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