[Support] Extend sys::path with user_cache_directory function.

Summary:
The new function sys::path::user_cache_directory tries to discover
a directory suitable for cache storage for current system user.

On Windows and Darwin it returns a path to system-specific user cache directory.

On Linux it follows XDG Base Directory Specification, what is:
- use non-empty $XDG_CACHE_HOME env var,
- use $HOME/.cache.

Reviewers: chapuni, aaron.ballman, rafael

Subscribers: rafael, aaron.ballman, llvm-commits

Differential Revision: http://reviews.llvm.org/D13801

llvm-svn: 251784

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index e5150bcbb7e..f45774bca7b 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -1094,3 +1094,20 @@ std::error_code directory_entry::status(file_status &result) const {
 #if defined(LLVM_ON_WIN32)
 #include "Windows/Path.inc"
 #endif
+
+namespace llvm {
+namespace sys {
+namespace path {
+
+bool user_cache_directory(SmallVectorImpl<char> &Result, const Twine &Path1,
+                          const Twine &Path2, const Twine &Path3) {
+  if (getUserCacheDir(Result)) {
+    append(Result, Path1, Path2, Path3);
+    return true;
+  }
+  return false;
+}
+
+} // end namespace path
+} // end namsspace sys
+} // end namespace llvm