llvm-6502/lib/Support/MemoryBuffer.cpp
Chris Lattner 7cf705461c add a MemoryBuffer::getOpenFile method, which turns an open
file descriptor into a MemoryBuffer (and closes the FD).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120065 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-23 22:20:27 +00:00

301 lines
10 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/Support/MathExtras.h"
#include "llvm/System/Errno.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() { }
/// 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;
}
//===----------------------------------------------------------------------===//
// MemoryBufferMem implementation.
//===----------------------------------------------------------------------===//
/// CopyStringRef - Copies contents of a StringRef into a block of memory and
/// null-terminates it.
static void CopyStringRef(char *Memory, StringRef Data) {
memcpy(Memory, Data.data(), Data.size());
Memory[Data.size()] = 0; // Null terminate string.
}
/// GetNamedBuffer - Allocates a new MemoryBuffer with Name copied after it.
template <typename T>
static T* GetNamedBuffer(StringRef Buffer, StringRef Name) {
char *Mem = static_cast<char*>(operator new(sizeof(T) + Name.size() + 1));
CopyStringRef(Mem + sizeof(T), Name);
return new (Mem) T(Buffer);
}
namespace {
/// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
class MemoryBufferMem : public MemoryBuffer {
public:
MemoryBufferMem(StringRef InputData) {
init(InputData.begin(), InputData.end());
}
virtual const char *getBufferIdentifier() const {
// The name is stored after the class itself.
return reinterpret_cast<const char*>(this + 1);
}
};
}
/// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
/// that EndPtr[0] must be a null byte and be accessible!
MemoryBuffer *MemoryBuffer::getMemBuffer(StringRef InputData,
StringRef BufferName) {
return GetNamedBuffer<MemoryBufferMem>(InputData, 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(StringRef InputData,
StringRef BufferName) {
MemoryBuffer *Buf = getNewUninitMemBuffer(InputData.size(), BufferName);
if (!Buf) return 0;
memcpy(const_cast<char*>(Buf->getBufferStart()), InputData.data(),
InputData.size());
return Buf;
}
/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
/// that is not initialized. 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) {
// Allocate space for the MemoryBuffer, the data and the name. It is important
// that MemoryBuffer and data are aligned so PointerIntPair works with them.
size_t AlignedStringLen =
RoundUpToAlignment(sizeof(MemoryBufferMem) + BufferName.size() + 1,
sizeof(void*)); // TODO: Is sizeof(void*) enough?
size_t RealLen = AlignedStringLen + Size + 1;
char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
if (!Mem) return 0;
// The name is stored after the class itself.
CopyStringRef(Mem + sizeof(MemoryBufferMem), BufferName);
// The buffer begins after the name and must be aligned.
char *Buf = Mem + AlignedStringLen;
Buf[Size] = 0; // Null terminate buffer.
return new (Mem) MemoryBufferMem(StringRef(Buf, Size));
}
/// 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, StringRef BufferName) {
MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
if (!SB) return 0;
memset(const_cast<char*>(SB->getBufferStart()), 0, Size);
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(ErrStr);
return getFile(Filename, ErrStr, FileSize);
}
MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *Filename,
std::string *ErrStr,
int64_t FileSize) {
if (strcmp(Filename, "-") == 0)
return getSTDIN(ErrStr);
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 MemoryBufferMem {
public:
MemoryBufferMMapFile(StringRef Buffer)
: MemoryBufferMem(Buffer) { }
~MemoryBufferMMapFile() {
sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
}
};
/// FileCloser - RAII object to make sure an FD gets closed properly.
class FileCloser {
int FD;
public:
explicit FileCloser(int FD) : FD(FD) {}
~FileCloser() { ::close(FD); }
};
}
MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
int64_t FileSize) {
// Ensure the path is null terminated.
SmallString<256> PathBuf(Filename.begin(), Filename.end());
return MemoryBuffer::getFile(PathBuf.c_str(), ErrStr, FileSize);
}
MemoryBuffer *MemoryBuffer::getFile(const char *Filename, std::string *ErrStr,
int64_t FileSize) {
int OpenFlags = O_RDONLY;
#ifdef O_BINARY
OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
#endif
int FD = ::open(Filename, OpenFlags);
if (FD == -1) {
if (ErrStr) *ErrStr = sys::StrError();
return 0;
}
return getOpenFile(FD, Filename, ErrStr, FileSize);
}
MemoryBuffer *MemoryBuffer::getOpenFile(int FD, const char *Filename,
std::string *ErrStr, int64_t FileSize) {
FileCloser FC(FD); // Close FD on return.
// 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 = sys::StrError();
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)) {
return GetNamedBuffer<MemoryBufferMMapFile>(StringRef(Pages, FileSize),
Filename);
}
}
MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
if (!Buf) {
// Failed to create a buffer.
if (ErrStr) *ErrStr = "could not allocate buffer";
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 == -1) {
if (errno == EINTR)
continue;
// Error while reading.
if (ErrStr) *ErrStr = sys::StrError();
return 0;
} else if (NumRead == 0) {
// We hit EOF early, truncate and terminate buffer.
Buf->BufferEnd = BufPtr;
*BufPtr = 0;
return SB.take();
}
BytesLeft -= NumRead;
BufPtr += NumRead;
}
return SB.take();
}
//===----------------------------------------------------------------------===//
// MemoryBuffer::getSTDIN implementation.
//===----------------------------------------------------------------------===//
MemoryBuffer *MemoryBuffer::getSTDIN(std::string *ErrStr) {
// 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();
const ssize_t ChunkSize = 4096*4;
SmallString<ChunkSize> Buffer;
ssize_t ReadBytes;
// Read into Buffer until we hit EOF.
do {
Buffer.reserve(Buffer.size() + ChunkSize);
ReadBytes = read(0, Buffer.end(), ChunkSize);
if (ReadBytes == -1) {
if (errno == EINTR) continue;
if (ErrStr) *ErrStr = sys::StrError();
return 0;
}
Buffer.set_size(Buffer.size() + ReadBytes);
} while (ReadBytes != 0);
return getMemBufferCopy(Buffer, "<stdin>");
}