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/ADT/StringSwitch.h" 25 #include "llvm/Support/FileSystem.h" 26 #include "llvm/Support/Path.h" 27 #include "llvm/Support/raw_ostream.h" 28 29 using namespace clang; 30 31 namespace { 32 struct DepCollectorPPCallbacks : public PPCallbacks { 33 DependencyCollector &DepCollector; 34 SourceManager &SM; 35 DiagnosticsEngine &Diags; 36 DepCollectorPPCallbacks(DependencyCollector &L, SourceManager &SM, 37 DiagnosticsEngine &Diags) 38 : DepCollector(L), SM(SM), Diags(Diags) {} 39 40 void FileChanged(SourceLocation Loc, FileChangeReason Reason, 41 SrcMgr::CharacteristicKind FileType, 42 FileID PrevFID) override { 43 if (Reason != PPCallbacks::EnterFile) 44 return; 45 46 // Dependency generation really does want to go all the way to the 47 // file entry for a source location to find out what is depended on. 48 // We do not want #line markers to affect dependency generation! 49 if (Optional<StringRef> Filename = SM.getNonBuiltinFilenameForID( 50 SM.getFileID(SM.getExpansionLoc(Loc)))) 51 DepCollector.maybeAddDependency( 52 llvm::sys::path::remove_leading_dotslash(*Filename), 53 /*FromModule*/ false, isSystem(FileType), /*IsModuleFile*/ false, 54 /*IsMissing*/ false); 55 } 56 57 void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok, 58 SrcMgr::CharacteristicKind FileType) override { 59 StringRef Filename = 60 llvm::sys::path::remove_leading_dotslash(SkippedFile.getName()); 61 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false, 62 /*IsSystem=*/isSystem(FileType), 63 /*IsModuleFile=*/false, 64 /*IsMissing=*/false); 65 } 66 67 void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok, 68 StringRef FileName, bool IsAngled, 69 CharSourceRange FilenameRange, const FileEntry *File, 70 StringRef SearchPath, StringRef RelativePath, 71 const Module *Imported, 72 SrcMgr::CharacteristicKind FileType) override { 73 if (!File) 74 DepCollector.maybeAddDependency(FileName, /*FromModule*/false, 75 /*IsSystem*/false, /*IsModuleFile*/false, 76 /*IsMissing*/true); 77 // Files that actually exist are handled by FileChanged. 78 } 79 80 void HasInclude(SourceLocation Loc, StringRef SpelledFilename, bool IsAngled, 81 Optional<FileEntryRef> File, 82 SrcMgr::CharacteristicKind FileType) override { 83 if (!File) 84 return; 85 StringRef Filename = 86 llvm::sys::path::remove_leading_dotslash(File->getName()); 87 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false, 88 /*IsSystem=*/isSystem(FileType), 89 /*IsModuleFile=*/false, 90 /*IsMissing=*/false); 91 } 92 93 void EndOfMainFile() override { DepCollector.finishedMainFile(Diags); } 94 }; 95 96 struct DepCollectorMMCallbacks : public ModuleMapCallbacks { 97 DependencyCollector &DepCollector; 98 DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {} 99 100 void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry, 101 bool IsSystem) override { 102 StringRef Filename = Entry.getName(); 103 DepCollector.maybeAddDependency(Filename, /*FromModule*/false, 104 /*IsSystem*/IsSystem, 105 /*IsModuleFile*/false, 106 /*IsMissing*/false); 107 } 108 }; 109 110 struct DepCollectorASTListener : public ASTReaderListener { 111 DependencyCollector &DepCollector; 112 DepCollectorASTListener(DependencyCollector &L) : DepCollector(L) { } 113 bool needsInputFileVisitation() override { return true; } 114 bool needsSystemInputFileVisitation() override { 115 return DepCollector.needSystemDependencies(); 116 } 117 void visitModuleFile(StringRef Filename, 118 serialization::ModuleKind Kind) override { 119 DepCollector.maybeAddDependency(Filename, /*FromModule*/true, 120 /*IsSystem*/false, /*IsModuleFile*/true, 121 /*IsMissing*/false); 122 } 123 bool visitInputFile(StringRef Filename, bool IsSystem, 124 bool IsOverridden, bool IsExplicitModule) override { 125 if (IsOverridden || IsExplicitModule) 126 return true; 127 128 DepCollector.maybeAddDependency(Filename, /*FromModule*/true, IsSystem, 129 /*IsModuleFile*/false, /*IsMissing*/false); 130 return true; 131 } 132 }; 133 } // end anonymous namespace 134 135 void DependencyCollector::maybeAddDependency(StringRef Filename, 136 bool FromModule, bool IsSystem, 137 bool IsModuleFile, 138 bool IsMissing) { 139 if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing)) 140 addDependency(Filename); 141 } 142 143 bool DependencyCollector::addDependency(StringRef Filename) { 144 StringRef SearchPath; 145 #ifdef _WIN32 146 // Make the search insensitive to case and separators. 147 llvm::SmallString<256> TmpPath = Filename; 148 llvm::sys::path::native(TmpPath); 149 std::transform(TmpPath.begin(), TmpPath.end(), TmpPath.begin(), ::tolower); 150 SearchPath = TmpPath.str(); 151 #else 152 SearchPath = Filename; 153 #endif 154 155 if (Seen.insert(SearchPath).second) { 156 Dependencies.push_back(std::string(Filename)); 157 return true; 158 } 159 return false; 160 } 161 162 static bool isSpecialFilename(StringRef Filename) { 163 return llvm::StringSwitch<bool>(Filename) 164 .Case("<built-in>", true) 165 .Case("<stdin>", true) 166 .Default(false); 167 } 168 169 bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule, 170 bool IsSystem, bool IsModuleFile, 171 bool IsMissing) { 172 return !isSpecialFilename(Filename) && 173 (needSystemDependencies() || !IsSystem); 174 } 175 176 DependencyCollector::~DependencyCollector() { } 177 void DependencyCollector::attachToPreprocessor(Preprocessor &PP) { 178 PP.addPPCallbacks(std::make_unique<DepCollectorPPCallbacks>( 179 *this, PP.getSourceManager(), PP.getDiagnostics())); 180 PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks( 181 std::make_unique<DepCollectorMMCallbacks>(*this)); 182 } 183 void DependencyCollector::attachToASTReader(ASTReader &R) { 184 R.addListener(std::make_unique<DepCollectorASTListener>(*this)); 185 } 186 187 DependencyFileGenerator::DependencyFileGenerator( 188 const DependencyOutputOptions &Opts) 189 : OutputFile(Opts.OutputFile), Targets(Opts.Targets), 190 IncludeSystemHeaders(Opts.IncludeSystemHeaders), 191 PhonyTarget(Opts.UsePhonyTargets), 192 AddMissingHeaderDeps(Opts.AddMissingHeaderDeps), SeenMissingHeader(false), 193 IncludeModuleFiles(Opts.IncludeModuleFiles), 194 OutputFormat(Opts.OutputFormat), InputFileIndex(0) { 195 for (const auto &ExtraDep : Opts.ExtraDeps) { 196 if (addDependency(ExtraDep.first)) 197 ++InputFileIndex; 198 } 199 } 200 201 void DependencyFileGenerator::attachToPreprocessor(Preprocessor &PP) { 202 // Disable the "file not found" diagnostic if the -MG option was given. 203 if (AddMissingHeaderDeps) 204 PP.SetSuppressIncludeNotFoundError(true); 205 206 DependencyCollector::attachToPreprocessor(PP); 207 } 208 209 bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule, 210 bool IsSystem, bool IsModuleFile, 211 bool IsMissing) { 212 if (IsMissing) { 213 // Handle the case of missing file from an inclusion directive. 214 if (AddMissingHeaderDeps) 215 return true; 216 SeenMissingHeader = true; 217 return false; 218 } 219 if (IsModuleFile && !IncludeModuleFiles) 220 return false; 221 222 if (isSpecialFilename(Filename)) 223 return false; 224 225 if (IncludeSystemHeaders) 226 return true; 227 228 return !IsSystem; 229 } 230 231 void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) { 232 outputDependencyFile(Diags); 233 } 234 235 /// Print the filename, with escaping or quoting that accommodates the three 236 /// most likely tools that use dependency files: GNU Make, BSD Make, and 237 /// NMake/Jom. 238 /// 239 /// BSD Make is the simplest case: It does no escaping at all. This means 240 /// characters that are normally delimiters, i.e. space and # (the comment 241 /// character) simply aren't supported in filenames. 242 /// 243 /// GNU Make does allow space and # in filenames, but to avoid being treated 244 /// as a delimiter or comment, these must be escaped with a backslash. Because 245 /// backslash is itself the escape character, if a backslash appears in a 246 /// filename, it should be escaped as well. (As a special case, $ is escaped 247 /// as $$, which is the normal Make way to handle the $ character.) 248 /// For compatibility with BSD Make and historical practice, if GNU Make 249 /// un-escapes characters in a filename but doesn't find a match, it will 250 /// retry with the unmodified original string. 251 /// 252 /// GCC tries to accommodate both Make formats by escaping any space or # 253 /// characters in the original filename, but not escaping backslashes. The 254 /// apparent intent is so that filenames with backslashes will be handled 255 /// correctly by BSD Make, and by GNU Make in its fallback mode of using the 256 /// unmodified original string; filenames with # or space characters aren't 257 /// supported by BSD Make at all, but will be handled correctly by GNU Make 258 /// due to the escaping. 259 /// 260 /// A corner case that GCC gets only partly right is when the original filename 261 /// has a backslash immediately followed by space or #. GNU Make would expect 262 /// this backslash to be escaped; however GCC escapes the original backslash 263 /// only when followed by space, not #. It will therefore take a dependency 264 /// from a directive such as 265 /// #include "a\ b\#c.h" 266 /// and emit it as 267 /// a\\\ b\\#c.h 268 /// which GNU Make will interpret as 269 /// a\ b\ 270 /// followed by a comment. Failing to find this file, it will fall back to the 271 /// original string, which probably doesn't exist either; in any case it won't 272 /// find 273 /// a\ b\#c.h 274 /// which is the actual filename specified by the include directive. 275 /// 276 /// Clang does what GCC does, rather than what GNU Make expects. 277 /// 278 /// NMake/Jom has a different set of scary characters, but wraps filespecs in 279 /// double-quotes to avoid misinterpreting them; see 280 /// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info, 281 /// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx 282 /// for Windows file-naming info. 283 static void PrintFilename(raw_ostream &OS, StringRef Filename, 284 DependencyOutputFormat OutputFormat) { 285 // Convert filename to platform native path 286 llvm::SmallString<256> NativePath; 287 llvm::sys::path::native(Filename.str(), NativePath); 288 289 if (OutputFormat == DependencyOutputFormat::NMake) { 290 // Add quotes if needed. These are the characters listed as "special" to 291 // NMake, that are legal in a Windows filespec, and that could cause 292 // misinterpretation of the dependency string. 293 if (NativePath.find_first_of(" #${}^!") != StringRef::npos) 294 OS << '\"' << NativePath << '\"'; 295 else 296 OS << NativePath; 297 return; 298 } 299 assert(OutputFormat == DependencyOutputFormat::Make); 300 for (unsigned i = 0, e = NativePath.size(); i != e; ++i) { 301 if (NativePath[i] == '#') // Handle '#' the broken gcc way. 302 OS << '\\'; 303 else if (NativePath[i] == ' ') { // Handle space correctly. 304 OS << '\\'; 305 unsigned j = i; 306 while (j > 0 && NativePath[--j] == '\\') 307 OS << '\\'; 308 } else if (NativePath[i] == '$') // $ is escaped by $$. 309 OS << '$'; 310 OS << NativePath[i]; 311 } 312 } 313 314 void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) { 315 if (SeenMissingHeader) { 316 llvm::sys::fs::remove(OutputFile); 317 return; 318 } 319 320 std::error_code EC; 321 llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_TextWithCRLF); 322 if (EC) { 323 Diags.Report(diag::err_fe_error_opening) << OutputFile << EC.message(); 324 return; 325 } 326 327 outputDependencyFile(OS); 328 } 329 330 void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) { 331 // Write out the dependency targets, trying to avoid overly long 332 // lines when possible. We try our best to emit exactly the same 333 // dependency file as GCC (4.2), assuming the included files are the 334 // same. 335 const unsigned MaxColumns = 75; 336 unsigned Columns = 0; 337 338 for (StringRef Target : Targets) { 339 unsigned N = Target.size(); 340 if (Columns == 0) { 341 Columns += N; 342 } else if (Columns + N + 2 > MaxColumns) { 343 Columns = N + 2; 344 OS << " \\\n "; 345 } else { 346 Columns += N + 1; 347 OS << ' '; 348 } 349 // Targets already quoted as needed. 350 OS << Target; 351 } 352 353 OS << ':'; 354 Columns += 1; 355 356 // Now add each dependency in the order it was seen, but avoiding 357 // duplicates. 358 ArrayRef<std::string> Files = getDependencies(); 359 for (StringRef File : Files) { 360 // Start a new line if this would exceed the column limit. Make 361 // sure to leave space for a trailing " \" in case we need to 362 // break the line on the next iteration. 363 unsigned N = File.size(); 364 if (Columns + (N + 1) + 2 > MaxColumns) { 365 OS << " \\\n "; 366 Columns = 2; 367 } 368 OS << ' '; 369 PrintFilename(OS, File, OutputFormat); 370 Columns += N + 1; 371 } 372 OS << '\n'; 373 374 // Create phony targets if requested. 375 if (PhonyTarget && !Files.empty()) { 376 unsigned Index = 0; 377 for (auto I = Files.begin(), E = Files.end(); I != E; ++I) { 378 if (Index++ == InputFileIndex) 379 continue; 380 OS << '\n'; 381 PrintFilename(OS, *I, OutputFormat); 382 OS << ":\n"; 383 } 384 } 385 } 386