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