[Support] Add llvm::sys::fs::remove_directories.

We already have a function create_directories() which can create
an entire tree, and remove() which can remove an empty directory,
but we do not have remove_directories() which can remove an entire
tree.  This patch adds such a function.

Because removing a directory tree can have dangerous consequences
when the tree contains a directory symlink, the patch here updates
the existing directory_iterator construct to optionally not follow
symlinks (previously it would always follow symlinks).  The delete
algorithm uses this flag so that for symlinks, only the links are
removed, and not the targets.

On Windows this is implemented with SHFileOperation, which also
does not recurse into symbolic links or junctions.

Differential Revision: https://reviews.llvm.org/D30676

llvm-svn: 297314

1 files changed, 43 insertions, 2 deletions

diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 76e1ed2..568b1b4 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -618,7 +618,8 @@ int mapped_file_region::alignment() {
 }
 
 std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
-                                                StringRef path){
+                                                     StringRef path,
+                                                     bool follow_symlinks) {
   SmallString<128> path_null(path);
   DIR *directory = ::opendir(path_null.c_str());
   if (!directory)
@@ -627,7 +628,7 @@ std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
   it.IterationHandle = reinterpret_cast<intptr_t>(directory);
   // Add something for replace_filename to replace.
   path::append(path_null, ".");
-  it.CurrentEntry = directory_entry(path_null.str());
+  it.CurrentEntry = directory_entry(path_null.str(), follow_symlinks);
   return directory_iterator_increment(it);
 }
 
@@ -795,6 +796,46 @@ std::error_code getPathFromOpenFD(int FD, SmallVectorImpl<char> &ResultPath) {
   return std::error_code();
 }
 
+template <typename T>
+static std::error_code remove_directories_impl(const T &Entry,
+                                               bool IgnoreErrors) {
+  std::error_code EC;
+  directory_iterator Begin(Entry, EC, false);
+  directory_iterator End;
+  while (Begin != End) {
+    auto &Item = *Begin;
+    file_status st;
+    EC = Item.status(st);
+    if (EC && !IgnoreErrors)
+      return EC;
+
+    if (is_directory(st)) {
+      EC = remove_directories_impl(Item, IgnoreErrors);
+      if (EC && !IgnoreErrors)
+        return EC;
+    }
+
+    EC = fs::remove(Item.path(), true);
+    if (EC && !IgnoreErrors)
+      return EC;
+
+    Begin.increment(EC);
+    if (EC && !IgnoreErrors)
+      return EC;
+  }
+  return std::error_code();
+}
+
+std::error_code remove_directories(const Twine &path, bool IgnoreErrors) {
+  auto EC = remove_directories_impl(path, IgnoreErrors);
+  if (EC && !IgnoreErrors)
+    return EC;
+  EC = fs::remove(path, true);
+  if (EC && !IgnoreErrors)
+    return EC;
+  return std::error_code();
+}
+
 } // end namespace fs
 
 namespace path {