[FileCollector] Add a VFS that records FS accesses using the FileCollector

This patch adds a VFS that can be overlaid on top of another VFS
to record file system accesses using the FileCollector.
This can help to gather files that are needed for reproducers.

Differential Revision: https://reviews.llvm.org/D65411

llvm-svn: 367278

1 files changed, 79 insertions, 0 deletions

diff --git a/llvm/lib/Support/FileCollector.cpp b/llvm/lib/Support/FileCollector.cpp
index 7e14282af08..556a3c03db5 100644
--- a/llvm/lib/Support/FileCollector.cpp
+++ b/llvm/lib/Support/FileCollector.cpp
@@ -187,3 +187,82 @@ std::error_code FileCollector::writeMapping(StringRef mapping_file) {
 
   return {};
 }
+
+namespace {
+
+class FileCollectorFileSystem : public vfs::FileSystem {
+public:
+  explicit FileCollectorFileSystem(IntrusiveRefCntPtr<vfs::FileSystem> FS,
+                                   std::shared_ptr<FileCollector> Collector)
+      : FS(std::move(FS)), Collector(std::move(Collector)) {}
+
+  llvm::ErrorOr<llvm::vfs::Status> status(const Twine &Path) override {
+    auto Result = FS->status(Path);
+    if (Result && Result->exists())
+      Collector->addFile(Path);
+    return Result;
+  }
+
+  llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
+  openFileForRead(const Twine &Path) override {
+    auto Result = FS->openFileForRead(Path);
+    if (Result && *Result)
+      Collector->addFile(Path);
+    return Result;
+  }
+
+  llvm::vfs::directory_iterator dir_begin(const llvm::Twine &Dir,
+                                          std::error_code &EC) override {
+    auto It = FS->dir_begin(Dir, EC);
+    if (EC)
+      return It;
+    // Collect everything that's listed in case the user needs it.
+    Collector->addFile(Dir);
+    for (; !EC && It != llvm::vfs::directory_iterator(); It.increment(EC)) {
+      if (It->type() == sys::fs::file_type::regular_file ||
+          It->type() == sys::fs::file_type::directory_file ||
+          It->type() == sys::fs::file_type::symlink_file) {
+        Collector->addFile(It->path());
+      }
+    }
+    if (EC)
+      return It;
+    // Return a new iterator.
+    return FS->dir_begin(Dir, EC);
+  }
+
+  std::error_code getRealPath(const Twine &Path,
+                              SmallVectorImpl<char> &Output) const override {
+    auto EC = FS->getRealPath(Path, Output);
+    if (!EC) {
+      Collector->addFile(Path);
+      if (Output.size() > 0)
+        Collector->addFile(Output);
+    }
+    return EC;
+  }
+
+  std::error_code isLocal(const Twine &Path, bool &Result) override {
+    return FS->isLocal(Path, Result);
+  }
+
+  llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
+    return FS->getCurrentWorkingDirectory();
+  }
+
+  std::error_code setCurrentWorkingDirectory(const llvm::Twine &Path) override {
+    return FS->setCurrentWorkingDirectory(Path);
+  }
+
+private:
+  IntrusiveRefCntPtr<vfs::FileSystem> FS;
+  std::shared_ptr<FileCollector> Collector;
+};
+
+} // end anonymous namespace
+
+IntrusiveRefCntPtr<vfs::FileSystem>
+FileCollector::createCollectorVFS(IntrusiveRefCntPtr<vfs::FileSystem> BaseFS,
+                                  std::shared_ptr<FileCollector> Collector) {
+  return new FileCollectorFileSystem(std::move(BaseFS), std::move(Collector));
+}