Print Preview: Fix failure to save with long page title

ui/shell_dialogs/select_file_dialog.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/shell_dialogs/select_file_dialog.h"
 
 #include <stddef.h>
+#include <algorithm>
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "ui/shell_dialogs/select_file_dialog_factory.h"
 #include "ui/shell_dialogs/select_file_policy.h"
 #include "ui/shell_dialogs/selected_file_info.h"
 
 namespace {
 
 // Optional dialog factory. Leaked.
 ui::SelectFileDialogFactory* dialog_factory_ = NULL;
 
+// Returns a file path with a base name at most 255 characters long. This
+// is the limit on Windows and Linux, and on Windows the system file

[Nico, 2017/04/14 14:03:34]

FWIW, on Windows, the limit for the full path (not just basename) is 260
characters unless you use advanced tactics
(https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).as...).
So this might not be enough on Windows?

[rbpotter, 2017/04/14 22:04:39]

It fails to save in the system dialog if the path length is > 260,
but the dialog still opens - the user gets a "File path is too long"
message from the Windows dialog and can fix the problem. If the file
name itself is > 255 characters, the dialog does not open at all and
we get a silent failure from print preview. The intent was to fix
the silent failure and allow the error from the dialog to handle the
long path case. We could change this to check the path as well,
though. What do you think? Should we let the system dialog handle
that issue or handle it here?

+// selection dialog will fail to open if the file name exceeds 255 characters.
+base::FilePath GetShortenedFilePath(const base::FilePath& path) {
+  base::FilePath filename = path.BaseName();

[Nico, 2017/04/14 14:03:34]

Move this below the early return, you currently always make a copy even you
won't need it 99.7% of the time.

[rbpotter, 2017/04/14 22:04:39]

Done.

+  const size_t kMaxNameLength = 255;
+  if (filename.value().length() <= kMaxNameLength)
+    return path;
+  base::FilePath::StringType extension = filename.FinalExtension();
+  filename = filename.RemoveFinalExtension();
+  base::FilePath::StringType file_string = filename.value();
+  // 1 for . plus 12 for longest known extension.
+  size_t max_extension_length = 13;
+  if (file_string.length() < kMaxNameLength) {
+    max_extension_length =
+        std::max(max_extension_length, kMaxNameLength - file_string.length());
+  }
+  if (extension.length() > max_extension_length) {
+    // Take the first max_extension_length characters (this will be the
+    // leading '.' plus the next max_extension_length - 1).
+    extension.resize(max_extension_length);
+  }
+  file_string.resize(kMaxNameLength - extension.length());
+  return path.DirName().Append(file_string).AddExtension(extension);
+}
+
 }  // namespace
 
 namespace ui {
 
 SelectFileDialog::FileTypeInfo::FileTypeInfo()
     : include_all_files(false), allowed_paths(NATIVE_PATH) {}
 
 SelectFileDialog::FileTypeInfo::FileTypeInfo(const FileTypeInfo& other) =
     default;
 
@@ skipping 57 matching lines @@
 
     // Inform the listener that no file was selected.
     // Post a task rather than calling FileSelectionCanceled directly to ensure
     // that the listener is called asynchronously.
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&SelectFileDialog::CancelFileSelection, this, params));
     return;
   }
 
+  base::FilePath path = GetShortenedFilePath(default_path);
+
   // Call the platform specific implementation of the file selection dialog.
-  SelectFileImpl(type, title, default_path, file_types, file_type_index,
+  SelectFileImpl(type, title, path, file_types, file_type_index,
                  default_extension, owning_window, params);
 }
 
 bool SelectFileDialog::HasMultipleFileTypeChoices() {
   return HasMultipleFileTypeChoicesImpl();
 }
 
 SelectFileDialog::SelectFileDialog(Listener* listener,
                                    ui::SelectFilePolicy* policy)
     : listener_(listener),
       select_file_policy_(policy) {
   DCHECK(listener_);
 }
 
 SelectFileDialog::~SelectFileDialog() {}
 
 void SelectFileDialog::CancelFileSelection(void* params) {
   if (listener_)
     listener_->FileSelectionCanceled(params);
 }
 
 }  // namespace ui