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