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 #include "llvm/ADT/OwningPtr.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/Support/raw_ostream.h"
18 #include "llvm/Support/system_error.h"
19
20 using llvm::sys::fs::mapped_file_region;
21
22 namespace llvm {
FileOutputBuffer(mapped_file_region * R,StringRef Path,StringRef TmpPath)23 FileOutputBuffer::FileOutputBuffer(mapped_file_region * R,
24 StringRef Path, StringRef TmpPath)
25 : Region(R)
26 , FinalPath(Path)
27 , TempPath(TmpPath) {
28 }
29
~FileOutputBuffer()30 FileOutputBuffer::~FileOutputBuffer() {
31 bool Existed;
32 sys::fs::remove(Twine(TempPath), Existed);
33 }
34
create(StringRef FilePath,size_t Size,OwningPtr<FileOutputBuffer> & Result,unsigned Flags)35 error_code FileOutputBuffer::create(StringRef FilePath,
36 size_t Size,
37 OwningPtr<FileOutputBuffer> &Result,
38 unsigned Flags) {
39 // If file already exists, it must be a regular file (to be mappable).
40 sys::fs::file_status Stat;
41 error_code EC = sys::fs::status(FilePath, Stat);
42 switch (Stat.type()) {
43 case sys::fs::file_type::file_not_found:
44 // If file does not exist, we'll create one.
45 break;
46 case sys::fs::file_type::regular_file: {
47 // If file is not currently writable, error out.
48 // FIXME: There is no sys::fs:: api for checking this.
49 // FIXME: In posix, you use the access() call to check this.
50 }
51 break;
52 default:
53 if (EC)
54 return EC;
55 else
56 return make_error_code(errc::operation_not_permitted);
57 }
58
59 // Delete target file.
60 bool Existed;
61 EC = sys::fs::remove(FilePath, Existed);
62 if (EC)
63 return EC;
64
65 unsigned Mode = sys::fs::all_read | sys::fs::all_write;
66 // If requested, make the output file executable.
67 if (Flags & F_executable)
68 Mode |= sys::fs::all_exe;
69
70 // Create new file in same directory but with random name.
71 SmallString<128> TempFilePath;
72 int FD;
73 EC = sys::fs::createUniqueFile(Twine(FilePath) + ".tmp%%%%%%%", FD,
74 TempFilePath, Mode);
75 if (EC)
76 return EC;
77
78 OwningPtr<mapped_file_region> MappedFile(new mapped_file_region(
79 FD, true, mapped_file_region::readwrite, Size, 0, EC));
80 if (EC)
81 return EC;
82
83 Result.reset(new FileOutputBuffer(MappedFile.get(), FilePath, TempFilePath));
84 if (Result)
85 MappedFile.take();
86
87 return error_code::success();
88 }
89
commit(int64_t NewSmallerSize)90 error_code FileOutputBuffer::commit(int64_t NewSmallerSize) {
91 // Unmap buffer, letting OS flush dirty pages to file on disk.
92 Region.reset(0);
93
94 // If requested, resize file as part of commit.
95 if ( NewSmallerSize != -1 ) {
96 error_code EC = sys::fs::resize_file(Twine(TempPath), NewSmallerSize);
97 if (EC)
98 return EC;
99 }
100
101 // Rename file to final name.
102 return sys::fs::rename(Twine(TempPath), Twine(FinalPath));
103 }
104 } // namespace
105