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gbufferedinputstream.c
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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 Red Hat, Inc.
* Copyright (C) 2007 Jürg Billeter
*
* 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 2.1 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/>.
*
* Author: Christian Kellner <[email protected]>
*/
#include "config.h"
#include "gbufferedinputstream.h"
#include "ginputstream.h"
#include "gcancellable.h"
#include "gasyncresult.h"
#include "gtask.h"
#include "gseekable.h"
#include "gioerror.h"
#include <string.h>
#include "glibintl.h"
/**
* SECTION:gbufferedinputstream
* @short_description: Buffered Input Stream
* @include: gio/gio.h
* @see_also: #GFilterInputStream, #GInputStream
*
* Buffered input stream implements #GFilterInputStream and provides
* for buffered reads.
*
* By default, #GBufferedInputStream's buffer size is set at 4 kilobytes.
*
* To create a buffered input stream, use g_buffered_input_stream_new(),
* or g_buffered_input_stream_new_sized() to specify the buffer's size at
* construction.
*
* To get the size of a buffer within a buffered input stream, use
* g_buffered_input_stream_get_buffer_size(). To change the size of a
* buffered input stream's buffer, use
* g_buffered_input_stream_set_buffer_size(). Note that the buffer's size
* cannot be reduced below the size of the data within the buffer.
*/
#define DEFAULT_BUFFER_SIZE 4096
struct _GBufferedInputStreamPrivate {
guint8 *buffer;
gsize len;
gsize pos;
gsize end;
GAsyncReadyCallback outstanding_callback;
};
enum {
PROP_0,
PROP_BUFSIZE
};
static void g_buffered_input_stream_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec);
static void g_buffered_input_stream_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec);
static void g_buffered_input_stream_finalize (GObject *object);
static gssize g_buffered_input_stream_skip (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error);
static void g_buffered_input_stream_skip_async (GInputStream *stream,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data);
static gssize g_buffered_input_stream_skip_finish (GInputStream *stream,
GAsyncResult *result,
GError **error);
static gssize g_buffered_input_stream_read (GInputStream *stream,
void *buffer,
gsize count,
GCancellable *cancellable,
GError **error);
static gssize g_buffered_input_stream_real_fill (GBufferedInputStream *stream,
gssize count,
GCancellable *cancellable,
GError **error);
static void g_buffered_input_stream_real_fill_async (GBufferedInputStream *stream,
gssize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data);
static gssize g_buffered_input_stream_real_fill_finish (GBufferedInputStream *stream,
GAsyncResult *result,
GError **error);
static void g_buffered_input_stream_seekable_iface_init (GSeekableIface *iface);
static goffset g_buffered_input_stream_tell (GSeekable *seekable);
static gboolean g_buffered_input_stream_can_seek (GSeekable *seekable);
static gboolean g_buffered_input_stream_seek (GSeekable *seekable,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error);
static gboolean g_buffered_input_stream_can_truncate (GSeekable *seekable);
static gboolean g_buffered_input_stream_truncate (GSeekable *seekable,
goffset offset,
GCancellable *cancellable,
GError **error);
static void compact_buffer (GBufferedInputStream *stream);
G_DEFINE_TYPE_WITH_CODE (GBufferedInputStream,
g_buffered_input_stream,
G_TYPE_FILTER_INPUT_STREAM,
G_ADD_PRIVATE (GBufferedInputStream)
G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
g_buffered_input_stream_seekable_iface_init))
static void
g_buffered_input_stream_class_init (GBufferedInputStreamClass *klass)
{
GObjectClass *object_class;
GInputStreamClass *istream_class;
GBufferedInputStreamClass *bstream_class;
object_class = G_OBJECT_CLASS (klass);
object_class->get_property = g_buffered_input_stream_get_property;
object_class->set_property = g_buffered_input_stream_set_property;
object_class->finalize = g_buffered_input_stream_finalize;
istream_class = G_INPUT_STREAM_CLASS (klass);
istream_class->skip = g_buffered_input_stream_skip;
istream_class->skip_async = g_buffered_input_stream_skip_async;
istream_class->skip_finish = g_buffered_input_stream_skip_finish;
istream_class->read_fn = g_buffered_input_stream_read;
bstream_class = G_BUFFERED_INPUT_STREAM_CLASS (klass);
bstream_class->fill = g_buffered_input_stream_real_fill;
bstream_class->fill_async = g_buffered_input_stream_real_fill_async;
bstream_class->fill_finish = g_buffered_input_stream_real_fill_finish;
g_object_class_install_property (object_class,
PROP_BUFSIZE,
g_param_spec_uint ("buffer-size",
P_("Buffer Size"),
P_("The size of the backend buffer"),
1,
G_MAXUINT,
DEFAULT_BUFFER_SIZE,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT |
G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
}
/**
* g_buffered_input_stream_get_buffer_size:
* @stream: a #GBufferedInputStream
*
* Gets the size of the input buffer.
*
* Returns: the current buffer size.
*/
gsize
g_buffered_input_stream_get_buffer_size (GBufferedInputStream *stream)
{
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), 0);
return stream->priv->len;
}
/**
* g_buffered_input_stream_set_buffer_size:
* @stream: a #GBufferedInputStream
* @size: a #gsize
*
* Sets the size of the internal buffer of @stream to @size, or to the
* size of the contents of the buffer. The buffer can never be resized
* smaller than its current contents.
*/
void
g_buffered_input_stream_set_buffer_size (GBufferedInputStream *stream,
gsize size)
{
GBufferedInputStreamPrivate *priv;
gsize in_buffer;
guint8 *buffer;
g_return_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream));
priv = stream->priv;
if (priv->len == size)
return;
if (priv->buffer)
{
in_buffer = priv->end - priv->pos;
/* Never resize smaller than current buffer contents */
size = MAX (size, in_buffer);
buffer = g_malloc (size);
memcpy (buffer, priv->buffer + priv->pos, in_buffer);
priv->len = size;
priv->pos = 0;
priv->end = in_buffer;
g_free (priv->buffer);
priv->buffer = buffer;
}
else
{
priv->len = size;
priv->pos = 0;
priv->end = 0;
priv->buffer = g_malloc (size);
}
g_object_notify (G_OBJECT (stream), "buffer-size");
}
static void
g_buffered_input_stream_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GBufferedInputStream *bstream;
bstream = G_BUFFERED_INPUT_STREAM (object);
switch (prop_id)
{
case PROP_BUFSIZE:
g_buffered_input_stream_set_buffer_size (bstream, g_value_get_uint (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_buffered_input_stream_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GBufferedInputStreamPrivate *priv;
GBufferedInputStream *bstream;
bstream = G_BUFFERED_INPUT_STREAM (object);
priv = bstream->priv;
switch (prop_id)
{
case PROP_BUFSIZE:
g_value_set_uint (value, priv->len);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_buffered_input_stream_finalize (GObject *object)
{
GBufferedInputStreamPrivate *priv;
GBufferedInputStream *stream;
stream = G_BUFFERED_INPUT_STREAM (object);
priv = stream->priv;
g_free (priv->buffer);
G_OBJECT_CLASS (g_buffered_input_stream_parent_class)->finalize (object);
}
static void
g_buffered_input_stream_seekable_iface_init (GSeekableIface *iface)
{
iface->tell = g_buffered_input_stream_tell;
iface->can_seek = g_buffered_input_stream_can_seek;
iface->seek = g_buffered_input_stream_seek;
iface->can_truncate = g_buffered_input_stream_can_truncate;
iface->truncate_fn = g_buffered_input_stream_truncate;
}
static void
g_buffered_input_stream_init (GBufferedInputStream *stream)
{
stream->priv = g_buffered_input_stream_get_instance_private (stream);
}
/**
* g_buffered_input_stream_new:
* @base_stream: a #GInputStream
*
* Creates a new #GInputStream from the given @base_stream, with
* a buffer set to the default size (4 kilobytes).
*
* Returns: a #GInputStream for the given @base_stream.
*/
GInputStream *
g_buffered_input_stream_new (GInputStream *base_stream)
{
GInputStream *stream;
g_return_val_if_fail (G_IS_INPUT_STREAM (base_stream), NULL);
stream = g_object_new (G_TYPE_BUFFERED_INPUT_STREAM,
"base-stream", base_stream,
NULL);
return stream;
}
/**
* g_buffered_input_stream_new_sized:
* @base_stream: a #GInputStream
* @size: a #gsize
*
* Creates a new #GBufferedInputStream from the given @base_stream,
* with a buffer set to @size.
*
* Returns: a #GInputStream.
*/
GInputStream *
g_buffered_input_stream_new_sized (GInputStream *base_stream,
gsize size)
{
GInputStream *stream;
g_return_val_if_fail (G_IS_INPUT_STREAM (base_stream), NULL);
stream = g_object_new (G_TYPE_BUFFERED_INPUT_STREAM,
"base-stream", base_stream,
"buffer-size", (guint)size,
NULL);
return stream;
}
/**
* g_buffered_input_stream_fill:
* @stream: a #GBufferedInputStream
* @count: the number of bytes that will be read from the stream
* @cancellable: (nullable): optional #GCancellable object, %NULL to ignore
* @error: location to store the error occurring, or %NULL to ignore
*
* Tries to read @count bytes from the stream into the buffer.
* Will block during this read.
*
* If @count is zero, returns zero and does nothing. A value of @count
* larger than %G_MAXSSIZE will cause a %G_IO_ERROR_INVALID_ARGUMENT error.
*
* On success, the number of bytes read into the buffer is returned.
* It is not an error if this is not the same as the requested size, as it
* can happen e.g. near the end of a file. Zero is returned on end of file
* (or if @count is zero), but never otherwise.
*
* If @count is -1 then the attempted read size is equal to the number of
* bytes that are required to fill the buffer.
*
* If @cancellable is not %NULL, then the operation can be cancelled by
* triggering the cancellable object from another thread. If the operation
* was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
* operation was partially finished when the operation was cancelled the
* partial result will be returned, without an error.
*
* On error -1 is returned and @error is set accordingly.
*
* For the asynchronous, non-blocking, version of this function, see
* g_buffered_input_stream_fill_async().
*
* Returns: the number of bytes read into @stream's buffer, up to @count,
* or -1 on error.
*/
gssize
g_buffered_input_stream_fill (GBufferedInputStream *stream,
gssize count,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStreamClass *class;
GInputStream *input_stream;
gssize res;
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
input_stream = G_INPUT_STREAM (stream);
if (count < -1)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
_("Too large count value passed to %s"), G_STRFUNC);
return -1;
}
if (!g_input_stream_set_pending (input_stream, error))
return -1;
if (cancellable)
g_cancellable_push_current (cancellable);
class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
res = class->fill (stream, count, cancellable, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
g_input_stream_clear_pending (input_stream);
return res;
}
static void
async_fill_callback_wrapper (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GBufferedInputStream *stream = G_BUFFERED_INPUT_STREAM (source_object);
g_input_stream_clear_pending (G_INPUT_STREAM (stream));
(*stream->priv->outstanding_callback) (source_object, res, user_data);
g_object_unref (stream);
}
/**
* g_buffered_input_stream_fill_async:
* @stream: a #GBufferedInputStream
* @count: the number of bytes that will be read from the stream
* @io_priority: the [I/O priority][io-priority] of the request
* @cancellable: (nullable): optional #GCancellable object
* @callback: (scope async): a #GAsyncReadyCallback
* @user_data: (closure): a #gpointer
*
* Reads data into @stream's buffer asynchronously, up to @count size.
* @io_priority can be used to prioritize reads. For the synchronous
* version of this function, see g_buffered_input_stream_fill().
*
* If @count is -1 then the attempted read size is equal to the number
* of bytes that are required to fill the buffer.
*/
void
g_buffered_input_stream_fill_async (GBufferedInputStream *stream,
gssize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GBufferedInputStreamClass *class;
GError *error = NULL;
g_return_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream));
if (count == 0)
{
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_source_tag (task, g_buffered_input_stream_fill_async);
g_task_return_int (task, 0);
g_object_unref (task);
return;
}
if (count < -1)
{
g_task_report_new_error (stream, callback, user_data,
g_buffered_input_stream_fill_async,
G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
_("Too large count value passed to %s"),
G_STRFUNC);
return;
}
if (!g_input_stream_set_pending (G_INPUT_STREAM (stream), &error))
{
g_task_report_error (stream, callback, user_data,
g_buffered_input_stream_fill_async,
error);
return;
}
class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
stream->priv->outstanding_callback = callback;
g_object_ref (stream);
class->fill_async (stream, count, io_priority, cancellable,
async_fill_callback_wrapper, user_data);
}
/**
* g_buffered_input_stream_fill_finish:
* @stream: a #GBufferedInputStream
* @result: a #GAsyncResult
* @error: a #GError
*
* Finishes an asynchronous read.
*
* Returns: a #gssize of the read stream, or `-1` on an error.
*/
gssize
g_buffered_input_stream_fill_finish (GBufferedInputStream *stream,
GAsyncResult *result,
GError **error)
{
GBufferedInputStreamClass *class;
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
g_return_val_if_fail (G_IS_ASYNC_RESULT (result), -1);
if (g_async_result_legacy_propagate_error (result, error))
return -1;
else if (g_async_result_is_tagged (result, g_buffered_input_stream_fill_async))
return g_task_propagate_int (G_TASK (result), error);
class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
return class->fill_finish (stream, result, error);
}
/**
* g_buffered_input_stream_get_available:
* @stream: #GBufferedInputStream
*
* Gets the size of the available data within the stream.
*
* Returns: size of the available stream.
*/
gsize
g_buffered_input_stream_get_available (GBufferedInputStream *stream)
{
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
return stream->priv->end - stream->priv->pos;
}
/**
* g_buffered_input_stream_peek:
* @stream: a #GBufferedInputStream
* @buffer: (array length=count) (element-type guint8): a pointer to
* an allocated chunk of memory
* @offset: a #gsize
* @count: a #gsize
*
* Peeks in the buffer, copying data of size @count into @buffer,
* offset @offset bytes.
*
* Returns: a #gsize of the number of bytes peeked, or -1 on error.
*/
gsize
g_buffered_input_stream_peek (GBufferedInputStream *stream,
void *buffer,
gsize offset,
gsize count)
{
gsize available;
gsize end;
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
g_return_val_if_fail (buffer != NULL, -1);
available = g_buffered_input_stream_get_available (stream);
if (offset > available)
return 0;
end = MIN (offset + count, available);
count = end - offset;
memcpy (buffer, stream->priv->buffer + stream->priv->pos + offset, count);
return count;
}
/**
* g_buffered_input_stream_peek_buffer:
* @stream: a #GBufferedInputStream
* @count: (out): a #gsize to get the number of bytes available in the buffer
*
* Returns the buffer with the currently available bytes. The returned
* buffer must not be modified and will become invalid when reading from
* the stream or filling the buffer.
*
* Returns: (array length=count) (element-type guint8) (transfer none):
* read-only buffer
*/
const void*
g_buffered_input_stream_peek_buffer (GBufferedInputStream *stream,
gsize *count)
{
GBufferedInputStreamPrivate *priv;
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), NULL);
priv = stream->priv;
if (count)
*count = priv->end - priv->pos;
return priv->buffer + priv->pos;
}
static void
compact_buffer (GBufferedInputStream *stream)
{
GBufferedInputStreamPrivate *priv;
gsize current_size;
priv = stream->priv;
current_size = priv->end - priv->pos;
memmove (priv->buffer, priv->buffer + priv->pos, current_size);
priv->pos = 0;
priv->end = current_size;
}
static gssize
g_buffered_input_stream_real_fill (GBufferedInputStream *stream,
gssize count,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStreamPrivate *priv;
GInputStream *base_stream;
gssize nread;
gsize in_buffer;
priv = stream->priv;
if (count == -1)
count = priv->len;
in_buffer = priv->end - priv->pos;
/* Never fill more than can fit in the buffer */
count = MIN (count, priv->len - in_buffer);
/* If requested length does not fit at end, compact */
if (priv->len - priv->end < count)
compact_buffer (stream);
base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
nread = g_input_stream_read (base_stream,
priv->buffer + priv->end,
count,
cancellable,
error);
if (nread > 0)
priv->end += nread;
return nread;
}
static gssize
g_buffered_input_stream_skip (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStream *bstream;
GBufferedInputStreamPrivate *priv;
GBufferedInputStreamClass *class;
GInputStream *base_stream;
gsize available, bytes_skipped;
gssize nread;
bstream = G_BUFFERED_INPUT_STREAM (stream);
priv = bstream->priv;
available = priv->end - priv->pos;
if (count <= available)
{
priv->pos += count;
return count;
}
/* Full request not available, skip all currently available and
* request refill for more
*/
priv->pos = 0;
priv->end = 0;
bytes_skipped = available;
count -= available;
if (bytes_skipped > 0)
error = NULL; /* Ignore further errors if we already read some data */
if (count > priv->len)
{
/* Large request, shortcut buffer */
base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
nread = g_input_stream_skip (base_stream,
count,
cancellable,
error);
if (nread < 0 && bytes_skipped == 0)
return -1;
if (nread > 0)
bytes_skipped += nread;
return bytes_skipped;
}
class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
nread = class->fill (bstream, priv->len, cancellable, error);
if (nread < 0)
{
if (bytes_skipped == 0)
return -1;
else
return bytes_skipped;
}
available = priv->end - priv->pos;
count = MIN (count, available);
bytes_skipped += count;
priv->pos += count;
return bytes_skipped;
}
static gssize
g_buffered_input_stream_read (GInputStream *stream,
void *buffer,
gsize count,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStream *bstream;
GBufferedInputStreamPrivate *priv;
GBufferedInputStreamClass *class;
GInputStream *base_stream;
gsize available, bytes_read;
gssize nread;
bstream = G_BUFFERED_INPUT_STREAM (stream);
priv = bstream->priv;
available = priv->end - priv->pos;
if (count <= available)
{
memcpy (buffer, priv->buffer + priv->pos, count);
priv->pos += count;
return count;
}
/* Full request not available, read all currently available and
* request refill for more
*/
memcpy (buffer, priv->buffer + priv->pos, available);
priv->pos = 0;
priv->end = 0;
bytes_read = available;
count -= available;
if (bytes_read > 0)
error = NULL; /* Ignore further errors if we already read some data */
if (count > priv->len)
{
/* Large request, shortcut buffer */
base_stream = G_FILTER_INPUT_STREAM (stream)->base_stream;
nread = g_input_stream_read (base_stream,
(char *)buffer + bytes_read,
count,
cancellable,
error);
if (nread < 0 && bytes_read == 0)
return -1;
if (nread > 0)
bytes_read += nread;
return bytes_read;
}
class = G_BUFFERED_INPUT_STREAM_GET_CLASS (stream);
nread = class->fill (bstream, priv->len, cancellable, error);
if (nread < 0)
{
if (bytes_read == 0)
return -1;
else
return bytes_read;
}
available = priv->end - priv->pos;
count = MIN (count, available);
memcpy ((char *)buffer + bytes_read, (char *)priv->buffer + priv->pos, count);
bytes_read += count;
priv->pos += count;
return bytes_read;
}
static goffset
g_buffered_input_stream_tell (GSeekable *seekable)
{
GBufferedInputStream *bstream;
GBufferedInputStreamPrivate *priv;
GInputStream *base_stream;
GSeekable *base_stream_seekable;
gsize available;
goffset base_offset;
bstream = G_BUFFERED_INPUT_STREAM (seekable);
priv = bstream->priv;
base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
if (!G_IS_SEEKABLE (base_stream))
return 0;
base_stream_seekable = G_SEEKABLE (base_stream);
available = priv->end - priv->pos;
base_offset = g_seekable_tell (base_stream_seekable);
return base_offset - available;
}
static gboolean
g_buffered_input_stream_can_seek (GSeekable *seekable)
{
GInputStream *base_stream;
base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
return G_IS_SEEKABLE (base_stream) && g_seekable_can_seek (G_SEEKABLE (base_stream));
}
static gboolean
g_buffered_input_stream_seek (GSeekable *seekable,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStream *bstream;
GBufferedInputStreamPrivate *priv;
GInputStream *base_stream;
GSeekable *base_stream_seekable;
bstream = G_BUFFERED_INPUT_STREAM (seekable);
priv = bstream->priv;
base_stream = G_FILTER_INPUT_STREAM (seekable)->base_stream;
if (!G_IS_SEEKABLE (base_stream))
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
_("Seek not supported on base stream"));
return FALSE;
}
base_stream_seekable = G_SEEKABLE (base_stream);
if (type == G_SEEK_CUR)
{
if (offset <= priv->end - priv->pos && offset >= -priv->pos)
{
priv->pos += offset;
return TRUE;
}
else
{
offset -= priv->end - priv->pos;
}
}
if (g_seekable_seek (base_stream_seekable, offset, type, cancellable, error))
{
priv->pos = 0;
priv->end = 0;
return TRUE;
}
else
{
return FALSE;
}
}
static gboolean
g_buffered_input_stream_can_truncate (GSeekable *seekable)
{
return FALSE;
}
static gboolean
g_buffered_input_stream_truncate (GSeekable *seekable,
goffset offset,
GCancellable *cancellable,
GError **error)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NOT_SUPPORTED,
_("Cannot truncate GBufferedInputStream"));
return FALSE;
}
/**
* g_buffered_input_stream_read_byte:
* @stream: a #GBufferedInputStream
* @cancellable: (nullable): optional #GCancellable object, %NULL to ignore
* @error: location to store the error occurring, or %NULL to ignore
*
* Tries to read a single byte from the stream or the buffer. Will block
* during this read.
*
* On success, the byte read from the stream is returned. On end of stream
* -1 is returned but it's not an exceptional error and @error is not set.
*
* If @cancellable is not %NULL, then the operation can be cancelled by
* triggering the cancellable object from another thread. If the operation
* was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
* operation was partially finished when the operation was cancelled the
* partial result will be returned, without an error.
*
* On error -1 is returned and @error is set accordingly.
*
* Returns: the byte read from the @stream, or -1 on end of stream or error.
*/
int
g_buffered_input_stream_read_byte (GBufferedInputStream *stream,
GCancellable *cancellable,
GError **error)
{
GBufferedInputStreamPrivate *priv;
GBufferedInputStreamClass *class;
GInputStream *input_stream;
gsize available;
gssize nread;
g_return_val_if_fail (G_IS_BUFFERED_INPUT_STREAM (stream), -1);
priv = stream->priv;
input_stream = G_INPUT_STREAM (stream);
if (g_input_stream_is_closed (input_stream))
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
_("Stream is already closed"));
return -1;
}
if (!g_input_stream_set_pending (input_stream, error))
return -1;
available = priv->end - priv->pos;
if (available != 0)
{
g_input_stream_clear_pending (input_stream);
return priv->buffer[priv->pos++];
}
/* Byte not available, request refill for more */
if (cancellable)
g_cancellable_push_current (cancellable);