92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
// 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.
|
|
|
|
#ifndef DBUS_FILE_DESCRIPTOR_H_
|
|
#define DBUS_FILE_DESCRIPTOR_H_
|
|
|
|
#include <memory>
|
|
|
|
#include "base/macros.h"
|
|
#include "dbus/dbus_export.h"
|
|
|
|
namespace dbus {
|
|
|
|
// FileDescriptor is a type used to encapsulate D-Bus file descriptors
|
|
// and to follow the RAII idiom appropiate for use with message operations
|
|
// where the descriptor might be easily leaked. To guard against this the
|
|
// descriptor is closed when an instance is destroyed if it is owned.
|
|
// Ownership is asserted only when PutValue is used and TakeValue can be
|
|
// used to take ownership.
|
|
//
|
|
// For example, in the following
|
|
// FileDescriptor fd;
|
|
// if (!reader->PopString(&name) ||
|
|
// !reader->PopFileDescriptor(&fd) ||
|
|
// !reader->PopUint32(&flags)) {
|
|
// the descriptor in fd will be closed if the PopUint32 fails. But
|
|
// writer.AppendFileDescriptor(dbus::FileDescriptor(1));
|
|
// will not automatically close "1" because it is not owned.
|
|
//
|
|
// Descriptors must be validated before marshalling in a D-Bus message
|
|
// or using them after unmarshalling. We disallow descriptors to a
|
|
// directory to reduce the security risks. Splitting out validation
|
|
// also allows the caller to do this work on the File thread to conform
|
|
// with i/o restrictions.
|
|
class CHROME_DBUS_EXPORT FileDescriptor {
|
|
public:
|
|
// This provides a simple way to pass around file descriptors since they must
|
|
// be closed on a thread that is allowed to perform I/O.
|
|
struct Deleter {
|
|
void CHROME_DBUS_EXPORT operator()(FileDescriptor* fd);
|
|
};
|
|
|
|
// Permits initialization without a value for passing to
|
|
// dbus::MessageReader::PopFileDescriptor to fill in and from int values.
|
|
FileDescriptor() : value_(-1), owner_(false), valid_(false) {}
|
|
explicit FileDescriptor(int value) : value_(value), owner_(false),
|
|
valid_(false) {}
|
|
|
|
FileDescriptor(FileDescriptor&& other);
|
|
|
|
virtual ~FileDescriptor();
|
|
|
|
FileDescriptor& operator=(FileDescriptor&& other);
|
|
|
|
// Retrieves value as an int without affecting ownership.
|
|
int value() const;
|
|
|
|
// Retrieves whether or not the descriptor is ok to send/receive.
|
|
int is_valid() const { return valid_; }
|
|
|
|
// Sets the value and assign ownership.
|
|
void PutValue(int value) {
|
|
value_ = value;
|
|
owner_ = true;
|
|
valid_ = false;
|
|
}
|
|
|
|
// Takes the value and ownership.
|
|
int TakeValue();
|
|
|
|
// Checks (and records) validity of the file descriptor.
|
|
// We disallow directories to avoid potential sandbox escapes.
|
|
// Note this call must be made on a thread where file i/o is allowed.
|
|
void CheckValidity();
|
|
|
|
private:
|
|
void Swap(FileDescriptor* other);
|
|
|
|
int value_;
|
|
bool owner_;
|
|
bool valid_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(FileDescriptor);
|
|
};
|
|
|
|
using ScopedFileDescriptor =
|
|
std::unique_ptr<FileDescriptor, FileDescriptor::Deleter>;
|
|
|
|
} // namespace dbus
|
|
|
|
#endif // DBUS_FILE_DESCRIPTOR_H_
|