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 Optional<FileEntryRef> File = 50 SM.getFileEntryRefForID(SM.getFileID(SM.getExpansionLoc(Loc))); 51 if (!File) 52 return; 53 54 StringRef Filename = 55 llvm::sys::path::remove_leading_dotslash(File->getName()); 56 57 DepCollector.maybeAddDependency(Filename, /*FromModule*/false, 58 isSystem(FileType), 59 /*IsModuleFile*/false, /*IsMissing*/false); 60 } 61 62 void FileSkipped(const FileEntryRef &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 Optional<FileEntryRef> 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(std::make_unique<DepCollectorPPCallbacks>( 172 *this, PP.getSourceManager(), PP.getDiagnostics())); 173 PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks( 174 std::make_unique<DepCollectorMMCallbacks>(*this)); 175 } 176 void DependencyCollector::attachToASTReader(ASTReader &R) { 177 R.addListener(std::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 // Disable the "file not found" diagnostic if the -MG option was given. 196 if (AddMissingHeaderDeps) 197 PP.SetSuppressIncludeNotFoundError(true); 198 199 DependencyCollector::attachToPreprocessor(PP); 200 } 201 202 bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule, 203 bool IsSystem, bool IsModuleFile, 204 bool IsMissing) { 205 if (IsMissing) { 206 // Handle the case of missing file from an inclusion directive. 207 if (AddMissingHeaderDeps) 208 return true; 209 SeenMissingHeader = true; 210 return false; 211 } 212 if (IsModuleFile && !IncludeModuleFiles) 213 return false; 214 215 if (isSpecialFilename(Filename)) 216 return false; 217 218 if (IncludeSystemHeaders) 219 return true; 220 221 return !IsSystem; 222 } 223 224 void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) { 225 outputDependencyFile(Diags); 226 } 227 228 /// Print the filename, with escaping or quoting that accommodates the three 229 /// most likely tools that use dependency files: GNU Make, BSD Make, and 230 /// NMake/Jom. 231 /// 232 /// BSD Make is the simplest case: It does no escaping at all. This means 233 /// characters that are normally delimiters, i.e. space and # (the comment 234 /// character) simply aren't supported in filenames. 235 /// 236 /// GNU Make does allow space and # in filenames, but to avoid being treated 237 /// as a delimiter or comment, these must be escaped with a backslash. Because 238 /// backslash is itself the escape character, if a backslash appears in a 239 /// filename, it should be escaped as well. (As a special case, $ is escaped 240 /// as $$, which is the normal Make way to handle the $ character.) 241 /// For compatibility with BSD Make and historical practice, if GNU Make 242 /// un-escapes characters in a filename but doesn't find a match, it will 243 /// retry with the unmodified original string. 244 /// 245 /// GCC tries to accommodate both Make formats by escaping any space or # 246 /// characters in the original filename, but not escaping backslashes. The 247 /// apparent intent is so that filenames with backslashes will be handled 248 /// correctly by BSD Make, and by GNU Make in its fallback mode of using the 249 /// unmodified original string; filenames with # or space characters aren't 250 /// supported by BSD Make at all, but will be handled correctly by GNU Make 251 /// due to the escaping. 252 /// 253 /// A corner case that GCC gets only partly right is when the original filename 254 /// has a backslash immediately followed by space or #. GNU Make would expect 255 /// this backslash to be escaped; however GCC escapes the original backslash 256 /// only when followed by space, not #. It will therefore take a dependency 257 /// from a directive such as 258 /// #include "a\ b\#c.h" 259 /// and emit it as 260 /// a\\\ b\\#c.h 261 /// which GNU Make will interpret as 262 /// a\ b\ 263 /// followed by a comment. Failing to find this file, it will fall back to the 264 /// original string, which probably doesn't exist either; in any case it won't 265 /// find 266 /// a\ b\#c.h 267 /// which is the actual filename specified by the include directive. 268 /// 269 /// Clang does what GCC does, rather than what GNU Make expects. 270 /// 271 /// NMake/Jom has a different set of scary characters, but wraps filespecs in 272 /// double-quotes to avoid misinterpreting them; see 273 /// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info, 274 /// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx 275 /// for Windows file-naming info. 276 static void PrintFilename(raw_ostream &OS, StringRef Filename, 277 DependencyOutputFormat OutputFormat) { 278 // Convert filename to platform native path 279 llvm::SmallString<256> NativePath; 280 llvm::sys::path::native(Filename.str(), NativePath); 281 282 if (OutputFormat == DependencyOutputFormat::NMake) { 283 // Add quotes if needed. These are the characters listed as "special" to 284 // NMake, that are legal in a Windows filespec, and that could cause 285 // misinterpretation of the dependency string. 286 if (NativePath.find_first_of(" #${}^!") != StringRef::npos) 287 OS << '\"' << NativePath << '\"'; 288 else 289 OS << NativePath; 290 return; 291 } 292 assert(OutputFormat == DependencyOutputFormat::Make); 293 for (unsigned i = 0, e = NativePath.size(); i != e; ++i) { 294 if (NativePath[i] == '#') // Handle '#' the broken gcc way. 295 OS << '\\'; 296 else if (NativePath[i] == ' ') { // Handle space correctly. 297 OS << '\\'; 298 unsigned j = i; 299 while (j > 0 && NativePath[--j] == '\\') 300 OS << '\\'; 301 } else if (NativePath[i] == '$') // $ is escaped by $$. 302 OS << '$'; 303 OS << NativePath[i]; 304 } 305 } 306 307 void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) { 308 if (SeenMissingHeader) { 309 llvm::sys::fs::remove(OutputFile); 310 return; 311 } 312 313 std::error_code EC; 314 llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_Text); 315 if (EC) { 316 Diags.Report(diag::err_fe_error_opening) << OutputFile << EC.message(); 317 return; 318 } 319 320 outputDependencyFile(OS); 321 } 322 323 void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) { 324 // Write out the dependency targets, trying to avoid overly long 325 // lines when possible. We try our best to emit exactly the same 326 // dependency file as GCC (4.2), assuming the included files are the 327 // same. 328 const unsigned MaxColumns = 75; 329 unsigned Columns = 0; 330 331 for (StringRef Target : Targets) { 332 unsigned N = Target.size(); 333 if (Columns == 0) { 334 Columns += N; 335 } else if (Columns + N + 2 > MaxColumns) { 336 Columns = N + 2; 337 OS << " \\\n "; 338 } else { 339 Columns += N + 1; 340 OS << ' '; 341 } 342 // Targets already quoted as needed. 343 OS << Target; 344 } 345 346 OS << ':'; 347 Columns += 1; 348 349 // Now add each dependency in the order it was seen, but avoiding 350 // duplicates. 351 ArrayRef<std::string> Files = getDependencies(); 352 for (StringRef File : Files) { 353 // Start a new line if this would exceed the column limit. Make 354 // sure to leave space for a trailing " \" in case we need to 355 // break the line on the next iteration. 356 unsigned N = File.size(); 357 if (Columns + (N + 1) + 2 > MaxColumns) { 358 OS << " \\\n "; 359 Columns = 2; 360 } 361 OS << ' '; 362 PrintFilename(OS, File, OutputFormat); 363 Columns += N + 1; 364 } 365 OS << '\n'; 366 367 // Create phony targets if requested. 368 if (PhonyTarget && !Files.empty()) { 369 unsigned Index = 0; 370 for (auto I = Files.begin(), E = Files.end(); I != E; ++I) { 371 if (Index++ == InputFileIndex) 372 continue; 373 OS << '\n'; 374 PrintFilename(OS, *I, OutputFormat); 375 OS << ":\n"; 376 } 377 } 378 } 379