source: trunk/third/gnome-vfs2/libgnomevfs/gnome-vfs-socket-buffer.c @ 21416

/* -*- 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>
#include <glib/gmem.h>
#include <glib/gmessages.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;
}

/**
 * gnome_vfs_socket_buffer_new:
 * @socket: socket to be buffered
 *
 * Create a socket buffer around @socket. A buffered
 * socket allows data to be poked at without reading it
 * as it will be buffered. A future read will retrieve
 * the data again.
 *
 * Return value: a newly allocated GnomeVFSSocketBuffer
 **/
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;
}

/**
 * gnome_vfs_socket_buffer_destroy:
 * @socket_buffer: buffered socket to destroy.
 * @close_socket: if %TRUE the socket being buffered will be closed too.
 * @cancellation: handle allowing cancellation of the operation.
 *
 * Free the socket buffer.
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 **/
GnomeVFSResult   
gnome_vfs_socket_buffer_destroy  (GnomeVFSSocketBuffer *socket_buffer, 
                                  gboolean close_socket,
                                  GnomeVFSCancellation *cancellation)
{
        gnome_vfs_socket_buffer_flush (socket_buffer, cancellation);

        if (close_socket) {
                gnome_vfs_socket_close (socket_buffer->socket, cancellation);
        }
        g_free (socket_buffer);
        return GNOME_VFS_OK;
}




static gboolean
refill_input_buffer (GnomeVFSSocketBuffer *socket_buffer,
                     GnomeVFSCancellation *cancellation)
{
        Buffer *input_buffer;
        GnomeVFSResult result;
        GnomeVFSFileSize bytes_read;
        char *data_pos;

        input_buffer = &socket_buffer->input_buffer;

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

        data_pos = &(input_buffer->data[input_buffer->offset]);

        /* If there is data left in the buffer move it to the front */
        if (input_buffer->offset > 0) {
                memmove (input_buffer->data, data_pos, input_buffer->byte_count);
                data_pos = input_buffer->data;
        }
        
        result = gnome_vfs_socket_read (socket_buffer->socket,
                                        data_pos,
                                        BUFFER_SIZE - input_buffer->byte_count,
                                        &bytes_read,
                                        cancellation);

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

        input_buffer->byte_count += bytes_read;

        return TRUE;
}

/**
 * gnome_vfs_socket_buffer_read:
 * @socket_buffer: buffered socket to read data from.
 * @buffer: allocated buffer of at least @bytes bytes to be read into.
 * @bytes: number of bytes to read from @socket into @socket_buffer.
 * @bytes_read: pointer to a GnomeVFSFileSize, will contain
 * the number of bytes actually read from the socket on return.
 * @cancellation: handle allowing cancellation of the operation.
 *
 * Read @bytes bytes of data from the @socket into @socket_buffer.
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 **/
GnomeVFSResult   
gnome_vfs_socket_buffer_read (GnomeVFSSocketBuffer *socket_buffer,
                              gpointer buffer,
                              GnomeVFSFileSize bytes,
                              GnomeVFSFileSize *bytes_read,
                              GnomeVFSCancellation *cancellation)
{
        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) {
                if (bytes_read != NULL);
                        *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, cancellation)) {
                        /* 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;
                }
        }

        n = 0;
        
        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;
        }
        
        return result;
}

/**
 * gnome_vfs_socket_buffer_read_until:
 * @socket_buffer: buffered socket to read data from.
 * @buffer: allocated buffer of at least @bytes bytes to be read into.
 * @bytes: maximum number of bytes to read from @socket into @socket_buffer.
 * @boundary: the boundary until wich is read.
 * @boundary_len: the length of the boundary.
 * @bytes_read: pointer to a GnomeVFSFileSize, will contain
 * the number of bytes actually read from the socket on return.
 * @got_boundary: pointer to a gboolean  which will be %TRUE if the boundary
 * was found or FALSE otherwise.
 * @cancellation: handle allowing cancellation of the operation.
 *
 * Read up to @bytes bytes of data from the @socket into @socket_buffer 
 * until boundary is reached. @got_boundary will be set accordingly.
 *
 * Note that if @bytes is smaller than @boundary_len there is no way
 * to detected the boundary! So if you want to make sure that every boundary
 * is found (in a loop maybe) asure that @bytes is at least as big as 
 * @boundary_len.
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 *
 * Since: 2.8
 **/
GnomeVFSResult
gnome_vfs_socket_buffer_read_until (GnomeVFSSocketBuffer *socket_buffer,
                                    gpointer buffer,
                                    GnomeVFSFileSize bytes,
                                    gconstpointer boundary,
                                    GnomeVFSFileSize boundary_len,
                                    GnomeVFSFileSize *bytes_read,
                                    gboolean *got_boundary,
                                    GnomeVFSCancellation *cancellation)
{
        Buffer *input_buffer;
        GnomeVFSResult result;
        GnomeVFSFileSize n, max_scan;
        char *iter, *start, *delim;

        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 (boundary != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (got_boundary != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (boundary_len < BUFFER_SIZE, GNOME_VFS_ERROR_TOO_BIG);

        *got_boundary = FALSE;

        /* Quote from UNIX 98:
           "If nbyte is 0, read() will return 0 and have no other results."
        */
        if (bytes == 0) {
                if (bytes_read != NULL)
                        *bytes_read = 0;

                return GNOME_VFS_OK;
        }

        input_buffer = &socket_buffer->input_buffer;
        result = GNOME_VFS_OK;
        
        /* we are looping here to catch the case where we are close
         * to eof and haveing less or equal bytes then boundary_len */
        while (input_buffer->byte_count <= boundary_len) {
                if (! refill_input_buffer (socket_buffer, cancellation)) {
                        break;
                }
        }

        /* At this point we have either byte_count > boundary_len or
         * we have and error during refill */

        n = 0;
        start = input_buffer->data + input_buffer->offset;
        max_scan = MIN (input_buffer->byte_count, bytes);

        /* if max_scan is greater then boundary_len do a scan (I) 
         * otherwise we had an error during the loop above or bytes is
         * too small. (II) We handle the case where boundary_len ==
         * max_scan in (II). */

        if (max_scan > boundary_len) {

                delim = start + max_scan;
                for (iter = start; iter + boundary_len <= delim; iter++) {
                        if (!memcmp (iter, boundary, boundary_len)) {
                                *got_boundary = TRUE;
                                /* We wanna have the boundary fetched */
                                iter += boundary_len;
                                break;
                        }
                }

                /* Fetch data data until iter */
                n = iter - start;

        } else /* (II) */ {

                if (max_scan == boundary_len &&
                        !memcmp (start, boundary, boundary_len)) {
                        *got_boundary = TRUE;
                }

                n = max_scan;
        }

        if (n > 0) {

                memcpy (buffer, start, n);
                input_buffer->byte_count -= n;
                input_buffer->offset += n;
                /* queque up the fill buffer error if any
                 * until the buffer is flushed */
        } else {
                result = input_buffer->last_error;
                input_buffer->last_error = GNOME_VFS_OK;
        }

        if (bytes_read != NULL) {
                *bytes_read = n;
        }

        return result;
}

/**
 * gnome_vfs_socket_buffer_peekc:
 * @socket_buffer: the socket buffer to read from.
 * @character: pointer to a char, will contain a character on return from
 * a successful "peek".
 * @cancellation: handle allowing cancellation of the operation.
 *
 * Peek at the next character in @socket_buffer without actually reading
 * the character in. The next read will retrieve @c (as well as any following
 * data if requested).
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 **/
GnomeVFSResult
gnome_vfs_socket_buffer_peekc (GnomeVFSSocketBuffer *socket_buffer,
                               gchar *character,
                               GnomeVFSCancellation *cancellation)
{
        GnomeVFSResult result;
        Buffer *input_buffer;

        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);
        g_return_val_if_fail (character != 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, cancellation)) {
                        /* 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) {
                *character = *(input_buffer->data + input_buffer->offset);
        }

        return result;
}



static GnomeVFSResult
flush (GnomeVFSSocketBuffer *socket_buffer,
       GnomeVFSCancellation *cancellation)
{
        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,
                                                 cancellation);
                output_buffer->last_error = result;

                if (result != GNOME_VFS_OK) {
                        return result;
                }

                memmove (output_buffer->data,
                         output_buffer->data + bytes_written,
                         output_buffer->byte_count - bytes_written);
                output_buffer->byte_count -= bytes_written;
        }

        return GNOME_VFS_OK;
}

/**
 * gnome_vfs_socket_buffer_write:
 * @socket_buffer: buffered socket to write data to
 * @buffer: data to write to the socket
 * @bytes: number of bytes from @buffer to write to @socket_buffer
 * @bytes_written: pointer to a GnomeVFSFileSize, will contain
 * the number of bytes actually written to the socket on return.
 * @cancellation: handle allowing cancellation of the operation
 *
 * Write @bytes bytes of data from @buffer to @socket_buffer.
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 **/ 
GnomeVFSResult   
gnome_vfs_socket_buffer_write (GnomeVFSSocketBuffer *socket_buffer, 
                               gconstpointer buffer,
                               GnomeVFSFileSize bytes,
                               GnomeVFSFileSize *bytes_written,
                               GnomeVFSCancellation *cancellation)
{
        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 - write_count);
                        memcpy (output_buffer->data + output_buffer->byte_count,
                                p, n);
                        p += n;
                        write_count += n;
                        output_buffer->byte_count += n;
                }
                if (output_buffer->byte_count >= BUFFER_SIZE) {
                        result = flush (socket_buffer, cancellation);
                        if (result != GNOME_VFS_OK) {
                                break;
                        }
                }
        }

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

/**
 * gnome_vfs_socket_buffer_flush:
 * @socket_buffer: buffer to flush
 * @cancellation: handle allowing cancellation of the operation
 *
 * Write all outstanding data to @socket_buffer.
 *
 * Return value: GnomeVFSResult indicating the success of the operation
 **/
GnomeVFSResult   
gnome_vfs_socket_buffer_flush (GnomeVFSSocketBuffer *socket_buffer,
                               GnomeVFSCancellation *cancellation)
{
        g_return_val_if_fail (socket_buffer != NULL, GNOME_VFS_ERROR_BAD_PARAMETERS);

        return flush (socket_buffer, cancellation);
}