source: libwandio/ior-zlib.c @ 60f3c4c

/*
 * This file is part of libtrace
 *
 * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton, 
 * New Zealand.
 *
 * Authors: Daniel Lawson 
 *          Perry Lorier
 *          Shane Alcock 
 *          
 * All rights reserved.
 *
 * This code has been developed by the University of Waikato WAND 
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libtrace is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * libtrace 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with libtrace; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id$
 *
 */


#include "wandio.h"
#include <zlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

/* Libtrace IO module implementing a zlib reader */

enum err_t {
        ERR_OK  = 1,
        ERR_EOF = 0,
        ERR_ERROR = -1
};

struct zlib_t {
        Bytef inbuff[1024*1024]; /* bytef is what zlib uses for buffer pointers */
        z_stream strm;
        io_t *parent;
        int outoffset;
        enum err_t err;
};


extern io_source_t zlib_source; 

#define DATA(io) ((struct zlib_t *)((io)->data))
#define min(a,b) ((a)<(b) ? (a) : (b))

io_t *zlib_open(io_t *parent)
{
        io_t *io;
        if (!parent)
                return NULL;
        io = malloc(sizeof(io_t));
        io->source = &zlib_source;
        io->data = malloc(sizeof(struct zlib_t));

        DATA(io)->parent = parent;

        DATA(io)->strm.next_in = NULL;
        DATA(io)->strm.avail_in = 0;
        DATA(io)->strm.next_out = NULL;
        DATA(io)->strm.avail_out = 0;
        DATA(io)->strm.zalloc = Z_NULL;
        DATA(io)->strm.zfree = Z_NULL;
        DATA(io)->strm.opaque = NULL;
        DATA(io)->err = ERR_OK;

        inflateInit2(&DATA(io)->strm, 15 | 32);

        return io;
}


static off_t zlib_read(io_t *io, void *buffer, off_t len)
{
        if (DATA(io)->err == ERR_EOF)
                return 0; /* EOF */
        if (DATA(io)->err == ERR_ERROR) {
                errno=EIO;
                return -1; /* ERROR! */
        }

        DATA(io)->strm.avail_out = len;
        DATA(io)->strm.next_out = (Bytef*)buffer;

        while (DATA(io)->err == ERR_OK && DATA(io)->strm.avail_out > 0) {
                while (DATA(io)->strm.avail_in <= 0) {
                        int bytes_read = wandio_read(DATA(io)->parent, 
                                (char*)DATA(io)->inbuff,
                                sizeof(DATA(io)->inbuff));
                        if (bytes_read == 0) {
                                /* EOF */
                                if (DATA(io)->strm.avail_out == (uint32_t)len) {
                                        DATA(io)->err = ERR_EOF;
                                        return 0;
                                }
                                /* Return how much data we've managed to read so far. */
                                return len-DATA(io)->strm.avail_out;
                        }
                        if (bytes_read < 0) { /* Error */
                                /* errno should be set */
                                DATA(io)->err = ERR_ERROR;
                                /* Return how much data we managed to read ok */
                                if (DATA(io)->strm.avail_out != (uint32_t)len) {
                                        return len-DATA(io)->strm.avail_out;
                                }
                                /* Now return error */
                                return -1;
                        }
                        DATA(io)->strm.next_in = DATA(io)->inbuff;
                        DATA(io)->strm.avail_in = bytes_read;
                }
                /* Decompress some data into the output buffer */
                int err=inflate(&DATA(io)->strm, 0);
                switch(err) {
                        case Z_OK:
                                DATA(io)->err = ERR_OK;
                                break;
                        case Z_STREAM_END:
                                /* You would think that an "EOF" on the stream would mean we'd
                                 * want to pass on an EOF?  Nope.  Some tools (*cough* corel *cough*)
                                 * annoyingly close and reopen the gzip stream leaving Z_STREAM_END
                                 * mines for us to find.
                                 */
                                inflateEnd(&DATA(io)->strm);
                                inflateInit2(&DATA(io)->strm, 15 | 32);
                                DATA(io)->err = ERR_OK;
                                break;
                        default:
                                errno=EIO;
                                DATA(io)->err = ERR_ERROR;
                }
        }
        /* Return the number of bytes decompressed */
        return len-DATA(io)->strm.avail_out;
}

static void zlib_close(io_t *io)
{
        inflateEnd(&DATA(io)->strm);
        wandio_destroy(DATA(io)->parent);
        free(io->data);
        free(io);
}

io_source_t zlib_source = {
        "zlib",
        zlib_read,
        NULL,   /* peek */
        NULL,   /* tell */
        NULL,   /* seek */
        zlib_close
};