Support/FileSystem: Add resize_file implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120819 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Unix/PathV2.inc b/lib/Support/Unix/PathV2.inc
index 8ecf2a4..75cfce8 100644
--- a/lib/Support/Unix/PathV2.inc
+++ b/lib/Support/Unix/PathV2.inc
@@ -213,6 +213,16 @@
   return make_error_code(errc::success);
 }
 
+error_code resize_file(const Twine &path, uint64_t size) {
+  SmallString<128> path_storage;
+  StringRef p = path.toNullTerminatedStringRef(path_storage);
+
+  if (::truncate(p.begin(), size) == -1)
+    return error_code(errno, system_category());
+
+  return make_error_code(errc::success);
+}
+
 error_code exists(const Twine &path, bool &result) {
   SmallString<128> path_storage;
   StringRef p = path.toNullTerminatedStringRef(path_storage);