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/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/*
* gnome-vfs-mime-sniff-buffer.c
* Utility for implementing gnome_vfs_mime_type_from_magic, and other
* mime-type sniffing calls.
*
* Copyright (C) 2000 Eazel, Inc.
* All rights reserved.
*
* This file is part of the Gnome Library.
*
* 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.
*/
#include <config.h>
#include "gnome-vfs-mime-sniff-buffer.h"
#include "gnome-vfs-handle.h"
#include "gnome-vfs-mime-sniff-buffer-private.h"
#include "gnome-vfs-ops.h"
#include <string.h>
static GnomeVFSResult
handle_seek_glue (gpointer context, GnomeVFSSeekPosition whence,
GnomeVFSFileOffset offset)
{
GnomeVFSHandle *handle = (GnomeVFSHandle *)context;
return gnome_vfs_seek (handle, whence, offset);
}
static GnomeVFSResult
handle_read_glue (gpointer context, gpointer buffer,
GnomeVFSFileSize bytes, GnomeVFSFileSize *bytes_read)
{
GnomeVFSHandle *handle = (GnomeVFSHandle *)context;
return gnome_vfs_read (handle, buffer, bytes, bytes_read);
}
GnomeVFSMimeSniffBuffer *
_gnome_vfs_mime_sniff_buffer_new_from_handle (GnomeVFSHandle *file)
{
GnomeVFSMimeSniffBuffer *result;
result = g_new0 (GnomeVFSMimeSniffBuffer, 1);
result->owning = TRUE;
result->context = file;
result->seek = handle_seek_glue;
result->read = handle_read_glue;
return result;
}
GnomeVFSMimeSniffBuffer *
_gnome_vfs_mime_sniff_buffer_new_generic (GnomeVFSSniffBufferSeekCall seek_callback,
GnomeVFSSniffBufferReadCall read_callback,
gpointer context)
{
GnomeVFSMimeSniffBuffer * result;
result = g_new0 (GnomeVFSMimeSniffBuffer, 1);
result->owning = TRUE;
result->seek = seek_callback;
result->read = read_callback;
result->context = context;
return result;
}
GnomeVFSMimeSniffBuffer *
_gnome_vfs_mime_sniff_buffer_new_from_memory (const guchar *buffer,
gssize buffer_length)
{
GnomeVFSMimeSniffBuffer *result;
result = g_new0 (GnomeVFSMimeSniffBuffer, 1);
result->owning = TRUE;
result->buffer = g_malloc (buffer_length);
result->buffer_length = buffer_length;
memcpy (result->buffer, buffer, buffer_length);
result->read_whole_file = TRUE;
return result;
}
GnomeVFSMimeSniffBuffer *
gnome_vfs_mime_sniff_buffer_new_from_existing_data (const guchar *buffer,
gssize buffer_length)
{
GnomeVFSMimeSniffBuffer *result;
result = g_new0 (GnomeVFSMimeSniffBuffer, 1);
result->owning = FALSE;
result->buffer = (guchar *)buffer;
result->buffer_length = buffer_length;
result->read_whole_file = TRUE;
return result;
}
void
gnome_vfs_mime_sniff_buffer_free (GnomeVFSMimeSniffBuffer *buffer)
{
if (buffer->owning)
g_free (buffer->buffer);
g_free (buffer);
}
enum {
GNOME_VFS_SNIFF_BUFFER_INITIAL_CHUNK = 256,
GNOME_VFS_SNIFF_BUFFER_MIN_CHUNK = 128
};
GnomeVFSResult
_gnome_vfs_mime_sniff_buffer_get (GnomeVFSMimeSniffBuffer *buffer,
gssize size)
{
GnomeVFSResult result;
GnomeVFSFileSize bytes_to_read, bytes_read;
/* check to see if we already have enough data */
if (buffer->buffer_length >= size) {
return GNOME_VFS_OK;
}
/* if we've read the whole file, don't try to read any more */
if (buffer->read_whole_file) {
return GNOME_VFS_ERROR_EOF;
}
/* figure out how much to read */
bytes_to_read = size - buffer->buffer_length;
/* don't bother to read less than this */
if (bytes_to_read < GNOME_VFS_SNIFF_BUFFER_MIN_CHUNK) {
bytes_to_read = GNOME_VFS_SNIFF_BUFFER_MIN_CHUNK;
}
/* make room in buffer for new data */
buffer->buffer = g_realloc (buffer->buffer,
buffer->buffer_length + bytes_to_read);
/* read in more data */
result = (* buffer->read) (buffer->context,
buffer->buffer + buffer->buffer_length,
bytes_to_read,
&bytes_read);
if (result == GNOME_VFS_ERROR_EOF) {
buffer->read_whole_file = TRUE;
} else if (result != GNOME_VFS_OK) {
return result;
}
buffer->buffer_length += bytes_read;
/* check to see if we have enough data */
if (buffer->buffer_length >= size) {
return GNOME_VFS_OK;
}
/* not enough data */
return GNOME_VFS_ERROR_EOF;
}
/*
* gnome_vfs_get_mime_type_for_buffer:
* @buffer: a sniff buffer referencing either a file or data in memory
*
* This routine uses a magic database to guess the mime type of the
* data represented by @buffer.
*
* Returns a pointer to an internal copy of the mime-type for @buffer.
*/
const char *
gnome_vfs_get_mime_type_for_buffer (GnomeVFSMimeSniffBuffer *buffer)
{
return _gnome_vfs_get_mime_type_internal (buffer, NULL, FALSE);
}
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