llvm-6502/lib/Support/MemoryBuffer.cpp

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//===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the MemoryBuffer interface.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/System/MappedFile.h"
#include "llvm/System/Process.h"
#include "llvm/System/Program.h"
#include <cassert>
#include <cstdio>
#include <cstring>
#include <cerrno>
using namespace llvm;
//===----------------------------------------------------------------------===//
// MemoryBuffer implementation itself.
//===----------------------------------------------------------------------===//
MemoryBuffer::~MemoryBuffer() {
if (MustDeleteBuffer)
delete [] BufferStart;
}
/// initCopyOf - Initialize this source buffer with a copy of the specified
/// memory range. We make the copy so that we can null terminate it
/// successfully.
void MemoryBuffer::initCopyOf(const char *BufStart, const char *BufEnd) {
size_t Size = BufEnd-BufStart;
BufferStart = new char[Size+1];
BufferEnd = BufferStart+Size;
memcpy(const_cast<char*>(BufferStart), BufStart, Size);
*const_cast<char*>(BufferEnd) = 0; // Null terminate buffer.
MustDeleteBuffer = true;
}
/// init - Initialize this MemoryBuffer as a reference to externally allocated
/// memory, memory that we know is already null terminated.
void MemoryBuffer::init(const char *BufStart, const char *BufEnd) {
assert(BufEnd[0] == 0 && "Buffer is not null terminated!");
BufferStart = BufStart;
BufferEnd = BufEnd;
MustDeleteBuffer = false;
}
//===----------------------------------------------------------------------===//
// MemoryBufferMem implementation.
//===----------------------------------------------------------------------===//
namespace {
class MemoryBufferMem : public MemoryBuffer {
std::string FileID;
public:
MemoryBufferMem(const char *Start, const char *End, const char *FID,
bool Copy = false)
: FileID(FID) {
if (!Copy)
init(Start, End);
else
initCopyOf(Start, End);
}
virtual const char *getBufferIdentifier() const {
return FileID.c_str();
}
};
}
/// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
/// that EndPtr[0] must be a null byte and be accessible!
MemoryBuffer *MemoryBuffer::getMemBuffer(const char *StartPtr,
const char *EndPtr,
const char *BufferName) {
return new MemoryBufferMem(StartPtr, EndPtr, BufferName);
}
/// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
/// copying the contents and taking ownership of it. This has no requirements
/// on EndPtr[0].
MemoryBuffer *MemoryBuffer::getMemBufferCopy(const char *StartPtr,
const char *EndPtr,
const char *BufferName) {
return new MemoryBufferMem(StartPtr, EndPtr, BufferName, true);
}
/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
/// that is completely initialized to zeros. Note that the caller should
/// initialize the memory allocated by this method. The memory is owned by
/// the MemoryBuffer object.
MemoryBuffer *MemoryBuffer::getNewUninitMemBuffer(unsigned Size,
const char *BufferName) {
char *Buf = new char[Size+1];
Buf[Size] = 0;
MemoryBufferMem *SB = new MemoryBufferMem(Buf, Buf+Size, BufferName);
// The memory for this buffer is owned by the MemoryBuffer.
SB->MustDeleteBuffer = true;
return SB;
}
/// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
/// is completely initialized to zeros. Note that the caller should
/// initialize the memory allocated by this method. The memory is owned by
/// the MemoryBuffer object.
MemoryBuffer *MemoryBuffer::getNewMemBuffer(unsigned Size,
const char *BufferName) {
MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
memset(const_cast<char*>(SB->getBufferStart()), 0, Size+1);
return SB;
}
/// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
/// if the Filename is "-". If an error occurs, this returns null and fills
/// in *ErrStr with a reason. If stdin is empty, this API (unlike getSTDIN)
/// returns an empty buffer.
MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *FilenameStart,
unsigned FnSize,
std::string *ErrStr,
int64_t FileSize) {
if (FnSize != 1 || FilenameStart[0] != '-')
return getFile(FilenameStart, FnSize, ErrStr, FileSize);
MemoryBuffer *M = getSTDIN();
if (M) return M;
// If stdin was empty, M is null. Cons up an empty memory buffer now.
const char *EmptyStr = "";
return MemoryBuffer::getMemBuffer(EmptyStr, EmptyStr, "<stdin>");
}
//===----------------------------------------------------------------------===//
// MemoryBufferMMapFile implementation.
//===----------------------------------------------------------------------===//
namespace {
class MemoryBufferMMapFile : public MemoryBuffer {
sys::MappedFile File;
public:
MemoryBufferMMapFile() {}
bool open(const sys::Path &Filename, std::string *ErrStr);
virtual const char *getBufferIdentifier() const {
return File.path().c_str();
}
~MemoryBufferMMapFile();
};
}
bool MemoryBufferMMapFile::open(const sys::Path &Filename,
std::string *ErrStr) {
// FIXME: This does an extra stat syscall to figure out the size, but we
// already know the size!
bool Failure = File.open(Filename, sys::MappedFile::READ_ACCESS, ErrStr);
if (Failure) return true;
if (!File.map(ErrStr))
return true;
size_t Size = File.size();
static unsigned PageSize = sys::Process::GetPageSize();
assert(((PageSize & (PageSize-1)) == 0) && PageSize &&
"Page size is not a power of 2!");
// If this file is not an exact multiple of the system page size (common
// case), then the OS has zero terminated the buffer for us.
if ((Size & (PageSize-1))) {
init(File.charBase(), File.charBase()+Size);
} else {
// Otherwise, we allocate a new memory buffer and copy the data over
initCopyOf(File.charBase(), File.charBase()+Size);
// No need to keep the file mapped any longer.
File.unmap();
}
return false;
}
MemoryBufferMMapFile::~MemoryBufferMMapFile() {
if (File.isMapped())
File.unmap();
}
//===----------------------------------------------------------------------===//
// MemoryBuffer::getFile implementation.
//===----------------------------------------------------------------------===//
MemoryBuffer *MemoryBuffer::getFile(const char *FilenameStart, unsigned FnSize,
std::string *ErrStr, int64_t FileSize){
// FIXME: it would be nice if PathWithStatus didn't copy the filename into a
// temporary string. :(
sys::PathWithStatus P(FilenameStart, FnSize);
#if 1
MemoryBufferMMapFile *M = new MemoryBufferMMapFile();
if (!M->open(P, ErrStr))
return M;
delete M;
return 0;
#else
// FIXME: We need an efficient and portable method to open a file and then use
// 'read' to copy the bits out. The unix implementation is below. This is
// an important optimization for clients that want to open large numbers of
// small files (using mmap on everything can easily exhaust address space!).
// If the user didn't specify a filesize, do a stat to find it.
if (FileSize == -1) {
const sys::FileStatus *FS = P.getFileStatus();
if (FS == 0) return 0; // Error stat'ing file.
FileSize = FS->fileSize;
}
// If the file is larger than some threshold, use mmap, otherwise use 'read'.
if (FileSize >= 4096*4) {
MemoryBufferMMapFile *M = new MemoryBufferMMapFile();
if (!M->open(P, ErrStr))
return M;
delete M;
return 0;
}
MemoryBuffer *SB = getNewUninitMemBuffer(FileSize, FilenameStart);
char *BufPtr = const_cast<char*>(SB->getBufferStart());
int FD = ::open(FilenameStart, O_RDONLY);
if (FD == -1) {
delete SB;
return 0;
}
unsigned BytesLeft = FileSize;
while (BytesLeft) {
ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
if (NumRead != -1) {
BytesLeft -= NumRead;
BufPtr += NumRead;
} else if (errno == EINTR) {
// try again
} else {
// error reading.
close(FD);
delete SB;
return 0;
}
}
close(FD);
return SB;
#endif
}
//===----------------------------------------------------------------------===//
// MemoryBuffer::getSTDIN implementation.
//===----------------------------------------------------------------------===//
namespace {
class STDINBufferFile : public MemoryBuffer {
public:
virtual const char *getBufferIdentifier() const {
return "<stdin>";
}
};
}
MemoryBuffer *MemoryBuffer::getSTDIN() {
char Buffer[4096*4];
std::vector<char> FileData;
// Read in all of the data from stdin, we cannot mmap stdin.
sys::Program::ChangeStdinToBinary();
while (size_t ReadBytes = fread(Buffer, sizeof(char), 4096*4, stdin))
FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
size_t Size = FileData.size();
if (Size <= 1)
return 0;
MemoryBuffer *B = new STDINBufferFile();
B->initCopyOf(&FileData[0], &FileData[Size-1]);
return B;
}