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/* 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: (allow-none): 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: (allow-none): 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;
}
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