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__)
29 #include <sys/fcntl.h>
36 //===----------------------------------------------------------------------===//
37 // MemoryBuffer implementation itself.
38 //===----------------------------------------------------------------------===//
40 MemoryBuffer::~MemoryBuffer() {
42 delete [] BufferStart;
45 /// initCopyOf - Initialize this source buffer with a copy of the specified
46 /// memory range. We make the copy so that we can null terminate it
48 void MemoryBuffer::initCopyOf(const char *BufStart, const char *BufEnd) {
49 size_t Size = BufEnd-BufStart;
50 BufferStart = new char[Size+1];
51 BufferEnd = BufferStart+Size;
52 memcpy(const_cast<char*>(BufferStart), BufStart, Size);
53 *const_cast<char*>(BufferEnd) = 0; // Null terminate buffer.
54 MustDeleteBuffer = true;
57 /// init - Initialize this MemoryBuffer as a reference to externally allocated
58 /// memory, memory that we know is already null terminated.
59 void MemoryBuffer::init(const char *BufStart, const char *BufEnd) {
60 assert(BufEnd[0] == 0 && "Buffer is not null terminated!");
61 BufferStart = BufStart;
63 MustDeleteBuffer = false;
66 //===----------------------------------------------------------------------===//
67 // MemoryBufferMem implementation.
68 //===----------------------------------------------------------------------===//
71 class MemoryBufferMem : public MemoryBuffer {
74 MemoryBufferMem(const char *Start, const char *End, const char *FID,
80 initCopyOf(Start, End);
83 virtual const char *getBufferIdentifier() const {
84 return FileID.c_str();
89 /// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
90 /// that EndPtr[0] must be a null byte and be accessible!
91 MemoryBuffer *MemoryBuffer::getMemBuffer(const char *StartPtr,
93 const char *BufferName) {
94 return new MemoryBufferMem(StartPtr, EndPtr, BufferName);
97 /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
98 /// copying the contents and taking ownership of it. This has no requirements
100 MemoryBuffer *MemoryBuffer::getMemBufferCopy(const char *StartPtr,
102 const char *BufferName) {
103 return new MemoryBufferMem(StartPtr, EndPtr, BufferName, true);
106 /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
107 /// that is completely initialized to zeros. Note that the caller should
108 /// initialize the memory allocated by this method. The memory is owned by
109 /// the MemoryBuffer object.
110 MemoryBuffer *MemoryBuffer::getNewUninitMemBuffer(unsigned Size,
111 const char *BufferName) {
112 char *Buf = new char[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(unsigned Size,
125 const char *BufferName) {
126 MemoryBuffer *SB = getNewUninitMemBuffer(Size, BufferName);
127 memset(const_cast<char*>(SB->getBufferStart()), 0, Size+1);
132 /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
133 /// if the Filename is "-". If an error occurs, this returns null and fills
134 /// in *ErrStr with a reason. If stdin is empty, this API (unlike getSTDIN)
135 /// returns an empty buffer.
136 MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *Filename,
139 if (Filename[0] != '-' || Filename[1] != 0)
140 return getFile(Filename, ErrStr, FileSize);
141 MemoryBuffer *M = getSTDIN();
144 // If stdin was empty, M is null. Cons up an empty memory buffer now.
145 const char *EmptyStr = "";
146 return MemoryBuffer::getMemBuffer(EmptyStr, EmptyStr, "<stdin>");
149 //===----------------------------------------------------------------------===//
150 // MemoryBuffer::getFile implementation.
151 //===----------------------------------------------------------------------===//
154 /// MemoryBufferMMapFile - This represents a file that was mapped in with the
155 /// sys::Path::MapInFilePages method. When destroyed, it calls the
156 /// sys::Path::UnMapFilePages method.
157 class MemoryBufferMMapFile : public MemoryBuffer {
158 std::string Filename;
160 MemoryBufferMMapFile(const char *filename, const char *Pages, uint64_t Size)
161 : Filename(filename) {
162 init(Pages, Pages+Size);
165 virtual const char *getBufferIdentifier() const {
166 return Filename.c_str();
169 ~MemoryBufferMMapFile() {
170 sys::Path::UnMapFilePages(getBufferStart(), getBufferSize());
175 MemoryBuffer *MemoryBuffer::getFile(const char *Filename, std::string *ErrStr,
179 OpenFlags |= O_BINARY; // Open input file in binary mode on win32.
181 int FD = ::open(Filename, O_RDONLY|OpenFlags);
183 if (ErrStr) *ErrStr = "could not open file";
187 // If we don't know the file size, use fstat to find out. fstat on an open
188 // file descriptor is cheaper than stat on a random path.
189 if (FileSize == -1) {
190 struct stat FileInfo;
191 // TODO: This should use fstat64 when available.
192 if (fstat(FD, &FileInfo) == -1) {
193 if (ErrStr) *ErrStr = "could not get file length";
197 FileSize = FileInfo.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.
205 if (FileSize >= 4096*4 &&
206 (FileSize & (sys::Process::GetPageSize()-1)) != 0) {
207 if (const char *Pages = sys::Path::MapInFilePages(FD, FileSize)) {
208 // Close the file descriptor, now that the whole file is in memory.
210 return new MemoryBufferMMapFile(Filename, Pages, FileSize);
214 OwningPtr<MemoryBuffer> SB;
215 SB.reset(MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename));
216 char *BufPtr = const_cast<char*>(SB->getBufferStart());
218 unsigned BytesLeft = FileSize;
220 ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
222 BytesLeft -= NumRead;
224 } else if (errno == EINTR) {
229 if (ErrStr) *ErrStr = "error reading file data";
238 //===----------------------------------------------------------------------===//
239 // MemoryBuffer::getSTDIN implementation.
240 //===----------------------------------------------------------------------===//
243 class STDINBufferFile : public MemoryBuffer {
245 virtual const char *getBufferIdentifier() const {
251 MemoryBuffer *MemoryBuffer::getSTDIN() {
254 std::vector<char> FileData;
256 // Read in all of the data from stdin, we cannot mmap stdin.
257 sys::Program::ChangeStdinToBinary();
258 while (size_t ReadBytes = fread(Buffer, sizeof(char), 4096*4, stdin))
259 FileData.insert(FileData.end(), Buffer, Buffer+ReadBytes);
261 FileData.push_back(0); // &FileData[Size] is invalid. So is &*FileData.end().
262 size_t Size = FileData.size();
265 MemoryBuffer *B = new STDINBufferFile();
266 B->initCopyOf(&FileData[0], &FileData[Size-1]);