goutputstream.c 95.2 KB
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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
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 * version 2.1 of the License, or (at your option) any later version.
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 *
 * 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
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 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
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 *
 * Author: Alexander Larsson <alexl@redhat.com>
 */

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#include "config.h"
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#include <string.h>
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#include "goutputstream.h"
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#include "gcancellable.h"
#include "gasyncresult.h"
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#include "gtask.h"
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#include "ginputstream.h"
#include "gioerror.h"
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#include "gioprivate.h"
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#include "glibintl.h"
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#include "gpollableoutputstream.h"
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/**
 * SECTION:goutputstream
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 * @short_description: Base class for implementing streaming output
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 * @include: gio/gio.h
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 *
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 * #GOutputStream has functions to write to a stream (g_output_stream_write()),
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 * to close a stream (g_output_stream_close()) and to flush pending writes
 * (g_output_stream_flush()). 
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 *
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 * To copy the content of an input stream to an output stream without 
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 * manually handling the reads and writes, use g_output_stream_splice().
 *
 * See the documentation for #GIOStream for details of thread safety of
 * streaming APIs.
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 *
 * All of these functions have async variants too.
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 **/

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struct _GOutputStreamPrivate {
  guint closed : 1;
  guint pending : 1;
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  guint closing : 1;
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  GAsyncReadyCallback outstanding_callback;
};

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G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GOutputStream, g_output_stream, G_TYPE_OBJECT)

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static gssize   g_output_stream_real_splice        (GOutputStream             *stream,
						    GInputStream              *source,
						    GOutputStreamSpliceFlags   flags,
						    GCancellable              *cancellable,
						    GError                   **error);
static void     g_output_stream_real_write_async   (GOutputStream             *stream,
						    const void                *buffer,
						    gsize                      count,
						    int                        io_priority,
						    GCancellable              *cancellable,
						    GAsyncReadyCallback        callback,
						    gpointer                   data);
static gssize   g_output_stream_real_write_finish  (GOutputStream             *stream,
						    GAsyncResult              *result,
						    GError                   **error);
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static gboolean g_output_stream_real_writev        (GOutputStream             *stream,
						    const GOutputVector       *vectors,
						    gsize                      n_vectors,
						    gsize                     *bytes_written,
						    GCancellable              *cancellable,
						    GError                   **error);
static void     g_output_stream_real_writev_async  (GOutputStream             *stream,
						    const GOutputVector       *vectors,
						    gsize                      n_vectors,
						    int                        io_priority,
						    GCancellable              *cancellable,
						    GAsyncReadyCallback        callback,
						    gpointer                   data);
static gboolean g_output_stream_real_writev_finish (GOutputStream             *stream,
						    GAsyncResult              *result,
						    gsize                     *bytes_written,
						    GError                   **error);
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static void     g_output_stream_real_splice_async  (GOutputStream             *stream,
						    GInputStream              *source,
						    GOutputStreamSpliceFlags   flags,
						    int                        io_priority,
						    GCancellable              *cancellable,
						    GAsyncReadyCallback        callback,
						    gpointer                   data);
static gssize   g_output_stream_real_splice_finish (GOutputStream             *stream,
						    GAsyncResult              *result,
						    GError                   **error);
static void     g_output_stream_real_flush_async   (GOutputStream             *stream,
						    int                        io_priority,
						    GCancellable              *cancellable,
						    GAsyncReadyCallback        callback,
						    gpointer                   data);
static gboolean g_output_stream_real_flush_finish  (GOutputStream             *stream,
						    GAsyncResult              *result,
						    GError                   **error);
static void     g_output_stream_real_close_async   (GOutputStream             *stream,
						    int                        io_priority,
						    GCancellable              *cancellable,
						    GAsyncReadyCallback        callback,
						    gpointer                   data);
static gboolean g_output_stream_real_close_finish  (GOutputStream             *stream,
						    GAsyncResult              *result,
						    GError                   **error);
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static gboolean g_output_stream_internal_close     (GOutputStream             *stream,
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                                                    GCancellable              *cancellable,
                                                    GError                   **error);
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static void     g_output_stream_internal_close_async (GOutputStream           *stream,
                                                      int                      io_priority,
                                                      GCancellable            *cancellable,
                                                      GAsyncReadyCallback      callback,
                                                      gpointer                 data);
static gboolean g_output_stream_internal_close_finish (GOutputStream          *stream,
                                                       GAsyncResult           *result,
                                                       GError                **error);
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static void
g_output_stream_dispose (GObject *object)
{
  GOutputStream *stream;

  stream = G_OUTPUT_STREAM (object);
  
  if (!stream->priv->closed)
    g_output_stream_close (stream, NULL, NULL);
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  G_OBJECT_CLASS (g_output_stream_parent_class)->dispose (object);
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}

static void
g_output_stream_class_init (GOutputStreamClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
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  gobject_class->dispose = g_output_stream_dispose;

  klass->splice = g_output_stream_real_splice;
  
  klass->write_async = g_output_stream_real_write_async;
  klass->write_finish = g_output_stream_real_write_finish;
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  klass->writev_fn = g_output_stream_real_writev;
  klass->writev_async = g_output_stream_real_writev_async;
  klass->writev_finish = g_output_stream_real_writev_finish;
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  klass->splice_async = g_output_stream_real_splice_async;
  klass->splice_finish = g_output_stream_real_splice_finish;
  klass->flush_async = g_output_stream_real_flush_async;
  klass->flush_finish = g_output_stream_real_flush_finish;
  klass->close_async = g_output_stream_real_close_async;
  klass->close_finish = g_output_stream_real_close_finish;
}

static void
g_output_stream_init (GOutputStream *stream)
{
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  stream->priv = g_output_stream_get_instance_private (stream);
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}

/**
 * g_output_stream_write:
 * @stream: a #GOutputStream.
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 * @buffer: (array length=count) (element-type guint8): the buffer containing the data to write. 
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 * @count: the number of bytes to write
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 * @cancellable: (nullable): optional cancellable object
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 * @error: location to store the error occurring, or %NULL to ignore
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 *
 * Tries to write @count bytes from @buffer into the stream. Will block
 * during the operation.
 * 
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 * If count is 0, returns 0 and does nothing. A value of @count
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 * larger than %G_MAXSSIZE will cause a %G_IO_ERROR_INVALID_ARGUMENT error.
 *
 * On success, the number of bytes written to the stream is returned.
 * It is not an error if this is not the same as the requested size, as it
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 * can happen e.g. on a partial I/O error, or if there is not enough
 * storage in the stream. All writes block until at least one byte
 * is written or an error occurs; 0 is never returned (unless
 * @count is 0).
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 * 
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 * If @cancellable is not %NULL, then the operation can be cancelled by
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 * triggering the cancellable object from another thread. If the operation
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 * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
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 * 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.
 * 
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 * Virtual: write_fn
 *
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 * Returns: Number of bytes written, or -1 on error
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 **/
gssize
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g_output_stream_write (GOutputStream  *stream,
		       const void     *buffer,
		       gsize           count,
		       GCancellable   *cancellable,
		       GError        **error)
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{
  GOutputStreamClass *class;
  gssize res;

  g_return_val_if_fail (G_IS_OUTPUT_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,
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		   _("Too large count value passed to %s"), G_STRFUNC);
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      return -1;
    }

  class = G_OUTPUT_STREAM_GET_CLASS (stream);

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  if (class->write_fn == NULL) 
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    {
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      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
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                           _("Output stream doesn’t implement write"));
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      return -1;
    }
  
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  if (!g_output_stream_set_pending (stream, error))
    return -1;
  
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  if (cancellable)
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    g_cancellable_push_current (cancellable);
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  res = class->write_fn (stream, buffer, count, cancellable, error);
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  if (cancellable)
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    g_cancellable_pop_current (cancellable);
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  g_output_stream_clear_pending (stream);

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  return res; 
}

/**
 * g_output_stream_write_all:
 * @stream: a #GOutputStream.
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 * @buffer: (array length=count) (element-type guint8): the buffer containing the data to write. 
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 * @count: the number of bytes to write
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 * @bytes_written: (out) (optional): location to store the number of bytes that was
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 *     written to the stream
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
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 * @error: location to store the error occurring, or %NULL to ignore
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 *
 * Tries to write @count bytes from @buffer into the stream. Will block
 * during the operation.
 * 
 * This function is similar to g_output_stream_write(), except it tries to
 * write as many bytes as requested, only stopping on an error.
 *
 * On a successful write of @count bytes, %TRUE is returned, and @bytes_written
 * is set to @count.
 * 
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 * If there is an error during the operation %FALSE is returned and @error
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 * 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_written will be set to the number of bytes that were
 * successfully written 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_output_stream_write().
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 *
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 * Returns: %TRUE on success, %FALSE if there was an error
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 **/
gboolean
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g_output_stream_write_all (GOutputStream  *stream,
			   const void     *buffer,
			   gsize           count,
			   gsize          *bytes_written,
			   GCancellable   *cancellable,
			   GError        **error)
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{
  gsize _bytes_written;
  gssize res;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
  g_return_val_if_fail (buffer != NULL, FALSE);

  _bytes_written = 0;
  while (_bytes_written < count)
    {
      res = g_output_stream_write (stream, (char *)buffer + _bytes_written, count - _bytes_written,
				   cancellable, error);
      if (res == -1)
	{
	  if (bytes_written)
	    *bytes_written = _bytes_written;
	  return FALSE;
	}
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      g_return_val_if_fail (res > 0, FALSE);
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      _bytes_written += res;
    }
  
  if (bytes_written)
    *bytes_written = _bytes_written;
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  return TRUE;
}

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/**
 * g_output_stream_writev:
 * @stream: a #GOutputStream.
 * @vectors: (array length=n_vectors): the buffer containing the #GOutputVectors to write.
 * @n_vectors: the number of vectors to write
 * @bytes_written: (out) (optional): location to store the number of bytes that were
 *     written to the stream
 * @cancellable: (nullable): optional cancellable object
 * @error: location to store the error occurring, or %NULL to ignore
 *
 * Tries to write the bytes contained in the @n_vectors @vectors into the
 * stream. Will block during the operation.
 *
 * If @n_vectors is 0 or the sum of all bytes in @vectors is 0, returns 0 and
 * does nothing.
 *
 * On success, the number of bytes written to the stream is returned.
 * It is not an error if this is not the same as the requested size, as it
 * can happen e.g. on a partial I/O error, or if there is not enough
 * storage in the stream. All writes block until at least one byte
 * is written or an error occurs; 0 is never returned (unless
 * @n_vectors is 0 or the sum of all bytes in @vectors is 0).
 *
 * 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.
 *
 * Some implementations of g_output_stream_writev() may have limitations on the
 * aggregate buffer size, and will return %G_IO_ERROR_INVALID_ARGUMENT if these
 * are exceeded. For example, when writing to a local file on UNIX platforms,
 * the aggregate buffer size must not exceed %G_MAXSSIZE bytes.
 *
 * Virtual: writev_fn
 *
 * Returns: %TRUE on success, %FALSE if there was an error
 *
 * Since: 2.60
 */
gboolean
g_output_stream_writev (GOutputStream        *stream,
		        const GOutputVector  *vectors,
		        gsize                 n_vectors,
		        gsize                *bytes_written,
		        GCancellable         *cancellable,
		        GError              **error)
{
  GOutputStreamClass *class;
  gboolean res;
  gsize _bytes_written = 0;

  if (bytes_written)
    *bytes_written = 0;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
  g_return_val_if_fail (vectors != NULL || n_vectors == 0, FALSE);
  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  if (n_vectors == 0)
    return TRUE;

  class = G_OUTPUT_STREAM_GET_CLASS (stream);

  g_return_val_if_fail (class->writev_fn != NULL, FALSE);

  if (!g_output_stream_set_pending (stream, error))
    return FALSE;

  if (cancellable)
    g_cancellable_push_current (cancellable);

  res = class->writev_fn (stream, vectors, n_vectors, &_bytes_written, cancellable, error);

  g_warn_if_fail (res || _bytes_written == 0);
  g_warn_if_fail (res || (error == NULL || *error != NULL));

  if (cancellable)
    g_cancellable_pop_current (cancellable);

  g_output_stream_clear_pending (stream);

  if (bytes_written)
    *bytes_written = _bytes_written;

  return res;
}

/**
 * g_output_stream_writev_all:
 * @stream: a #GOutputStream.
 * @vectors: (array length=n_vectors): the buffer containing the #GOutputVectors to write.
 * @n_vectors: the number of vectors to write
 * @bytes_written: (out) (optional): location to store the number of bytes that were
 *     written to the stream
 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
 * @error: location to store the error occurring, or %NULL to ignore
 *
 * Tries to write the bytes contained in the @n_vectors @vectors into the
 * stream. Will block during the operation.
 *
 * This function is similar to g_output_stream_writev(), except it tries to
 * write as many bytes as requested, only stopping on an error.
 *
 * On a successful write of all @n_vectors vectors, %TRUE is returned, and
 * @bytes_written is set to the sum of all the sizes of @vectors.
 *
 * 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_written will be set to the number of bytes that were
 * successfully written 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_output_stream_write().
 *
 * The content of the individual elements of @vectors might be changed by this
 * function.
 *
 * Returns: %TRUE on success, %FALSE if there was an error
 *
 * Since: 2.60
 */
gboolean
g_output_stream_writev_all (GOutputStream  *stream,
			    GOutputVector  *vectors,
			    gsize           n_vectors,
			    gsize          *bytes_written,
			    GCancellable   *cancellable,
			    GError        **error)
{
  gsize _bytes_written = 0;
  gsize i, to_be_written = 0;

  if (bytes_written)
    *bytes_written = 0;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
  g_return_val_if_fail (vectors != NULL || n_vectors == 0, FALSE);
  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  /* We can't write more than G_MAXSIZE bytes overall, otherwise we
   * would overflow the bytes_written counter */
  for (i = 0; i < n_vectors; i++)
    {
       if (to_be_written > G_MAXSIZE - vectors[i].size)
         {
           g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
                        _("Sum of vectors passed to %s too large"), G_STRFUNC);
           return FALSE;
         }
       to_be_written += vectors[i].size;
    }

  _bytes_written = 0;
  while (n_vectors > 0 && to_be_written > 0)
    {
      gsize n_written = 0;
      gboolean res;

      res = g_output_stream_writev (stream, vectors, n_vectors, &n_written, cancellable, error);

      if (!res)
        {
          if (bytes_written)
            *bytes_written = _bytes_written;
          return FALSE;
        }

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      g_return_val_if_fail (n_written > 0, FALSE);
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      _bytes_written += n_written;

      /* skip vectors that have been written in full */
      while (n_vectors > 0 && n_written >= vectors[0].size)
        {
          n_written -= vectors[0].size;
          ++vectors;
          --n_vectors;
        }
      /* skip partially written vector data */
      if (n_written > 0 && n_vectors > 0)
        {
          vectors[0].size -= n_written;
          vectors[0].buffer = ((guint8 *) vectors[0].buffer) + n_written;
        }
    }

  if (bytes_written)
    *bytes_written = _bytes_written;

  return TRUE;
}

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/**
 * g_output_stream_printf:
 * @stream: a #GOutputStream.
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 * @bytes_written: (out) (optional): location to store the number of bytes that was
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 *     written to the stream
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
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 * @error: location to store the error occurring, or %NULL to ignore
 * @format: the format string. See the printf() documentation
 * @...: the parameters to insert into the format string
 *
 * This is a utility function around g_output_stream_write_all(). It
 * uses g_strdup_vprintf() to turn @format and @... into a string that
 * is then written to @stream.
 *
 * See the documentation of g_output_stream_write_all() about the
 * behavior of the actual write operation.
 *
 * Note that partial writes cannot be properly checked with this
 * function due to the variable length of the written string, if you
 * need precise control over partial write failures, you need to
 * create you own printf()-like wrapper around g_output_stream_write()
 * or g_output_stream_write_all().
 *
 * Since: 2.40
 *
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 * Returns: %TRUE on success, %FALSE if there was an error
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 **/
gboolean
g_output_stream_printf (GOutputStream  *stream,
                        gsize          *bytes_written,
                        GCancellable   *cancellable,
                        GError        **error,
                        const gchar    *format,
                        ...)
{
  va_list  args;
  gboolean success;

  va_start (args, format);
  success = g_output_stream_vprintf (stream, bytes_written, cancellable,
                                     error, format, args);
  va_end (args);

  return success;
}

/**
 * g_output_stream_vprintf:
 * @stream: a #GOutputStream.
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 * @bytes_written: (out) (optional): location to store the number of bytes that was
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 *     written to the stream
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
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 * @error: location to store the error occurring, or %NULL to ignore
 * @format: the format string. See the printf() documentation
 * @args: the parameters to insert into the format string
 *
 * This is a utility function around g_output_stream_write_all(). It
 * uses g_strdup_vprintf() to turn @format and @args into a string that
 * is then written to @stream.
 *
 * See the documentation of g_output_stream_write_all() about the
 * behavior of the actual write operation.
 *
 * Note that partial writes cannot be properly checked with this
 * function due to the variable length of the written string, if you
 * need precise control over partial write failures, you need to
 * create you own printf()-like wrapper around g_output_stream_write()
 * or g_output_stream_write_all().
 *
 * Since: 2.40
 *
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 * Returns: %TRUE on success, %FALSE if there was an error
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 **/
gboolean
g_output_stream_vprintf (GOutputStream  *stream,
                         gsize          *bytes_written,
                         GCancellable   *cancellable,
                         GError        **error,
                         const gchar    *format,
                         va_list         args)
{
  gchar    *text;
  gboolean  success;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
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  g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
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  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
  g_return_val_if_fail (format != NULL, FALSE);

  text = g_strdup_vprintf (format, args);
  success = g_output_stream_write_all (stream,
                                       text, strlen (text),
                                       bytes_written, cancellable, error);
  g_free (text);

  return success;
}

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/**
 * g_output_stream_write_bytes:
 * @stream: a #GOutputStream.
 * @bytes: the #GBytes to write
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 * @cancellable: (nullable): optional cancellable object
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 * @error: location to store the error occurring, or %NULL to ignore
 *
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 * A wrapper function for g_output_stream_write() which takes a
 * #GBytes as input.  This can be more convenient for use by language
 * bindings or in other cases where the refcounted nature of #GBytes
 * is helpful over a bare pointer interface.
 *
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 * However, note that this function may still perform partial writes,
 * just like g_output_stream_write().  If that occurs, to continue
 * writing, you will need to create a new #GBytes containing just the
 * remaining bytes, using g_bytes_new_from_bytes(). Passing the same
 * #GBytes instance multiple times potentially can result in duplicated
 * data in the output stream.
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 *
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 * Returns: Number of bytes written, or -1 on error
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 **/
gssize
g_output_stream_write_bytes (GOutputStream  *stream,
			     GBytes         *bytes,
			     GCancellable   *cancellable,
			     GError        **error)
{
  gsize size;
  gconstpointer data;

  data = g_bytes_get_data (bytes, &size);

  return g_output_stream_write (stream,
                                data, size,
				cancellable,
				error);
}

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/**
 * g_output_stream_flush:
 * @stream: a #GOutputStream.
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 * @cancellable: (nullable): optional cancellable object
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 * @error: location to store the error occurring, or %NULL to ignore
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 *
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 * Forces a write of all user-space buffered data for the given
 * @stream. Will block during the operation. Closing the stream will
 * implicitly cause a flush.
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 *
 * This function is optional for inherited classes.
 * 
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 * If @cancellable is not %NULL, then the operation can be cancelled by
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 * triggering the cancellable object from another thread. If the operation
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 * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned.
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 *
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 * Returns: %TRUE on success, %FALSE on error
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 **/
gboolean
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g_output_stream_flush (GOutputStream  *stream,
                       GCancellable   *cancellable,
                       GError        **error)
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{
  GOutputStreamClass *class;
  gboolean res;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);

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  if (!g_output_stream_set_pending (stream, error))
    return FALSE;
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  class = G_OUTPUT_STREAM_GET_CLASS (stream);

  res = TRUE;
  if (class->flush)
    {
      if (cancellable)
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	g_cancellable_push_current (cancellable);
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      res = class->flush (stream, cancellable, error);
      
      if (cancellable)
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	g_cancellable_pop_current (cancellable);
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    }
  
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  g_output_stream_clear_pending (stream);

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  return res;
}

/**
 * g_output_stream_splice:
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 * @stream: a #GOutputStream.
 * @source: a #GInputStream.
 * @flags: a set of #GOutputStreamSpliceFlags.
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
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 * @error: a #GError location to store the error occurring, or %NULL to
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 * ignore.
 *
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 * Splices an input stream into an output stream.
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 *
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 * Returns: a #gssize containing the size of the data spliced, or
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 *     -1 if an error occurred. Note that if the number of bytes
 *     spliced is greater than %G_MAXSSIZE, then that will be
 *     returned, and there is no way to determine the actual number
 *     of bytes spliced.
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 **/
gssize
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g_output_stream_splice (GOutputStream             *stream,
			GInputStream              *source,
			GOutputStreamSpliceFlags   flags,
			GCancellable              *cancellable,
			GError                   **error)
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{
  GOutputStreamClass *class;
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  gssize bytes_copied;
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  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), -1);
  g_return_val_if_fail (G_IS_INPUT_STREAM (source), -1);

  if (g_input_stream_is_closed (source))
    {
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      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
                           _("Source stream is already closed"));
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      return -1;
    }

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  if (!g_output_stream_set_pending (stream, error))
    return -1;
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  class = G_OUTPUT_STREAM_GET_CLASS (stream);

  if (cancellable)
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    g_cancellable_push_current (cancellable);
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  bytes_copied = class->splice (stream, source, flags, cancellable, error);

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  if (cancellable)
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    g_cancellable_pop_current (cancellable);
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  g_output_stream_clear_pending (stream);

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  return bytes_copied;
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}

static gssize
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g_output_stream_real_splice (GOutputStream             *stream,
                             GInputStream              *source,
                             GOutputStreamSpliceFlags   flags,
                             GCancellable              *cancellable,
                             GError                   **error)
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{
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  GOutputStreamClass *class = G_OUTPUT_STREAM_GET_CLASS (stream);
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  gssize n_read, n_written;
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  gsize bytes_copied;
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  char buffer[8192], *p;
  gboolean res;

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  bytes_copied = 0;
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  if (class->write_fn == NULL)
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    {
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      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
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                           _("Output stream doesn’t implement write"));
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      res = FALSE;
      goto notsupported;
    }
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  res = TRUE;
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  do
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    {
      n_read = g_input_stream_read (source, buffer, sizeof (buffer), cancellable, error);
      if (n_read == -1)
	{
	  res = FALSE;
	  break;
	}
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      if (n_read == 0)
	break;

      p = buffer;
      while (n_read > 0)
	{
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	  n_written = class->write_fn (stream, p, n_read, cancellable, error);
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	  if (n_written == -1)
	    {
	      res = FALSE;
	      break;
	    }

	  p += n_written;
	  n_read -= n_written;
	  bytes_copied += n_written;
	}
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      if (bytes_copied > G_MAXSSIZE)
	bytes_copied = G_MAXSSIZE;
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    }
  while (res);

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 notsupported:
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  if (!res)
    error = NULL; /* Ignore further errors */

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  if (flags & G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE)
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    {
      /* Don't care about errors in source here */
      g_input_stream_close (source, cancellable, NULL);
    }

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  if (flags & G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET)
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    {
      /* But write errors on close are bad! */
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      if (!g_output_stream_internal_close (stream, cancellable, error))
        res = FALSE;
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    }

  if (res)
    return bytes_copied;
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  return -1;
}

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/* Must always be called inside
 * g_output_stream_set_pending()/g_output_stream_clear_pending(). */
static gboolean
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g_output_stream_internal_close (GOutputStream  *stream,
                                GCancellable   *cancellable,
                                GError        **error)
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{
  GOutputStreamClass *class;
  gboolean res;

  if (stream->priv->closed)
    return TRUE;

  class = G_OUTPUT_STREAM_GET_CLASS (stream);

  stream->priv->closing = TRUE;

  if (cancellable)
    g_cancellable_push_current (cancellable);

  if (class->flush)
    res = class->flush (stream, cancellable, error);
  else
    res = TRUE;

  if (!res)
    {
      /* flushing caused the error that we want to return,
       * but we still want to close the underlying stream if possible
       */
      if (class->close_fn)
        class->close_fn (stream, cancellable, NULL);
    }
  else
    {
      res = TRUE;
      if (class->close_fn)
        res = class->close_fn (stream, cancellable, error);
    }

  if (cancellable)
    g_cancellable_pop_current (cancellable);

  stream->priv->closing = FALSE;
  stream->priv->closed = TRUE;

  return res;
}
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/**
 * g_output_stream_close:
 * @stream: A #GOutputStream.
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 * @cancellable: (nullable): optional cancellable object
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 * @error: location to store the error occurring, or %NULL to ignore
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 *
 * 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.
 *
 * Closing a stream will automatically flush any outstanding buffers in the
 * stream.
 *
 * Streams will be automatically closed when the last reference
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 * is dropped, but you might want to call this function to make sure 
 * resources are released as early as possible.
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 *
 * 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
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 * close will still return %G_IO_ERROR_CLOSED for all operations. Still, it
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 * is important to check and report the error to the user, otherwise
 * there might be a loss of data as all data might not be written.
 * 
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 * If @cancellable is not %NULL, then the operation can be cancelled by
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 * 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 there some streams
 * can use a faster close that doesn't block to e.g. check errors. On
 * cancellation (as with any error) there is no guarantee that all written
 * data will reach the target. 
 *
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 * Returns: %TRUE on success, %FALSE on failure
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 **/
gboolean
g_output_stream_close (GOutputStream  *stream,
		       GCancellable   *cancellable,
		       GError        **error)
{
  gboolean res;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);

  if (stream->priv->closed)
    return TRUE;

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  if (!g_output_stream_set_pending (stream, error))
    return FALSE;
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  res = g_output_stream_internal_close (stream, cancellable, error);
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  g_output_stream_clear_pending (stream);
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  return res;
}

static void
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async_ready_write_callback_wrapper (GObject      *source_object,
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                                    GAsyncResult *res,
                                    gpointer      user_data)
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{
  GOutputStream *stream = G_OUTPUT_STREAM (source_object);
  GOutputStreamClass *class;
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  GTask *task = user_data;
  gssize nwrote;
  GError *error = NULL;
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  g_output_stream_clear_pending (stream);
  
  if (g_async_result_legacy_propagate_error (res, &error))
    nwrote = -1;
  else
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    {
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      class = G_OUTPUT_STREAM_GET_CLASS (stream);
      nwrote = class->write_finish (stream, res, &error);
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    }

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  if (nwrote >= 0)
    g_task_return_int (task, nwrote);
  else
    g_task_return_error (task, error);
  g_object_unref (task);
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}

/**
 * g_output_stream_write_async:
 * @stream: A #GOutputStream.
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 * @buffer: (array length=count) (element-type guint8): the buffer containing the data to write. 
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 * @count: the number of bytes to write
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 * @io_priority: the io priority of the request.
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
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 * @callback: (scope async): callback to call when the request is satisfied
 * @user_data: (closure): the data to pass to callback function
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 *
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 * Request an asynchronous write of @count bytes from @buffer into 
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 * the stream. When the operation is finished @callback will be called.
 * You can then call g_output_stream_write_finish() to get the result of the 
 * operation.
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 *
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 * During an async request no other sync and async calls are allowed, 
 * and will result in %G_IO_ERROR_PENDING errors. 
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 *
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 * A value of @count larger than %G_MAXSSIZE will cause a 
 * %G_IO_ERROR_INVALID_ARGUMENT error.
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 *
 * On success, the number of bytes written will be passed to the
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 * @callback. It is not an error if this is not the same as the 
 * requested size, as it can happen e.g. on a partial I/O error, 
 * but generally we try to write as many bytes as requested. 
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 *
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 * You are guaranteed that this method will never fail with
 * %G_IO_ERROR_WOULD_BLOCK - if @stream can't accept more data, the
 * method will just wait until this changes.
 *
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 * 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.
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 *
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 * The asynchronous methods have a default fallback that uses threads
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 * to implement asynchronicity, so they are optional for inheriting 
 * classes. However, if you override one you must override all.
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 *
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 * For the synchronous, blocking version of this function, see 
 * g_output_stream_write().
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 *
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 * Note that no copy of @buffer will be made, so it must stay valid
 * until @callback is called. See g_output_stream_write_bytes_async()
 * for a #GBytes version that will automatically hold a reference to
 * the contents (without copying) for the duration of the call.
 */
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void
g_output_stream_write_async (GOutputStream       *stream,
			     const void          *buffer,
			     gsize                count,
			     int                  io_priority,
			     GCancellable        *cancellable,
			     GAsyncReadyCallback  callback,
			     gpointer             user_data)
{
  GOutputStreamClass *class;
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  GError *error = NULL;
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  GTask *task;
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  g_return_if_fail (G_IS_OUTPUT_STREAM (stream));
  g_return_if_fail (buffer != NULL);

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  task = g_task_new (stream, cancellable, callback, user_data);
  g_task_set_source_tag (task, g_output_stream_write_async);
  g_task_set_priority (task, io_priority);

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  if (count == 0)
    {
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      g_task_return_int (task, 0);
      g_object_unref (task);
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      return;
    }

  if (((gssize) count) < 0)
    {
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      g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
                               _("Too large count value passed to %s"),
                               G_STRFUNC);
      g_object_unref (task);
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      return;
    }

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  if (!g_output_stream_set_pending (stream, &error))
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    {
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      g_task_return_error (task, error);
      g_object_unref (task);
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      return;
    }
  
  class = G_OUTPUT_STREAM_GET_CLASS (stream);

  class->write_async (stream, buffer, count, io_priority, cancellable,
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                      async_ready_write_callback_wrapper, task);
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}

/**
 * g_output_stream_write_finish:
 * @stream: a #GOutputStream.
 * @result: a #GAsyncResult.
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 * @error: a #GError location to store the error occurring, or %NULL to 
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 * ignore.
 * 
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 * Finishes a stream write operation.
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 * 
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 * Returns: a #gssize containing the number of bytes written to the stream.
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 **/
gssize
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g_output_stream_write_finish (GOutputStream  *stream,
                              GAsyncResult   *result,
                              GError        **error)
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{
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  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
  g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);
  g_return_val_if_fail (g_async_result_is_tagged (result, g_output_stream_write_async), FALSE);
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  /* @result is always the GTask created by g_output_stream_write_async();
   * we called class->write_finish() from async_ready_write_callback_wrapper.
   */
  return g_task_propagate_int (G_TASK (result), error);
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}

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typedef struct
{
  const guint8 *buffer;
  gsize to_write;
  gsize bytes_written;
} AsyncWriteAll;

static void
free_async_write_all (gpointer data)
{
  g_slice_free (AsyncWriteAll, data);
}

static void
write_all_callback (GObject      *stream,
                    GAsyncResult *result,
                    gpointer      user_data)
{
  GTask *task = user_data;
  AsyncWriteAll *data = g_task_get_task_data (task);

  if (result)
    {
      GError *error = NULL;
      gssize nwritten;

      nwritten = g_output_stream_write_finish (G_OUTPUT_STREAM (stream), result, &error);

      if (nwritten == -1)
        {
          g_task_return_error (task, error);
          g_object_unref (task);
          return;
        }

      g_assert_cmpint (nwritten, <=, data->to_write);
      g_warn_if_fail (nwritten > 0);

      data->to_write -= nwritten;
      data->bytes_written += nwritten;
    }

  if (data->to_write == 0)
    {
      g_task_return_boolean (task, TRUE);
      g_object_unref (task);
    }
  else
    g_output_stream_write_async (G_OUTPUT_STREAM (stream),
                                 data->buffer + data->bytes_written,
                                 data->to_write,
                                 g_task_get_priority (task),
                                 g_task_get_cancellable (task),
                                 write_all_callback, task);
}

static void
write_all_async_thread (GTask        *task,
                        gpointer      source_object,
                        gpointer      task_data,
                        GCancellable *cancellable)
{
  GOutputStream *stream = source_object;
  AsyncWriteAll *data = task_data;
  GError *error = NULL;

  if (g_output_stream_write_all (stream, data->buffer, data->to_write, &data->bytes_written,
                                 g_task_get_cancellable (task), &error))
    g_task_return_boolean (task, TRUE);
  else
    g_task_return_error (task, error);
}

/**
 * g_output_stream_write_all_async:
 * @stream: A #GOutputStream
 * @buffer: (array length=count) (element-type guint8): the buffer containing the data to write
 * @count: the number of bytes to write
 * @io_priority: the io priority of the request
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 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore
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 * @callback: (scope async): callback to call when the request is satisfied
 * @user_data: (closure): the data to pass to callback function
 *
 * Request an asynchronous write of @count bytes from @buffer into
 * the stream. When the operation is finished @callback will be called.
 * You can then call g_output_stream_write_all_finish() to get the result of the
 * operation.
 *
 * This is the asynchronous version of g_output_stream_write_all().
 *
 * Call g_output_stream_write_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.
 *
 * Note that no copy of @buffer will be made, so it must stay valid
 * until @callback is called.
 *
 * Since: 2.44
 */
void
g_output_stream_write_all_async (GOutputStream       *stream,
                                 const void          *buffer,
                                 gsize                count,
                                 int                  io_priority,
                                 GCancellable        *cancellable,
                                 GAsyncReadyCallback  callback,
                                 gpointer             user_data)
{
  AsyncWriteAll *data;
  GTask *task;

  g_return_if_fail (G_IS_OUTPUT_STREAM (stream));
  g_return_if_fail (buffer != NULL || count == 0);

  task = g_task_new (stream, cancellable, callback, user_data);
  data = g_slice_new0 (AsyncWriteAll);
  data->buffer = buffer;
  data->to_write = count;

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  g_task_set_source_tag (task, g_output_stream_write_all_async);
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  g_task_set_task_data (task, data, free_async_write_all);
  g_task_set_priority (task, io_priority);

  /* If async writes 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_output_stream_async_write_is_via_threads (stream))
    {
      g_task_run_in_thread (task, write_all_async_thread);
      g_object_unref (task);
    }
  else
    write_all_callback (G_OBJECT (stream), NULL, task);
}

/**
 * g_output_stream_write_all_finish:
 * @stream: a #GOutputStream
 * @result: a #GAsyncResult
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 * @bytes_written: (out) (optional): location to store the number of bytes that was written to the stream
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 * @error: a #GError location to store the error occurring, or %NULL to ignore.
 *
 * Finishes an asynchronous stream write operation started with
 * g_output_stream_write_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_written will be set to the number of bytes that were
 * successfully written 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_output_stream_write_async().
 *
 * Returns: %TRUE on success, %FALSE if there was an error
 *
 * Since: 2.44
 **/
gboolean
g_output_stream_write_all_finish (GOutputStream  *stream,
                                  GAsyncResult   *result,
                                  gsize          *bytes_written,
                                  GError        **error)
{
  GTask *task;

  g_return_val_if_fail (G_IS_OUTPUT_STREAM (stream), FALSE);
  g_return_val_if_fail (g_task_is_valid (result, stream), FALSE);

  task = G_TASK (result);

  if (bytes_written)
    {
      AsyncWriteAll *data = (AsyncWriteAll *)g_task_get_task_data (task);

      *bytes_written = data->bytes_written;
    }

  return g_task_propagate_boolean (task, error);
}

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/**
 * g_output_stream_writev_async:
 * @stream: A #GOutputStream.
 * @vectors: (array length=n_vectors): the buffer containing the #GOutputVectors to write.
 * @n_vectors: the number of vectors to write
 * @io_priority: the I/O priority of the request.
 * @cancellable: (nullable): 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 write of the bytes contained in @n_vectors @vectors into
 * the stream. When the operation is finished @callback will be called.
 * You can then call g_output_stream_writev_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.
 *
 * On success, the number of bytes written 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. on a partial I/O error,
 * but generally we try to write as many bytes as requested.
 *
 * You are guaranteed that this method will never fail with
 * %G_IO_ERROR_WOULD_BLOCK — if @stream can't accept more data, the
 * method will just wait until this changes.
 *
 * 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.
 *
 * For the synchronous, blocking version of this function, see
 * g_output_stream_writev().
 *
 * Note that no copy o