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) * sizeof(char));
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, const char *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 const char *BufferName) {
111 char *Buf = (char *)malloc((Size+1) * sizeof(char));
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(const char *Filename,
140 if (Filename[0] != '-' || Filename[1] != 0)
141 return getFile(Filename, ErrStr, FileSize);
142 MemoryBuffer *M = getSTDIN();
145 // If stdin was empty, M is null. Cons up an empty memory buffer now.
146 const char *EmptyStr = "";
147 return MemoryBuffer::getMemBuffer(EmptyStr, EmptyStr, "<stdin>");
150 //===----------------------------------------------------------------------===//
151 // MemoryBuffer::getFile implementation.
152 //===----------------------------------------------------------------------===//
155 /// MemoryBufferMMapFile - This represents a file that was mapped in with the
156 /// sys::Path::MapInFilePages method. When destroyed, it calls the
157 /// sys::Path::UnMapFilePages method.
158 class MemoryBufferMMapFile : public MemoryBuffer {
159 std::string Filename;
161 MemoryBufferMMapFile(const char *filename, const char *Pages, uint64_t Size)
162 : Filename(filename) {
163 init(Pages, Pages+Size);
166 virtual const char *getBufferIdentifier() const {
167 return Filename.c_str();
170 ~MemoryBufferMMapFile() {
171 sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
176 MemoryBuffer *MemoryBuffer::getFile(const char *Filename, std::string *ErrStr,
180 OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
182 int FD = ::open(Filename, O_RDONLY|OpenFlags);
184 if (ErrStr) *ErrStr = "could not open file";
188 // If we don't know the file size, use fstat to find out. fstat on an open
189 // file descriptor is cheaper than stat on a random path.
190 if (FileSize == -1) {
191 struct stat FileInfo;
192 // TODO: This should use fstat64 when available.
193 if (fstat(FD, &FileInfo) == -1) {
194 if (ErrStr) *ErrStr = "could not get file length";
198 FileSize = FileInfo.st_size;
202 // If the file is large, try to use mmap to read it in. We don't use mmap
203 // for small files, because this can severely fragment our address space. Also
204 // don't try to map files that are exactly a multiple of the system page size,
205 // as the file would not have the required null terminator.
206 if (FileSize >= 4096*4 &&
207 (FileSize & (sys::Process::GetPageSize()-1)) != 0) {
208 if (const char *Pages = sys::Path::MapInFilePages(FD, FileSize)) {
209 // Close the file descriptor, now that the whole file is in memory.
211 return new MemoryBufferMMapFile(Filename, Pages, FileSize);
215 MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
217 // Failed to create a buffer.
218 if (ErrStr) *ErrStr = "could not allocate buffer";
223 OwningPtr<MemoryBuffer> SB(Buf);
224 char *BufPtr = const_cast<char*>(SB->getBufferStart());
226 size_t BytesLeft = FileSize;
228 ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
230 BytesLeft -= NumRead;
232 } else if (NumRead == -1 && errno == EINTR) {
237 if (ErrStr) *ErrStr = "error reading file data";
246 //===----------------------------------------------------------------------===//
247 // MemoryBuffer::getSTDIN implementation.
248 //===----------------------------------------------------------------------===//
251 class STDINBufferFile : public MemoryBuffer {
253 virtual const char *getBufferIdentifier() const {
259 MemoryBuffer *MemoryBuffer::getSTDIN() {
262 std::vector<char> FileData;
264 // Read in all of the data from stdin, we cannot mmap stdin.
265 sys::Program::ChangeStdinToBinary();
268 ReadBytes = fread(Buffer, sizeof(char), sizeof(Buffer), stdin);
269 FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
270 } while (ReadBytes == sizeof(Buffer));
272 FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
273 size_t Size = FileData.size();
276 MemoryBuffer *B = new STDINBufferFile();
277 B->initCopyOf(&FileData[0], &FileData[Size-1]);