| //===--- 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/SmallString.h" |
| #include "llvm/Config/config.h" |
| #include "llvm/Support/Errc.h" |
| #include "llvm/Support/Errno.h" |
| #include "llvm/Support/FileSystem.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/Path.h" |
| #include "llvm/Support/Process.h" |
| #include "llvm/Support/Program.h" |
| #include <cassert> |
| #include <cerrno> |
| #include <cstring> |
| #include <new> |
| #include <sys/types.h> |
| #include <system_error> |
| #if !defined(_MSC_VER) && !defined(__MINGW32__) |
| #include <unistd.h> |
| #else |
| #include <io.h> |
| #endif |
| 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, |
| bool RequiresNullTerminator) { |
| assert((!RequiresNullTerminator || 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) { |
| if (!Data.empty()) |
| memcpy(Memory, Data.data(), Data.size()); |
| Memory[Data.size()] = 0; // Null terminate string. |
| } |
| |
| namespace { |
| struct NamedBufferAlloc { |
| const Twine &Name; |
| NamedBufferAlloc(const Twine &Name) : Name(Name) {} |
| }; |
| } |
| |
| void *operator new(size_t N, const NamedBufferAlloc &Alloc) { |
| SmallString<256> NameBuf; |
| StringRef NameRef = Alloc.Name.toStringRef(NameBuf); |
| |
| char *Mem = static_cast<char *>(operator new(N + NameRef.size() + 1)); |
| CopyStringRef(Mem + N, NameRef); |
| return Mem; |
| } |
| |
| namespace { |
| /// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory. |
| class MemoryBufferMem : public MemoryBuffer { |
| public: |
| MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) { |
| init(InputData.begin(), InputData.end(), RequiresNullTerminator); |
| } |
| |
| /// Disable sized deallocation for MemoryBufferMem, because it has |
| /// tail-allocated data. |
| void operator delete(void *p) { ::operator delete(p); } |
| |
| const char *getBufferIdentifier() const override { |
| // The name is stored after the class itself. |
| return reinterpret_cast<const char*>(this + 1); |
| } |
| |
| BufferKind getBufferKind() const override { |
| return MemoryBuffer_Malloc; |
| } |
| }; |
| } |
| |
| static ErrorOr<std::unique_ptr<MemoryBuffer>> |
| getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize, |
| uint64_t Offset, bool RequiresNullTerminator, bool IsVolatileSize); |
| |
| std::unique_ptr<MemoryBuffer> |
| MemoryBuffer::getMemBuffer(StringRef InputData, StringRef BufferName, |
| bool RequiresNullTerminator) { |
| auto *Ret = new (NamedBufferAlloc(BufferName)) |
| MemoryBufferMem(InputData, RequiresNullTerminator); |
| return std::unique_ptr<MemoryBuffer>(Ret); |
| } |
| |
| std::unique_ptr<MemoryBuffer> |
| MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) { |
| return std::unique_ptr<MemoryBuffer>(getMemBuffer( |
| Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator)); |
| } |
| |
| std::unique_ptr<MemoryBuffer> |
| MemoryBuffer::getMemBufferCopy(StringRef InputData, const Twine &BufferName) { |
| std::unique_ptr<MemoryBuffer> Buf = |
| getNewUninitMemBuffer(InputData.size(), BufferName); |
| if (!Buf) |
| return nullptr; |
| memcpy(const_cast<char*>(Buf->getBufferStart()), InputData.data(), |
| InputData.size()); |
| return Buf; |
| } |
| |
| std::unique_ptr<MemoryBuffer> |
| MemoryBuffer::getNewUninitMemBuffer(size_t Size, const Twine &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. |
| // TODO: Is 16-byte alignment enough? We copy small object files with large |
| // alignment expectations into this buffer. |
| SmallString<256> NameBuf; |
| StringRef NameRef = BufferName.toStringRef(NameBuf); |
| size_t AlignedStringLen = |
| alignTo(sizeof(MemoryBufferMem) + NameRef.size() + 1, 16); |
| size_t RealLen = AlignedStringLen + Size + 1; |
| char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow)); |
| if (!Mem) |
| return nullptr; |
| |
| // The name is stored after the class itself. |
| CopyStringRef(Mem + sizeof(MemoryBufferMem), NameRef); |
| |
| // The buffer begins after the name and must be aligned. |
| char *Buf = Mem + AlignedStringLen; |
| Buf[Size] = 0; // Null terminate buffer. |
| |
| auto *Ret = new (Mem) MemoryBufferMem(StringRef(Buf, Size), true); |
| return std::unique_ptr<MemoryBuffer>(Ret); |
| } |
| |
| std::unique_ptr<MemoryBuffer> |
| MemoryBuffer::getNewMemBuffer(size_t Size, StringRef BufferName) { |
| std::unique_ptr<MemoryBuffer> SB = getNewUninitMemBuffer(Size, BufferName); |
| if (!SB) |
| return nullptr; |
| memset(const_cast<char*>(SB->getBufferStart()), 0, Size); |
| return SB; |
| } |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> |
| MemoryBuffer::getFileOrSTDIN(const Twine &Filename, int64_t FileSize, |
| bool RequiresNullTerminator) { |
| SmallString<256> NameBuf; |
| StringRef NameRef = Filename.toStringRef(NameBuf); |
| |
| if (NameRef == "-") |
| return getSTDIN(); |
| return getFile(Filename, FileSize, RequiresNullTerminator); |
| } |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> |
| MemoryBuffer::getFileSlice(const Twine &FilePath, uint64_t MapSize, |
| uint64_t Offset) { |
| return getFileAux(FilePath, -1, MapSize, Offset, false, false); |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // MemoryBuffer::getFile implementation. |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| /// \brief Memory maps a file descriptor using sys::fs::mapped_file_region. |
| /// |
| /// This handles converting the offset into a legal offset on the platform. |
| class MemoryBufferMMapFile : public MemoryBuffer { |
| sys::fs::mapped_file_region MFR; |
| |
| static uint64_t getLegalMapOffset(uint64_t Offset) { |
| return Offset & ~(sys::fs::mapped_file_region::alignment() - 1); |
| } |
| |
| static uint64_t getLegalMapSize(uint64_t Len, uint64_t Offset) { |
| return Len + (Offset - getLegalMapOffset(Offset)); |
| } |
| |
| const char *getStart(uint64_t Len, uint64_t Offset) { |
| return MFR.const_data() + (Offset - getLegalMapOffset(Offset)); |
| } |
| |
| public: |
| MemoryBufferMMapFile(bool RequiresNullTerminator, int FD, uint64_t Len, |
| uint64_t Offset, std::error_code &EC) |
| : MFR(FD, sys::fs::mapped_file_region::readonly, |
| getLegalMapSize(Len, Offset), getLegalMapOffset(Offset), EC) { |
| if (!EC) { |
| const char *Start = getStart(Len, Offset); |
| init(Start, Start + Len, RequiresNullTerminator); |
| } |
| } |
| |
| /// Disable sized deallocation for MemoryBufferMMapFile, because it has |
| /// tail-allocated data. |
| void operator delete(void *p) { ::operator delete(p); } |
| |
| const char *getBufferIdentifier() const override { |
| // The name is stored after the class itself. |
| return reinterpret_cast<const char *>(this + 1); |
| } |
| |
| BufferKind getBufferKind() const override { |
| return MemoryBuffer_MMap; |
| } |
| }; |
| } |
| |
| static ErrorOr<std::unique_ptr<MemoryBuffer>> |
| getMemoryBufferForStream(int FD, const Twine &BufferName) { |
| 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(FD, Buffer.end(), ChunkSize); |
| if (ReadBytes == -1) { |
| if (errno == EINTR) continue; |
| return std::error_code(errno, std::generic_category()); |
| } |
| Buffer.set_size(Buffer.size() + ReadBytes); |
| } while (ReadBytes != 0); |
| |
| return MemoryBuffer::getMemBufferCopy(Buffer, BufferName); |
| } |
| |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> |
| MemoryBuffer::getFile(const Twine &Filename, int64_t FileSize, |
| bool RequiresNullTerminator, bool IsVolatileSize) { |
| return getFileAux(Filename, FileSize, FileSize, 0, |
| RequiresNullTerminator, IsVolatileSize); |
| } |
| |
| static ErrorOr<std::unique_ptr<MemoryBuffer>> |
| getOpenFileImpl(int FD, const Twine &Filename, uint64_t FileSize, |
| uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator, |
| bool IsVolatileSize); |
| |
| static ErrorOr<std::unique_ptr<MemoryBuffer>> |
| getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize, |
| uint64_t Offset, bool RequiresNullTerminator, bool IsVolatileSize) { |
| int FD; |
| std::error_code EC = sys::fs::openFileForRead(Filename, FD); |
| if (EC) |
| return EC; |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> Ret = |
| getOpenFileImpl(FD, Filename, FileSize, MapSize, Offset, |
| RequiresNullTerminator, IsVolatileSize); |
| close(FD); |
| return Ret; |
| } |
| |
| static bool shouldUseMmap(int FD, |
| size_t FileSize, |
| size_t MapSize, |
| off_t Offset, |
| bool RequiresNullTerminator, |
| int PageSize, |
| bool IsVolatileSize) { |
| // mmap may leave the buffer without null terminator if the file size changed |
| // by the time the last page is mapped in, so avoid it if the file size is |
| // likely to change. |
| if (IsVolatileSize) |
| return false; |
| |
| // We don't use mmap for small files because this can severely fragment our |
| // address space. |
| if (MapSize < 4 * 4096 || MapSize < (unsigned)PageSize) |
| return false; |
| |
| if (!RequiresNullTerminator) |
| return true; |
| |
| |
| // 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. |
| // FIXME: this chunk of code is duplicated, but it avoids a fstat when |
| // RequiresNullTerminator = false and MapSize != -1. |
| if (FileSize == size_t(-1)) { |
| sys::fs::file_status Status; |
| if (sys::fs::status(FD, Status)) |
| return false; |
| FileSize = Status.getSize(); |
| } |
| |
| // If we need a null terminator and the end of the map is inside the file, |
| // we cannot use mmap. |
| size_t End = Offset + MapSize; |
| assert(End <= FileSize); |
| if (End != FileSize) |
| return false; |
| |
| // Don't try to map files that are exactly a multiple of the system page size |
| // if we need a null terminator. |
| if ((FileSize & (PageSize -1)) == 0) |
| return false; |
| |
| #if defined(__CYGWIN__) |
| // Don't try to map files that are exactly a multiple of the physical page size |
| // if we need a null terminator. |
| // FIXME: We should reorganize again getPageSize() on Win32. |
| if ((FileSize & (4096 - 1)) == 0) |
| return false; |
| #endif |
| |
| return true; |
| } |
| |
| static ErrorOr<std::unique_ptr<MemoryBuffer>> |
| getOpenFileImpl(int FD, const Twine &Filename, uint64_t FileSize, |
| uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator, |
| bool IsVolatileSize) { |
| static int PageSize = sys::Process::getPageSize(); |
| |
| // Default is to map the full file. |
| if (MapSize == uint64_t(-1)) { |
| // 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 == uint64_t(-1)) { |
| sys::fs::file_status Status; |
| std::error_code EC = sys::fs::status(FD, Status); |
| if (EC) |
| return EC; |
| |
| // If this not a file or a block device (e.g. it's a named pipe |
| // or character device), we can't trust the size. Create the memory |
| // buffer by copying off the stream. |
| sys::fs::file_type Type = Status.type(); |
| if (Type != sys::fs::file_type::regular_file && |
| Type != sys::fs::file_type::block_file) |
| return getMemoryBufferForStream(FD, Filename); |
| |
| FileSize = Status.getSize(); |
| } |
| MapSize = FileSize; |
| } |
| |
| if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator, |
| PageSize, IsVolatileSize)) { |
| std::error_code EC; |
| std::unique_ptr<MemoryBuffer> Result( |
| new (NamedBufferAlloc(Filename)) |
| MemoryBufferMMapFile(RequiresNullTerminator, FD, MapSize, Offset, EC)); |
| if (!EC) |
| return std::move(Result); |
| } |
| |
| std::unique_ptr<MemoryBuffer> Buf = |
| MemoryBuffer::getNewUninitMemBuffer(MapSize, Filename); |
| if (!Buf) { |
| // Failed to create a buffer. The only way it can fail is if |
| // new(std::nothrow) returns 0. |
| return make_error_code(errc::not_enough_memory); |
| } |
| |
| char *BufPtr = const_cast<char *>(Buf->getBufferStart()); |
| |
| size_t BytesLeft = MapSize; |
| #ifndef HAVE_PREAD |
| if (lseek(FD, Offset, SEEK_SET) == -1) |
| return std::error_code(errno, std::generic_category()); |
| #endif |
| |
| while (BytesLeft) { |
| #ifdef HAVE_PREAD |
| ssize_t NumRead = ::pread(FD, BufPtr, BytesLeft, MapSize-BytesLeft+Offset); |
| #else |
| ssize_t NumRead = ::read(FD, BufPtr, BytesLeft); |
| #endif |
| if (NumRead == -1) { |
| if (errno == EINTR) |
| continue; |
| // Error while reading. |
| return std::error_code(errno, std::generic_category()); |
| } |
| if (NumRead == 0) { |
| memset(BufPtr, 0, BytesLeft); // zero-initialize rest of the buffer. |
| break; |
| } |
| BytesLeft -= NumRead; |
| BufPtr += NumRead; |
| } |
| |
| return std::move(Buf); |
| } |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> |
| MemoryBuffer::getOpenFile(int FD, const Twine &Filename, uint64_t FileSize, |
| bool RequiresNullTerminator, bool IsVolatileSize) { |
| return getOpenFileImpl(FD, Filename, FileSize, FileSize, 0, |
| RequiresNullTerminator, IsVolatileSize); |
| } |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> |
| MemoryBuffer::getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize, |
| int64_t Offset) { |
| assert(MapSize != uint64_t(-1)); |
| return getOpenFileImpl(FD, Filename, -1, MapSize, Offset, false, |
| /*IsVolatileSize*/ false); |
| } |
| |
| ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() { |
| // 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::ChangeStdinToBinary(); |
| |
| return getMemoryBufferForStream(0, "<stdin>"); |
| } |
| |
| MemoryBufferRef MemoryBuffer::getMemBufferRef() const { |
| StringRef Data = getBuffer(); |
| StringRef Identifier = getBufferIdentifier(); |
| return MemoryBufferRef(Data, Identifier); |
| } |