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      1 //===--- ModuleDependencyCollector.cpp - Collect module dependencies ------===//
      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 // Collect the dependencies of a set of modules.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/Frontend/Utils.h"
     15 #include "clang/Serialization/ASTReader.h"
     16 #include "llvm/ADT/iterator_range.h"
     17 #include "llvm/ADT/StringSet.h"
     18 #include "llvm/Support/FileSystem.h"
     19 #include "llvm/Support/Path.h"
     20 #include "llvm/Support/raw_ostream.h"
     21 
     22 using namespace clang;
     23 
     24 namespace {
     25 /// Private implementation for ModuleDependencyCollector
     26 class ModuleDependencyListener : public ASTReaderListener {
     27   ModuleDependencyCollector &Collector;
     28 
     29   std::error_code copyToRoot(StringRef Src);
     30 public:
     31   ModuleDependencyListener(ModuleDependencyCollector &Collector)
     32       : Collector(Collector) {}
     33   bool needsInputFileVisitation() override { return true; }
     34   bool needsSystemInputFileVisitation() override { return true; }
     35   bool visitInputFile(StringRef Filename, bool IsSystem,
     36                       bool IsOverridden) override;
     37 };
     38 }
     39 
     40 void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
     41   R.addListener(new ModuleDependencyListener(*this));
     42 }
     43 
     44 void ModuleDependencyCollector::writeFileMap() {
     45   if (Seen.empty())
     46     return;
     47 
     48   SmallString<256> Dest = getDest();
     49   llvm::sys::path::append(Dest, "vfs.yaml");
     50 
     51   std::string ErrorInfo;
     52   llvm::raw_fd_ostream OS(Dest.c_str(), ErrorInfo, llvm::sys::fs::F_Text);
     53   if (!ErrorInfo.empty()) {
     54     setHasErrors();
     55     return;
     56   }
     57   VFSWriter.write(OS);
     58 }
     59 
     60 /// Remove traversal (ie, . or ..) from the given absolute path.
     61 static void removePathTraversal(SmallVectorImpl<char> &Path) {
     62   using namespace llvm::sys;
     63   SmallVector<StringRef, 16> ComponentStack;
     64   StringRef P(Path.data(), Path.size());
     65 
     66   // Skip the root path, then look for traversal in the components.
     67   StringRef Rel = path::relative_path(P);
     68   for (StringRef C : llvm::make_range(path::begin(Rel), path::end(Rel))) {
     69     if (C == ".")
     70       continue;
     71     if (C == "..") {
     72       assert(ComponentStack.size() && "Path traverses out of parent");
     73       ComponentStack.pop_back();
     74     } else
     75       ComponentStack.push_back(C);
     76   }
     77 
     78   // The stack is now the path without any directory traversal.
     79   SmallString<256> Buffer = path::root_path(P);
     80   for (StringRef C : ComponentStack)
     81     path::append(Buffer, C);
     82 
     83   // Put the result in Path.
     84   Path.swap(Buffer);
     85 }
     86 
     87 std::error_code ModuleDependencyListener::copyToRoot(StringRef Src) {
     88   using namespace llvm::sys;
     89 
     90   // We need an absolute path to append to the root.
     91   SmallString<256> AbsoluteSrc = Src;
     92   fs::make_absolute(AbsoluteSrc);
     93   removePathTraversal(AbsoluteSrc);
     94 
     95   // Build the destination path.
     96   SmallString<256> Dest = Collector.getDest();
     97   path::append(Dest, path::relative_path(AbsoluteSrc));
     98 
     99   // Copy the file into place.
    100   if (std::error_code EC = fs::create_directories(path::parent_path(Dest),
    101                                                    /*IgnoreExisting=*/true))
    102     return EC;
    103   if (std::error_code EC = fs::copy_file(AbsoluteSrc.str(), Dest.str()))
    104     return EC;
    105   // Use the absolute path under the root for the file mapping.
    106   Collector.addFileMapping(AbsoluteSrc.str(), Dest.str());
    107   return std::error_code();
    108 }
    109 
    110 bool ModuleDependencyListener::visitInputFile(StringRef Filename, bool IsSystem,
    111                                               bool IsOverridden) {
    112   if (Collector.insertSeen(Filename))
    113     if (copyToRoot(Filename))
    114       Collector.setHasErrors();
    115   return true;
    116 }
    117