llvm-6502/lib/Support/MemoryBuffer.cpp
Daniel Dunbar d65267ee62 Fix MemoryBuffer::getSTDIN to *not* return null if stdin is empty, this is a lame API.
Also, Stringrefify some more MemoryBuffer functions, and add two performance FIXMEs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86630 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 00:43:58 +00:00

278 lines
9.2 KiB
C++

//===--- 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/ADT/OwningPtr.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/System/Path.h"
#include "llvm/System/Process.h"
#include "llvm/System/Program.h"
#include <cassert>
#include <cstdio>
#include <cstring>
#include <cerrno>
#include <sys/types.h>
#include <sys/stat.h>
#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#include <sys/uio.h>
#else
#include <io.h>
#endif
#include <fcntl.h>
using namespace llvm;
//===----------------------------------------------------------------------===//
// MemoryBuffer implementation itself.
//===----------------------------------------------------------------------===//
MemoryBuffer::~MemoryBuffer() {
if (MustDeleteBuffer)
free((void*)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 = (char *)malloc((Size+1) * sizeof(char));
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, StringRef 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(size_t Size,
StringRef BufferName) {
char *Buf = (char *)malloc((Size+1) * sizeof(char));
if (!Buf) return 0;
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(size_t Size,
const char *BufferName) {
MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
if (!SB) return 0;
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(StringRef Filename,
std::string *ErrStr,
int64_t FileSize) {
if (Filename == "-")
return getSTDIN();
return getFile(Filename, ErrStr, FileSize);
}
//===----------------------------------------------------------------------===//
// MemoryBuffer::getFile implementation.
//===----------------------------------------------------------------------===//
namespace {
/// MemoryBufferMMapFile - This represents a file that was mapped in with the
/// sys::Path::MapInFilePages method. When destroyed, it calls the
/// sys::Path::UnMapFilePages method.
class MemoryBufferMMapFile : public MemoryBuffer {
std::string Filename;
public:
MemoryBufferMMapFile(StringRef filename, const char *Pages, uint64_t Size)
: Filename(filename) {
init(Pages, Pages+Size);
}
virtual const char *getBufferIdentifier() const {
return Filename.c_str();
}
~MemoryBufferMMapFile() {
sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
}
};
}
MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
int64_t FileSize) {
int OpenFlags = 0;
#ifdef O_BINARY
OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
#endif
int FD = ::open(Filename.str().c_str(), O_RDONLY|OpenFlags);
if (FD == -1) {
if (ErrStr) *ErrStr = "could not open file";
return 0;
}
// If we don't know the file size, use fstat to find out. fstat on an open
// file descriptor is cheaper than stat on a random path.
if (FileSize == -1) {
struct stat FileInfo;
// TODO: This should use fstat64 when available.
if (fstat(FD, &FileInfo) == -1) {
if (ErrStr) *ErrStr = "could not get file length";
::close(FD);
return 0;
}
FileSize = FileInfo.st_size;
}
// If the file is large, try to use mmap to read it in. We don't use mmap
// for small files, because this can severely fragment our address space. Also
// don't try to map files that are exactly a multiple of the system page size,
// as the file would not have the required null terminator.
//
// FIXME: Can we just mmap an extra page in the latter case?
if (FileSize >= 4096*4 &&
(FileSize & (sys::Process::GetPageSize()-1)) != 0) {
if (const char *Pages = sys::Path::MapInFilePages(FD, FileSize)) {
// Close the file descriptor, now that the whole file is in memory.
::close(FD);
return new MemoryBufferMMapFile(Filename, Pages, FileSize);
}
}
MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
if (!Buf) {
// Failed to create a buffer.
if (ErrStr) *ErrStr = "could not allocate buffer";
::close(FD);
return 0;
}
OwningPtr<MemoryBuffer> SB(Buf);
char *BufPtr = const_cast<char*>(SB->getBufferStart());
size_t BytesLeft = FileSize;
while (BytesLeft) {
ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
if (NumRead > 0) {
BytesLeft -= NumRead;
BufPtr += NumRead;
} else if (NumRead == -1 && errno == EINTR) {
// try again
} else {
// error reading.
close(FD);
if (ErrStr) *ErrStr = "error reading file data";
return 0;
}
}
close(FD);
return SB.take();
}
//===----------------------------------------------------------------------===//
// 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.
//
// FIXME: That isn't necessarily true, we should try to mmap stdin and
// fallback if it fails.
sys::Program::ChangeStdinToBinary();
size_t ReadBytes;
do {
ReadBytes = fread(Buffer, sizeof(char), sizeof(Buffer), stdin);
FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
} while (ReadBytes == sizeof(Buffer));
FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
size_t Size = FileData.size();
MemoryBuffer *B = new STDINBufferFile();
B->initCopyOf(&FileData[0], &FileData[Size-1]);
return B;
}