glib/gio/gpollableinputstream.c
Christian Hergert 18a33f72db introspection: use (nullable) or (optional) instead of (allow-none)
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.
2016-11-22 14:14:37 -08:00

220 lines
7.3 KiB
C

/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2010 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <errno.h>
#include "gpollableinputstream.h"
#include "gasynchelper.h"
#include "glibintl.h"
/**
* SECTION:gpollableinputstream
* @short_description: Interface for pollable input streams
* @include: gio/gio.h
* @see_also: #GInputStream, #GPollableOutputStream, #GFileDescriptorBased
*
* #GPollableInputStream is implemented by #GInputStreams that
* can be polled for readiness to read. This can be used when
* interfacing with a non-GIO API that expects
* UNIX-file-descriptor-style asynchronous I/O rather than GIO-style.
*
* Since: 2.28
*/
G_DEFINE_INTERFACE (GPollableInputStream, g_pollable_input_stream, G_TYPE_INPUT_STREAM)
static gboolean g_pollable_input_stream_default_can_poll (GPollableInputStream *stream);
static gssize g_pollable_input_stream_default_read_nonblocking (GPollableInputStream *stream,
void *buffer,
gsize count,
GError **error);
static void
g_pollable_input_stream_default_init (GPollableInputStreamInterface *iface)
{
iface->can_poll = g_pollable_input_stream_default_can_poll;
iface->read_nonblocking = g_pollable_input_stream_default_read_nonblocking;
}
static gboolean
g_pollable_input_stream_default_can_poll (GPollableInputStream *stream)
{
return TRUE;
}
/**
* g_pollable_input_stream_can_poll:
* @stream: a #GPollableInputStream.
*
* Checks if @stream is actually pollable. Some classes may implement
* #GPollableInputStream but have only certain instances of that class
* be pollable. If this method returns %FALSE, then the behavior of
* other #GPollableInputStream methods is undefined.
*
* For any given stream, the value returned by this method is constant;
* a stream cannot switch from pollable to non-pollable or vice versa.
*
* Returns: %TRUE if @stream is pollable, %FALSE if not.
*
* Since: 2.28
*/
gboolean
g_pollable_input_stream_can_poll (GPollableInputStream *stream)
{
g_return_val_if_fail (G_IS_POLLABLE_INPUT_STREAM (stream), FALSE);
return G_POLLABLE_INPUT_STREAM_GET_INTERFACE (stream)->can_poll (stream);
}
/**
* g_pollable_input_stream_is_readable:
* @stream: a #GPollableInputStream.
*
* Checks if @stream can be read.
*
* Note that some stream types may not be able to implement this 100%
* reliably, and it is possible that a call to g_input_stream_read()
* after this returns %TRUE would still block. To guarantee
* non-blocking behavior, you should always use
* g_pollable_input_stream_read_nonblocking(), which will return a
* %G_IO_ERROR_WOULD_BLOCK error rather than blocking.
*
* Returns: %TRUE if @stream is readable, %FALSE if not. If an error
* has occurred on @stream, this will result in
* g_pollable_input_stream_is_readable() returning %TRUE, and the
* next attempt to read will return the error.
*
* Since: 2.28
*/
gboolean
g_pollable_input_stream_is_readable (GPollableInputStream *stream)
{
g_return_val_if_fail (G_IS_POLLABLE_INPUT_STREAM (stream), FALSE);
return G_POLLABLE_INPUT_STREAM_GET_INTERFACE (stream)->is_readable (stream);
}
/**
* g_pollable_input_stream_create_source:
* @stream: a #GPollableInputStream.
* @cancellable: (nullable): a #GCancellable, or %NULL
*
* Creates a #GSource that triggers when @stream can be read, or
* @cancellable is triggered or an error occurs. The callback on the
* source is of the #GPollableSourceFunc type.
*
* As with g_pollable_input_stream_is_readable(), it is possible that
* the stream may not actually be readable even after the source
* triggers, so you should use g_pollable_input_stream_read_nonblocking()
* rather than g_input_stream_read() from the callback.
*
* Returns: (transfer full): a new #GSource
*
* Since: 2.28
*/
GSource *
g_pollable_input_stream_create_source (GPollableInputStream *stream,
GCancellable *cancellable)
{
g_return_val_if_fail (G_IS_POLLABLE_INPUT_STREAM (stream), NULL);
return G_POLLABLE_INPUT_STREAM_GET_INTERFACE (stream)->
create_source (stream, cancellable);
}
static gssize
g_pollable_input_stream_default_read_nonblocking (GPollableInputStream *stream,
void *buffer,
gsize count,
GError **error)
{
if (!g_pollable_input_stream_is_readable (stream))
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_WOULD_BLOCK,
g_strerror (EAGAIN));
return -1;
}
return G_INPUT_STREAM_GET_CLASS (stream)->
read_fn (G_INPUT_STREAM (stream), buffer, count, NULL, error);
}
/**
* g_pollable_input_stream_read_nonblocking:
* @stream: a #GPollableInputStream
* @buffer: (array length=count) (element-type guint8): a buffer to
* read data into (which should be at least @count bytes long).
* @count: the number of bytes you want to read
* @cancellable: (nullable): a #GCancellable, or %NULL
* @error: #GError for error reporting, or %NULL to ignore.
*
* Attempts to read up to @count bytes from @stream into @buffer, as
* with g_input_stream_read(). If @stream is not currently readable,
* this will immediately return %G_IO_ERROR_WOULD_BLOCK, and you can
* use g_pollable_input_stream_create_source() to create a #GSource
* that will be triggered when @stream is readable.
*
* Note that since this method never blocks, you cannot actually
* use @cancellable to cancel it. However, it will return an error
* if @cancellable has already been cancelled when you call, which
* may happen if you call this method after a source triggers due
* to having been cancelled.
*
* Virtual: read_nonblocking
* Returns: the number of bytes read, or -1 on error (including
* %G_IO_ERROR_WOULD_BLOCK).
*/
gssize
g_pollable_input_stream_read_nonblocking (GPollableInputStream *stream,
void *buffer,
gsize count,
GCancellable *cancellable,
GError **error)
{
gssize res;
g_return_val_if_fail (G_IS_POLLABLE_INPUT_STREAM (stream), -1);
g_return_val_if_fail (buffer != NULL, 0);
if (g_cancellable_set_error_if_cancelled (cancellable, error))
return -1;
if (count == 0)
return 0;
if (((gssize) count) < 0)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
_("Too large count value passed to %s"), G_STRFUNC);
return -1;
}
if (cancellable)
g_cancellable_push_current (cancellable);
res = G_POLLABLE_INPUT_STREAM_GET_INTERFACE (stream)->
read_nonblocking (stream, buffer, count, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
return res;
}