src/llvm/include/llvm/Support/FileOutputBuffer.h

   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
  22 namespace 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.
  30 class FileOutputBuffer {
  31 public:
  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();
  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
  76 private:
  77   FileOutputBuffer(const FileOutputBuffer &) LLVM_DELETED_FUNCTION;
  78   FileOutputBuffer &operator=(const FileOutputBuffer &) LLVM_DELETED_FUNCTION;
  79
  80   FileOutputBuffer(std::unique_ptr<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