source: trunk/third/gnome-vfs/libgnomevfs/gnome-vfs-socket-buffer.c @ 17128

/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/* gnome-vfs-socket-buffer.c
 *
 * Copyright (C) 2001 Seth Nickell
 * Copyright (C) 2001 Maciej Stachowiak
 *
 * The Gnome Library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * The Gnome 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with the Gnome Library; see the file COPYING.LIB.  If not,
 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA. 
 *
 */
/*
 * Authors: Seth Nickell <snickell@stanford.edu>
 *          Maciej Stachowiak <mjs@noisehavoc.org>
 *          (reverse-engineered from code by Ian McKellar <yakk@yakk.net>)
 */

#include <config.h>
#include "gnome-vfs-socket-buffer.h"

#include <string.h>



#define BUFFER_SIZE 4096

struct Buffer {
        gchar data[BUFFER_SIZE];
        guint offset;
        guint byte_count;
        GnomeVFSResult last_error;
};
typedef struct Buffer Buffer;


struct  GnomeVFSSocketBuffer {
        GnomeVFSSocket *socket;
        Buffer input_buffer;
        Buffer output_buffer;
};


static void
buffer_init (Buffer *buffer)
{
        buffer->byte_count = 0;
        buffer->offset = 0;
        buffer->last_error = GNOME_VFS_OK;
}


GnomeVFSSocketBuffer*  
gnome_vfs_socket_buffer_new (GnomeVFSSocket *socket)
{
        GnomeVFSSocketBuffer *socket_buffer;

        g_return_val_if_fail (socket != NULL, NULL);

        socket_buffer = g_new (GnomeVFSSocketBuffer, 1);
        socket_buffer->socket = socket;

        buffer_init (&socket_buffer->input_buffer);
        buffer_init (&socket_buffer->output_buffer);

        return socket_buffer;
}

GnomeVFSResult   
gnome_vfs_socket_buffer_destroy  (GnomeVFSSocketBuffer *buffer, 
                                  gboolean close_socket)
{
        gnome_vfs_socket_buffer_flush (buffer);

        if (close_socket) {
                gnome_vfs_socket_close (buffer->socket);
        }
        g_free (buffer);
        return GNOME_VFS_OK;
}




static gboolean
refill_input_buffer (GnomeVFSSocketBuffer *socket_buffer)
{
        Buffer *input_buffer;
        GnomeVFSResult result;
        GnomeVFSFileSize bytes_read;
        
        input_buffer = &socket_buffer->input_buffer;

        if (input_buffer->last_error != GNOME_VFS_OK
            || input_buffer->byte_count > 0) {
                return FALSE;
        }

        input_buffer->offset = 0;

        result = gnome_vfs_socket_read (socket_buffer->socket,
                                        &input_buffer->data, 
                                        BUFFER_SIZE,
                                        &bytes_read);
        
        if (bytes_read == 0) {
                input_buffer->last_error = GNOME_VFS_ERROR_EOF;
                return FALSE;
        }

        input_buffer->byte_count = bytes_read;

        return TRUE;
}
 
GnomeVFSResult   
gnome_vfs_socket_buffer_read (GnomeVFSSocketBuffer *socket_buffer,
                              gpointer buffer,
                              GnomeVFSFileSize bytes,
                              GnomeVFSFileSize *bytes_read)
{
        Buffer *input_buffer;
        GnomeVFSResult result;
        GnomeVFSFileSize n;
        
        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        
        /* Quote from UNIX 98:
           "If nbyte is 0, read() will return 0 and have no other results."
        */
        if (bytes == 0) {
                *bytes_read = 0;
                return GNOME_VFS_OK;
        }
                
        input_buffer = &socket_buffer->input_buffer;

        result = GNOME_VFS_OK;

        if (input_buffer->byte_count == 0) {
                if (! refill_input_buffer (socket_buffer)) {
                        /* The buffer is empty but we had an error last time we
                           filled it, so we report the error.  */
                        result = input_buffer->last_error;
                        input_buffer->last_error = GNOME_VFS_OK;
                }
        }

        if (input_buffer->byte_count != 0) {
                n = MIN (bytes, input_buffer->byte_count);
                memcpy (buffer, input_buffer->data + input_buffer->offset, n);
                input_buffer->byte_count -= n;
                input_buffer->offset += n;
                if (bytes_read != NULL) {
                        *bytes_read = n;
                }
        } else {
                if (bytes_read != NULL) {
                        *bytes_read = 0;
                }
        }

        if (result == GNOME_VFS_ERROR_EOF) {
                result = GNOME_VFS_OK;
        }

        return result;
}

GnomeVFSResult
gnome_vfs_socket_buffer_peekc (GnomeVFSSocketBuffer *socket_buffer,
                               gchar *c)
{
        GnomeVFSResult result;
        Buffer *input_buffer;

        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (c != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);

        input_buffer = &socket_buffer->input_buffer;
        result = GNOME_VFS_OK;

        if (input_buffer->byte_count == 0) {
                if (!refill_input_buffer (socket_buffer)) {
                        /* The buffer is empty but we had an error last time we
                           filled it, so we report the error.  */
                        result = input_buffer->last_error;
                        input_buffer->last_error = GNOME_VFS_OK;
                }
        }

        if (result == GNOME_VFS_OK) {
                *c = *input_buffer->data;
        }

        return result;
}



static GnomeVFSResult
flush (GnomeVFSSocketBuffer *socket_buffer)
{
        Buffer *output_buffer;
        GnomeVFSResult result;
        GnomeVFSFileSize bytes_written;

        output_buffer = &socket_buffer->output_buffer;

        while (output_buffer->byte_count > 0) {
                result = gnome_vfs_socket_write (socket_buffer->socket, 
                                                 output_buffer->data,
                                                 output_buffer->byte_count,
                                                 &bytes_written);
                output_buffer->last_error = result;
                output_buffer->byte_count -= bytes_written;
        }

        return GNOME_VFS_OK;
}


GnomeVFSResult   
gnome_vfs_socket_buffer_write (GnomeVFSSocketBuffer *socket_buffer, 
                               gconstpointer buffer,
                               GnomeVFSFileSize bytes,
                               GnomeVFSFileSize *bytes_written)
{
        Buffer *output_buffer;
        GnomeVFSFileSize write_count;
        GnomeVFSResult result;
        const gchar *p;

        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (bytes_written != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);

        output_buffer = &socket_buffer->output_buffer;

        result = GNOME_VFS_OK;

        p = buffer;
        write_count = 0;
        while (write_count < bytes) {
                if (output_buffer->byte_count < BUFFER_SIZE) {
                        GnomeVFSFileSize n;

                        n = MIN (BUFFER_SIZE - output_buffer->byte_count,
                                 bytes);
                        memcpy (output_buffer->data + output_buffer->byte_count,
                                p, n);
                        p += n;
                        write_count += n;
                        output_buffer->byte_count += n;
                } else {
                        result = flush (socket_buffer);
                        if (result != GNOME_VFS_OK) {
                                break;
                        }
                }
        }

        if (bytes_written != NULL) {
                *bytes_written = write_count;
        }
                
        return result;
}

GnomeVFSResult   
gnome_vfs_socket_buffer_flush (GnomeVFSSocketBuffer *socket_buffer)
{
        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);

        return flush (socket_buffer);
}