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glib/gio/gmemoryoutputstream.c
Matthias Clasen 0a51b58e07 Minor doc clarification 
Mention g_realloc() as a possible function to use with
g_memory_output_stream_new(). Bug 612041.
2010-03-08 00:12:33 -05:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 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, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors:
* Christian Kellner <gicmo@gnome.org>
* Krzysztof Kosiński <tweenk.pl@gmail.com>
*/
#include "config.h"
#include "gmemoryoutputstream.h"
#include "goutputstream.h"
#include "gseekable.h"
#include "gsimpleasyncresult.h"
#include "gioerror.h"
#include "string.h"
#include "glibintl.h"
#include "gioalias.h"
/**
* SECTION:gmemoryoutputstream
* @short_description: Streaming output operations on memory chunks
* @include: gio/gio.h
* @see_also: #GMemoryInputStream
*
* #GMemoryOutputStream is a class for using arbitrary
* memory chunks as output for GIO streaming output operations.
*
*/
#define MIN_ARRAY_SIZE 16
enum {
PROP_0,
PROP_DATA,
PROP_SIZE,
PROP_DATA_SIZE,
PROP_REALLOC_FUNCTION,
PROP_DESTROY_FUNCTION
};
struct _GMemoryOutputStreamPrivate {
gpointer data; /* Write buffer */
gsize len; /* Current length of the data buffer. Can change with resizing. */
gsize valid_len; /* The part of data that has been written to */
gsize pos; /* Current position in the stream. Distinct from valid_len,
because the stream is seekable. */
GReallocFunc realloc_fn;
GDestroyNotify destroy;
};
static void g_memory_output_stream_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec);
static void g_memory_output_stream_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec);
static void g_memory_output_stream_finalize (GObject *object);
static gssize g_memory_output_stream_write (GOutputStream *stream,
const void *buffer,
gsize count,
GCancellable *cancellable,
GError **error);
static gboolean g_memory_output_stream_close (GOutputStream *stream,
GCancellable *cancellable,
GError **error);
static void g_memory_output_stream_write_async (GOutputStream *stream,
const void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data);
static gssize g_memory_output_stream_write_finish (GOutputStream *stream,
GAsyncResult *result,
GError **error);
static void g_memory_output_stream_close_async (GOutputStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data);
static gboolean g_memory_output_stream_close_finish (GOutputStream *stream,
GAsyncResult *result,
GError **error);
static void g_memory_output_stream_seekable_iface_init (GSeekableIface *iface);
static goffset g_memory_output_stream_tell (GSeekable *seekable);
static gboolean g_memory_output_stream_can_seek (GSeekable *seekable);
static gboolean g_memory_output_stream_seek (GSeekable *seekable,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error);
static gboolean g_memory_output_stream_can_truncate (GSeekable *seekable);
static gboolean g_memory_output_stream_truncate (GSeekable *seekable,
goffset offset,
GCancellable *cancellable,
GError **error);
G_DEFINE_TYPE_WITH_CODE (GMemoryOutputStream, g_memory_output_stream, G_TYPE_OUTPUT_STREAM,
G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
g_memory_output_stream_seekable_iface_init))
static void
g_memory_output_stream_class_init (GMemoryOutputStreamClass *klass)
{
GOutputStreamClass *ostream_class;
GObjectClass *gobject_class;
g_type_class_add_private (klass, sizeof (GMemoryOutputStreamPrivate));
gobject_class = G_OBJECT_CLASS (klass);
gobject_class->set_property = g_memory_output_stream_set_property;
gobject_class->get_property = g_memory_output_stream_get_property;
gobject_class->finalize = g_memory_output_stream_finalize;
ostream_class = G_OUTPUT_STREAM_CLASS (klass);
ostream_class->write_fn = g_memory_output_stream_write;
ostream_class->close_fn = g_memory_output_stream_close;
ostream_class->write_async = g_memory_output_stream_write_async;
ostream_class->write_finish = g_memory_output_stream_write_finish;
ostream_class->close_async = g_memory_output_stream_close_async;
ostream_class->close_finish = g_memory_output_stream_close_finish;
/**
* GMemoryOutputStream:data:
*
* Pointer to buffer where data will be written.
*
* Since: 2.24
**/
g_object_class_install_property (gobject_class,
PROP_DATA,
g_param_spec_pointer ("data",
P_("Data Buffer"),
P_("Pointer to buffer where data will be written."),
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GMemoryOutputStream:size:
*
* Current size of the data buffer.
*
* Since: 2.24
**/
g_object_class_install_property (gobject_class,
PROP_SIZE,
g_param_spec_ulong ("size",
P_("Data Buffer Size"),
P_("Current size of the data buffer."),
0, G_MAXULONG, 0,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GMemoryOutputStream:data-size:
*
* Size of data written to the buffer.
*
* Since: 2.24
**/
g_object_class_install_property (gobject_class,
PROP_DATA_SIZE,
g_param_spec_ulong ("data-size",
P_("Data Size"),
P_("Size of data written to the buffer."),
0, G_MAXULONG, 0,
G_PARAM_READABLE |
G_PARAM_STATIC_STRINGS));
/**
* GMemoryOutputStream:realloc-function:
*
* Function with realloc semantics called to enlarge the buffer.
*
* Since: 2.24
**/
g_object_class_install_property (gobject_class,
PROP_REALLOC_FUNCTION,
g_param_spec_pointer ("realloc-function",
P_("Memory Reallocation Function"),
P_("Function with realloc semantics called to enlarge the buffer."),
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GMemoryOutputStream:destroy-function:
*
* Function called with the buffer as argument when the stream is destroyed.
*
* Since: 2.24
**/
g_object_class_install_property (gobject_class,
PROP_DESTROY_FUNCTION,
g_param_spec_pointer ("destroy-function",
P_("Destroy Notification Function"),
P_("Function called with the buffer as argument when the stream is destroyed."),
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
}
static void
g_memory_output_stream_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GMemoryOutputStream *stream;
GMemoryOutputStreamPrivate *priv;
stream = G_MEMORY_OUTPUT_STREAM (object);
priv = stream->priv;
switch (prop_id)
{
case PROP_DATA:
priv->data = g_value_get_pointer (value);
break;
case PROP_SIZE:
priv->len = g_value_get_ulong (value);
break;
case PROP_REALLOC_FUNCTION:
priv->realloc_fn = g_value_get_pointer (value);
break;
case PROP_DESTROY_FUNCTION:
priv->destroy = g_value_get_pointer (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_memory_output_stream_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GMemoryOutputStream *stream;
GMemoryOutputStreamPrivate *priv;
stream = G_MEMORY_OUTPUT_STREAM (object);
priv = stream->priv;
switch (prop_id)
{
case PROP_DATA:
g_value_set_pointer (value, priv->data);
break;
case PROP_SIZE:
g_value_set_ulong (value, priv->len);
break;
case PROP_DATA_SIZE:
g_value_set_ulong (value, priv->valid_len);
break;
case PROP_REALLOC_FUNCTION:
g_value_set_pointer (value, priv->realloc_fn);
break;
case PROP_DESTROY_FUNCTION:
g_value_set_pointer (value, priv->destroy);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_memory_output_stream_finalize (GObject *object)
{
GMemoryOutputStream *stream;
GMemoryOutputStreamPrivate *priv;
stream = G_MEMORY_OUTPUT_STREAM (object);
priv = stream->priv;
if (priv->destroy)
priv->destroy (priv->data);
G_OBJECT_CLASS (g_memory_output_stream_parent_class)->finalize (object);
}
static void
g_memory_output_stream_seekable_iface_init (GSeekableIface *iface)
{
iface->tell = g_memory_output_stream_tell;
iface->can_seek = g_memory_output_stream_can_seek;
iface->seek = g_memory_output_stream_seek;
iface->can_truncate = g_memory_output_stream_can_truncate;
iface->truncate_fn = g_memory_output_stream_truncate;
}
static void
g_memory_output_stream_init (GMemoryOutputStream *stream)
{
stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
G_TYPE_MEMORY_OUTPUT_STREAM,
GMemoryOutputStreamPrivate);
stream->priv->pos = 0;
stream->priv->valid_len = 0;
}
/**
* g_memory_output_stream_new:
* @data: pointer to a chunk of memory to use, or %NULL
* @size: the size of @data
* @realloc_function: a function with realloc() semantics (like g_realloc())
* to be called when @data needs to be grown, or %NULL
* @destroy_function: a function to be called on @data when the stream is
* finalized, or %NULL
*
* Creates a new #GMemoryOutputStream.
*
* If @data is non-%NULL, the stream will use that for its internal storage.
* If @realloc_fn is non-%NULL, it will be used for resizing the internal
* storage when necessary. To construct a fixed-size output stream,
* pass %NULL as @realloc_fn.
*
* |[
* /&ast; a stream that can grow &ast;/
* stream = g_memory_output_stream_new (NULL, 0, realloc, free);
*
* /&ast; another stream that can grow &ast;/
* stream2 = g_memory_output_stream_new (NULL, 0, g_realloc, g_free);
*
* /&ast; a fixed-size stream &ast;/
* data = malloc (200);
* stream3 = g_memory_output_stream_new (data, 200, NULL, free);
* ]|
*
* Return value: A newly created #GMemoryOutputStream object.
**/
GOutputStream *
g_memory_output_stream_new (gpointer data,
gsize size,
GReallocFunc realloc_function,
GDestroyNotify destroy_function)
{
GOutputStream *stream;
stream = g_object_new (G_TYPE_MEMORY_OUTPUT_STREAM,
"data", data,
"size", size,
"realloc-function", realloc_function,
"destroy-function", destroy_function,
NULL);
return stream;
}
/**
* g_memory_output_stream_get_data:
* @ostream: a #GMemoryOutputStream
*
* Gets any loaded data from the @ostream.
*
* Note that the returned pointer may become invalid on the next
* write or truncate operation on the stream.
*
* Returns: pointer to the stream's data
**/
gpointer
g_memory_output_stream_get_data (GMemoryOutputStream *ostream)
{
g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), NULL);
return ostream->priv->data;
}
/**
* g_memory_output_stream_get_size:
* @ostream: a #GMemoryOutputStream
*
* Gets the size of the currently allocated data area (availible from
* g_memory_output_stream_get_data()). If the stream isn't
* growable (no realloc was passed to g_memory_output_stream_new()) then
* this is the maximum size of the stream and further writes
* will return %G_IO_ERROR_NO_SPACE.
*
* Note that for growable streams the returned size may become invalid on
* the next write or truncate operation on the stream.
*
* If you want the number of bytes currently written to the stream, use
* g_memory_output_stream_get_data_size().
*
* Returns: the number of bytes allocated for the data buffer
*/
gsize
g_memory_output_stream_get_size (GMemoryOutputStream *ostream)
{
g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), 0);
return ostream->priv->len;
}
/**
* g_memory_output_stream_get_data_size:
* @ostream: a #GMemoryOutputStream
*
* Returns the number of bytes from the start up
* to including the last byte written in the stream
* that has not been truncated away.
*
* Returns: the number of bytes written to the stream
*
* Since: 2.18
*/
gsize
g_memory_output_stream_get_data_size (GMemoryOutputStream *ostream)
{
g_return_val_if_fail (G_IS_MEMORY_OUTPUT_STREAM (ostream), 0);
return ostream->priv->valid_len;
}
static gboolean
array_resize (GMemoryOutputStream *ostream,
gsize size,
gboolean allow_partial,
GError **error)
{
GMemoryOutputStreamPrivate *priv;
gpointer data;
gsize len;
priv = ostream->priv;
if (priv->len == size)
return TRUE;
if (!priv->realloc_fn)
{
if (allow_partial &&
priv->pos < priv->len)
return TRUE; /* Short write */
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NO_SPACE,
_("Memory output stream not resizable"));
return FALSE;
}
len = priv->len;
data = priv->realloc_fn (priv->data, size);
if (size > 0 && !data)
{
if (allow_partial &&
priv->pos < priv->len)
return TRUE; /* Short write */
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NO_SPACE,
_("Failed to resize memory output stream"));
return FALSE;
}
if (size > len)
memset ((guint8 *)data + len, 0, size - len);
priv->data = data;
priv->len = size;
if (priv->len < priv->valid_len)
priv->valid_len = priv->len;
return TRUE;
}
static gint
g_nearest_pow (gint num)
{
gint n = 1;
while (n < num)
n <<= 1;
return n;
}
static gssize
g_memory_output_stream_write (GOutputStream *stream,
const void *buffer,
gsize count,
GCancellable *cancellable,
GError **error)
{
GMemoryOutputStream *ostream;
GMemoryOutputStreamPrivate *priv;
guint8 *dest;
gsize new_size;
ostream = G_MEMORY_OUTPUT_STREAM (stream);
priv = ostream->priv;
if (count == 0)
return 0;
/* Check for address space overflow, but only if the buffer is resizable.
Otherwise we just do a short write and don't worry. */
if (priv->realloc_fn && priv->pos + count < priv->pos)
goto overflow;
if (priv->pos + count > priv->len)
{
/* At least enought to fit the write, rounded up
for greater than linear growth.
TODO: This wastes a lot of memory at large stream sizes.
Figure out a more rational allocation strategy. */
new_size = g_nearest_pow (priv->pos + count);
/* Check for overflow again. We have only checked if
pos + count > G_MAXSIZE, but it only catches the case of writing
more than 4GiB total on a 32-bit system. There's still the problem
of g_nearest_pow overflowing above 0x7fffffff, so we're
effectively limited to 2GiB. */
if (new_size < priv->len)
goto overflow;
new_size = MAX (new_size, MIN_ARRAY_SIZE);
if (!array_resize (ostream, new_size, TRUE, error))
return -1;
}
/* Make sure we handle short writes if the array_resize
only added part of the required memory */
count = MIN (count, priv->len - priv->pos);
dest = (guint8 *)priv->data + priv->pos;
memcpy (dest, buffer, count);
priv->pos += count;
if (priv->pos > priv->valid_len)
priv->valid_len = priv->pos;
return count;
overflow:
/* Overflow: buffer size would need to be bigger than G_MAXSIZE. */
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_NO_SPACE,
_("Amount of memory required to process the write is "
"larger than available address space"));
return -1;
}
static gboolean
g_memory_output_stream_close (GOutputStream *stream,
GCancellable *cancellable,
GError **error)
{
return TRUE;
}
static void
g_memory_output_stream_write_async (GOutputStream *stream,
const void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data)
{
GSimpleAsyncResult *simple;
gssize nwritten;
nwritten = g_memory_output_stream_write (stream,
buffer,
count,
cancellable,
NULL);
simple = g_simple_async_result_new (G_OBJECT (stream),
callback,
data,
g_memory_output_stream_write_async);
g_simple_async_result_set_op_res_gssize (simple, nwritten);
g_simple_async_result_complete_in_idle (simple);
g_object_unref (simple);
}
static gssize
g_memory_output_stream_write_finish (GOutputStream *stream,
GAsyncResult *result,
GError **error)
{
GSimpleAsyncResult *simple;
gssize nwritten;
simple = G_SIMPLE_ASYNC_RESULT (result);
g_warn_if_fail (g_simple_async_result_get_source_tag (simple) ==
g_memory_output_stream_write_async);
nwritten = g_simple_async_result_get_op_res_gssize (simple);
return nwritten;
}
static void
g_memory_output_stream_close_async (GOutputStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data)
{
GSimpleAsyncResult *simple;
simple = g_simple_async_result_new (G_OBJECT (stream),
callback,
data,
g_memory_output_stream_close_async);
/* will always return TRUE */
g_memory_output_stream_close (stream, cancellable, NULL);
g_simple_async_result_complete_in_idle (simple);
g_object_unref (simple);
}
static gboolean
g_memory_output_stream_close_finish (GOutputStream *stream,
GAsyncResult *result,
GError **error)
{
GSimpleAsyncResult *simple;
simple = G_SIMPLE_ASYNC_RESULT (result);
g_warn_if_fail (g_simple_async_result_get_source_tag (simple) ==
g_memory_output_stream_close_async);
return TRUE;
}
static goffset
g_memory_output_stream_tell (GSeekable *seekable)
{
GMemoryOutputStream *stream;
GMemoryOutputStreamPrivate *priv;
stream = G_MEMORY_OUTPUT_STREAM (seekable);
priv = stream->priv;
return priv->pos;
}
static gboolean
g_memory_output_stream_can_seek (GSeekable *seekable)
{
return TRUE;
}
static gboolean
g_memory_output_stream_seek (GSeekable *seekable,
goffset offset,
GSeekType type,
GCancellable *cancellable,
GError **error)
{
GMemoryOutputStream *stream;
GMemoryOutputStreamPrivate *priv;
goffset absolute;
stream = G_MEMORY_OUTPUT_STREAM (seekable);
priv = stream->priv;
switch (type)
{
case G_SEEK_CUR:
absolute = priv->pos + offset;
break;
case G_SEEK_SET:
absolute = offset;
break;
case G_SEEK_END:
absolute = priv->len + offset;
break;
default:
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_INVALID_ARGUMENT,
_("Invalid GSeekType supplied"));
return FALSE;
}
if (absolute < 0)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_INVALID_ARGUMENT,
_("Requested seek before the beginning of the stream"));
return FALSE;
}
if (absolute > priv->len)
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_INVALID_ARGUMENT,
_("Requested seek beyond the end of the stream"));
return FALSE;
}
priv->pos = absolute;
return TRUE;
}
static gboolean
g_memory_output_stream_can_truncate (GSeekable *seekable)
{
GMemoryOutputStream *ostream;
GMemoryOutputStreamPrivate *priv;
ostream = G_MEMORY_OUTPUT_STREAM (seekable);
priv = ostream->priv;
return priv->realloc_fn != NULL;
}
static gboolean
g_memory_output_stream_truncate (GSeekable *seekable,
goffset offset,
GCancellable *cancellable,
GError **error)
{
GMemoryOutputStream *ostream = G_MEMORY_OUTPUT_STREAM (seekable);
if (!array_resize (ostream, offset, FALSE, error))
return FALSE;
return TRUE;
}
#define __G_MEMORY_OUTPUT_STREAM_C__
#include "gioaliasdef.c"
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