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18a33f72db
If we have an input parameter (or return value) we need to use (nullable). However, if it is an (inout) or (out) parameter, (optional) is sufficient. It looks like (nullable) could be used for everything according to the Annotation documentation, but (optional) is more specific.
475 lines
20 KiB
C
475 lines
20 KiB
C
/* GIO - GLib Input, Output and Streaming Library
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*
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* Copyright 2015 Collabora Ltd.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General
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* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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* Authors: Philip Withnall <philip.withnall@collabora.co.uk>
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*/
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#include "config.h"
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#include "gdatagrambased.h"
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#include "gcancellable.h"
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#include "gioenumtypes.h"
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#include "gioerror.h"
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#include "gnetworkingprivate.h"
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#include "gsocketaddress.h"
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#include "glibintl.h"
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/**
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* SECTION:gdatagrambased
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* @short_description: Low-level datagram communications interface
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* @include: gio/gio.h
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* @see_also: #GSocket, [<gnetworking.h>][gio-gnetworking.h]
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*
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* A #GDatagramBased is a networking interface for representing datagram-based
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* communications. It is a more or less direct mapping of the core parts of the
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* BSD socket API in a portable GObject interface. It is implemented by
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* #GSocket, which wraps the UNIX socket API on UNIX and winsock2 on Windows.
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*
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* #GDatagramBased is entirely platform independent, and is intended to be used
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* alongside higher-level networking APIs such as #GIOStream.
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*
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* It uses vectored scatter/gather I/O by default, allowing for many messages
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* to be sent or received in a single call. Where possible, implementations of
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* the interface should take advantage of vectored I/O to minimise processing
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* or system calls. For example, #GSocket uses recvmmsg() and sendmmsg() where
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* possible. Callers should take advantage of scatter/gather I/O (the use of
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* multiple buffers per message) to avoid unnecessary copying of data to
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* assemble or disassemble a message.
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*
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* Each #GDatagramBased operation has a timeout parameter which may be negative
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* for blocking behaviour, zero for non-blocking behaviour, or positive for
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* timeout behaviour. A blocking operation blocks until finished or there is an
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* error. A non-blocking operation will return immediately with a
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* %G_IO_ERROR_WOULD_BLOCK error if it cannot make progress. A timeout operation
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* will block until the operation is complete or the timeout expires; if the
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* timeout expires it will return what progress it made, or
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* %G_IO_ERROR_TIMED_OUT if no progress was made. To know when a call would
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* successfully run you can call g_datagram_based_condition_check() or
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* g_datagram_based_condition_wait(). You can also use
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* g_datagram_based_create_source() and attach it to a #GMainContext to get
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* callbacks when I/O is possible.
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*
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* When running a non-blocking operation applications should always be able to
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* handle getting a %G_IO_ERROR_WOULD_BLOCK error even when some other function
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* said that I/O was possible. This can easily happen in case of a race
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* condition in the application, but it can also happen for other reasons. For
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* instance, on Windows a socket is always seen as writable until a write
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* returns %G_IO_ERROR_WOULD_BLOCK.
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*
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* As with #GSocket, #GDatagramBaseds can be either connection oriented (for
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* example, SCTP) or connectionless (for example, UDP). #GDatagramBaseds must be
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* datagram-based, not stream-based. The interface does not cover connection
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* establishment — use methods on the underlying type to establish a connection
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* before sending and receiving data through the #GDatagramBased API. For
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* connectionless socket types the target/source address is specified or
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* received in each I/O operation.
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*
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* Like most other APIs in GLib, #GDatagramBased is not inherently thread safe.
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* To use a #GDatagramBased concurrently from multiple threads, you must
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* implement your own locking.
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*
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* Since: 2.48
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*/
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G_DEFINE_INTERFACE (GDatagramBased, g_datagram_based, G_TYPE_OBJECT)
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static void
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g_datagram_based_default_init (GDatagramBasedInterface *iface)
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{
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/* Nothing here. */
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}
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/**
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* g_datagram_based_receive_messages:
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* @datagram_based: a #GDatagramBased
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* @messages: (array length=num_messages): an array of #GInputMessage structs
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* @num_messages: the number of elements in @messages
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* @flags: an int containing #GSocketMsgFlags flags for the overall operation
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* @timeout: the maximum time (in microseconds) to wait, 0 to not block, or -1
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* to block indefinitely
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* @cancellable: (nullable): a %GCancellable
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* @error: return location for a #GError
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*
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* Receive one or more data messages from @datagram_based in one go.
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*
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* @messages must point to an array of #GInputMessage structs and
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* @num_messages must be the length of this array. Each #GInputMessage
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* contains a pointer to an array of #GInputVector structs describing the
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* buffers that the data received in each message will be written to.
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*
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* @flags modify how all messages are received. The commonly available
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* arguments for this are available in the #GSocketMsgFlags enum, but the
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* values there are the same as the system values, and the flags
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* are passed in as-is, so you can pass in system-specific flags too. These
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* flags affect the overall receive operation. Flags affecting individual
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* messages are returned in #GInputMessage.flags.
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*
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* The other members of #GInputMessage are treated as described in its
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* documentation.
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*
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* If @timeout is negative the call will block until @num_messages have been
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* received, the connection is closed remotely (EOS), @cancellable is cancelled,
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* or an error occurs.
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*
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* If @timeout is 0 the call will return up to @num_messages without blocking,
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* or %G_IO_ERROR_WOULD_BLOCK if no messages are queued in the operating system
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* to be received.
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*
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* If @timeout is positive the call will block on the same conditions as if
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* @timeout were negative. If the timeout is reached
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* before any messages are received, %G_IO_ERROR_TIMED_OUT is returned,
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* otherwise it will return the number of messages received before timing out.
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* (Note: This is effectively the behaviour of `MSG_WAITFORONE` with
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* recvmmsg().)
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*
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* To be notified when messages are available, wait for the %G_IO_IN condition.
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* Note though that you may still receive %G_IO_ERROR_WOULD_BLOCK from
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* g_datagram_based_receive_messages() even if you were previously notified of a
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* %G_IO_IN condition.
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*
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* If the remote peer closes the connection, any messages queued in the
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* underlying receive buffer will be returned, and subsequent calls to
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* g_datagram_based_receive_messages() will return 0 (with no error set).
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*
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* If the connection is shut down or closed (by calling g_socket_close() or
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* g_socket_shutdown() with @shutdown_read set, if it’s a #GSocket, for
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* example), all calls to this function will return %G_IO_ERROR_CLOSED.
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*
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* On error -1 is returned and @error is set accordingly. An error will only
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* be returned if zero messages could be received; otherwise the number of
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* messages successfully received before the error will be returned. If
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* @cancellable is cancelled, %G_IO_ERROR_CANCELLED is returned as with any
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* other error.
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*
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* Returns: number of messages received, or -1 on error. Note that the number
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* of messages received may be smaller than @num_messages if @timeout is
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* zero or positive, if the peer closed the connection, or if @num_messages
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* was larger than `UIO_MAXIOV` (1024), in which case the caller may re-try
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* to receive the remaining messages.
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*
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* Since: 2.48
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*/
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gint
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g_datagram_based_receive_messages (GDatagramBased *datagram_based,
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GInputMessage *messages,
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guint num_messages,
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gint flags,
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gint64 timeout,
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GCancellable *cancellable,
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GError **error)
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{
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GDatagramBasedInterface *iface;
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gint retval;
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GError *child_error = NULL;
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g_return_val_if_fail (G_IS_DATAGRAM_BASED (datagram_based), -1);
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g_return_val_if_fail (num_messages == 0 || messages != NULL, -1);
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g_return_val_if_fail (cancellable == NULL ||
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G_IS_CANCELLABLE (cancellable), -1);
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g_return_val_if_fail (error == NULL || *error == NULL, -1);
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iface = G_DATAGRAM_BASED_GET_IFACE (datagram_based);
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g_assert (iface->receive_messages != NULL);
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retval = iface->receive_messages (datagram_based, messages, num_messages,
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flags, timeout, cancellable, &child_error);
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/* Postconditions. */
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g_return_val_if_fail ((retval < 0) == (child_error != NULL), -1);
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g_return_val_if_fail (timeout == 0 ||
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!g_error_matches (child_error, G_IO_ERROR,
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G_IO_ERROR_WOULD_BLOCK), -1);
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g_return_val_if_fail (timeout > 0 ||
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!g_error_matches (child_error, G_IO_ERROR,
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G_IO_ERROR_TIMED_OUT), -1);
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g_return_val_if_fail (retval < 0 || (guint) retval <= num_messages, -1);
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if (child_error != NULL)
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g_propagate_error (error, child_error);
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return retval;
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}
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/**
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* g_datagram_based_send_messages:
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* @datagram_based: a #GDatagramBased
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* @messages: (array length=num_messages): an array of #GOutputMessage structs
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* @num_messages: the number of elements in @messages
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* @flags: an int containing #GSocketMsgFlags flags
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* @timeout: the maximum time (in microseconds) to wait, 0 to not block, or -1
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* to block indefinitely
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* @cancellable: (nullable): a %GCancellable
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* @error: return location for a #GError
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*
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* Send one or more data messages from @datagram_based in one go.
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*
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* @messages must point to an array of #GOutputMessage structs and
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* @num_messages must be the length of this array. Each #GOutputMessage
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* contains an address to send the data to, and a pointer to an array of
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* #GOutputVector structs to describe the buffers that the data to be sent
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* for each message will be gathered from.
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*
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* @flags modify how the message is sent. The commonly available arguments
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* for this are available in the #GSocketMsgFlags enum, but the
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* values there are the same as the system values, and the flags
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* are passed in as-is, so you can pass in system-specific flags too.
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*
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* The other members of #GOutputMessage are treated as described in its
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* documentation.
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*
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* If @timeout is negative the call will block until @num_messages have been
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* sent, @cancellable is cancelled, or an error occurs.
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*
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* If @timeout is 0 the call will send up to @num_messages without blocking,
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* or will return %G_IO_ERROR_WOULD_BLOCK if there is no space to send messages.
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*
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* If @timeout is positive the call will block on the same conditions as if
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* @timeout were negative. If the timeout is reached before any messages are
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* sent, %G_IO_ERROR_TIMED_OUT is returned, otherwise it will return the number
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* of messages sent before timing out.
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*
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* To be notified when messages can be sent, wait for the %G_IO_OUT condition.
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* Note though that you may still receive %G_IO_ERROR_WOULD_BLOCK from
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* g_datagram_based_send_messages() even if you were previously notified of a
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* %G_IO_OUT condition. (On Windows in particular, this is very common due to
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* the way the underlying APIs work.)
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*
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* If the connection is shut down or closed (by calling g_socket_close() or
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* g_socket_shutdown() with @shutdown_write set, if it’s a #GSocket, for
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* example), all calls to this function will return %G_IO_ERROR_CLOSED.
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*
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* On error -1 is returned and @error is set accordingly. An error will only
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* be returned if zero messages could be sent; otherwise the number of messages
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* successfully sent before the error will be returned. If @cancellable is
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* cancelled, %G_IO_ERROR_CANCELLED is returned as with any other error.
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*
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* Returns: number of messages sent, or -1 on error. Note that the number of
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* messages sent may be smaller than @num_messages if @timeout is zero
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* or positive, or if @num_messages was larger than `UIO_MAXIOV` (1024), in
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* which case the caller may re-try to send the remaining messages.
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*
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* Since: 2.48
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*/
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gint
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g_datagram_based_send_messages (GDatagramBased *datagram_based,
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GOutputMessage *messages,
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guint num_messages,
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gint flags,
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gint64 timeout,
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GCancellable *cancellable,
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GError **error)
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{
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GDatagramBasedInterface *iface;
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gint retval;
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GError *child_error = NULL;
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g_return_val_if_fail (G_IS_DATAGRAM_BASED (datagram_based), -1);
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g_return_val_if_fail (num_messages == 0 || messages != NULL, -1);
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g_return_val_if_fail (cancellable == NULL ||
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G_IS_CANCELLABLE (cancellable), -1);
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g_return_val_if_fail (error == NULL || *error == NULL, -1);
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iface = G_DATAGRAM_BASED_GET_IFACE (datagram_based);
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g_assert (iface->send_messages != NULL);
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retval = iface->send_messages (datagram_based, messages, num_messages, flags,
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timeout, cancellable, &child_error);
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/* Postconditions. */
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g_return_val_if_fail ((retval < 0) == (child_error != NULL), -1);
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g_return_val_if_fail (timeout == 0 ||
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!g_error_matches (child_error, G_IO_ERROR,
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G_IO_ERROR_WOULD_BLOCK), -1);
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g_return_val_if_fail (timeout > 0 ||
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!g_error_matches (child_error, G_IO_ERROR,
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G_IO_ERROR_TIMED_OUT), -1);
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g_return_val_if_fail (retval < 0 || (guint) retval <= num_messages, -1);
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g_return_val_if_fail (!(timeout < 0 && num_messages > 0) || retval != 0, -1);
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if (child_error != NULL)
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g_propagate_error (error, child_error);
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return retval;
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}
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/**
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* g_datagram_based_create_source:
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* @datagram_based: a #GDatagramBased
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* @condition: a #GIOCondition mask to monitor
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* @cancellable: (nullable): a #GCancellable
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*
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* Creates a #GSource that can be attached to a #GMainContext to monitor for
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* the availability of the specified @condition on the #GDatagramBased. The
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* #GSource keeps a reference to the @datagram_based.
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*
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* The callback on the source is of the #GDatagramBasedSourceFunc type.
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*
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* It is meaningless to specify %G_IO_ERR or %G_IO_HUP in @condition; these
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* conditions will always be reported in the callback if they are true.
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*
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* If non-%NULL, @cancellable can be used to cancel the source, which will
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* cause the source to trigger, reporting the current condition (which is
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* likely 0 unless cancellation happened at the same time as a condition
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* change). You can check for this in the callback using
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* g_cancellable_is_cancelled().
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*
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* Returns: (transfer full): a newly allocated #GSource
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*
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* Since: 2.48
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*/
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GSource *
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g_datagram_based_create_source (GDatagramBased *datagram_based,
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GIOCondition condition,
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GCancellable *cancellable)
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{
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GDatagramBasedInterface *iface;
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g_return_val_if_fail (G_IS_DATAGRAM_BASED (datagram_based), NULL);
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g_return_val_if_fail (cancellable == NULL ||
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G_IS_CANCELLABLE (cancellable), NULL);
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iface = G_DATAGRAM_BASED_GET_IFACE (datagram_based);
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g_assert (iface->create_source != NULL);
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return iface->create_source (datagram_based, condition, cancellable);
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}
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/**
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* g_datagram_based_condition_check:
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* @datagram_based: a #GDatagramBased
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* @condition: a #GIOCondition mask to check
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*
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* Checks on the readiness of @datagram_based to perform operations. The
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* operations specified in @condition are checked for and masked against the
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* currently-satisfied conditions on @datagram_based. The result is returned.
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*
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* %G_IO_IN will be set in the return value if data is available to read with
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* g_datagram_based_receive_messages(), or if the connection is closed remotely
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* (EOS); and if the datagram_based has not been closed locally using some
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* implementation-specific method (such as g_socket_close() or
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* g_socket_shutdown() with @shutdown_read set, if it’s a #GSocket).
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*
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* If the connection is shut down or closed (by calling g_socket_close() or
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* g_socket_shutdown() with @shutdown_read set, if it’s a #GSocket, for
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* example), all calls to this function will return %G_IO_ERROR_CLOSED.
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*
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* %G_IO_OUT will be set if it is expected that at least one byte can be sent
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* using g_datagram_based_send_messages() without blocking. It will not be set
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* if the datagram_based has been closed locally.
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*
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* %G_IO_HUP will be set if the connection has been closed locally.
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*
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* %G_IO_ERR will be set if there was an asynchronous error in transmitting data
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* previously enqueued using g_datagram_based_send_messages().
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*
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* Note that on Windows, it is possible for an operation to return
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* %G_IO_ERROR_WOULD_BLOCK even immediately after
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* g_datagram_based_condition_check() has claimed that the #GDatagramBased is
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* ready for writing. Rather than calling g_datagram_based_condition_check() and
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* then writing to the #GDatagramBased if it succeeds, it is generally better to
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* simply try writing right away, and try again later if the initial attempt
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* returns %G_IO_ERROR_WOULD_BLOCK.
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*
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* It is meaningless to specify %G_IO_ERR or %G_IO_HUP in @condition; these
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* conditions will always be set in the output if they are true. Apart from
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* these flags, the output is guaranteed to be masked by @condition.
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*
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* This call never blocks.
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*
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* Returns: the #GIOCondition mask of the current state
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*
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* Since: 2.48
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*/
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GIOCondition
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g_datagram_based_condition_check (GDatagramBased *datagram_based,
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GIOCondition condition)
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{
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GDatagramBasedInterface *iface;
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GIOCondition out;
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g_return_val_if_fail (G_IS_DATAGRAM_BASED (datagram_based), 0);
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iface = G_DATAGRAM_BASED_GET_IFACE (datagram_based);
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g_assert (iface->condition_check != NULL);
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out = iface->condition_check (datagram_based, condition);
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/* Postconditions. G_IO_OUT and G_IO_HUP are mutually exclusive. G_IO_IN and
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* G_IO_HUP are mutually exclusive. The return value must be a subset of
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* (condition | G_IO_ERR | G_IO_HUP). */
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g_return_val_if_fail ((out & (G_IO_OUT | G_IO_HUP)) != (G_IO_OUT | G_IO_HUP),
|
||
out & ~G_IO_OUT);
|
||
g_return_val_if_fail ((out & (G_IO_IN | G_IO_HUP)) != (G_IO_IN | G_IO_HUP),
|
||
out & ~G_IO_IN);
|
||
g_return_val_if_fail ((out & ~(condition | G_IO_ERR | G_IO_HUP)) == 0,
|
||
out & (condition | G_IO_ERR | G_IO_HUP));
|
||
|
||
return out;
|
||
}
|
||
|
||
/**
|
||
* g_datagram_based_condition_wait:
|
||
* @datagram_based: a #GDatagramBased
|
||
* @condition: a #GIOCondition mask to wait for
|
||
* @timeout: the maximum time (in microseconds) to wait, 0 to not block, or -1
|
||
* to block indefinitely
|
||
* @cancellable: (nullable): a #GCancellable
|
||
* @error: return location for a #GError
|
||
*
|
||
* Waits for up to @timeout microseconds for condition to become true on
|
||
* @datagram_based. If the condition is met, %TRUE is returned.
|
||
*
|
||
* If @cancellable is cancelled before the condition is met, or if @timeout is
|
||
* reached before the condition is met, then %FALSE is returned and @error is
|
||
* set appropriately (%G_IO_ERROR_CANCELLED or %G_IO_ERROR_TIMED_OUT).
|
||
*
|
||
* Returns: %TRUE if the condition was met, %FALSE otherwise
|
||
*
|
||
* Since: 2.48
|
||
*/
|
||
gboolean
|
||
g_datagram_based_condition_wait (GDatagramBased *datagram_based,
|
||
GIOCondition condition,
|
||
gint64 timeout,
|
||
GCancellable *cancellable,
|
||
GError **error)
|
||
{
|
||
GDatagramBasedInterface *iface;
|
||
gboolean out;
|
||
GError *child_error = NULL;
|
||
|
||
g_return_val_if_fail (G_IS_DATAGRAM_BASED (datagram_based), FALSE);
|
||
g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable),
|
||
FALSE);
|
||
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
|
||
|
||
iface = G_DATAGRAM_BASED_GET_IFACE (datagram_based);
|
||
g_assert (iface->condition_wait != NULL);
|
||
|
||
out = iface->condition_wait (datagram_based, condition, timeout,
|
||
cancellable, &child_error);
|
||
|
||
/* Postconditions. */
|
||
g_return_val_if_fail (out == (child_error == NULL), FALSE);
|
||
|
||
if (child_error != NULL)
|
||
g_propagate_error (error, child_error);
|
||
|
||
return out;
|
||
}
|