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1 //===--- DependencyFile.cpp - Generate dependency file --------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This code generates dependency files.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Frontend/Utils.h"
15 #include "clang/Basic/FileManager.h"
16 #include "clang/Basic/SourceManager.h"
17 #include "clang/Frontend/DependencyOutputOptions.h"
18 #include "clang/Frontend/FrontendDiagnostic.h"
19 #include "clang/Lex/DirectoryLookup.h"
20 #include "clang/Lex/LexDiagnostic.h"
21 #include "clang/Lex/ModuleMap.h"
22 #include "clang/Lex/PPCallbacks.h"
23 #include "clang/Lex/Preprocessor.h"
24 #include "clang/Serialization/ASTReader.h"
25 #include "llvm/ADT/StringSet.h"
26 #include "llvm/ADT/StringSwitch.h"
27 #include "llvm/Support/FileSystem.h"
28 #include "llvm/Support/Path.h"
29 #include "llvm/Support/raw_ostream.h"
30 
31 using namespace clang;
32 
33 namespace {
34 struct DepCollectorPPCallbacks : public PPCallbacks {
35   DependencyCollector &DepCollector;
36   SourceManager &SM;
DepCollectorPPCallbacks__anon480112ef0111::DepCollectorPPCallbacks37   DepCollectorPPCallbacks(DependencyCollector &L, SourceManager &SM)
38       : DepCollector(L), SM(SM) { }
39 
FileChanged__anon480112ef0111::DepCollectorPPCallbacks40   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                                    FileType != SrcMgr::C_User,
59                                    /*IsModuleFile*/false, /*IsMissing*/false);
60   }
61 
InclusionDirective__anon480112ef0111::DepCollectorPPCallbacks62   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
63                           StringRef FileName, bool IsAngled,
64                           CharSourceRange FilenameRange, const FileEntry *File,
65                           StringRef SearchPath, StringRef RelativePath,
66                           const Module *Imported) override {
67     if (!File)
68       DepCollector.maybeAddDependency(FileName, /*FromModule*/false,
69                                      /*IsSystem*/false, /*IsModuleFile*/false,
70                                      /*IsMissing*/true);
71     // Files that actually exist are handled by FileChanged.
72   }
73 
EndOfMainFile__anon480112ef0111::DepCollectorPPCallbacks74   void EndOfMainFile() override {
75     DepCollector.finishedMainFile();
76   }
77 };
78 
79 struct DepCollectorMMCallbacks : public ModuleMapCallbacks {
80   DependencyCollector &DepCollector;
DepCollectorMMCallbacks__anon480112ef0111::DepCollectorMMCallbacks81   DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {}
82 
moduleMapFileRead__anon480112ef0111::DepCollectorMMCallbacks83   void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry,
84                          bool IsSystem) override {
85     StringRef Filename = Entry.getName();
86     DepCollector.maybeAddDependency(Filename, /*FromModule*/false,
87                                     /*IsSystem*/IsSystem,
88                                     /*IsModuleFile*/false,
89                                     /*IsMissing*/false);
90   }
91 };
92 
93 struct DepCollectorASTListener : public ASTReaderListener {
94   DependencyCollector &DepCollector;
DepCollectorASTListener__anon480112ef0111::DepCollectorASTListener95   DepCollectorASTListener(DependencyCollector &L) : DepCollector(L) { }
needsInputFileVisitation__anon480112ef0111::DepCollectorASTListener96   bool needsInputFileVisitation() override { return true; }
needsSystemInputFileVisitation__anon480112ef0111::DepCollectorASTListener97   bool needsSystemInputFileVisitation() override {
98     return DepCollector.needSystemDependencies();
99   }
visitModuleFile__anon480112ef0111::DepCollectorASTListener100   void visitModuleFile(StringRef Filename,
101                        serialization::ModuleKind Kind) override {
102     DepCollector.maybeAddDependency(Filename, /*FromModule*/true,
103                                    /*IsSystem*/false, /*IsModuleFile*/true,
104                                    /*IsMissing*/false);
105   }
visitInputFile__anon480112ef0111::DepCollectorASTListener106   bool visitInputFile(StringRef Filename, bool IsSystem,
107                       bool IsOverridden, bool IsExplicitModule) override {
108     if (IsOverridden || IsExplicitModule)
109       return true;
110 
111     DepCollector.maybeAddDependency(Filename, /*FromModule*/true, IsSystem,
112                                    /*IsModuleFile*/false, /*IsMissing*/false);
113     return true;
114   }
115 };
116 } // end anonymous namespace
117 
maybeAddDependency(StringRef Filename,bool FromModule,bool IsSystem,bool IsModuleFile,bool IsMissing)118 void DependencyCollector::maybeAddDependency(StringRef Filename, bool FromModule,
119                                             bool IsSystem, bool IsModuleFile,
120                                             bool IsMissing) {
121   if (Seen.insert(Filename).second &&
122       sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing))
123     Dependencies.push_back(Filename);
124 }
125 
isSpecialFilename(StringRef Filename)126 static bool isSpecialFilename(StringRef Filename) {
127   return llvm::StringSwitch<bool>(Filename)
128       .Case("<built-in>", true)
129       .Case("<stdin>", true)
130       .Default(false);
131 }
132 
sawDependency(StringRef Filename,bool FromModule,bool IsSystem,bool IsModuleFile,bool IsMissing)133 bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule,
134                                        bool IsSystem, bool IsModuleFile,
135                                        bool IsMissing) {
136   return !isSpecialFilename(Filename) &&
137          (needSystemDependencies() || !IsSystem);
138 }
139 
~DependencyCollector()140 DependencyCollector::~DependencyCollector() { }
attachToPreprocessor(Preprocessor & PP)141 void DependencyCollector::attachToPreprocessor(Preprocessor &PP) {
142   PP.addPPCallbacks(
143       llvm::make_unique<DepCollectorPPCallbacks>(*this, PP.getSourceManager()));
144   PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
145       llvm::make_unique<DepCollectorMMCallbacks>(*this));
146 }
attachToASTReader(ASTReader & R)147 void DependencyCollector::attachToASTReader(ASTReader &R) {
148   R.addListener(llvm::make_unique<DepCollectorASTListener>(*this));
149 }
150 
151 namespace {
152 /// Private implementation for DependencyFileGenerator
153 class DFGImpl : public PPCallbacks {
154   std::vector<std::string> Files;
155   llvm::StringSet<> FilesSet;
156   const Preprocessor *PP;
157   std::string OutputFile;
158   std::vector<std::string> Targets;
159   bool IncludeSystemHeaders;
160   bool PhonyTarget;
161   bool AddMissingHeaderDeps;
162   bool SeenMissingHeader;
163   bool IncludeModuleFiles;
164   DependencyOutputFormat OutputFormat;
165 
166 private:
167   bool FileMatchesDepCriteria(const char *Filename,
168                               SrcMgr::CharacteristicKind FileType);
169   void OutputDependencyFile();
170 
171 public:
DFGImpl(const Preprocessor * _PP,const DependencyOutputOptions & Opts)172   DFGImpl(const Preprocessor *_PP, const DependencyOutputOptions &Opts)
173     : PP(_PP), OutputFile(Opts.OutputFile), Targets(Opts.Targets),
174       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
175       PhonyTarget(Opts.UsePhonyTargets),
176       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps),
177       SeenMissingHeader(false),
178       IncludeModuleFiles(Opts.IncludeModuleFiles),
179       OutputFormat(Opts.OutputFormat) {
180     for (auto ExtraDep : Opts.ExtraDeps) {
181       AddFilename(ExtraDep);
182     }
183   }
184 
185   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
186                    SrcMgr::CharacteristicKind FileType,
187                    FileID PrevFID) override;
188   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
189                           StringRef FileName, bool IsAngled,
190                           CharSourceRange FilenameRange, const FileEntry *File,
191                           StringRef SearchPath, StringRef RelativePath,
192                           const Module *Imported) override;
193 
EndOfMainFile()194   void EndOfMainFile() override {
195     OutputDependencyFile();
196   }
197 
198   void AddFilename(StringRef Filename);
includeSystemHeaders() const199   bool includeSystemHeaders() const { return IncludeSystemHeaders; }
includeModuleFiles() const200   bool includeModuleFiles() const { return IncludeModuleFiles; }
201 };
202 
203 class DFGMMCallback : public ModuleMapCallbacks {
204   DFGImpl &Parent;
205 public:
DFGMMCallback(DFGImpl & Parent)206   DFGMMCallback(DFGImpl &Parent) : Parent(Parent) {}
moduleMapFileRead(SourceLocation Loc,const FileEntry & Entry,bool IsSystem)207   void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry,
208                          bool IsSystem) override {
209     if (!IsSystem || Parent.includeSystemHeaders())
210       Parent.AddFilename(Entry.getName());
211   }
212 };
213 
214 class DFGASTReaderListener : public ASTReaderListener {
215   DFGImpl &Parent;
216 public:
DFGASTReaderListener(DFGImpl & Parent)217   DFGASTReaderListener(DFGImpl &Parent)
218   : Parent(Parent) { }
needsInputFileVisitation()219   bool needsInputFileVisitation() override { return true; }
needsSystemInputFileVisitation()220   bool needsSystemInputFileVisitation() override {
221     return Parent.includeSystemHeaders();
222   }
223   void visitModuleFile(StringRef Filename,
224                        serialization::ModuleKind Kind) override;
225   bool visitInputFile(StringRef Filename, bool isSystem,
226                       bool isOverridden, bool isExplicitModule) override;
227 };
228 }
229 
DependencyFileGenerator(void * Impl)230 DependencyFileGenerator::DependencyFileGenerator(void *Impl)
231 : Impl(Impl) { }
232 
CreateAndAttachToPreprocessor(clang::Preprocessor & PP,const clang::DependencyOutputOptions & Opts)233 DependencyFileGenerator *DependencyFileGenerator::CreateAndAttachToPreprocessor(
234     clang::Preprocessor &PP, const clang::DependencyOutputOptions &Opts) {
235 
236   if (Opts.Targets.empty()) {
237     PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
238     return nullptr;
239   }
240 
241   // Disable the "file not found" diagnostic if the -MG option was given.
242   if (Opts.AddMissingHeaderDeps)
243     PP.SetSuppressIncludeNotFoundError(true);
244 
245   DFGImpl *Callback = new DFGImpl(&PP, Opts);
246   PP.addPPCallbacks(std::unique_ptr<PPCallbacks>(Callback));
247   PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
248       llvm::make_unique<DFGMMCallback>(*Callback));
249   return new DependencyFileGenerator(Callback);
250 }
251 
AttachToASTReader(ASTReader & R)252 void DependencyFileGenerator::AttachToASTReader(ASTReader &R) {
253   DFGImpl *I = reinterpret_cast<DFGImpl *>(Impl);
254   assert(I && "missing implementation");
255   R.addListener(llvm::make_unique<DFGASTReaderListener>(*I));
256 }
257 
258 /// FileMatchesDepCriteria - Determine whether the given Filename should be
259 /// considered as a dependency.
FileMatchesDepCriteria(const char * Filename,SrcMgr::CharacteristicKind FileType)260 bool DFGImpl::FileMatchesDepCriteria(const char *Filename,
261                                      SrcMgr::CharacteristicKind FileType) {
262   if (isSpecialFilename(Filename))
263     return false;
264 
265   if (IncludeSystemHeaders)
266     return true;
267 
268   return FileType == SrcMgr::C_User;
269 }
270 
FileChanged(SourceLocation Loc,FileChangeReason Reason,SrcMgr::CharacteristicKind FileType,FileID PrevFID)271 void DFGImpl::FileChanged(SourceLocation Loc,
272                           FileChangeReason Reason,
273                           SrcMgr::CharacteristicKind FileType,
274                           FileID PrevFID) {
275   if (Reason != PPCallbacks::EnterFile)
276     return;
277 
278   // Dependency generation really does want to go all the way to the
279   // file entry for a source location to find out what is depended on.
280   // We do not want #line markers to affect dependency generation!
281   SourceManager &SM = PP->getSourceManager();
282 
283   const FileEntry *FE =
284     SM.getFileEntryForID(SM.getFileID(SM.getExpansionLoc(Loc)));
285   if (!FE) return;
286 
287   StringRef Filename = FE->getName();
288   if (!FileMatchesDepCriteria(Filename.data(), FileType))
289     return;
290 
291   AddFilename(llvm::sys::path::remove_leading_dotslash(Filename));
292 }
293 
InclusionDirective(SourceLocation HashLoc,const Token & IncludeTok,StringRef FileName,bool IsAngled,CharSourceRange FilenameRange,const FileEntry * File,StringRef SearchPath,StringRef RelativePath,const Module * Imported)294 void DFGImpl::InclusionDirective(SourceLocation HashLoc,
295                                  const Token &IncludeTok,
296                                  StringRef FileName,
297                                  bool IsAngled,
298                                  CharSourceRange FilenameRange,
299                                  const FileEntry *File,
300                                  StringRef SearchPath,
301                                  StringRef RelativePath,
302                                  const Module *Imported) {
303   if (!File) {
304     if (AddMissingHeaderDeps)
305       AddFilename(FileName);
306     else
307       SeenMissingHeader = true;
308   }
309 }
310 
AddFilename(StringRef Filename)311 void DFGImpl::AddFilename(StringRef Filename) {
312   if (FilesSet.insert(Filename).second)
313     Files.push_back(Filename);
314 }
315 
316 /// Print the filename, with escaping or quoting that accommodates the three
317 /// most likely tools that use dependency files: GNU Make, BSD Make, and
318 /// NMake/Jom.
319 ///
320 /// BSD Make is the simplest case: It does no escaping at all.  This means
321 /// characters that are normally delimiters, i.e. space and # (the comment
322 /// character) simply aren't supported in filenames.
323 ///
324 /// GNU Make does allow space and # in filenames, but to avoid being treated
325 /// as a delimiter or comment, these must be escaped with a backslash. Because
326 /// backslash is itself the escape character, if a backslash appears in a
327 /// filename, it should be escaped as well.  (As a special case, $ is escaped
328 /// as $$, which is the normal Make way to handle the $ character.)
329 /// For compatibility with BSD Make and historical practice, if GNU Make
330 /// un-escapes characters in a filename but doesn't find a match, it will
331 /// retry with the unmodified original string.
332 ///
333 /// GCC tries to accommodate both Make formats by escaping any space or #
334 /// characters in the original filename, but not escaping backslashes.  The
335 /// apparent intent is so that filenames with backslashes will be handled
336 /// correctly by BSD Make, and by GNU Make in its fallback mode of using the
337 /// unmodified original string; filenames with # or space characters aren't
338 /// supported by BSD Make at all, but will be handled correctly by GNU Make
339 /// due to the escaping.
340 ///
341 /// A corner case that GCC gets only partly right is when the original filename
342 /// has a backslash immediately followed by space or #.  GNU Make would expect
343 /// this backslash to be escaped; however GCC escapes the original backslash
344 /// only when followed by space, not #.  It will therefore take a dependency
345 /// from a directive such as
346 ///     #include "a\ b\#c.h"
347 /// and emit it as
348 ///     a\\\ b\\#c.h
349 /// which GNU Make will interpret as
350 ///     a\ b\
351 /// followed by a comment. Failing to find this file, it will fall back to the
352 /// original string, which probably doesn't exist either; in any case it won't
353 /// find
354 ///     a\ b\#c.h
355 /// which is the actual filename specified by the include directive.
356 ///
357 /// Clang does what GCC does, rather than what GNU Make expects.
358 ///
359 /// NMake/Jom has a different set of scary characters, but wraps filespecs in
360 /// double-quotes to avoid misinterpreting them; see
361 /// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
362 /// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
363 /// for Windows file-naming info.
PrintFilename(raw_ostream & OS,StringRef Filename,DependencyOutputFormat OutputFormat)364 static void PrintFilename(raw_ostream &OS, StringRef Filename,
365                           DependencyOutputFormat OutputFormat) {
366   if (OutputFormat == DependencyOutputFormat::NMake) {
367     // Add quotes if needed. These are the characters listed as "special" to
368     // NMake, that are legal in a Windows filespec, and that could cause
369     // misinterpretation of the dependency string.
370     if (Filename.find_first_of(" #${}^!") != StringRef::npos)
371       OS << '\"' << Filename << '\"';
372     else
373       OS << Filename;
374     return;
375   }
376   assert(OutputFormat == DependencyOutputFormat::Make);
377   for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
378     if (Filename[i] == '#') // Handle '#' the broken gcc way.
379       OS << '\\';
380     else if (Filename[i] == ' ') { // Handle space correctly.
381       OS << '\\';
382       unsigned j = i;
383       while (j > 0 && Filename[--j] == '\\')
384         OS << '\\';
385     } else if (Filename[i] == '$') // $ is escaped by $$.
386       OS << '$';
387     OS << Filename[i];
388   }
389 }
390 
OutputDependencyFile()391 void DFGImpl::OutputDependencyFile() {
392   if (SeenMissingHeader) {
393     llvm::sys::fs::remove(OutputFile);
394     return;
395   }
396 
397   std::error_code EC;
398   llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::F_Text);
399   if (EC) {
400     PP->getDiagnostics().Report(diag::err_fe_error_opening) << OutputFile
401                                                             << EC.message();
402     return;
403   }
404 
405   // Write out the dependency targets, trying to avoid overly long
406   // lines when possible. We try our best to emit exactly the same
407   // dependency file as GCC (4.2), assuming the included files are the
408   // same.
409   const unsigned MaxColumns = 75;
410   unsigned Columns = 0;
411 
412   for (std::vector<std::string>::iterator
413          I = Targets.begin(), E = Targets.end(); I != E; ++I) {
414     unsigned N = I->length();
415     if (Columns == 0) {
416       Columns += N;
417     } else if (Columns + N + 2 > MaxColumns) {
418       Columns = N + 2;
419       OS << " \\\n  ";
420     } else {
421       Columns += N + 1;
422       OS << ' ';
423     }
424     // Targets already quoted as needed.
425     OS << *I;
426   }
427 
428   OS << ':';
429   Columns += 1;
430 
431   // Now add each dependency in the order it was seen, but avoiding
432   // duplicates.
433   for (std::vector<std::string>::iterator I = Files.begin(),
434          E = Files.end(); I != E; ++I) {
435     // Start a new line if this would exceed the column limit. Make
436     // sure to leave space for a trailing " \" in case we need to
437     // break the line on the next iteration.
438     unsigned N = I->length();
439     if (Columns + (N + 1) + 2 > MaxColumns) {
440       OS << " \\\n ";
441       Columns = 2;
442     }
443     OS << ' ';
444     PrintFilename(OS, *I, OutputFormat);
445     Columns += N + 1;
446   }
447   OS << '\n';
448 
449   // Create phony targets if requested.
450   if (PhonyTarget && !Files.empty()) {
451     // Skip the first entry, this is always the input file itself.
452     for (std::vector<std::string>::iterator I = Files.begin() + 1,
453            E = Files.end(); I != E; ++I) {
454       OS << '\n';
455       PrintFilename(OS, *I, OutputFormat);
456       OS << ":\n";
457     }
458   }
459 }
460 
visitInputFile(llvm::StringRef Filename,bool IsSystem,bool IsOverridden,bool IsExplicitModule)461 bool DFGASTReaderListener::visitInputFile(llvm::StringRef Filename,
462                                           bool IsSystem, bool IsOverridden,
463                                           bool IsExplicitModule) {
464   assert(!IsSystem || needsSystemInputFileVisitation());
465   if (IsOverridden || IsExplicitModule)
466     return true;
467 
468   Parent.AddFilename(Filename);
469   return true;
470 }
471 
visitModuleFile(llvm::StringRef Filename,serialization::ModuleKind Kind)472 void DFGASTReaderListener::visitModuleFile(llvm::StringRef Filename,
473                                            serialization::ModuleKind Kind) {
474   if (Parent.includeModuleFiles())
475     Parent.AddFilename(Filename);
476 }
477