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f5736f87f2
the caller requested a null-terminated one. When mapping the file there could be a racing issue that resulted in the file being larger than the FileSize passed by the caller. We already have an assertion for this in MemoryBuffer::init() but have a runtime guarantee that the buffer will be null-terminated, so do a copy that adds a null-terminator. Protects against crash of rdar://11161822. llvm-svn: 154082
391 lines
14 KiB
C++
391 lines
14 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/Config/config.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/Errno.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/Process.h"
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#include "llvm/Support/Program.h"
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#include "llvm/Support/system_error.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 <new>
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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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#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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/// 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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bool RequiresNullTerminator) {
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assert((!RequiresNullTerminator || BufEnd[0] == 0) &&
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"Buffer is not null terminated!");
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BufferStart = BufStart;
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BufferEnd = BufEnd;
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}
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//===----------------------------------------------------------------------===//
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// MemoryBufferMem implementation.
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//===----------------------------------------------------------------------===//
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/// CopyStringRef - Copies contents of a StringRef into a block of memory and
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/// null-terminates it.
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static void CopyStringRef(char *Memory, StringRef Data) {
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memcpy(Memory, Data.data(), Data.size());
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Memory[Data.size()] = 0; // Null terminate string.
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}
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/// GetNamedBuffer - Allocates a new MemoryBuffer with Name copied after it.
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template <typename T>
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static T *GetNamedBuffer(StringRef Buffer, StringRef Name,
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bool RequiresNullTerminator) {
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char *Mem = static_cast<char*>(operator new(sizeof(T) + Name.size() + 1));
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CopyStringRef(Mem + sizeof(T), Name);
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return new (Mem) T(Buffer, RequiresNullTerminator);
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}
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namespace {
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/// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
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class MemoryBufferMem : public MemoryBuffer {
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public:
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MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) {
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init(InputData.begin(), InputData.end(), RequiresNullTerminator);
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}
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virtual const char *getBufferIdentifier() const {
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// The name is stored after the class itself.
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return reinterpret_cast<const char*>(this + 1);
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}
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virtual BufferKind getBufferKind() const {
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return MemoryBuffer_Malloc;
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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 InputData must be a null terminated if RequiresNullTerminator is true!
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MemoryBuffer *MemoryBuffer::getMemBuffer(StringRef InputData,
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StringRef BufferName,
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bool RequiresNullTerminator) {
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return GetNamedBuffer<MemoryBufferMem>(InputData, BufferName,
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RequiresNullTerminator);
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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(StringRef InputData,
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StringRef BufferName) {
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MemoryBuffer *Buf = getNewUninitMemBuffer(InputData.size(), BufferName);
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if (!Buf) return 0;
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memcpy(const_cast<char*>(Buf->getBufferStart()), InputData.data(),
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InputData.size());
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return Buf;
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}
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/// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
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/// that is not initialized. Note that the caller should initialize the
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/// memory allocated by this method. The memory is owned by the MemoryBuffer
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/// object.
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MemoryBuffer *MemoryBuffer::getNewUninitMemBuffer(size_t Size,
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StringRef BufferName) {
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// Allocate space for the MemoryBuffer, the data and the name. It is important
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// that MemoryBuffer and data are aligned so PointerIntPair works with them.
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size_t AlignedStringLen =
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RoundUpToAlignment(sizeof(MemoryBufferMem) + BufferName.size() + 1,
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sizeof(void*)); // TODO: Is sizeof(void*) enough?
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size_t RealLen = AlignedStringLen + Size + 1;
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char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
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if (!Mem) return 0;
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// The name is stored after the class itself.
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CopyStringRef(Mem + sizeof(MemoryBufferMem), BufferName);
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// The buffer begins after the name and must be aligned.
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char *Buf = Mem + AlignedStringLen;
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Buf[Size] = 0; // Null terminate buffer.
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return new (Mem) MemoryBufferMem(StringRef(Buf, Size), true);
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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, StringRef 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);
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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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error_code MemoryBuffer::getFileOrSTDIN(StringRef Filename,
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OwningPtr<MemoryBuffer> &result,
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int64_t FileSize) {
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if (Filename == "-")
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return getSTDIN(result);
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return getFile(Filename, result, FileSize);
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}
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error_code MemoryBuffer::getFileOrSTDIN(const char *Filename,
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OwningPtr<MemoryBuffer> &result,
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int64_t FileSize) {
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if (strcmp(Filename, "-") == 0)
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return getSTDIN(result);
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return getFile(Filename, result, 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 MemoryBufferMem {
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public:
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MemoryBufferMMapFile(StringRef Buffer, bool RequiresNullTerminator)
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: MemoryBufferMem(Buffer, RequiresNullTerminator) { }
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~MemoryBufferMMapFile() {
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static int PageSize = sys::Process::GetPageSize();
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uintptr_t Start = reinterpret_cast<uintptr_t>(getBufferStart());
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size_t Size = getBufferSize();
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uintptr_t RealStart = Start & ~(PageSize - 1);
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size_t RealSize = Size + (Start - RealStart);
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sys::Path::UnMapFilePages(reinterpret_cast<const char*>(RealStart),
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RealSize);
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}
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virtual BufferKind getBufferKind() const {
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return MemoryBuffer_MMap;
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}
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};
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}
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error_code MemoryBuffer::getFile(StringRef Filename,
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OwningPtr<MemoryBuffer> &result,
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int64_t FileSize,
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bool RequiresNullTerminator) {
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// Ensure the path is null terminated.
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SmallString<256> PathBuf(Filename.begin(), Filename.end());
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return MemoryBuffer::getFile(PathBuf.c_str(), result, FileSize,
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RequiresNullTerminator);
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}
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error_code MemoryBuffer::getFile(const char *Filename,
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OwningPtr<MemoryBuffer> &result,
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int64_t FileSize,
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bool RequiresNullTerminator) {
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int OpenFlags = O_RDONLY;
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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, OpenFlags);
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if (FD == -1)
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return error_code(errno, posix_category());
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error_code ret = getOpenFile(FD, Filename, result, FileSize, FileSize,
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0, RequiresNullTerminator);
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close(FD);
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return ret;
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}
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static bool shouldUseMmap(int FD,
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size_t FileSize,
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size_t MapSize,
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off_t Offset,
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bool RequiresNullTerminator,
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int PageSize) {
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// We don't use mmap for small files because this can severely fragment our
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// address space.
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if (MapSize < 4096*4)
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return false;
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if (!RequiresNullTerminator)
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return true;
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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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// FIXME: this chunk of code is duplicated, but it avoids a fstat when
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// RequiresNullTerminator = false and MapSize != -1.
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if (FileSize == size_t(-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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return error_code(errno, posix_category());
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}
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FileSize = FileInfo.st_size;
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}
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// If we need a null terminator and the end of the map is inside the file,
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// we cannot use mmap.
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size_t End = Offset + MapSize;
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assert(End <= FileSize);
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if (End != FileSize)
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return false;
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// Don't try to map files that are exactly a multiple of the system page size
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// if we need a null terminator.
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if ((FileSize & (PageSize -1)) == 0)
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return false;
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return true;
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}
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error_code MemoryBuffer::getOpenFile(int FD, const char *Filename,
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OwningPtr<MemoryBuffer> &result,
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uint64_t FileSize, uint64_t MapSize,
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int64_t Offset,
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bool RequiresNullTerminator) {
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static int PageSize = sys::Process::GetPageSize();
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// Default is to map the full file.
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if (MapSize == uint64_t(-1)) {
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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 == uint64_t(-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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return error_code(errno, posix_category());
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}
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FileSize = FileInfo.st_size;
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}
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MapSize = FileSize;
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}
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if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
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PageSize)) {
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off_t RealMapOffset = Offset & ~(PageSize - 1);
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off_t Delta = Offset - RealMapOffset;
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size_t RealMapSize = MapSize + Delta;
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if (const char *Pages = sys::Path::MapInFilePages(FD,
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RealMapSize,
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RealMapOffset)) {
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result.reset(GetNamedBuffer<MemoryBufferMMapFile>(
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StringRef(Pages + Delta, MapSize), Filename, RequiresNullTerminator));
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if (RequiresNullTerminator && result->getBufferEnd()[0] != '\0') {
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// There could be a racing issue that resulted in the file being larger
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// than the FileSize passed by the caller. We already have an assertion
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// for this in MemoryBuffer::init() but have a runtime guarantee that
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// the buffer will be null-terminated here, so do a copy that adds a
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// null-terminator.
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result.reset(MemoryBuffer::getMemBufferCopy(result->getBuffer(),
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Filename));
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}
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return error_code::success();
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}
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}
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MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(MapSize, Filename);
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if (!Buf) {
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// Failed to create a buffer. The only way it can fail is if
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// new(std::nothrow) returns 0.
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return make_error_code(errc::not_enough_memory);
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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 = MapSize;
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#ifndef HAVE_PREAD
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if (lseek(FD, Offset, SEEK_SET) == -1)
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return error_code(errno, posix_category());
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#endif
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while (BytesLeft) {
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#ifdef HAVE_PREAD
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ssize_t NumRead = ::pread(FD, BufPtr, BytesLeft, MapSize-BytesLeft+Offset);
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#else
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ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
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#endif
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if (NumRead == -1) {
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if (errno == EINTR)
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continue;
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// Error while reading.
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return error_code(errno, posix_category());
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}
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if (NumRead == 0) {
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assert(0 && "We got inaccurate FileSize value or fstat reported an "
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"invalid file size.");
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*BufPtr = '\0'; // null-terminate at the actual size.
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break;
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}
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BytesLeft -= NumRead;
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BufPtr += NumRead;
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}
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result.swap(SB);
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return error_code::success();
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}
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//===----------------------------------------------------------------------===//
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// MemoryBuffer::getSTDIN implementation.
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//===----------------------------------------------------------------------===//
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error_code MemoryBuffer::getSTDIN(OwningPtr<MemoryBuffer> &result) {
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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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const ssize_t ChunkSize = 4096*4;
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SmallString<ChunkSize> Buffer;
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ssize_t ReadBytes;
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// Read into Buffer until we hit EOF.
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do {
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Buffer.reserve(Buffer.size() + ChunkSize);
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ReadBytes = read(0, Buffer.end(), ChunkSize);
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if (ReadBytes == -1) {
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if (errno == EINTR) continue;
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return error_code(errno, posix_category());
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}
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Buffer.set_size(Buffer.size() + ReadBytes);
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} while (ReadBytes != 0);
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result.reset(getMemBufferCopy(Buffer, "<stdin>"));
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return error_code::success();
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}
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