Add TaskMemory, which can read another Mach task’s memory, and its test

util/mach/task_memory.h

Index: util/mach/task_memory.h
diff --git a/util/mach/task_memory.h b/util/mach/task_memory.h
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+// 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_UTIL_MACH_TASK_MEMORY_H_
+#define CRASHPAD_UTIL_MACH_TASK_MEMORY_H_
+
+#include <mach/mach.h>
+
+#include <string>
+
+#include "base/basictypes.h"
+
+namespace crashpad {
+
+//! \brief Accesses the memory of another Mach task.
+class TaskMemory {
+ public:
+  //! \param[in] task A send right to the target task’s task port. This object
+  //!     does not take ownership of the send right.
+  explicit TaskMemory(mach_port_t task);
+
+  ~TaskMemory() {}
+
+  //! \brief Copies memory from the target task into a user-provided buffer in
+  //!     the current task.
+  //!
+  //! \param[in] address The address, in the target task’s address space, of the
+  //!     memory region to copy.
+  //! \param[in] size The size, in bytes, of the memory region to copy. \a
+  //!     buffer must be at least this size.
+  //! \param[out] buffer The buffer into which the contents of the other task’s
+  //!     memory will be copied.
+  //!
+  //! \return `true` on success, with \a buffer filled appropriately. `false` on
+  //!     failure, with a warning logged. Failures can occur, for example, when
+  //!     encountering unmapped or unreadable pages.
+  bool Read(mach_vm_address_t address, size_t size, void* buffer);
+
+  //! \brief Reads a `NUL`-terminated C string from the target task into a
+  //!     string in the current task.
+  //!
+  //! The length of the string need not be known ahead of time. This method will
+  //! read contiguous memory until a `NUL` terminator is found.
+  //!
+  //! \param[in] address The address, in the target task’s address space, of the
+  //!     string to copy.
+  //! \param[out] string The string read from the other task.
+  //!
+  //! \return `true` on success, with \a string set appropriately. `false` on
+  //!     failure, with a warning logged. Failures can occur, for example, when
+  //!     encountering unmapped or unreadable pages.
+  bool ReadCString(mach_vm_address_t address, std::string* string);
+
+  //! \brief Reads a `NUL`-terminated C string from the target task into a
+  //!     string in the current task.
+  //!
+  //! \param[in] address The address, in the target task’s address space, of the
+  //!     string to copy.
+  //! \param[in] size The maximum number of bytes to read. The string is
+  //!     required to be `NUL`-terminated within this many bytes.
+  //! \param[out] string The string read from the other task.
+  //!
+  //! \return `true` on success, with \a string set appropriately. `false` on
+  //!     failure, with a warning logged. Failures can occur, for example, when
+  //!     a `NUL` terminator is not found within \a size bytes, or when
+  //!     encountering unmapped or unreadable pages.
+  bool ReadCStringSizeLimited(mach_vm_address_t address,
+                              mach_vm_size_t size,
+                              std::string* string);
+
+ private:
+  // The common internal implementation shared by the ReadCString*() methods.
+  bool ReadCStringInternal(mach_vm_address_t address,
+                           bool has_size,
+                           mach_vm_size_t size,
+                           std::string* string);
+
+  mach_port_t task_;  // weak
+
+  DISALLOW_COPY_AND_ASSIGN(TaskMemory);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_MACH_TASK_MEMORY_H_