1//=== FileOutputBuffer.h - File Output Buffer -------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Utility for creating a in-memory buffer that will be written to a file.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_SUPPORT_FILEOUTPUTBUFFER_H
15#define LLVM_SUPPORT_FILEOUTPUTBUFFER_H
16
17#include "llvm/ADT/OwningPtr.h"
18#include "llvm/ADT/SmallString.h"
19#include "llvm/ADT/StringRef.h"
20#include "llvm/Support/DataTypes.h"
21#include "llvm/Support/FileSystem.h"
22
23namespace llvm {
24class error_code;
25
26/// FileOutputBuffer - This interface provides simple way to create an in-memory
27/// buffer which will be written to a file. During the lifetime of these
28/// objects, the content or existence of the specified file is undefined. That
29/// is, creating an OutputBuffer for a file may immediately remove the file.
30/// If the FileOutputBuffer is committed, the target file's content will become
31/// the buffer content at the time of the commit.  If the FileOutputBuffer is
32/// not committed, the file will be deleted in the FileOutputBuffer destructor.
33class FileOutputBuffer {
34public:
35
36  enum  {
37    F_executable = 1  /// set the 'x' bit on the resulting file
38  };
39
40  /// Factory method to create an OutputBuffer object which manages a read/write
41  /// buffer of the specified size. When committed, the buffer will be written
42  /// to the file at the specified path.
43  static error_code create(StringRef FilePath, size_t Size,
44                           OwningPtr<FileOutputBuffer> &Result,
45                           unsigned Flags = 0);
46
47  /// Returns a pointer to the start of the buffer.
48  uint8_t *getBufferStart() {
49    return (uint8_t*)Region->data();
50  }
51
52  /// Returns a pointer to the end of the buffer.
53  uint8_t *getBufferEnd() {
54    return (uint8_t*)Region->data() + Region->size();
55  }
56
57  /// Returns size of the buffer.
58  size_t getBufferSize() const {
59    return Region->size();
60  }
61
62  /// Returns path where file will show up if buffer is committed.
63  StringRef getPath() const {
64    return FinalPath;
65  }
66
67  /// Flushes the content of the buffer to its file and deallocates the
68  /// buffer.  If commit() is not called before this object's destructor
69  /// is called, the file is deleted in the destructor. The optional parameter
70  /// is used if it turns out you want the file size to be smaller than
71  /// initially requested.
72  error_code commit(int64_t NewSmallerSize = -1);
73
74  /// If this object was previously committed, the destructor just deletes
75  /// this object.  If this object was not committed, the destructor
76  /// deallocates the buffer and the target file is never written.
77  ~FileOutputBuffer();
78
79private:
80  FileOutputBuffer(const FileOutputBuffer &) LLVM_DELETED_FUNCTION;
81  FileOutputBuffer &operator=(const FileOutputBuffer &) LLVM_DELETED_FUNCTION;
82
83  FileOutputBuffer(llvm::sys::fs::mapped_file_region *R,
84                   StringRef Path, StringRef TempPath);
85
86  OwningPtr<llvm::sys::fs::mapped_file_region> Region;
87  SmallString<128>    FinalPath;
88  SmallString<128>    TempPath;
89};
90} // end namespace llvm
91
92#endif
93