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