1 //===--- DependencyFile.cpp - Generate dependency file --------------------===// 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 // This code generates dependency files. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "clang/Frontend/Utils.h" 14 #include "clang/Basic/FileManager.h" 15 #include "clang/Basic/SourceManager.h" 16 #include "clang/Frontend/DependencyOutputOptions.h" 17 #include "clang/Frontend/FrontendDiagnostic.h" 18 #include "clang/Lex/DirectoryLookup.h" 19 #include "clang/Lex/ModuleMap.h" 20 #include "clang/Lex/PPCallbacks.h" 21 #include "clang/Lex/Preprocessor.h" 22 #include "clang/Serialization/ASTReader.h" 23 #include "llvm/ADT/StringSet.h" 24 #include "llvm/Support/FileSystem.h" 25 #include "llvm/Support/Path.h" 26 #include "llvm/Support/raw_ostream.h" 27 28 using namespace clang; 29 30 namespace { 31 struct DepCollectorPPCallbacks : public PPCallbacks { 32 DependencyCollector &DepCollector; 33 Preprocessor &PP; 34 DepCollectorPPCallbacks(DependencyCollector &L, Preprocessor &PP) 35 : DepCollector(L), PP(PP) {} 36 37 void LexedFileChanged(FileID FID, LexedFileChangeReason Reason, 38 SrcMgr::CharacteristicKind FileType, FileID PrevFID, 39 SourceLocation Loc) override { 40 if (Reason != PPCallbacks::LexedFileChangeReason::EnterFile) 41 return; 42 43 // Dependency generation really does want to go all the way to the 44 // file entry for a source location to find out what is depended on. 45 // We do not want #line markers to affect dependency generation! 46 if (Optional<StringRef> Filename = 47 PP.getSourceManager().getNonBuiltinFilenameForID(FID)) 48 DepCollector.maybeAddDependency( 49 llvm::sys::path::remove_leading_dotslash(*Filename), 50 /*FromModule*/ false, isSystem(FileType), /*IsModuleFile*/ false, 51 /*IsMissing*/ false); 52 } 53 54 void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok, 55 SrcMgr::CharacteristicKind FileType) override { 56 StringRef Filename = 57 llvm::sys::path::remove_leading_dotslash(SkippedFile.getName()); 58 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false, 59 /*IsSystem=*/isSystem(FileType), 60 /*IsModuleFile=*/false, 61 /*IsMissing=*/false); 62 } 63 64 void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok, 65 StringRef FileName, bool IsAngled, 66 CharSourceRange FilenameRange, 67 Optional<FileEntryRef> File, StringRef SearchPath, 68 StringRef RelativePath, const Module *Imported, 69 SrcMgr::CharacteristicKind FileType) override { 70 if (!File) 71 DepCollector.maybeAddDependency(FileName, /*FromModule*/false, 72 /*IsSystem*/false, /*IsModuleFile*/false, 73 /*IsMissing*/true); 74 // Files that actually exist are handled by FileChanged. 75 } 76 77 void HasInclude(SourceLocation Loc, StringRef SpelledFilename, bool IsAngled, 78 Optional<FileEntryRef> File, 79 SrcMgr::CharacteristicKind FileType) override { 80 if (!File) 81 return; 82 StringRef Filename = 83 llvm::sys::path::remove_leading_dotslash(File->getName()); 84 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false, 85 /*IsSystem=*/isSystem(FileType), 86 /*IsModuleFile=*/false, 87 /*IsMissing=*/false); 88 } 89 90 void EndOfMainFile() override { 91 DepCollector.finishedMainFile(PP.getDiagnostics()); 92 } 93 }; 94 95 struct DepCollectorMMCallbacks : public ModuleMapCallbacks { 96 DependencyCollector &DepCollector; 97 DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {} 98 99 void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry, 100 bool IsSystem) override { 101 StringRef Filename = Entry.getName(); 102 DepCollector.maybeAddDependency(Filename, /*FromModule*/false, 103 /*IsSystem*/IsSystem, 104 /*IsModuleFile*/false, 105 /*IsMissing*/false); 106 } 107 }; 108 109 struct DepCollectorASTListener : public ASTReaderListener { 110 DependencyCollector &DepCollector; 111 DepCollectorASTListener(DependencyCollector &L) : DepCollector(L) { } 112 bool needsInputFileVisitation() override { return true; } 113 bool needsSystemInputFileVisitation() override { 114 return DepCollector.needSystemDependencies(); 115 } 116 void visitModuleFile(StringRef Filename, 117 serialization::ModuleKind Kind) override { 118 DepCollector.maybeAddDependency(Filename, /*FromModule*/true, 119 /*IsSystem*/false, /*IsModuleFile*/true, 120 /*IsMissing*/false); 121 } 122 bool visitInputFile(StringRef Filename, bool IsSystem, 123 bool IsOverridden, bool IsExplicitModule) override { 124 if (IsOverridden || IsExplicitModule) 125 return true; 126 127 DepCollector.maybeAddDependency(Filename, /*FromModule*/true, IsSystem, 128 /*IsModuleFile*/false, /*IsMissing*/false); 129 return true; 130 } 131 }; 132 } // end anonymous namespace 133 134 void DependencyCollector::maybeAddDependency(StringRef Filename, 135 bool FromModule, bool IsSystem, 136 bool IsModuleFile, 137 bool IsMissing) { 138 if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing)) 139 addDependency(Filename); 140 } 141 142 bool DependencyCollector::addDependency(StringRef Filename) { 143 StringRef SearchPath; 144 #ifdef _WIN32 145 // Make the search insensitive to case and separators. 146 llvm::SmallString<256> TmpPath = Filename; 147 llvm::sys::path::native(TmpPath); 148 std::transform(TmpPath.begin(), TmpPath.end(), TmpPath.begin(), ::tolower); 149 SearchPath = TmpPath.str(); 150 #else 151 SearchPath = Filename; 152 #endif 153 154 if (Seen.insert(SearchPath).second) { 155 Dependencies.push_back(std::string(Filename)); 156 return true; 157 } 158 return false; 159 } 160 161 static bool isSpecialFilename(StringRef Filename) { 162 return Filename == "<built-in>"; 163 } 164 165 bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule, 166 bool IsSystem, bool IsModuleFile, 167 bool IsMissing) { 168 return !isSpecialFilename(Filename) && 169 (needSystemDependencies() || !IsSystem); 170 } 171 172 DependencyCollector::~DependencyCollector() { } 173 void DependencyCollector::attachToPreprocessor(Preprocessor &PP) { 174 PP.addPPCallbacks(std::make_unique<DepCollectorPPCallbacks>(*this, PP)); 175 PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks( 176 std::make_unique<DepCollectorMMCallbacks>(*this)); 177 } 178 void DependencyCollector::attachToASTReader(ASTReader &R) { 179 R.addListener(std::make_unique<DepCollectorASTListener>(*this)); 180 } 181 182 DependencyFileGenerator::DependencyFileGenerator( 183 const DependencyOutputOptions &Opts) 184 : OutputFile(Opts.OutputFile), Targets(Opts.Targets), 185 IncludeSystemHeaders(Opts.IncludeSystemHeaders), 186 PhonyTarget(Opts.UsePhonyTargets), 187 AddMissingHeaderDeps(Opts.AddMissingHeaderDeps), SeenMissingHeader(false), 188 IncludeModuleFiles(Opts.IncludeModuleFiles), 189 OutputFormat(Opts.OutputFormat), InputFileIndex(0) { 190 for (const auto &ExtraDep : Opts.ExtraDeps) { 191 if (addDependency(ExtraDep.first)) 192 ++InputFileIndex; 193 } 194 } 195 196 void DependencyFileGenerator::attachToPreprocessor(Preprocessor &PP) { 197 // Disable the "file not found" diagnostic if the -MG option was given. 198 if (AddMissingHeaderDeps) 199 PP.SetSuppressIncludeNotFoundError(true); 200 201 DependencyCollector::attachToPreprocessor(PP); 202 } 203 204 bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule, 205 bool IsSystem, bool IsModuleFile, 206 bool IsMissing) { 207 if (IsMissing) { 208 // Handle the case of missing file from an inclusion directive. 209 if (AddMissingHeaderDeps) 210 return true; 211 SeenMissingHeader = true; 212 return false; 213 } 214 if (IsModuleFile && !IncludeModuleFiles) 215 return false; 216 217 if (isSpecialFilename(Filename)) 218 return false; 219 220 if (IncludeSystemHeaders) 221 return true; 222 223 return !IsSystem; 224 } 225 226 void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) { 227 outputDependencyFile(Diags); 228 } 229 230 /// Print the filename, with escaping or quoting that accommodates the three 231 /// most likely tools that use dependency files: GNU Make, BSD Make, and 232 /// NMake/Jom. 233 /// 234 /// BSD Make is the simplest case: It does no escaping at all. This means 235 /// characters that are normally delimiters, i.e. space and # (the comment 236 /// character) simply aren't supported in filenames. 237 /// 238 /// GNU Make does allow space and # in filenames, but to avoid being treated 239 /// as a delimiter or comment, these must be escaped with a backslash. Because 240 /// backslash is itself the escape character, if a backslash appears in a 241 /// filename, it should be escaped as well. (As a special case, $ is escaped 242 /// as $$, which is the normal Make way to handle the $ character.) 243 /// For compatibility with BSD Make and historical practice, if GNU Make 244 /// un-escapes characters in a filename but doesn't find a match, it will 245 /// retry with the unmodified original string. 246 /// 247 /// GCC tries to accommodate both Make formats by escaping any space or # 248 /// characters in the original filename, but not escaping backslashes. The 249 /// apparent intent is so that filenames with backslashes will be handled 250 /// correctly by BSD Make, and by GNU Make in its fallback mode of using the 251 /// unmodified original string; filenames with # or space characters aren't 252 /// supported by BSD Make at all, but will be handled correctly by GNU Make 253 /// due to the escaping. 254 /// 255 /// A corner case that GCC gets only partly right is when the original filename 256 /// has a backslash immediately followed by space or #. GNU Make would expect 257 /// this backslash to be escaped; however GCC escapes the original backslash 258 /// only when followed by space, not #. It will therefore take a dependency 259 /// from a directive such as 260 /// #include "a\ b\#c.h" 261 /// and emit it as 262 /// a\\\ b\\#c.h 263 /// which GNU Make will interpret as 264 /// a\ b\ 265 /// followed by a comment. Failing to find this file, it will fall back to the 266 /// original string, which probably doesn't exist either; in any case it won't 267 /// find 268 /// a\ b\#c.h 269 /// which is the actual filename specified by the include directive. 270 /// 271 /// Clang does what GCC does, rather than what GNU Make expects. 272 /// 273 /// NMake/Jom has a different set of scary characters, but wraps filespecs in 274 /// double-quotes to avoid misinterpreting them; see 275 /// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info, 276 /// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx 277 /// for Windows file-naming info. 278 static void PrintFilename(raw_ostream &OS, StringRef Filename, 279 DependencyOutputFormat OutputFormat) { 280 // Convert filename to platform native path 281 llvm::SmallString<256> NativePath; 282 llvm::sys::path::native(Filename.str(), NativePath); 283 284 if (OutputFormat == DependencyOutputFormat::NMake) { 285 // Add quotes if needed. These are the characters listed as "special" to 286 // NMake, that are legal in a Windows filespec, and that could cause 287 // misinterpretation of the dependency string. 288 if (NativePath.find_first_of(" #${}^!") != StringRef::npos) 289 OS << '\"' << NativePath << '\"'; 290 else 291 OS << NativePath; 292 return; 293 } 294 assert(OutputFormat == DependencyOutputFormat::Make); 295 for (unsigned i = 0, e = NativePath.size(); i != e; ++i) { 296 if (NativePath[i] == '#') // Handle '#' the broken gcc way. 297 OS << '\\'; 298 else if (NativePath[i] == ' ') { // Handle space correctly. 299 OS << '\\'; 300 unsigned j = i; 301 while (j > 0 && NativePath[--j] == '\\') 302 OS << '\\'; 303 } else if (NativePath[i] == '$') // $ is escaped by $$. 304 OS << '$'; 305 OS << NativePath[i]; 306 } 307 } 308 309 void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) { 310 if (SeenMissingHeader) { 311 llvm::sys::fs::remove(OutputFile); 312 return; 313 } 314 315 std::error_code EC; 316 llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_TextWithCRLF); 317 if (EC) { 318 Diags.Report(diag::err_fe_error_opening) << OutputFile << EC.message(); 319 return; 320 } 321 322 outputDependencyFile(OS); 323 } 324 325 void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) { 326 // Write out the dependency targets, trying to avoid overly long 327 // lines when possible. We try our best to emit exactly the same 328 // dependency file as GCC>=10, assuming the included files are the 329 // same. 330 const unsigned MaxColumns = 75; 331 unsigned Columns = 0; 332 333 for (StringRef Target : Targets) { 334 unsigned N = Target.size(); 335 if (Columns == 0) { 336 Columns += N; 337 } else if (Columns + N + 2 > MaxColumns) { 338 Columns = N + 2; 339 OS << " \\\n "; 340 } else { 341 Columns += N + 1; 342 OS << ' '; 343 } 344 // Targets already quoted as needed. 345 OS << Target; 346 } 347 348 OS << ':'; 349 Columns += 1; 350 351 // Now add each dependency in the order it was seen, but avoiding 352 // duplicates. 353 ArrayRef<std::string> Files = getDependencies(); 354 for (StringRef File : Files) { 355 if (File == "<stdin>") 356 continue; 357 // Start a new line if this would exceed the column limit. Make 358 // sure to leave space for a trailing " \" in case we need to 359 // break the line on the next iteration. 360 unsigned N = File.size(); 361 if (Columns + (N + 1) + 2 > MaxColumns) { 362 OS << " \\\n "; 363 Columns = 2; 364 } 365 OS << ' '; 366 PrintFilename(OS, File, OutputFormat); 367 Columns += N + 1; 368 } 369 OS << '\n'; 370 371 // Create phony targets if requested. 372 if (PhonyTarget && !Files.empty()) { 373 unsigned Index = 0; 374 for (auto I = Files.begin(), E = Files.end(); I != E; ++I) { 375 if (Index++ == InputFileIndex) 376 continue; 377 PrintFilename(OS, *I, OutputFormat); 378 OS << ":\n"; 379 } 380 } 381 } 382