mojo/edk/platform/platform_pipe_utils_posix.h

// Copyright 2014 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 MOJO_EDK_PLATFORM_PLATFORM_PIPE_UTILS_POSIX_H_
#define MOJO_EDK_PLATFORM_PLATFORM_PIPE_UTILS_POSIX_H_

#include <stddef.h>
#include <sys/types.h>  // For |ssize_t|.

#include <deque>

#include "mojo/edk/platform/platform_handle.h"
#include "mojo/edk/platform/scoped_platform_handle.h"

struct iovec;  // Declared in <sys/uio.h>.

namespace mojo {
namespace platform {

// The maximum number of handles that can be sent "at once" using
// |PlatformPipeSendmsgWithHandles()|.
// TODO(vtl): This number is taken from ipc/ipc_message_attachment_set.h:
// |IPC::MessageAttachmentSet::kMaxDescriptorsPerMessage|.
const size_t kPlatformPipeMaxNumHandles = 128;

// Use these to write to a socket created using |PlatformPipe| (or equivalent).
// These are like |write()| and |writev()|, but handle |EINTR| and never raise
// |SIGPIPE|. (Note: On Mac, the suppression of |SIGPIPE| is set up by
// |PlatformPipe|.)
ssize_t PlatformPipeWrite(PlatformHandle h,
                          const void* bytes,
                          size_t num_bytes);
ssize_t PlatformPipeWritev(PlatformHandle h, struct iovec* iov, size_t num_iov);

// Writes data, and the given set of |PlatformHandle|s (i.e., file descriptors)
// over the Unix domain socket given by |h| (e.g., created using
// |PlatformPipe()|). All the handles must be valid, and there must be at least
// one and at most |kPlatformPipeMaxNumHandles| handles. The return value is as
// for |sendmsg()|, namely -1 on failure and otherwise the number of bytes of
// data sent on success (note that this may not be all the data specified by
// |iov|). (The handles are not closed, regardless of success or failure.)
ssize_t PlatformPipeSendmsgWithHandles(PlatformHandle h,
                                       struct iovec* iov,
                                       size_t num_iov,
                                       PlatformHandle* platform_handles,
                                       size_t num_platform_handles);

// Wrapper around |recvmsg()|, which will extract any attached file descriptors
// (in the control message) to |ScopedPlatformHandle|s (and append them to
// |platform_handles|). (This also handles |EINTR|.)
ssize_t PlatformPipeRecvmsg(PlatformHandle h,
                            void* buf,
                            size_t num_bytes,
                            std::deque<ScopedPlatformHandle>* platform_handles);

}  // namespace platform
}  // namespace mojo

#endif  // MOJO_EDK_PLATFORM_PLATFORM_PIPE_UTILS_POSIX_H_