Support/FileSystem: Add equivalent implementation.

llvm-svn: 120827

llvm/lib/Support/Unix/PathV2.inc

@@ -238,6 +238,31 @@ error_code exists(const Twine &path, bool &result) {
   return make_error_code(errc::success);
 }
 
+error_code equivalent(const Twine &A, const Twine &B, bool &result) {
+  // Get arguments.
+  SmallString<128> a_storage;
+  SmallString<128> b_storage;
+  StringRef a = A.toNullTerminatedStringRef(a_storage);
+  StringRef b = B.toNullTerminatedStringRef(b_storage);
+
+  struct stat stat_a, stat_b;
+  int error_b = ::stat(b.begin(), &stat_b);
+  int error_a = ::stat(a.begin(), &stat_a);
+
+  // If both are invalid, it's an error. If only one is, the result is false.
+  if (error_a != 0 || error_b != 0) {
+    if (error_a == error_b)
+      return error_code(errno, system_category());
+    result = false;
+  } else {
+    result =
+      stat_a.st_dev == stat_b.st_dev &&
+      stat_a.st_ino == stat_b.st_ino;
+  }
+
+  return make_error_code(errc::success);
+}
+
 error_code unique_file(const Twine &model, int &result_fd,
                              SmallVectorImpl<char> &result_path) {
   SmallString<128> Model;

llvm/lib/Support/Windows/PathV2.inc

@@ -341,6 +341,71 @@ error_code exists(const Twine &path, bool &result) {
   return make_error_code(errc::success);
 }
 
+error_code equivalent(const Twine &A, const Twine &B, bool &result) {
+  // Get arguments.
+  SmallString<128> a_storage;
+  SmallString<128> b_storage;
+  StringRef a = A.toStringRef(a_storage);
+  StringRef b = B.toStringRef(b_storage);
+
+  // Convert to utf-16.
+  SmallVector<wchar_t, 128> wide_a;
+  SmallVector<wchar_t, 128> wide_b;
+  if (error_code ec = UTF8ToUTF16(a, wide_a)) return ec;
+  if (error_code ec = UTF8ToUTF16(b, wide_b)) return ec;
+
+  AutoHandle HandleB(
+    ::CreateFileW(wide_b.begin(),
+                  0,
+                  FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE,
+                  0,
+                  OPEN_EXISTING,
+                  FILE_FLAG_BACKUP_SEMANTICS,
+                  0));
+
+  AutoHandle HandleA(
+    ::CreateFileW(wide_a.begin(),
+                  0,
+                  FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE,
+                  0,
+                  OPEN_EXISTING,
+                  FILE_FLAG_BACKUP_SEMANTICS,
+                  0));
+
+  // If both handles are invalid, it's an error.
+  if (HandleA == INVALID_HANDLE_VALUE &&
+      HandleB == INVALID_HANDLE_VALUE)
+    return make_error_code(windows_error(::GetLastError()));
+
+  // If only one is invalid, it's false.
+  if (HandleA == INVALID_HANDLE_VALUE &&
+      HandleB == INVALID_HANDLE_VALUE) {
+    result = false;
+    return make_error_code(errc::success);
+  }
+
+  // Get file information.
+  BY_HANDLE_FILE_INFORMATION InfoA, InfoB;
+  if (!::GetFileInformationByHandle(HandleA, &InfoA))
+    return make_error_code(windows_error(::GetLastError()));
+  if (!::GetFileInformationByHandle(HandleB, &InfoB))
+    return make_error_code(windows_error(::GetLastError()));
+
+  // See if it's all the same.
+  result =
+    InfoA.dwVolumeSerialNumber           == InfoB.dwVolumeSerialNumber &&
+    InfoA.nFileIndexHigh                 == InfoB.nFileIndexHigh &&
+    InfoA.nFileIndexLow                  == InfoB.nFileIndexLow &&
+    InfoA.nFileSizeHigh                  == InfoB.nFileSizeHigh &&
+    InfoA.nFileSizeLow                   == InfoB.nFileSizeLow &&
+    InfoA.ftLastWriteTime.dwLowDateTime  ==
+      InfoB.ftLastWriteTime.dwLowDateTime &&
+    InfoA.ftLastWriteTime.dwHighDateTime ==
+      InfoB.ftLastWriteTime.dwHighDateTime;
+
+  return make_error_code(errc::success);
+}
+
 error_code unique_file(const Twine &model, int &result_fd,
                              SmallVectorImpl<char> &result_path) {
   // Use result_path as temp storage.