
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unsigned 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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BytesLeft -= NumRead;
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BufPtr += NumRead;
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} else if (errno == EINTR) {
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// try again
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} else {
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// error reading.
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close(FD);
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delete SB;
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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;
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#endif
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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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sys::Program::ChangeStdinToBinary();
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while (size_t ReadBytes = fread(Buffer, sizeof(char), 4096*4, stdin))
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FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
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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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if (Size <= 1)
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return 0;
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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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