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272c3fc7100e3f059bdba0fbfa691c6dd3b7de9a
glib/gio/ginputstream.c
Ryan Lortie 223b5f757f docs: explain inconsistency of _{read,write}_all() 
These functions are inconsistent with our normal conventions in that
they set an output variable to a specified value, even in the case that
an error is thrown.

Document very clearly that this should be considered exceptional.

https://bugzilla.gnome.org/show_bug.cgi?id=737451
2014-10-21 12:09:57 -04:00

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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, see <http://www.gnu.org/licenses/>.
*
* Author: Alexander Larsson <alexl@redhat.com>
*/
#include "config.h"
#include <glib.h>
#include "glibintl.h"
#include "ginputstream.h"
#include "gioprivate.h"
#include "gseekable.h"
#include "gcancellable.h"
#include "gasyncresult.h"
#include "gioerror.h"
#include "gpollableinputstream.h"
/**
* SECTION:ginputstream
* @short_description: Base class for implementing streaming input
* @include: gio/gio.h
*
* #GInputStream has functions to read from a stream (g_input_stream_read()),
* to close a stream (g_input_stream_close()) and to skip some content
* (g_input_stream_skip()).
*
* To copy the content of an input stream to an output stream without
* manually handling the reads and writes, use g_output_stream_splice().
*
* All of these functions have async variants too.
**/
struct _GInputStreamPrivate {
guint closed : 1;
guint pending : 1;
GAsyncReadyCallback outstanding_callback;
};
G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GInputStream, g_input_stream, G_TYPE_OBJECT)
static gssize g_input_stream_real_skip (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error);
static void g_input_stream_real_read_async (GInputStream *stream,
void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data);
static gssize g_input_stream_real_read_finish (GInputStream *stream,
GAsyncResult *result,
GError **error);
static void g_input_stream_real_skip_async (GInputStream *stream,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data);
static gssize g_input_stream_real_skip_finish (GInputStream *stream,
GAsyncResult *result,
GError **error);
static void g_input_stream_real_close_async (GInputStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer data);
static gboolean g_input_stream_real_close_finish (GInputStream *stream,
GAsyncResult *result,
GError **error);
static void
g_input_stream_dispose (GObject *object)
{
GInputStream *stream;
stream = G_INPUT_STREAM (object);
if (!stream->priv->closed)
g_input_stream_close (stream, NULL, NULL);
G_OBJECT_CLASS (g_input_stream_parent_class)->dispose (object);
}
static void
g_input_stream_class_init (GInputStreamClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->dispose = g_input_stream_dispose;
klass->skip = g_input_stream_real_skip;
klass->read_async = g_input_stream_real_read_async;
klass->read_finish = g_input_stream_real_read_finish;
klass->skip_async = g_input_stream_real_skip_async;
klass->skip_finish = g_input_stream_real_skip_finish;
klass->close_async = g_input_stream_real_close_async;
klass->close_finish = g_input_stream_real_close_finish;
}
static void
g_input_stream_init (GInputStream *stream)
{
stream->priv = g_input_stream_get_instance_private (stream);
}
/**
* g_input_stream_read:
* @stream: a #GInputStream.
* @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 that will be read from the stream
* @cancellable: (allow-none): 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 starting at
* @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.
*
* The returned @buffer is not a nul-terminated string, it can contain nul bytes
* at any position, and this function doesn't nul-terminate 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.
*
* Returns: Number of bytes read, or -1 on error, or 0 on end of file.
**/
gssize
g_input_stream_read (GInputStream *stream,
void *buffer,
gsize count,
GCancellable *cancellable,
GError **error)
{
GInputStreamClass *class;
gssize res;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), -1);
g_return_val_if_fail (buffer != NULL, 0);
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;
}
class = G_INPUT_STREAM_GET_CLASS (stream);
if (class->read_fn == NULL)
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
_("Input stream doesn't implement read"));
return -1;
}
if (!g_input_stream_set_pending (stream, error))
return -1;
if (cancellable)
g_cancellable_push_current (cancellable);
res = class->read_fn (stream, buffer, count, cancellable, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
g_input_stream_clear_pending (stream);
return res;
}
/**
* g_input_stream_read_all:
* @stream: a #GInputStream.
* @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 that will be read from the stream
* @bytes_read: (out): location to store the number of bytes that was read from the stream
* @cancellable: (allow-none): 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 starting at
* @buffer. Will block during this read.
*
* This function is similar to g_input_stream_read(), except it tries to
* read as many bytes as requested, only stopping on an error or end of stream.
*
* On a successful read of @count bytes, or if we reached the end of the
* stream, %TRUE is returned, and @bytes_read is set to the number of bytes
* read into @buffer.
*
* If there is an error during the operation %FALSE is returned and @error
* is set to indicate the error status.
*
* As a special exception to the normal conventions for functions that
* use #GError, if this function returns %FALSE (and sets @error) then
* @bytes_read will be set to the number of bytes that were successfully
* read before the error was encountered. This functionality is only
* available from C. If you need it from another language then you must
* write your own loop around g_input_stream_read().
*
* Returns: %TRUE on success, %FALSE if there was an error
**/
gboolean
g_input_stream_read_all (GInputStream *stream,
void *buffer,
gsize count,
gsize *bytes_read,
GCancellable *cancellable,
GError **error)
{
gsize _bytes_read;
gssize res;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
g_return_val_if_fail (buffer != NULL, FALSE);
_bytes_read = 0;
while (_bytes_read < count)
{
res = g_input_stream_read (stream, (char *)buffer + _bytes_read, count - _bytes_read,
cancellable, error);
if (res == -1)
{
if (bytes_read)
*bytes_read = _bytes_read;
return FALSE;
}
if (res == 0)
break;
_bytes_read += res;
}
if (bytes_read)
*bytes_read = _bytes_read;
return TRUE;
}
/**
* g_input_stream_read_bytes:
* @stream: a #GInputStream.
* @count: maximum number of bytes that will be read from the stream. Common
* values include 4096 and 8192.
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @error: location to store the error occurring, or %NULL to ignore
*
* Like g_input_stream_read(), this tries to read @count bytes from
* the stream in a blocking fashion. However, rather than reading into
* a user-supplied buffer, this will create a new #GBytes containing
* the data that was read. This may be easier to use from language
* bindings.
*
* If count is zero, returns a zero-length #GBytes and does nothing. A
* value of @count larger than %G_MAXSSIZE will cause a
* %G_IO_ERROR_INVALID_ARGUMENT error.
*
* On success, a new #GBytes is returned. It is not an error if the
* size of this object is not the same as the requested size, as it
* can happen e.g. near the end of a file. A zero-length #GBytes is
* returned on end of file (or if @count is zero), but never
* otherwise.
*
* 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 %NULL is returned and @error is set accordingly.
*
* Returns: a new #GBytes, or %NULL on error
*
* Since: 2.34
**/
GBytes *
g_input_stream_read_bytes (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error)
{
guchar *buf;
gssize nread;
buf = g_malloc (count);
nread = g_input_stream_read (stream, buf, count, cancellable, error);
if (nread == -1)
{
g_free (buf);
return NULL;
}
else if (nread == 0)
{
g_free (buf);
return g_bytes_new_static ("", 0);
}
else
return g_bytes_new_take (buf, nread);
}
/**
* g_input_stream_skip:
* @stream: a #GInputStream.
* @count: the number of bytes that will be skipped from the stream
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @error: location to store the error occurring, or %NULL to ignore
*
* Tries to skip @count bytes from the stream. Will block during the operation.
*
* This is identical to g_input_stream_read(), from a behaviour standpoint,
* but the bytes that are skipped are not returned to the user. Some
* streams have an implementation that is more efficient than reading the data.
*
* This function is optional for inherited classes, as the default implementation
* emulates it using read.
*
* 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.
*
* Returns: Number of bytes skipped, or -1 on error
**/
gssize
g_input_stream_skip (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error)
{
GInputStreamClass *class;
gssize res;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), -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;
}
class = G_INPUT_STREAM_GET_CLASS (stream);
if (!g_input_stream_set_pending (stream, error))
return -1;
if (cancellable)
g_cancellable_push_current (cancellable);
res = class->skip (stream, count, cancellable, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
g_input_stream_clear_pending (stream);
return res;
}
static gssize
g_input_stream_real_skip (GInputStream *stream,
gsize count,
GCancellable *cancellable,
GError **error)
{
GInputStreamClass *class;
gssize ret, read_bytes;
char buffer[8192];
GError *my_error;
if (G_IS_SEEKABLE (stream) && g_seekable_can_seek (G_SEEKABLE (stream)))
{
if (g_seekable_seek (G_SEEKABLE (stream),
count,
G_SEEK_CUR,
cancellable,
NULL))
return count;
}
/* If not seekable, or seek failed, fall back to reading data: */
class = G_INPUT_STREAM_GET_CLASS (stream);
read_bytes = 0;
while (1)
{
my_error = NULL;
ret = class->read_fn (stream, buffer, MIN (sizeof (buffer), count),
cancellable, &my_error);
if (ret == -1)
{
if (read_bytes > 0 &&
my_error->domain == G_IO_ERROR &&
my_error->code == G_IO_ERROR_CANCELLED)
{
g_error_free (my_error);
return read_bytes;
}
g_propagate_error (error, my_error);
return -1;
}
count -= ret;
read_bytes += ret;
if (ret == 0 || count == 0)
return read_bytes;
}
}
/**
* g_input_stream_close:
* @stream: A #GInputStream.
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @error: location to store the error occurring, or %NULL to ignore
*
* Closes the stream, releasing resources related to it.
*
* Once the stream is closed, all other operations will return %G_IO_ERROR_CLOSED.
* Closing a stream multiple times will not return an error.
*
* Streams will be automatically closed when the last reference
* is dropped, but you might want to call this function to make sure
* resources are released as early as possible.
*
* Some streams might keep the backing store of the stream (e.g. a file descriptor)
* open after the stream is closed. See the documentation for the individual
* stream for details.
*
* On failure the first error that happened will be reported, but the close
* operation will finish as much as possible. A stream that failed to
* close will still return %G_IO_ERROR_CLOSED for all operations. Still, it
* is important to check and report the error to the user.
*
* 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.
* Cancelling a close will still leave the stream closed, but some streams
* can use a faster close that doesn't block to e.g. check errors.
*
* Returns: %TRUE on success, %FALSE on failure
**/
gboolean
g_input_stream_close (GInputStream *stream,
GCancellable *cancellable,
GError **error)
{
GInputStreamClass *class;
gboolean res;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
class = G_INPUT_STREAM_GET_CLASS (stream);
if (stream->priv->closed)
return TRUE;
res = TRUE;
if (!g_input_stream_set_pending (stream, error))
return FALSE;
if (cancellable)
g_cancellable_push_current (cancellable);
if (class->close_fn)
res = class->close_fn (stream, cancellable, error);
if (cancellable)
g_cancellable_pop_current (cancellable);
g_input_stream_clear_pending (stream);
stream->priv->closed = TRUE;
return res;
}
static void
async_ready_callback_wrapper (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GInputStream *stream = G_INPUT_STREAM (source_object);
g_input_stream_clear_pending (stream);
if (stream->priv->outstanding_callback)
(*stream->priv->outstanding_callback) (source_object, res, user_data);
g_object_unref (stream);
}
static void
async_ready_close_callback_wrapper (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GInputStream *stream = G_INPUT_STREAM (source_object);
g_input_stream_clear_pending (stream);
stream->priv->closed = TRUE;
if (stream->priv->outstanding_callback)
(*stream->priv->outstanding_callback) (source_object, res, user_data);
g_object_unref (stream);
}
/**
* g_input_stream_read_async:
* @stream: A #GInputStream.
* @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 that will be read from the stream
* @io_priority: the [I/O priority][io-priority]
* of the request.
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Request an asynchronous read of @count bytes from the stream into the buffer
* starting at @buffer. When the operation is finished @callback will be called.
* You can then call g_input_stream_read_finish() to get the result of the
* operation.
*
* During an async request no other sync and async calls are allowed on @stream, and will
* result in %G_IO_ERROR_PENDING errors.
*
* 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 will be passed to the
* callback. 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, but generally we try to read
* as many bytes as requested. Zero is returned on end of file
* (or if @count is zero), but never otherwise.
*
* Any outstanding i/o request with higher priority (lower numerical value) will
* be executed before an outstanding request with lower priority. Default
* priority is %G_PRIORITY_DEFAULT.
*
* The asyncronous methods have a default fallback that uses threads to implement
* asynchronicity, so they are optional for inheriting classes. However, if you
* override one you must override all.
**/
void
g_input_stream_read_async (GInputStream *stream,
void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GInputStreamClass *class;
GError *error = NULL;
g_return_if_fail (G_IS_INPUT_STREAM (stream));
g_return_if_fail (buffer != NULL);
if (count == 0)
{
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_source_tag (task, g_input_stream_read_async);
g_task_return_int (task, 0);
g_object_unref (task);
return;
}
if (((gssize) count) < 0)
{
g_task_report_new_error (stream, callback, user_data,
g_input_stream_read_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 (stream, &error))
{
g_task_report_error (stream, callback, user_data,
g_input_stream_read_async,
error);
return;
}
class = G_INPUT_STREAM_GET_CLASS (stream);
stream->priv->outstanding_callback = callback;
g_object_ref (stream);
class->read_async (stream, buffer, count, io_priority, cancellable,
async_ready_callback_wrapper, user_data);
}
/**
* g_input_stream_read_finish:
* @stream: a #GInputStream.
* @result: a #GAsyncResult.
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Finishes an asynchronous stream read operation.
*
* Returns: number of bytes read in, or -1 on error, or 0 on end of file.
**/
gssize
g_input_stream_read_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
GInputStreamClass *class;
g_return_val_if_fail (G_IS_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_input_stream_read_async))
return g_task_propagate_int (G_TASK (result), error);
class = G_INPUT_STREAM_GET_CLASS (stream);
return class->read_finish (stream, result, error);
}
typedef struct
{
gchar *buffer;
gsize to_read;
gsize bytes_read;
} AsyncReadAll;
static void
free_async_read_all (gpointer data)
{
g_slice_free (AsyncReadAll, data);
}
static void
read_all_callback (GObject *stream,
GAsyncResult *result,
gpointer user_data)
{
GTask *task = user_data;
AsyncReadAll *data = g_task_get_task_data (task);
gboolean got_eof = FALSE;
if (result)
{
GError *error = NULL;
gssize nread;
nread = g_input_stream_read_finish (G_INPUT_STREAM (stream), result, &error);
if (nread == -1)
{
g_task_return_error (task, error);
g_object_unref (task);
return;
}
g_assert_cmpint (nread, <=, data->to_read);
data->to_read -= nread;
data->bytes_read += nread;
got_eof = (nread == 0);
}
if (got_eof || data->to_read == 0)
{
g_task_return_boolean (task, TRUE);
g_object_unref (task);
}
else
g_input_stream_read_async (G_INPUT_STREAM (stream),
data->buffer + data->bytes_read,
data->to_read,
g_task_get_priority (task),
g_task_get_cancellable (task),
read_all_callback, task);
}
static void
read_all_async_thread (GTask *task,
gpointer source_object,
gpointer task_data,
GCancellable *cancellable)
{
GInputStream *stream = source_object;
AsyncReadAll *data = task_data;
GError *error = NULL;
if (g_input_stream_read_all (stream, data->buffer, data->to_read, &data->bytes_read,
g_task_get_cancellable (task), &error))
g_task_return_boolean (task, TRUE);
else
g_task_return_error (task, error);
}
/**
* g_input_stream_read_all_async:
* @stream: A #GInputStream
* @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 that will be read from the stream
* @io_priority: the [I/O priority][io-priority] of the request
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Request an asynchronous read of @count bytes from the stream into the
* buffer starting at @buffer.
*
* This is the asynchronous equivalent of g_input_stream_read_all().
*
* Call g_input_stream_read_all_finish() to collect the result.
*
* Any outstanding I/O request with higher priority (lower numerical
* value) will be executed before an outstanding request with lower
* priority. Default priority is %G_PRIORITY_DEFAULT.
*
* Since: 2.44
**/
void
g_input_stream_read_all_async (GInputStream *stream,
void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
AsyncReadAll *data;
GTask *task;
g_return_if_fail (G_IS_INPUT_STREAM (stream));
g_return_if_fail (buffer != NULL || count == 0);
task = g_task_new (stream, cancellable, callback, user_data);
data = g_slice_new0 (AsyncReadAll);
data->buffer = buffer;
data->to_read = count;
g_task_set_task_data (task, data, free_async_read_all);
g_task_set_priority (task, io_priority);
/* If async reads are going to be handled via the threadpool anyway
* then we may as well do it with a single dispatch instead of
* bouncing in and out.
*/
if (g_input_stream_async_read_is_via_threads (stream))
{
g_task_run_in_thread (task, read_all_async_thread);
g_object_unref (task);
}
else
read_all_callback (G_OBJECT (stream), NULL, task);
}
/**
* g_input_stream_read_all_finish:
* @stream: a #GInputStream
* @result: a #GAsyncResult
* @bytes_read: (out): location to store the number of bytes that was read from the stream
* @error: a #GError location to store the error occurring, or %NULL to ignore
*
* Finishes an asynchronous stream read operation started with
* g_input_stream_read_all_async().
*
* As a special exception to the normal conventions for functions that
* use #GError, if this function returns %FALSE (and sets @error) then
* @bytes_read will be set to the number of bytes that were successfully
* read before the error was encountered. This functionality is only
* available from C. If you need it from another language then you must
* write your own loop around g_input_stream_read_async().
*
* Returns: %TRUE on success, %FALSE if there was an error
*
* Since: 2.44
**/
gboolean
g_input_stream_read_all_finish (GInputStream *stream,
GAsyncResult *result,
gsize *bytes_read,
GError **error)
{
GTask *task;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);
task = G_TASK (result);
if (bytes_read)
{
AsyncReadAll *data = g_task_get_task_data (task);
*bytes_read = data->bytes_read;
}
return g_task_propagate_boolean (task, error);
}
static void
read_bytes_callback (GObject *stream,
GAsyncResult *result,
gpointer user_data)
{
GTask *task = user_data;
guchar *buf = g_task_get_task_data (task);
GError *error = NULL;
gssize nread;
GBytes *bytes = NULL;
nread = g_input_stream_read_finish (G_INPUT_STREAM (stream),
result, &error);
if (nread == -1)
{
g_free (buf);
g_task_return_error (task, error);
}
else if (nread == 0)
{
g_free (buf);
bytes = g_bytes_new_static ("", 0);
}
else
bytes = g_bytes_new_take (buf, nread);
if (bytes)
g_task_return_pointer (task, bytes, (GDestroyNotify)g_bytes_unref);
g_object_unref (task);
}
/**
* g_input_stream_read_bytes_async:
* @stream: A #GInputStream.
* @count: the number of bytes that will be read from the stream
* @io_priority: the [I/O priority][io-priority] of the request
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Request an asynchronous read of @count bytes from the stream into a
* new #GBytes. When the operation is finished @callback will be
* called. You can then call g_input_stream_read_bytes_finish() to get the
* result of the operation.
*
* During an async request no other sync and async calls are allowed
* on @stream, and will result in %G_IO_ERROR_PENDING errors.
*
* A value of @count larger than %G_MAXSSIZE will cause a
* %G_IO_ERROR_INVALID_ARGUMENT error.
*
* On success, the new #GBytes will be passed to the callback. It is
* not an error if this is smaller than the requested size, as it can
* happen e.g. near the end of a file, but generally we try to read as
* many bytes as requested. Zero is returned on end of file (or if
* @count is zero), but never otherwise.
*
* Any outstanding I/O request with higher priority (lower numerical
* value) will be executed before an outstanding request with lower
* priority. Default priority is %G_PRIORITY_DEFAULT.
*
* Since: 2.34
**/
void
g_input_stream_read_bytes_async (GInputStream *stream,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GTask *task;
guchar *buf;
task = g_task_new (stream, cancellable, callback, user_data);
buf = g_malloc (count);
g_task_set_task_data (task, buf, NULL);
g_input_stream_read_async (stream, buf, count,
io_priority, cancellable,
read_bytes_callback, task);
}
/**
* g_input_stream_read_bytes_finish:
* @stream: a #GInputStream.
* @result: a #GAsyncResult.
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Finishes an asynchronous stream read-into-#GBytes operation.
*
* Returns: the newly-allocated #GBytes, or %NULL on error
*
* Since: 2.34
**/
GBytes *
g_input_stream_read_bytes_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), NULL);
g_return_val_if_fail (g_task_is_valid (result, stream), NULL);
return g_task_propagate_pointer (G_TASK (result), error);
}
/**
* g_input_stream_skip_async:
* @stream: A #GInputStream.
* @count: the number of bytes that will be skipped from the stream
* @io_priority: the [I/O priority][io-priority] of the request
* @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Request an asynchronous skip of @count bytes from the stream.
* When the operation is finished @callback will be called.
* You can then call g_input_stream_skip_finish() to get the result
* of the operation.
*
* During an async request no other sync and async calls are allowed,
* and will result in %G_IO_ERROR_PENDING errors.
*
* A value of @count larger than %G_MAXSSIZE will cause a %G_IO_ERROR_INVALID_ARGUMENT error.
*
* On success, the number of bytes skipped will be passed to the callback.
* 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, but generally we try to skip
* as many bytes as requested. Zero is returned on end of file
* (or if @count is zero), but never otherwise.
*
* Any outstanding i/o request with higher priority (lower numerical value)
* will be executed before an outstanding request with lower priority.
* Default priority is %G_PRIORITY_DEFAULT.
*
* The asynchronous methods have a default fallback that uses threads to
* implement asynchronicity, so they are optional for inheriting classes.
* However, if you override one, you must override all.
**/
void
g_input_stream_skip_async (GInputStream *stream,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GInputStreamClass *class;
GError *error = NULL;
g_return_if_fail (G_IS_INPUT_STREAM (stream));
if (count == 0)
{
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_source_tag (task, g_input_stream_skip_async);
g_task_return_int (task, 0);
g_object_unref (task);
return;
}
if (((gssize) count) < 0)
{
g_task_report_new_error (stream, callback, user_data,
g_input_stream_skip_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 (stream, &error))
{
g_task_report_error (stream, callback, user_data,
g_input_stream_skip_async,
error);
return;
}
class = G_INPUT_STREAM_GET_CLASS (stream);
stream->priv->outstanding_callback = callback;
g_object_ref (stream);
class->skip_async (stream, count, io_priority, cancellable,
async_ready_callback_wrapper, user_data);
}
/**
* g_input_stream_skip_finish:
* @stream: a #GInputStream.
* @result: a #GAsyncResult.
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Finishes a stream skip operation.
*
* Returns: the size of the bytes skipped, or %-1 on error.
**/
gssize
g_input_stream_skip_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
GInputStreamClass *class;
g_return_val_if_fail (G_IS_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_input_stream_skip_async))
return g_task_propagate_int (G_TASK (result), error);
class = G_INPUT_STREAM_GET_CLASS (stream);
return class->skip_finish (stream, result, error);
}
/**
* g_input_stream_close_async:
* @stream: A #GInputStream.
* @io_priority: the [I/O priority][io-priority] of the request
* @cancellable: (allow-none): optional cancellable object
* @callback: (scope async): callback to call when the request is satisfied
* @user_data: (closure): the data to pass to callback function
*
* Requests an asynchronous closes of the stream, releasing resources related to it.
* When the operation is finished @callback will be called.
* You can then call g_input_stream_close_finish() to get the result of the
* operation.
*
* For behaviour details see g_input_stream_close().
*
* The asyncronous methods have a default fallback that uses threads to implement
* asynchronicity, so they are optional for inheriting classes. However, if you
* override one you must override all.
**/
void
g_input_stream_close_async (GInputStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GInputStreamClass *class;
GError *error = NULL;
g_return_if_fail (G_IS_INPUT_STREAM (stream));
if (stream->priv->closed)
{
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_source_tag (task, g_input_stream_close_async);
g_task_return_boolean (task, TRUE);
g_object_unref (task);
return;
}
if (!g_input_stream_set_pending (stream, &error))
{
g_task_report_error (stream, callback, user_data,
g_input_stream_close_async,
error);
return;
}
class = G_INPUT_STREAM_GET_CLASS (stream);
stream->priv->outstanding_callback = callback;
g_object_ref (stream);
class->close_async (stream, io_priority, cancellable,
async_ready_close_callback_wrapper, user_data);
}
/**
* g_input_stream_close_finish:
* @stream: a #GInputStream.
* @result: a #GAsyncResult.
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Finishes closing a stream asynchronously, started from g_input_stream_close_async().
*
* Returns: %TRUE if the stream was closed successfully.
**/
gboolean
g_input_stream_close_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
GInputStreamClass *class;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
g_return_val_if_fail (G_IS_ASYNC_RESULT (result), FALSE);
if (g_async_result_legacy_propagate_error (result, error))
return FALSE;
else if (g_async_result_is_tagged (result, g_input_stream_close_async))
return g_task_propagate_boolean (G_TASK (result), error);
class = G_INPUT_STREAM_GET_CLASS (stream);
return class->close_finish (stream, result, error);
}
/**
* g_input_stream_is_closed:
* @stream: input stream.
*
* Checks if an input stream is closed.
*
* Returns: %TRUE if the stream is closed.
**/
gboolean
g_input_stream_is_closed (GInputStream *stream)
{
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), TRUE);
return stream->priv->closed;
}
/**
* g_input_stream_has_pending:
* @stream: input stream.
*
* Checks if an input stream has pending actions.
*
* Returns: %TRUE if @stream has pending actions.
**/
gboolean
g_input_stream_has_pending (GInputStream *stream)
{
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), TRUE);
return stream->priv->pending;
}
/**
* g_input_stream_set_pending:
* @stream: input stream
* @error: a #GError location to store the error occurring, or %NULL to
* ignore.
*
* Sets @stream to have actions pending. If the pending flag is
* already set or @stream is closed, it will return %FALSE and set
* @error.
*
* Returns: %TRUE if pending was previously unset and is now set.
**/
gboolean
g_input_stream_set_pending (GInputStream *stream, GError **error)
{
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
if (stream->priv->closed)
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
_("Stream is already closed"));
return FALSE;
}
if (stream->priv->pending)
{
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_PENDING,
/* Translators: This is an error you get if there is already an
* operation running against this stream when you try to start
* one */
_("Stream has outstanding operation"));
return FALSE;
}
stream->priv->pending = TRUE;
return TRUE;
}
/**
* g_input_stream_clear_pending:
* @stream: input stream
*
* Clears the pending flag on @stream.
**/
void
g_input_stream_clear_pending (GInputStream *stream)
{
g_return_if_fail (G_IS_INPUT_STREAM (stream));
stream->priv->pending = FALSE;
}
/**
* g_input_stream_async_read_is_via_threads:
* @stream: input stream
*
* Checks if an input stream's read_async function uses threads.
*
* Returns: %TRUE if @stream's read_async function uses threads.
**/
gboolean
g_input_stream_async_read_is_via_threads (GInputStream *stream)
{
GInputStreamClass *class;
g_return_val_if_fail (G_IS_INPUT_STREAM (stream), FALSE);
class = G_INPUT_STREAM_GET_CLASS (stream);
return (class->read_async == g_input_stream_real_read_async &&
!(G_IS_POLLABLE_INPUT_STREAM (stream) &&
g_pollable_input_stream_can_poll (G_POLLABLE_INPUT_STREAM (stream))));
}
/********************************************
* Default implementation of async ops *
********************************************/
typedef struct {
void *buffer;
gsize count;
} ReadData;
static void
free_read_data (ReadData *op)
{
g_slice_free (ReadData, op);
}
static void
read_async_thread (GTask *task,
gpointer source_object,
gpointer task_data,
GCancellable *cancellable)
{
GInputStream *stream = source_object;
ReadData *op = task_data;
GInputStreamClass *class;
GError *error = NULL;
gssize nread;
class = G_INPUT_STREAM_GET_CLASS (stream);
nread = class->read_fn (stream,
op->buffer, op->count,
g_task_get_cancellable (task),
&error);
if (nread == -1)
g_task_return_error (task, error);
else
g_task_return_int (task, nread);
}
static void read_async_pollable (GPollableInputStream *stream,
GTask *task);
static gboolean
read_async_pollable_ready (GPollableInputStream *stream,
gpointer user_data)
{
GTask *task = user_data;
read_async_pollable (stream, task);
return FALSE;
}
static void
read_async_pollable (GPollableInputStream *stream,
GTask *task)
{
ReadData *op = g_task_get_task_data (task);
GError *error = NULL;
gssize nread;
if (g_task_return_error_if_cancelled (task))
return;
nread = G_POLLABLE_INPUT_STREAM_GET_INTERFACE (stream)->
read_nonblocking (stream, op->buffer, op->count, &error);
if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_WOULD_BLOCK))
{
GSource *source;
g_error_free (error);
source = g_pollable_input_stream_create_source (stream,
g_task_get_cancellable (task));
g_task_attach_source (task, source,
(GSourceFunc) read_async_pollable_ready);
g_source_unref (source);
return;
}
if (nread == -1)
g_task_return_error (task, error);
else
g_task_return_int (task, nread);
/* g_input_stream_real_read_async() unrefs task */
}
static void
g_input_stream_real_read_async (GInputStream *stream,
void *buffer,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GTask *task;
ReadData *op;
op = g_slice_new0 (ReadData);
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_task_data (task, op, (GDestroyNotify) free_read_data);
g_task_set_priority (task, io_priority);
op->buffer = buffer;
op->count = count;
if (!g_input_stream_async_read_is_via_threads (stream))
read_async_pollable (G_POLLABLE_INPUT_STREAM (stream), task);
else
g_task_run_in_thread (task, read_async_thread);
g_object_unref (task);
}
static gssize
g_input_stream_real_read_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (g_task_is_valid (result, stream), -1);
return g_task_propagate_int (G_TASK (result), error);
}
static void
skip_async_thread (GTask *task,
gpointer source_object,
gpointer task_data,
GCancellable *cancellable)
{
GInputStream *stream = source_object;
gsize count = GPOINTER_TO_SIZE (task_data);
GInputStreamClass *class;
GError *error = NULL;
gssize ret;
class = G_INPUT_STREAM_GET_CLASS (stream);
ret = class->skip (stream, count,
g_task_get_cancellable (task),
&error);
if (ret == -1)
g_task_return_error (task, error);
else
g_task_return_int (task, ret);
}
typedef struct {
char buffer[8192];
gsize count;
gsize count_skipped;
} SkipFallbackAsyncData;
static void
skip_callback_wrapper (GObject *source_object,
GAsyncResult *res,
gpointer user_data)
{
GInputStreamClass *class;
GTask *task = user_data;
SkipFallbackAsyncData *data = g_task_get_task_data (task);
GError *error = NULL;
gssize ret;
ret = g_input_stream_read_finish (G_INPUT_STREAM (source_object), res, &error);
if (ret > 0)
{
data->count -= ret;
data->count_skipped += ret;
if (data->count > 0)
{
class = G_INPUT_STREAM_GET_CLASS (source_object);
class->read_async (G_INPUT_STREAM (source_object),
data->buffer, MIN (8192, data->count),
g_task_get_priority (task),
g_task_get_cancellable (task),
skip_callback_wrapper, task);
return;
}
}
if (ret == -1 &&
g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED) &&
data->count_skipped)
{
/* No error, return partial read */
g_clear_error (&error);
}
if (error)
g_task_return_error (task, error);
else
g_task_return_int (task, data->count_skipped);
g_object_unref (task);
}
static void
g_input_stream_real_skip_async (GInputStream *stream,
gsize count,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GInputStreamClass *class;
SkipFallbackAsyncData *data;
GTask *task;
class = G_INPUT_STREAM_GET_CLASS (stream);
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_priority (task, io_priority);
if (g_input_stream_async_read_is_via_threads (stream))
{
/* Read is thread-using async fallback.
* Make skip use threads too, so that we can use a possible sync skip
* implementation. */
g_task_set_task_data (task, GSIZE_TO_POINTER (count), NULL);
g_task_run_in_thread (task, skip_async_thread);
g_object_unref (task);
}
else
{
/* TODO: Skip fallback uses too much memory, should do multiple read calls */
/* There is a custom async read function, lets use that. */
data = g_new (SkipFallbackAsyncData, 1);
data->count = count;
data->count_skipped = 0;
g_task_set_task_data (task, data, g_free);
g_task_set_check_cancellable (task, FALSE);
class->read_async (stream, data->buffer, MIN (8192, count), io_priority, cancellable,
skip_callback_wrapper, task);
}
}
static gssize
g_input_stream_real_skip_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (g_task_is_valid (result, stream), -1);
return g_task_propagate_int (G_TASK (result), error);
}
static void
close_async_thread (GTask *task,
gpointer source_object,
gpointer task_data,
GCancellable *cancellable)
{
GInputStream *stream = source_object;
GInputStreamClass *class;
GError *error = NULL;
gboolean result;
class = G_INPUT_STREAM_GET_CLASS (stream);
if (class->close_fn)
{
result = class->close_fn (stream,
g_task_get_cancellable (task),
&error);
if (!result)
{
g_task_return_error (task, error);
return;
}
}
g_task_return_boolean (task, TRUE);
}
static void
g_input_stream_real_close_async (GInputStream *stream,
int io_priority,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
GTask *task;
task = g_task_new (stream, cancellable, callback, user_data);
g_task_set_check_cancellable (task, FALSE);
g_task_set_priority (task, io_priority);
g_task_run_in_thread (task, close_async_thread);
g_object_unref (task);
}
static gboolean
g_input_stream_real_close_finish (GInputStream *stream,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);
return g_task_propagate_boolean (G_TASK (result), error);
}
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