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gnome-vfs-socket-buffer.c

/* -*- 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.
 * @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_buffer into @buffer.
 * @bytes_read: pointer to a #GnomeVFSFileSize, will contain
 * the number of bytes actually read from the @socket_buffer 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_buffer into @buffer.
 * @boundary: the boundary until which 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_buffer 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_buffer into @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) assure 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_buffer.
 * @bytes: number of bytes to write from @buffer to @socket_buffer.
 * @bytes_written: pointer to a #GnomeVFSFileSize, will contain
 * the number of bytes actually written to the @socket_buffer 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);
}




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