[FileCollector] add support for recording empty directories

The file collector class is useful for constructing reproducers by
creating a snapshot of the files that are accessed. Sometimes it might
also be important to construct directories that don't necessarily have files,
but are still accessed by some tool that we want to make a reproducer for.
This is useful for instance for modeling the behavior of Clang's header search,
which scans through a number of directories it doesn't actually access when
looking for framework headers. This commit extends the file collector to allow
it to work with paths that are just directories, by constructing them as the
files are copied over.

Differential Revision: https://reviews.llvm.org/D65297

llvm-svn: 367061

llvm/lib/Support/FileCollector.cpp

@@ -132,6 +132,25 @@ std::error_code FileCollector::copyFiles(bool StopOnError) {
         return EC;
     }
 
+    // Get the status of the original file/directory.
+    sys::fs::file_status Stat;
+    if (std::error_code EC = sys::fs::status(entry.VPath, Stat)) {
+      if (StopOnError)
+        return EC;
+      continue;
+    }
+
+    if (Stat.type() == sys::fs::file_type::directory_file) {
+      // Construct a directory when it's just a directory entry.
+      if (std::error_code EC =
+              sys::fs::create_directories(entry.RPath,
+                                          /*IgnoreExisting=*/true)) {
+        if (StopOnError)
+          return EC;
+      }
+      continue;
+    }
+
     // Copy file over.
     if (std::error_code EC = sys::fs::copy_file(entry.VPath, entry.RPath)) {
       if (StopOnError)
@@ -147,12 +166,6 @@ std::error_code FileCollector::copyFiles(bool StopOnError) {
     }
 
     // Copy over modification time.
-    sys::fs::file_status Stat;
-    if (std::error_code EC = sys::fs::status(entry.VPath, Stat)) {
-      if (StopOnError)
-        return EC;
-      continue;
-    }
     copyAccessAndModificationTime(entry.RPath, Stat);
   }
   return {};

llvm/unittests/Support/FileCollectorTest.cpp

@@ -148,6 +148,37 @@ TEST(FileCollectorTest, copyFiles) {
   EXPECT_FALSE(ec);
 }
 
+TEST(FileCollectorTest, recordAndConstructDirectory) {
+  ScopedDir file_root("dir_root", true);
+  ScopedDir subdir(file_root + "/subdir");
+  ScopedDir subdir2(file_root + "/subdir2");
+  ScopedFile a(subdir2 + "/a");
+
+  // Create file collector and add files.
+  ScopedDir root("copy_files_root", true);
+  std::string root_fs = root.Path.str();
+  TestingFileCollector FileCollector(root_fs, root_fs);
+  FileCollector.addFile(a.Path);
+
+  // The empty directory isn't seen until we add it.
+  EXPECT_TRUE(FileCollector.hasSeen(a.Path));
+  EXPECT_FALSE(FileCollector.hasSeen(subdir.Path));
+
+  FileCollector.addFile(subdir.Path);
+  EXPECT_TRUE(FileCollector.hasSeen(subdir.Path));
+
+  // Make sure we can construct the directory.
+  std::error_code ec = FileCollector.copyFiles(true);
+  EXPECT_FALSE(ec);
+  bool IsDirectory = false;
+  llvm::SmallString<128> SubdirInRoot = root.Path;
+  llvm::sys::path::append(SubdirInRoot,
+                          llvm::sys::path::relative_path(subdir.Path));
+  ec = sys::fs::is_directory(SubdirInRoot, IsDirectory);
+  EXPECT_FALSE(ec);
+  ASSERT_TRUE(IsDirectory);
+}
+
 #ifndef _WIN32
 TEST(FileCollectorTest, Symlinks) {
   // Root where the original files live.