Refactor minidump test utilities for MinidumpWritable, …

minidump/test/minidump_file_writer_test_util.h

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #ifndef CRASHPAD_MINIDUMP_TEST_MINIDUMP_FILE_WRITER_TEST_UTIL_H_
 #define CRASHPAD_MINIDUMP_TEST_MINIDUMP_FILE_WRITER_TEST_UTIL_H_
 
 #include <dbghelp.h>
 #include <stdint.h>
 
+#include <string>
+
 namespace crashpad {
 namespace test {
 
+//! \brief Returns the MINIDUMP_HEADER at the start of a minidump file, along
+//!     with the MINIDUMP_DIRECTORY it references.
+//!
+//! This function validates the MINIDUMP_HEADER::Signature and
+//! MINIDUMP_HEADER::Version fields.
+//!
+//! \param[in] file_contents The contents of the minidump file.
+//! \param[out] directory The MINIDUMP_DIRECTORY referenced by the
+//!     MINIDUMP_HEADER. If the MINIDUMP_HEADER does not reference a
+//!     MINIDUMP_DIRECTORY, `nullptr` without raising a gtest assertion. If the
+//!     referenced MINIDUMP_DIRECTORY is not valid, `nullptr` with a gtest
+//!     assertion raised. On failure, `nullptr`.
+//!
+//! \return On success, the MINIDUMP_HEADER at the beginning of the minidump
+//!     file. On failure, raises a gtest assertion and returns `nullptr`.
+const MINIDUMP_HEADER* MinidumpHeaderAtStart(
+    const std::string& file_contents,
+    const MINIDUMP_DIRECTORY** directory);
+
 //! \brief Verifies, via gtest assertions, that a MINIDUMP_HEADER contains
 //!     expected values.
 //!
 //! All fields in the MINIDUMP_HEADER will be evaluated. Most are compared to
 //! their correct default values. MINIDUMP_HEADER::NumberOfStreams is compared
 //! to \a streams, and MINIDUMP_HEADER::TimeDateStamp is compared to \a
 //! timestamp. Most fields are checked with nonfatal EXPECT-style assertions,
 //! but MINIDUMP_HEADER::NumberOfStreams and MINIDUMP_HEADER::StreamDirectoryRva
 //! are checked with fatal ASSERT-style assertions, because they must be
 //! correct in order for processing of the minidump to continue.
 void VerifyMinidumpHeader(const MINIDUMP_HEADER* header,
                           uint32_t streams,
                           uint32_t timestamp);
 
 }  // namespace test
 }  // namespace crashpad
 
 #endif  // CRASHPAD_MINIDUMP_TEST_MINIDUMP_FILE_WRITER_TEST_UTIL_H_