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/PPCallbacks.h"
22 #include "clang/Lex/Preprocessor.h"
23 #include "llvm/ADT/StringSet.h"
24 #include "llvm/Support/FileSystem.h"
25 #include "llvm/Support/Path.h"
26 #include "llvm/Support/raw_ostream.h"
27 
28 using namespace clang;
29 
30 namespace {
31 class DependencyFileCallback : public PPCallbacks {
32   std::vector<std::string> Files;
33   llvm::StringSet<> FilesSet;
34   const Preprocessor *PP;
35   std::string OutputFile;
36   std::vector<std::string> Targets;
37   bool IncludeSystemHeaders;
38   bool PhonyTarget;
39   bool AddMissingHeaderDeps;
40   bool SeenMissingHeader;
41 private:
42   bool FileMatchesDepCriteria(const char *Filename,
43                               SrcMgr::CharacteristicKind FileType);
44   void AddFilename(StringRef Filename);
45   void OutputDependencyFile();
46 
47 public:
48   DependencyFileCallback(const Preprocessor *_PP,
49                          const DependencyOutputOptions &Opts)
50     : PP(_PP), OutputFile(Opts.OutputFile), Targets(Opts.Targets),
51       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
52       PhonyTarget(Opts.UsePhonyTargets),
53       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps),
54       SeenMissingHeader(false) {}
55 
56   virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
57                            SrcMgr::CharacteristicKind FileType,
58                            FileID PrevFID);
59   virtual void InclusionDirective(SourceLocation HashLoc,
60                                   const Token &IncludeTok,
61                                   StringRef FileName,
62                                   bool IsAngled,
63                                   CharSourceRange FilenameRange,
64                                   const FileEntry *File,
65                                   StringRef SearchPath,
66                                   StringRef RelativePath,
67                                   const Module *Imported);
68 
69   virtual void EndOfMainFile() {
70     OutputDependencyFile();
71   }
72 };
73 }
74 
75 void clang::AttachDependencyFileGen(Preprocessor &PP,
76                                     const DependencyOutputOptions &Opts) {
77   if (Opts.Targets.empty()) {
78     PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
79     return;
80   }
81 
82   // Disable the "file not found" diagnostic if the -MG option was given.
83   if (Opts.AddMissingHeaderDeps)
84     PP.SetSuppressIncludeNotFoundError(true);
85 
86   PP.addPPCallbacks(new DependencyFileCallback(&PP, Opts));
87 }
88 
89 /// FileMatchesDepCriteria - Determine whether the given Filename should be
90 /// considered as a dependency.
91 bool DependencyFileCallback::FileMatchesDepCriteria(const char *Filename,
92                                           SrcMgr::CharacteristicKind FileType) {
93   if (strcmp("<built-in>", Filename) == 0)
94     return false;
95 
96   if (IncludeSystemHeaders)
97     return true;
98 
99   return FileType == SrcMgr::C_User;
100 }
101 
102 void DependencyFileCallback::FileChanged(SourceLocation Loc,
103                                          FileChangeReason Reason,
104                                          SrcMgr::CharacteristicKind FileType,
105                                          FileID PrevFID) {
106   if (Reason != PPCallbacks::EnterFile)
107     return;
108 
109   // Dependency generation really does want to go all the way to the
110   // file entry for a source location to find out what is depended on.
111   // We do not want #line markers to affect dependency generation!
112   SourceManager &SM = PP->getSourceManager();
113 
114   const FileEntry *FE =
115     SM.getFileEntryForID(SM.getFileID(SM.getExpansionLoc(Loc)));
116   if (FE == 0) return;
117 
118   StringRef Filename = FE->getName();
119   if (!FileMatchesDepCriteria(Filename.data(), FileType))
120     return;
121 
122   // Remove leading "./" (or ".//" or "././" etc.)
123   while (Filename.size() > 2 && Filename[0] == '.' &&
124          llvm::sys::path::is_separator(Filename[1])) {
125     Filename = Filename.substr(1);
126     while (llvm::sys::path::is_separator(Filename[0]))
127       Filename = Filename.substr(1);
128   }
129 
130   AddFilename(Filename);
131 }
132 
133 void DependencyFileCallback::InclusionDirective(SourceLocation HashLoc,
134                                                 const Token &IncludeTok,
135                                                 StringRef FileName,
136                                                 bool IsAngled,
137                                                 CharSourceRange FilenameRange,
138                                                 const FileEntry *File,
139                                                 StringRef SearchPath,
140                                                 StringRef RelativePath,
141                                                 const Module *Imported) {
142   if (!File) {
143     if (AddMissingHeaderDeps)
144       AddFilename(FileName);
145     else
146       SeenMissingHeader = true;
147   }
148 }
149 
150 void DependencyFileCallback::AddFilename(StringRef Filename) {
151   if (FilesSet.insert(Filename))
152     Files.push_back(Filename);
153 }
154 
155 /// PrintFilename - GCC escapes spaces, # and $, but apparently not ' or " or
156 /// other scary characters.
157 static void PrintFilename(raw_ostream &OS, StringRef Filename) {
158   for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
159     if (Filename[i] == ' ' || Filename[i] == '#')
160       OS << '\\';
161     else if (Filename[i] == '$') // $ is escaped by $$.
162       OS << '$';
163     OS << Filename[i];
164   }
165 }
166 
167 void DependencyFileCallback::OutputDependencyFile() {
168   if (SeenMissingHeader) {
169     llvm::sys::fs::remove(OutputFile);
170     return;
171   }
172 
173   std::string Err;
174   llvm::raw_fd_ostream OS(OutputFile.c_str(), Err);
175   if (!Err.empty()) {
176     PP->getDiagnostics().Report(diag::err_fe_error_opening)
177       << OutputFile << Err;
178     return;
179   }
180 
181   // Write out the dependency targets, trying to avoid overly long
182   // lines when possible. We try our best to emit exactly the same
183   // dependency file as GCC (4.2), assuming the included files are the
184   // same.
185   const unsigned MaxColumns = 75;
186   unsigned Columns = 0;
187 
188   for (std::vector<std::string>::iterator
189          I = Targets.begin(), E = Targets.end(); I != E; ++I) {
190     unsigned N = I->length();
191     if (Columns == 0) {
192       Columns += N;
193     } else if (Columns + N + 2 > MaxColumns) {
194       Columns = N + 2;
195       OS << " \\\n  ";
196     } else {
197       Columns += N + 1;
198       OS << ' ';
199     }
200     // Targets already quoted as needed.
201     OS << *I;
202   }
203 
204   OS << ':';
205   Columns += 1;
206 
207   // Now add each dependency in the order it was seen, but avoiding
208   // duplicates.
209   for (std::vector<std::string>::iterator I = Files.begin(),
210          E = Files.end(); I != E; ++I) {
211     // Start a new line if this would exceed the column limit. Make
212     // sure to leave space for a trailing " \" in case we need to
213     // break the line on the next iteration.
214     unsigned N = I->length();
215     if (Columns + (N + 1) + 2 > MaxColumns) {
216       OS << " \\\n ";
217       Columns = 2;
218     }
219     OS << ' ';
220     PrintFilename(OS, *I);
221     Columns += N + 1;
222   }
223   OS << '\n';
224 
225   // Create phony targets if requested.
226   if (PhonyTarget && !Files.empty()) {
227     // Skip the first entry, this is always the input file itself.
228     for (std::vector<std::string>::iterator I = Files.begin() + 1,
229            E = Files.end(); I != E; ++I) {
230       OS << '\n';
231       PrintFilename(OS, *I);
232       OS << ":\n";
233     }
234   }
235 }
236 
237