1 //===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the MemoryBuffer interface.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Support/MemoryBuffer.h"
15 #include "llvm/ADT/OwningPtr.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/System/Path.h"
18 #include "llvm/System/Process.h"
19 #include "llvm/System/Program.h"
24 #include <sys/types.h>
26 #if !defined(_MSC_VER) && !defined(__MINGW32__)
35 //===----------------------------------------------------------------------===//
36 // MemoryBuffer implementation itself.
37 //===----------------------------------------------------------------------===//
39 MemoryBuffer::~MemoryBuffer() {
41 free((void*)BufferStart);
44 /// initCopyOf - Initialize this source buffer with a copy of the specified
45 /// memory range. We make the copy so that we can null terminate it
47 void MemoryBuffer::initCopyOf(const char *BufStart, const char *BufEnd) {
48 size_t Size = BufEnd-BufStart;
49 BufferStart = (char *)malloc(Size+1);
50 BufferEnd = BufferStart+Size;
51 memcpy(const_cast<char*>(BufferStart), BufStart, Size);
52 *const_cast<char*>(BufferEnd) = 0; // Null terminate buffer.
53 MustDeleteBuffer = true;
56 /// init - Initialize this MemoryBuffer as a reference to externally allocated
57 /// memory, memory that we know is already null terminated.
58 void MemoryBuffer::init(const char *BufStart, const char *BufEnd) {
59 assert(BufEnd[0] == 0 && "Buffer is not null terminated!");
60 BufferStart = BufStart;
62 MustDeleteBuffer = false;
65 //===----------------------------------------------------------------------===//
66 // MemoryBufferMem implementation.
67 //===----------------------------------------------------------------------===//
70 class MemoryBufferMem : public MemoryBuffer {
73 MemoryBufferMem(const char *Start, const char *End, StringRef FID,
79 initCopyOf(Start, End);
82 virtual const char *getBufferIdentifier() const {
83 return FileID.c_str();
88 /// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
89 /// that EndPtr[0] must be a null byte and be accessible!
90 MemoryBuffer *MemoryBuffer::getMemBuffer(const char *StartPtr,
92 const char *BufferName) {
93 return new MemoryBufferMem(StartPtr, EndPtr, BufferName);
96 /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
97 /// copying the contents and taking ownership of it. This has no requirements
99 MemoryBuffer *MemoryBuffer::getMemBufferCopy(const char *StartPtr,
101 const char *BufferName) {
102 return new MemoryBufferMem(StartPtr, EndPtr, BufferName, true);
105 /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
106 /// that is completely initialized to zeros. Note that the caller should
107 /// initialize the memory allocated by this method. The memory is owned by
108 /// the MemoryBuffer object.
109 MemoryBuffer *MemoryBuffer::getNewUninitMemBuffer(size_t Size,
110 StringRef BufferName) {
111 char *Buf = (char *)malloc(Size+1);
114 MemoryBufferMem *SB = new MemoryBufferMem(Buf, Buf+Size, BufferName);
115 // The memory for this buffer is owned by the MemoryBuffer.
116 SB->MustDeleteBuffer = true;
120 /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
121 /// is completely initialized to zeros. Note that the caller should
122 /// initialize the memory allocated by this method. The memory is owned by
123 /// the MemoryBuffer object.
124 MemoryBuffer *MemoryBuffer::getNewMemBuffer(size_t Size,
125 const char *BufferName) {
126 MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
128 memset(const_cast<char*>(SB->getBufferStart()), 0, Size+1);
133 /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
134 /// if the Filename is "-". If an error occurs, this returns null and fills
135 /// in *ErrStr with a reason. If stdin is empty, this API (unlike getSTDIN)
136 /// returns an empty buffer.
137 MemoryBuffer *MemoryBuffer::getFileOrSTDIN(StringRef Filename,
140 struct stat *FileInfo) {
143 return getFile(Filename, ErrStr, FileSize, FileInfo);
146 //===----------------------------------------------------------------------===//
147 // MemoryBuffer::getFile implementation.
148 //===----------------------------------------------------------------------===//
151 /// MemoryBufferMMapFile - This represents a file that was mapped in with the
152 /// sys::Path::MapInFilePages method. When destroyed, it calls the
153 /// sys::Path::UnMapFilePages method.
154 class MemoryBufferMMapFile : public MemoryBuffer {
155 std::string Filename;
157 MemoryBufferMMapFile(StringRef filename, const char *Pages, uint64_t Size)
158 : Filename(filename) {
159 init(Pages, Pages+Size);
162 virtual const char *getBufferIdentifier() const {
163 return Filename.c_str();
166 ~MemoryBufferMMapFile() {
167 sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
172 MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
173 int64_t FileSize, struct stat *FileInfo) {
176 OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
178 SmallString<256> PathBuf(Filename.begin(), Filename.end());
179 int FD = ::open(PathBuf.c_str(), O_RDONLY|OpenFlags);
181 if (ErrStr) *ErrStr = strerror(errno);
185 // If we don't know the file size, use fstat to find out. fstat on an open
186 // file descriptor is cheaper than stat on a random path.
187 if (FileSize == -1 || FileInfo) {
188 struct stat MyFileInfo;
189 struct stat *FileInfoPtr = FileInfo? FileInfo : &MyFileInfo;
191 // TODO: This should use fstat64 when available.
192 if (fstat(FD, FileInfoPtr) == -1) {
193 if (ErrStr) *ErrStr = strerror(errno);
197 FileSize = FileInfoPtr->st_size;
201 // If the file is large, try to use mmap to read it in. We don't use mmap
202 // for small files, because this can severely fragment our address space. Also
203 // don't try to map files that are exactly a multiple of the system page size,
204 // as the file would not have the required null terminator.
206 // FIXME: Can we just mmap an extra page in the latter case?
207 if (FileSize >= 4096*4 &&
208 (FileSize & (sys::Process::GetPageSize()-1)) != 0) {
209 if (const char *Pages = sys::Path::MapInFilePages(FD, FileSize)) {
210 // Close the file descriptor, now that the whole file is in memory.
212 return new MemoryBufferMMapFile(Filename, Pages, FileSize);
216 MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
218 // Failed to create a buffer.
219 if (ErrStr) *ErrStr = "could not allocate buffer";
224 OwningPtr<MemoryBuffer> SB(Buf);
225 char *BufPtr = const_cast<char*>(SB->getBufferStart());
227 size_t BytesLeft = FileSize;
229 ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
231 BytesLeft -= NumRead;
233 } else if (NumRead == -1 && errno == EINTR) {
237 if (ErrStr) *ErrStr = strerror(errno);
247 //===----------------------------------------------------------------------===//
248 // MemoryBuffer::getSTDIN implementation.
249 //===----------------------------------------------------------------------===//
252 class STDINBufferFile : public MemoryBuffer {
254 virtual const char *getBufferIdentifier() const {
260 MemoryBuffer *MemoryBuffer::getSTDIN() {
263 std::vector<char> FileData;
265 // Read in all of the data from stdin, we cannot mmap stdin.
267 // FIXME: That isn't necessarily true, we should try to mmap stdin and
268 // fallback if it fails.
269 sys::Program::ChangeStdinToBinary();
272 ReadBytes = fread(Buffer, sizeof(char), sizeof(Buffer), stdin);
273 FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
274 } while (ReadBytes == sizeof(Buffer));
276 FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
277 size_t Size = FileData.size();
278 MemoryBuffer *B = new STDINBufferFile();
279 B->initCopyOf(&FileData[0], &FileData[Size-1]);