PDF: Yet another stab at getting WriteInto() buffer sizes correct.

pdf/pdfium/pdfium_api_string_buffer_adapter.cc

Index: pdf/pdfium/pdfium_api_string_buffer_adapter.cc
diff --git a/pdf/pdfium/pdfium_api_string_buffer_adapter.cc b/pdf/pdfium/pdfium_api_string_buffer_adapter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..92b46d2cd5956398aead597783afecffa18e91a3
--- /dev/null
+++ b/pdf/pdfium/pdfium_api_string_buffer_adapter.cc
@@ -0,0 +1,65 @@
+// Copyright 2015 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 "pdf/pdfium/pdfium_api_string_buffer_adapter.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/numerics/safe_math.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_util.h"
+
+namespace chrome_pdf {
+
+template <class StringType>
+PDFiumAPIStringBufferAdapter<StringType>::PDFiumAPIStringBufferAdapter(
+    StringType* str,
+    size_t expected_size,
+    bool check_expected_size)
+    : str_(str),
+      data_(WriteInto(str, expected_size + 1)),
+      expected_size_(expected_size),
+      check_expected_size_(check_expected_size),
+      is_closed_(false) {
+}
+
+template <class StringType>
+PDFiumAPIStringBufferAdapter<StringType>::~PDFiumAPIStringBufferAdapter() {
+  DCHECK(is_closed_);
+}
+
+template <class StringType>
+void* PDFiumAPIStringBufferAdapter<StringType>::GetData() {
+  DCHECK(!is_closed_);
+  return data_;
+}
+
+template <class StringType>
+void PDFiumAPIStringBufferAdapter<StringType>::Close(int actual_size) {
+  base::CheckedNumeric<size_t> unsigned_size = actual_size;
+  Close(unsigned_size.ValueOrDie());
+}
+
+template <class StringType>
+void PDFiumAPIStringBufferAdapter<StringType>::Close(size_t actual_size) {
+  DCHECK(!is_closed_);
+  is_closed_ = true;
+
+  if (check_expected_size_)
+    DCHECK_EQ(expected_size_, actual_size);
+
+  if (actual_size > 0) {
+    DCHECK((*str_)[actual_size - 1] == 0);
+    str_->resize(actual_size - 1);
+  } else {
+    str_->clear();
+  }
+}
+
+// explicit instantiations
+template class PDFiumAPIStringBufferAdapter<std::string>;
+template class PDFiumAPIStringBufferAdapter<base::string16>;
+
+}  // namespace chrome_pdf