[FileSystem] Migrate CommandCompletions

[JDevlieghere]

Summary

Make use of the convenience helpers from FileSystem.

[davide]

No objections from me, but I would appreciate if @labath can take a look.

[JDevlieghere]

Initialize the FS in the unit test.

[labath]

Looks good, modulo the filesystem copy comment.

source/Commands/CommandCompletions.cpp

180

This should surely be a reference, no? Making a copy of a filesystem sounds weird (and should probably be forbidden by deleting the copy constructor).

[JDevlieghere]

source/Commands/CommandCompletions.cpp

180

Correct, this is a typo but shouldn't compile. I'll include the fix when landing.

include/lldb/Host/FileSystem.h

public:
   FILE *Fopen(const char *path, const char *mode);
 
   /// Wraps ::open in a platform-independent way.
   int Open(const char *path, int flags, int mode);
 
   Status Open(File &File, const FileSpec &file_spec, uint32_t options,
               uint32_t permissions = lldb::eFilePermissionsFileDefault);
 
+  /// Get a directory iterator.
+  /// @{
+  llvm::vfs::directory_iterator DirBegin(const FileSpec &file_spec,
+                                         std::error_code &ec);
+  llvm::vfs::directory_iterator DirBegin(const llvm::Twine &dir,
+                                         std::error_code &ec);
+  /// @}
+
+  /// Returns the Status object for the given file.
+  /// @{
+  llvm::ErrorOr<llvm::vfs::Status> GetStatus(const FileSpec &file_spec) const;
+  llvm::ErrorOr<llvm::vfs::Status> GetStatus(const llvm::Twine &path) const;
+  /// @}
+
   /// Returns the modification time of the given file.
   /// @{
   llvm::sys::TimePoint<> GetModificationTime(const FileSpec &file_spec) const;
   llvm::sys::TimePoint<> GetModificationTime(const llvm::Twine &path) const;
   /// @}
 
   /// Returns the on-disk size of the given file in bytes.
   /// @{

source/Commands/CommandCompletions.cpp

static int DiskFilesOrDirectories(const llvm::Twine &partial_name,
 
   llvm::SmallString<256> CompletionBuffer;
   llvm::SmallString<256> Storage;
   partial_name.toVector(CompletionBuffer);
 
   if (CompletionBuffer.size() >= PATH_MAX)
     return matches.GetSize();
 
-  namespace fs = llvm::sys::fs;
   namespace path = llvm::sys::path;
 
   llvm::StringRef SearchDir;
   llvm::StringRef PartialItem;
 
   if (CompletionBuffer.startswith("~")) {
     llvm::StringRef Buffer(CompletionBuffer);
     size_t FirstSep =
if (SearchDir.empty()) {
     llvm::sys::fs::current_path(Storage);
     SearchDir = Storage;
   }
   assert(!PartialItem.contains(path::get_separator()));
 
   // SearchDir now contains the directory to search in, and Prefix contains the
   // text we want to match against items in that directory.
 
+  FileSystem fs = FileSystem::Instance();
   std::error_code EC;
-  fs::directory_iterator Iter(SearchDir, EC, false);
-  fs::directory_iterator End;
+  llvm::vfs::directory_iterator Iter = fs.DirBegin(SearchDir, EC);
+  llvm::vfs::directory_iterator End;
   for (; Iter != End && !EC; Iter.increment(EC)) {
     auto &Entry = *Iter;
+    llvm::ErrorOr<llvm::vfs::Status> Status = fs.GetStatus(Entry.path());
+
+    if (!Status)
+      continue;
 
     auto Name = path::filename(Entry.path());
 
     // Omit ".", ".."
     if (Name == "." || Name == ".." || !Name.startswith(PartialItem))
       continue;
 
-    // We have a match.
-
-    llvm::ErrorOr<fs::basic_file_status> st = Entry.status();
-    if (!st)
-      continue;
+    bool is_dir = Status->isDirectory();
 
     // If it's a symlink, then we treat it as a directory as long as the target
     // is a directory.
-    bool is_dir = fs::is_directory(*st);
-    if (fs::is_symlink_file(*st)) {
-      fs::file_status target_st;
-      if (!fs::status(Entry.path(), target_st))
-        is_dir = fs::is_directory(target_st);
+    if (Status->isSymlink()) {
+      FileSpec symlink_filespec(Entry.path());
+      FileSpec resolved_filespec;
+      auto error = fs.ResolveSymbolicLink(symlink_filespec, resolved_filespec);
+      if (error.Success())
+        is_dir = fs.IsDirectory(symlink_filespec);
     }
+
     if (only_directories && !is_dir)
       continue;
 
     // Shrink it back down so that it just has the original prefix the user
     // typed and remove the part of the name which is common to the located
     // item and what the user typed.
     CompletionBuffer.resize(FullPrefixLen);
     Name = Name.drop_front(PartialItem.size());

source/Host/common/FileSystem.cpp

void FileSystem::Terminate() {
   InstanceImpl().reset();
 }
 
 Optional<FileSystem> &FileSystem::InstanceImpl() {
   static Optional<FileSystem> g_fs;
   return g_fs;
 }
 
+vfs::directory_iterator FileSystem::DirBegin(const FileSpec &file_spec,
+                                             std::error_code &ec) {
+  return DirBegin(file_spec.GetPath(), ec);
+}
+
+vfs::directory_iterator FileSystem::DirBegin(const Twine &dir,
+                                             std::error_code &ec) {
+  return m_fs->dir_begin(dir, ec);
+}
+
+llvm::ErrorOr<vfs::Status>
+FileSystem::GetStatus(const FileSpec &file_spec) const {
+  return GetStatus(file_spec.GetPath());
+}
+
+llvm::ErrorOr<vfs::Status> FileSystem::GetStatus(const Twine &path) const {
+  return m_fs->status(path);
+}
+
 sys::TimePoint<>
 FileSystem::GetModificationTime(const FileSpec &file_spec) const {
   return GetModificationTime(file_spec.GetPath());
 }
 
 sys::TimePoint<> FileSystem::GetModificationTime(const Twine &path) const {
   ErrorOr<vfs::Status> status = m_fs->status(path);
   if (!status)