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