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;
37   DepCollectorPPCallbacks(DependencyCollector &L, SourceManager &SM)
38       : DepCollector(L), SM(SM) { }
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 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,
67                           SrcMgr::CharacteristicKind FileType) override {
68     if (!File)
69       DepCollector.maybeAddDependency(FileName, /*FromModule*/false,
70                                      /*IsSystem*/false, /*IsModuleFile*/false,
71                                      /*IsMissing*/true);
72     // Files that actually exist are handled by FileChanged.
73   }
74 
75   void EndOfMainFile() override {
76     DepCollector.finishedMainFile();
77   }
78 };
79 
80 struct DepCollectorMMCallbacks : public ModuleMapCallbacks {
81   DependencyCollector &DepCollector;
82   DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {}
83 
84   void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry,
85                          bool IsSystem) override {
86     StringRef Filename = Entry.getName();
87     DepCollector.maybeAddDependency(Filename, /*FromModule*/false,
88                                     /*IsSystem*/IsSystem,
89                                     /*IsModuleFile*/false,
90                                     /*IsMissing*/false);
91   }
92 };
93 
94 struct DepCollectorASTListener : public ASTReaderListener {
95   DependencyCollector &DepCollector;
96   DepCollectorASTListener(DependencyCollector &L) : DepCollector(L) { }
97   bool needsInputFileVisitation() override { return true; }
98   bool needsSystemInputFileVisitation() override {
99     return DepCollector.needSystemDependencies();
100   }
101   void visitModuleFile(StringRef Filename,
102                        serialization::ModuleKind Kind) override {
103     DepCollector.maybeAddDependency(Filename, /*FromModule*/true,
104                                    /*IsSystem*/false, /*IsModuleFile*/true,
105                                    /*IsMissing*/false);
106   }
107   bool visitInputFile(StringRef Filename, bool IsSystem,
108                       bool IsOverridden, bool IsExplicitModule) override {
109     if (IsOverridden || IsExplicitModule)
110       return true;
111 
112     DepCollector.maybeAddDependency(Filename, /*FromModule*/true, IsSystem,
113                                    /*IsModuleFile*/false, /*IsMissing*/false);
114     return true;
115   }
116 };
117 } // end anonymous namespace
118 
119 void DependencyCollector::maybeAddDependency(StringRef Filename, bool FromModule,
120                                             bool IsSystem, bool IsModuleFile,
121                                             bool IsMissing) {
122   if (Seen.insert(Filename).second &&
123       sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing))
124     Dependencies.push_back(Filename);
125 }
126 
127 static bool isSpecialFilename(StringRef Filename) {
128   return llvm::StringSwitch<bool>(Filename)
129       .Case("<built-in>", true)
130       .Case("<stdin>", true)
131       .Default(false);
132 }
133 
134 bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule,
135                                        bool IsSystem, bool IsModuleFile,
136                                        bool IsMissing) {
137   return !isSpecialFilename(Filename) &&
138          (needSystemDependencies() || !IsSystem);
139 }
140 
141 DependencyCollector::~DependencyCollector() { }
142 void DependencyCollector::attachToPreprocessor(Preprocessor &PP) {
143   PP.addPPCallbacks(
144       llvm::make_unique<DepCollectorPPCallbacks>(*this, PP.getSourceManager()));
145   PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
146       llvm::make_unique<DepCollectorMMCallbacks>(*this));
147 }
148 void DependencyCollector::attachToASTReader(ASTReader &R) {
149   R.addListener(llvm::make_unique<DepCollectorASTListener>(*this));
150 }
151 
152 namespace {
153 /// Private implementation for DependencyFileGenerator
154 class DFGImpl : public PPCallbacks {
155   std::vector<std::string> Files;
156   llvm::StringSet<> FilesSet;
157   const Preprocessor *PP;
158   std::string OutputFile;
159   std::vector<std::string> Targets;
160   bool IncludeSystemHeaders;
161   bool PhonyTarget;
162   bool AddMissingHeaderDeps;
163   bool SeenMissingHeader;
164   bool IncludeModuleFiles;
165   DependencyOutputFormat OutputFormat;
166   unsigned InputFileIndex;
167 
168 private:
169   bool FileMatchesDepCriteria(const char *Filename,
170                               SrcMgr::CharacteristicKind FileType);
171   void OutputDependencyFile();
172 
173 public:
174   DFGImpl(const Preprocessor *_PP, const DependencyOutputOptions &Opts)
175     : PP(_PP), OutputFile(Opts.OutputFile), Targets(Opts.Targets),
176       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
177       PhonyTarget(Opts.UsePhonyTargets),
178       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps),
179       SeenMissingHeader(false),
180       IncludeModuleFiles(Opts.IncludeModuleFiles),
181       OutputFormat(Opts.OutputFormat),
182       InputFileIndex(0) {
183     for (const auto &ExtraDep : Opts.ExtraDeps) {
184       if (AddFilename(ExtraDep))
185         ++InputFileIndex;
186     }
187   }
188 
189   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
190                    SrcMgr::CharacteristicKind FileType,
191                    FileID PrevFID) override;
192 
193   void FileSkipped(const FileEntry &SkippedFile, const Token &FilenameTok,
194                    SrcMgr::CharacteristicKind FileType) override;
195 
196   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
197                           StringRef FileName, bool IsAngled,
198                           CharSourceRange FilenameRange, const FileEntry *File,
199                           StringRef SearchPath, StringRef RelativePath,
200                           const Module *Imported,
201                           SrcMgr::CharacteristicKind FileType) override;
202 
203   void EndOfMainFile() override {
204     OutputDependencyFile();
205   }
206 
207   bool AddFilename(StringRef Filename);
208   bool includeSystemHeaders() const { return IncludeSystemHeaders; }
209   bool includeModuleFiles() const { return IncludeModuleFiles; }
210 };
211 
212 class DFGMMCallback : public ModuleMapCallbacks {
213   DFGImpl &Parent;
214 public:
215   DFGMMCallback(DFGImpl &Parent) : Parent(Parent) {}
216   void moduleMapFileRead(SourceLocation Loc, const FileEntry &Entry,
217                          bool IsSystem) override {
218     if (!IsSystem || Parent.includeSystemHeaders())
219       Parent.AddFilename(Entry.getName());
220   }
221 };
222 
223 class DFGASTReaderListener : public ASTReaderListener {
224   DFGImpl &Parent;
225 public:
226   DFGASTReaderListener(DFGImpl &Parent)
227   : Parent(Parent) { }
228   bool needsInputFileVisitation() override { return true; }
229   bool needsSystemInputFileVisitation() override {
230     return Parent.includeSystemHeaders();
231   }
232   void visitModuleFile(StringRef Filename,
233                        serialization::ModuleKind Kind) override;
234   bool visitInputFile(StringRef Filename, bool isSystem,
235                       bool isOverridden, bool isExplicitModule) override;
236 };
237 }
238 
239 DependencyFileGenerator::DependencyFileGenerator(void *Impl)
240 : Impl(Impl) { }
241 
242 DependencyFileGenerator *DependencyFileGenerator::CreateAndAttachToPreprocessor(
243     clang::Preprocessor &PP, const clang::DependencyOutputOptions &Opts) {
244 
245   if (Opts.Targets.empty()) {
246     PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
247     return nullptr;
248   }
249 
250   // Disable the "file not found" diagnostic if the -MG option was given.
251   if (Opts.AddMissingHeaderDeps)
252     PP.SetSuppressIncludeNotFoundError(true);
253 
254   DFGImpl *Callback = new DFGImpl(&PP, Opts);
255   PP.addPPCallbacks(std::unique_ptr<PPCallbacks>(Callback));
256   PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
257       llvm::make_unique<DFGMMCallback>(*Callback));
258   return new DependencyFileGenerator(Callback);
259 }
260 
261 void DependencyFileGenerator::AttachToASTReader(ASTReader &R) {
262   DFGImpl *I = reinterpret_cast<DFGImpl *>(Impl);
263   assert(I && "missing implementation");
264   R.addListener(llvm::make_unique<DFGASTReaderListener>(*I));
265 }
266 
267 /// FileMatchesDepCriteria - Determine whether the given Filename should be
268 /// considered as a dependency.
269 bool DFGImpl::FileMatchesDepCriteria(const char *Filename,
270                                      SrcMgr::CharacteristicKind FileType) {
271   if (isSpecialFilename(Filename))
272     return false;
273 
274   if (IncludeSystemHeaders)
275     return true;
276 
277   return !isSystem(FileType);
278 }
279 
280 void DFGImpl::FileChanged(SourceLocation Loc,
281                           FileChangeReason Reason,
282                           SrcMgr::CharacteristicKind FileType,
283                           FileID PrevFID) {
284   if (Reason != PPCallbacks::EnterFile)
285     return;
286 
287   // Dependency generation really does want to go all the way to the
288   // file entry for a source location to find out what is depended on.
289   // We do not want #line markers to affect dependency generation!
290   SourceManager &SM = PP->getSourceManager();
291 
292   const FileEntry *FE =
293     SM.getFileEntryForID(SM.getFileID(SM.getExpansionLoc(Loc)));
294   if (!FE) return;
295 
296   StringRef Filename = FE->getName();
297   if (!FileMatchesDepCriteria(Filename.data(), FileType))
298     return;
299 
300   AddFilename(llvm::sys::path::remove_leading_dotslash(Filename));
301 }
302 
303 void DFGImpl::FileSkipped(const FileEntry &SkippedFile,
304                           const Token &FilenameTok,
305                           SrcMgr::CharacteristicKind FileType) {
306   StringRef Filename = SkippedFile.getName();
307   if (!FileMatchesDepCriteria(Filename.data(), FileType))
308     return;
309 
310   AddFilename(llvm::sys::path::remove_leading_dotslash(Filename));
311 }
312 
313 void DFGImpl::InclusionDirective(SourceLocation HashLoc,
314                                  const Token &IncludeTok,
315                                  StringRef FileName,
316                                  bool IsAngled,
317                                  CharSourceRange FilenameRange,
318                                  const FileEntry *File,
319                                  StringRef SearchPath,
320                                  StringRef RelativePath,
321                                  const Module *Imported,
322                                  SrcMgr::CharacteristicKind FileType) {
323   if (!File) {
324     if (AddMissingHeaderDeps)
325       AddFilename(FileName);
326     else
327       SeenMissingHeader = true;
328   }
329 }
330 
331 bool DFGImpl::AddFilename(StringRef Filename) {
332   if (FilesSet.insert(Filename).second) {
333     Files.push_back(Filename);
334     return true;
335   }
336   return false;
337 }
338 
339 /// Print the filename, with escaping or quoting that accommodates the three
340 /// most likely tools that use dependency files: GNU Make, BSD Make, and
341 /// NMake/Jom.
342 ///
343 /// BSD Make is the simplest case: It does no escaping at all.  This means
344 /// characters that are normally delimiters, i.e. space and # (the comment
345 /// character) simply aren't supported in filenames.
346 ///
347 /// GNU Make does allow space and # in filenames, but to avoid being treated
348 /// as a delimiter or comment, these must be escaped with a backslash. Because
349 /// backslash is itself the escape character, if a backslash appears in a
350 /// filename, it should be escaped as well.  (As a special case, $ is escaped
351 /// as $$, which is the normal Make way to handle the $ character.)
352 /// For compatibility with BSD Make and historical practice, if GNU Make
353 /// un-escapes characters in a filename but doesn't find a match, it will
354 /// retry with the unmodified original string.
355 ///
356 /// GCC tries to accommodate both Make formats by escaping any space or #
357 /// characters in the original filename, but not escaping backslashes.  The
358 /// apparent intent is so that filenames with backslashes will be handled
359 /// correctly by BSD Make, and by GNU Make in its fallback mode of using the
360 /// unmodified original string; filenames with # or space characters aren't
361 /// supported by BSD Make at all, but will be handled correctly by GNU Make
362 /// due to the escaping.
363 ///
364 /// A corner case that GCC gets only partly right is when the original filename
365 /// has a backslash immediately followed by space or #.  GNU Make would expect
366 /// this backslash to be escaped; however GCC escapes the original backslash
367 /// only when followed by space, not #.  It will therefore take a dependency
368 /// from a directive such as
369 ///     #include "a\ b\#c.h"
370 /// and emit it as
371 ///     a\\\ b\\#c.h
372 /// which GNU Make will interpret as
373 ///     a\ b\
374 /// followed by a comment. Failing to find this file, it will fall back to the
375 /// original string, which probably doesn't exist either; in any case it won't
376 /// find
377 ///     a\ b\#c.h
378 /// which is the actual filename specified by the include directive.
379 ///
380 /// Clang does what GCC does, rather than what GNU Make expects.
381 ///
382 /// NMake/Jom has a different set of scary characters, but wraps filespecs in
383 /// double-quotes to avoid misinterpreting them; see
384 /// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
385 /// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
386 /// for Windows file-naming info.
387 static void PrintFilename(raw_ostream &OS, StringRef Filename,
388                           DependencyOutputFormat OutputFormat) {
389   if (OutputFormat == DependencyOutputFormat::NMake) {
390     // Add quotes if needed. These are the characters listed as "special" to
391     // NMake, that are legal in a Windows filespec, and that could cause
392     // misinterpretation of the dependency string.
393     if (Filename.find_first_of(" #${}^!") != StringRef::npos)
394       OS << '\"' << Filename << '\"';
395     else
396       OS << Filename;
397     return;
398   }
399   assert(OutputFormat == DependencyOutputFormat::Make);
400   for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
401     if (Filename[i] == '#') // Handle '#' the broken gcc way.
402       OS << '\\';
403     else if (Filename[i] == ' ') { // Handle space correctly.
404       OS << '\\';
405       unsigned j = i;
406       while (j > 0 && Filename[--j] == '\\')
407         OS << '\\';
408     } else if (Filename[i] == '$') // $ is escaped by $$.
409       OS << '$';
410     OS << Filename[i];
411   }
412 }
413 
414 void DFGImpl::OutputDependencyFile() {
415   if (SeenMissingHeader) {
416     llvm::sys::fs::remove(OutputFile);
417     return;
418   }
419 
420   std::error_code EC;
421   llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::F_Text);
422   if (EC) {
423     PP->getDiagnostics().Report(diag::err_fe_error_opening) << OutputFile
424                                                             << EC.message();
425     return;
426   }
427 
428   // Write out the dependency targets, trying to avoid overly long
429   // lines when possible. We try our best to emit exactly the same
430   // dependency file as GCC (4.2), assuming the included files are the
431   // same.
432   const unsigned MaxColumns = 75;
433   unsigned Columns = 0;
434 
435   for (StringRef Target : Targets) {
436     unsigned N = Target.size();
437     if (Columns == 0) {
438       Columns += N;
439     } else if (Columns + N + 2 > MaxColumns) {
440       Columns = N + 2;
441       OS << " \\\n  ";
442     } else {
443       Columns += N + 1;
444       OS << ' ';
445     }
446     // Targets already quoted as needed.
447     OS << Target;
448   }
449 
450   OS << ':';
451   Columns += 1;
452 
453   // Now add each dependency in the order it was seen, but avoiding
454   // duplicates.
455   for (StringRef File : Files) {
456     // Start a new line if this would exceed the column limit. Make
457     // sure to leave space for a trailing " \" in case we need to
458     // break the line on the next iteration.
459     unsigned N = File.size();
460     if (Columns + (N + 1) + 2 > MaxColumns) {
461       OS << " \\\n ";
462       Columns = 2;
463     }
464     OS << ' ';
465     PrintFilename(OS, File, OutputFormat);
466     Columns += N + 1;
467   }
468   OS << '\n';
469 
470   // Create phony targets if requested.
471   if (PhonyTarget && !Files.empty()) {
472     unsigned Index = 0;
473     for (auto I = Files.begin(), E = Files.end(); I != E; ++I) {
474       if (Index++ == InputFileIndex)
475         continue;
476       OS << '\n';
477       PrintFilename(OS, *I, OutputFormat);
478       OS << ":\n";
479     }
480   }
481 }
482 
483 bool DFGASTReaderListener::visitInputFile(llvm::StringRef Filename,
484                                           bool IsSystem, bool IsOverridden,
485                                           bool IsExplicitModule) {
486   assert(!IsSystem || needsSystemInputFileVisitation());
487   if (IsOverridden || IsExplicitModule)
488     return true;
489 
490   Parent.AddFilename(Filename);
491   return true;
492 }
493 
494 void DFGASTReaderListener::visitModuleFile(llvm::StringRef Filename,
495                                            serialization::ModuleKind Kind) {
496   if (Parent.includeModuleFiles())
497     Parent.AddFilename(Filename);
498 }
499