1//===- FileOutputBuffer.cpp - 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#include "llvm/Support/FileOutputBuffer.h" 15 16#include "llvm/ADT/OwningPtr.h" 17#include "llvm/ADT/SmallVector.h" 18#include "llvm/Support/FileSystem.h" 19#include "llvm/Support/raw_ostream.h" 20#include "llvm/Support/system_error.h" 21 22 23namespace llvm { 24 25 26FileOutputBuffer::FileOutputBuffer(uint8_t *Start, uint8_t *End, 27 StringRef Path, StringRef TmpPath) 28 : BufferStart(Start), BufferEnd(End) { 29 FinalPath.assign(Path); 30 TempPath.assign(TmpPath); 31} 32 33 34FileOutputBuffer::~FileOutputBuffer() { 35 // If not already commited, delete buffer and remove temp file. 36 if ( BufferStart != NULL ) { 37 sys::fs::unmap_file_pages((void*)BufferStart, getBufferSize()); 38 bool Existed; 39 sys::fs::remove(Twine(TempPath), Existed); 40 } 41} 42 43 44error_code FileOutputBuffer::create(StringRef FilePath, 45 size_t Size, 46 OwningPtr<FileOutputBuffer> &Result, 47 unsigned Flags) { 48 // If file already exists, it must be a regular file (to be mappable). 49 sys::fs::file_status Stat; 50 error_code EC = sys::fs::status(FilePath, Stat); 51 switch (Stat.type()) { 52 case sys::fs::file_type::file_not_found: 53 // If file does not exist, we'll create one. 54 break; 55 case sys::fs::file_type::regular_file: { 56 // If file is not currently writable, error out. 57 // FIXME: There is no sys::fs:: api for checking this. 58 // FIXME: In posix, you use the access() call to check this. 59 } 60 break; 61 default: 62 if (EC) 63 return EC; 64 else 65 return make_error_code(errc::operation_not_permitted); 66 } 67 68 // Delete target file. 69 bool Existed; 70 EC = sys::fs::remove(FilePath, Existed); 71 if (EC) 72 return EC; 73 74 // Create new file in same directory but with random name. 75 SmallString<128> TempFilePath; 76 int FD; 77 EC = sys::fs::unique_file(Twine(FilePath) + ".tmp%%%%%%%", 78 FD, TempFilePath, false, 0644); 79 if (EC) 80 return EC; 81 82 // The unique_file() interface leaks lower layers and returns a file 83 // descriptor. There is no way to directly close it, so use this hack 84 // to hand it off to raw_fd_ostream to close for us. 85 { 86 raw_fd_ostream Dummy(FD, /*shouldClose=*/true); 87 } 88 89 // Resize file to requested initial size 90 EC = sys::fs::resize_file(Twine(TempFilePath), Size); 91 if (EC) 92 return EC; 93 94 // If requested, make the output file executable. 95 if ( Flags & F_executable ) { 96 sys::fs::file_status Stat2; 97 EC = sys::fs::status(Twine(TempFilePath), Stat2); 98 if (EC) 99 return EC; 100 101 sys::fs::perms new_perms = Stat2.permissions(); 102 if ( new_perms & sys::fs::owner_read ) 103 new_perms |= sys::fs::owner_exe; 104 if ( new_perms & sys::fs::group_read ) 105 new_perms |= sys::fs::group_exe; 106 if ( new_perms & sys::fs::others_read ) 107 new_perms |= sys::fs::others_exe; 108 new_perms |= sys::fs::add_perms; 109 EC = sys::fs::permissions(Twine(TempFilePath), new_perms); 110 if (EC) 111 return EC; 112 } 113 114 // Memory map new file. 115 void *Base; 116 EC = sys::fs::map_file_pages(Twine(TempFilePath), 0, Size, true, Base); 117 if (EC) 118 return EC; 119 120 // Create FileOutputBuffer object to own mapped range. 121 uint8_t *Start = reinterpret_cast<uint8_t*>(Base); 122 Result.reset(new FileOutputBuffer(Start, Start+Size, FilePath, TempFilePath)); 123 124 return error_code::success(); 125} 126 127 128error_code FileOutputBuffer::commit(int64_t NewSmallerSize) { 129 // Unmap buffer, letting OS flush dirty pages to file on disk. 130 void *Start = reinterpret_cast<void*>(BufferStart); 131 error_code EC = sys::fs::unmap_file_pages(Start, getBufferSize()); 132 if (EC) 133 return EC; 134 135 // If requested, resize file as part of commit. 136 if ( NewSmallerSize != -1 ) { 137 EC = sys::fs::resize_file(Twine(TempPath), NewSmallerSize); 138 if (EC) 139 return EC; 140 } 141 142 // Rename file to final name. 143 return sys::fs::rename(Twine(TempPath), Twine(FinalPath)); 144} 145 146 147} // namespace 148 149