1 //===-- FileCollector.cpp ---------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/Support/FileCollector.h"
10 #include "llvm/ADT/SmallString.h"
11 #include "llvm/Support/FileSystem.h"
12 #include "llvm/Support/Path.h"
13 #include "llvm/Support/Process.h"
14 
15 using namespace llvm;
16 
17 static bool isCaseSensitivePath(StringRef Path) {
18   SmallString<256> TmpDest = Path, UpperDest, RealDest;
19 
20   // Remove component traversals, links, etc.
21   if (!sys::fs::real_path(Path, TmpDest))
22     return true; // Current default value in vfs.yaml
23   Path = TmpDest;
24 
25   // Change path to all upper case and ask for its real path, if the latter
26   // exists and is equal to path, it's not case sensitive. Default to case
27   // sensitive in the absence of real_path, since this is the YAMLVFSWriter
28   // default.
29   UpperDest = Path.upper();
30   if (sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))
31     return false;
32   return true;
33 }
34 
35 FileCollector::FileCollector(std::string Root, std::string OverlayRoot)
36     : Root(std::move(Root)), OverlayRoot(std::move(OverlayRoot)) {
37   sys::fs::create_directories(this->Root, true);
38 }
39 
40 bool FileCollector::getRealPath(StringRef SrcPath,
41                                 SmallVectorImpl<char> &Result) {
42   SmallString<256> RealPath;
43   StringRef FileName = sys::path::filename(SrcPath);
44   std::string Directory = sys::path::parent_path(SrcPath).str();
45   auto DirWithSymlink = SymlinkMap.find(Directory);
46 
47   // Use real_path to fix any symbolic link component present in a path.
48   // Computing the real path is expensive, cache the search through the parent
49   // path Directory.
50   if (DirWithSymlink == SymlinkMap.end()) {
51     auto EC = sys::fs::real_path(Directory, RealPath);
52     if (EC)
53       return false;
54     SymlinkMap[Directory] = std::string(RealPath.str());
55   } else {
56     RealPath = DirWithSymlink->second;
57   }
58 
59   sys::path::append(RealPath, FileName);
60   Result.swap(RealPath);
61   return true;
62 }
63 
64 void FileCollector::addFile(const Twine &File) {
65   std::lock_guard<std::mutex> lock(Mutex);
66   std::string FileStr = File.str();
67   if (markAsSeen(FileStr))
68     addFileImpl(FileStr);
69 }
70 
71 void FileCollector::addDirectory(const Twine &Dir) {
72   assert(sys::fs::is_directory(Dir));
73   std::error_code EC;
74   addDirectoryImpl(Dir, vfs::getRealFileSystem(), EC);
75 }
76 
77 void FileCollector::addFileImpl(StringRef SrcPath) {
78   // We need an absolute src path to append to the root.
79   SmallString<256> AbsoluteSrc = SrcPath;
80   sys::fs::make_absolute(AbsoluteSrc);
81 
82   // Canonicalize src to a native path to avoid mixed separator styles.
83   sys::path::native(AbsoluteSrc);
84 
85   // Remove redundant leading "./" pieces and consecutive separators.
86   AbsoluteSrc = sys::path::remove_leading_dotslash(AbsoluteSrc);
87 
88   // Canonicalize the source path by removing "..", "." components.
89   SmallString<256> VirtualPath = AbsoluteSrc;
90   sys::path::remove_dots(VirtualPath, /*remove_dot_dot=*/true);
91 
92   // If a ".." component is present after a symlink component, remove_dots may
93   // lead to the wrong real destination path. Let the source be canonicalized
94   // like that but make sure we always use the real path for the destination.
95   SmallString<256> CopyFrom;
96   if (!getRealPath(AbsoluteSrc, CopyFrom))
97     CopyFrom = VirtualPath;
98 
99   SmallString<256> DstPath = StringRef(Root);
100   sys::path::append(DstPath, sys::path::relative_path(CopyFrom));
101 
102   // Always map a canonical src path to its real path into the YAML, by doing
103   // this we map different virtual src paths to the same entry in the VFS
104   // overlay, which is a way to emulate symlink inside the VFS; this is also
105   // needed for correctness, not doing that can lead to module redefinition
106   // errors.
107   addFileToMapping(VirtualPath, DstPath);
108 }
109 
110 llvm::vfs::directory_iterator
111 FileCollector::addDirectoryImpl(const llvm::Twine &Dir,
112                                 IntrusiveRefCntPtr<vfs::FileSystem> FS,
113                                 std::error_code &EC) {
114   auto It = FS->dir_begin(Dir, EC);
115   if (EC)
116     return It;
117   addFile(Dir);
118   for (; !EC && It != llvm::vfs::directory_iterator(); It.increment(EC)) {
119     if (It->type() == sys::fs::file_type::regular_file ||
120         It->type() == sys::fs::file_type::directory_file ||
121         It->type() == sys::fs::file_type::symlink_file) {
122       addFile(It->path());
123     }
124   }
125   if (EC)
126     return It;
127   // Return a new iterator.
128   return FS->dir_begin(Dir, EC);
129 }
130 
131 /// Set the access and modification time for the given file from the given
132 /// status object.
133 static std::error_code
134 copyAccessAndModificationTime(StringRef Filename,
135                               const sys::fs::file_status &Stat) {
136   int FD;
137 
138   if (auto EC =
139           sys::fs::openFileForWrite(Filename, FD, sys::fs::CD_OpenExisting))
140     return EC;
141 
142   if (auto EC = sys::fs::setLastAccessAndModificationTime(
143           FD, Stat.getLastAccessedTime(), Stat.getLastModificationTime()))
144     return EC;
145 
146   if (auto EC = sys::Process::SafelyCloseFileDescriptor(FD))
147     return EC;
148 
149   return {};
150 }
151 
152 std::error_code FileCollector::copyFiles(bool StopOnError) {
153   for (auto &entry : VFSWriter.getMappings()) {
154     // Create directory tree.
155     if (std::error_code EC =
156             sys::fs::create_directories(sys::path::parent_path(entry.RPath),
157                                         /*IgnoreExisting=*/true)) {
158       if (StopOnError)
159         return EC;
160     }
161 
162     // Get the status of the original file/directory.
163     sys::fs::file_status Stat;
164     if (std::error_code EC = sys::fs::status(entry.VPath, Stat)) {
165       if (StopOnError)
166         return EC;
167       continue;
168     }
169 
170     if (Stat.type() == sys::fs::file_type::directory_file) {
171       // Construct a directory when it's just a directory entry.
172       if (std::error_code EC =
173               sys::fs::create_directories(entry.RPath,
174                                           /*IgnoreExisting=*/true)) {
175         if (StopOnError)
176           return EC;
177       }
178       continue;
179     }
180 
181     // Copy file over.
182     if (std::error_code EC = sys::fs::copy_file(entry.VPath, entry.RPath)) {
183       if (StopOnError)
184         return EC;
185     }
186 
187     // Copy over permissions.
188     if (auto perms = sys::fs::getPermissions(entry.VPath)) {
189       if (std::error_code EC = sys::fs::setPermissions(entry.RPath, *perms)) {
190         if (StopOnError)
191           return EC;
192       }
193     }
194 
195     // Copy over modification time.
196     copyAccessAndModificationTime(entry.RPath, Stat);
197   }
198   return {};
199 }
200 
201 std::error_code FileCollector::writeMapping(StringRef MappingFile) {
202   std::lock_guard<std::mutex> lock(Mutex);
203 
204   VFSWriter.setOverlayDir(OverlayRoot);
205   VFSWriter.setCaseSensitivity(isCaseSensitivePath(OverlayRoot));
206   VFSWriter.setUseExternalNames(false);
207 
208   std::error_code EC;
209   raw_fd_ostream os(MappingFile, EC, sys::fs::OF_Text);
210   if (EC)
211     return EC;
212 
213   VFSWriter.write(os);
214 
215   return {};
216 }
217 
218 namespace llvm {
219 
220 class FileCollectorFileSystem : public vfs::FileSystem {
221 public:
222   explicit FileCollectorFileSystem(IntrusiveRefCntPtr<vfs::FileSystem> FS,
223                                    std::shared_ptr<FileCollector> Collector)
224       : FS(std::move(FS)), Collector(std::move(Collector)) {}
225 
226   llvm::ErrorOr<llvm::vfs::Status> status(const Twine &Path) override {
227     auto Result = FS->status(Path);
228     if (Result && Result->exists())
229       Collector->addFile(Path);
230     return Result;
231   }
232 
233   llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
234   openFileForRead(const Twine &Path) override {
235     auto Result = FS->openFileForRead(Path);
236     if (Result && *Result)
237       Collector->addFile(Path);
238     return Result;
239   }
240 
241   llvm::vfs::directory_iterator dir_begin(const llvm::Twine &Dir,
242                                           std::error_code &EC) override {
243     return Collector->addDirectoryImpl(Dir, FS, EC);
244   }
245 
246   std::error_code getRealPath(const Twine &Path,
247                               SmallVectorImpl<char> &Output) const override {
248     auto EC = FS->getRealPath(Path, Output);
249     if (!EC) {
250       Collector->addFile(Path);
251       if (Output.size() > 0)
252         Collector->addFile(Output);
253     }
254     return EC;
255   }
256 
257   std::error_code isLocal(const Twine &Path, bool &Result) override {
258     return FS->isLocal(Path, Result);
259   }
260 
261   llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
262     return FS->getCurrentWorkingDirectory();
263   }
264 
265   std::error_code setCurrentWorkingDirectory(const llvm::Twine &Path) override {
266     return FS->setCurrentWorkingDirectory(Path);
267   }
268 
269 private:
270   IntrusiveRefCntPtr<vfs::FileSystem> FS;
271   std::shared_ptr<FileCollector> Collector;
272 };
273 
274 } // namespace llvm
275 
276 IntrusiveRefCntPtr<vfs::FileSystem>
277 FileCollector::createCollectorVFS(IntrusiveRefCntPtr<vfs::FileSystem> BaseFS,
278                                   std::shared_ptr<FileCollector> Collector) {
279   return new FileCollectorFileSystem(std::move(BaseFS), std::move(Collector));
280 }
281