[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, 31 insertions, 2 deletions

diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index d2a2c0fb8e9..dc6922291a4 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -26,6 +26,7 @@
 // These two headers must be included last, and make sure shlobj is required
 // after Windows.h to make sure it picks up our definition of _WIN32_WINNT
 #include "WindowsSupport.h"
+#include <shellapi.h>
 #include <shlobj.h>
 
 #undef max
@@ -693,7 +694,8 @@ int mapped_file_region::alignment() {
 }
 
 std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
-                                                StringRef path){
+                                                     StringRef path,
+                                                     bool follow_symlinks) {
   SmallVector<wchar_t, 128> path_utf16;
 
   if (std::error_code ec = widenPath(path, path_utf16))
@@ -738,7 +740,7 @@ std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
   it.IterationHandle = intptr_t(FindHandle.take());
   SmallString<128> directory_entry_path(path);
   path::append(directory_entry_path, directory_entry_name_utf8);
-  it.CurrentEntry = directory_entry(directory_entry_path);
+  it.CurrentEntry = directory_entry(directory_entry_path, follow_symlinks);
 
   return std::error_code();
 }
@@ -920,6 +922,33 @@ std::error_code getPathFromOpenFD(int FD, SmallVectorImpl<char> &ResultPath) {
 
   return windows::UTF16ToUTF8(TempPath.data(), CharCount, ResultPath);
 }
+
+std::error_code remove_directories(const Twine &path, bool IgnoreErrors) {
+  // Convert to utf-16.
+  SmallVector<wchar_t, 128> Path16;
+  std::error_code EC = widenPath(path, Path16);
+  if (EC && !IgnoreErrors)
+    return EC;
+
+  // SHFileOperation() accepts a list of paths, and so must be double null-
+  // terminated to indicate the end of the list.  The buffer is already null
+  // terminated, but since that null character is not considered part of the
+  // vector's size, pushing another one will just consume that byte.  So we
+  // need to push 2 null terminators.
+  Path16.push_back(0);
+  Path16.push_back(0);
+
+  SHFILEOPSTRUCTW shfos = {};
+  shfos.wFunc = FO_DELETE;
+  shfos.pFrom = Path16.data();
+  shfos.fFlags = FOF_NO_UI;
+
+  int result = ::SHFileOperationW(&shfos);
+  if (result != 0 && !IgnoreErrors)
+    return mapWindowsError(result);
+  return std::error_code();
+}
+
 } // end namespace fs
 
 namespace path {