/**
 * @file utils.h Zlib module utility functions
 * 
 * $Id: utils.h,v 1.6 2003/01/01 06:22:34 chipx86 Exp $
 *
 * @Copyright (C) 2001-2003 The GNUpdate Project.
 *
 * This 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.
 *
 * This 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 this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 */
#ifndef _MOD_ZLIB_UTILS_H_
#define _MOD_ZLIB_UTILS_H_

#include <zlib.h>
#include <ctype.h>

/*
 * Some code was borrowed from zlib, as zlib does not provide public
 * functions for retrieving the information we need. zlib's copyright
 * notice is shown below:
 *
 * zlib.h -- interface of the 'zlib' general purpose compression library
 * version 1.1.3, July 9th, 1998
 *
 * Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * Jean-loup Gailly        Mark Adler
 * jloup@gzip.org          madler@alumni.caltech.edu
 *
 *
 * The data format used by the zlib library is described by RFCs (Request for
 * Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
 * (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
 */

/* A copy of the gz_stream struct in zlib. */
typedef struct
{
	z_stream stream;
	int      z_err;       /* error code for last stream operation */
	int      z_eof;       /* set if end of input file             */
	FILE    *file;        /* .gz file                             */
	Byte    *inbuf;       /* input buffer                         */
	Byte    *outbuf;      /* output buffer                        */
	uLong    crc;         /* crc32 of uncompressed data           */
	char    *msg;         /* error message                        */
	char    *path;        /* path name for debugging only         */
	int      transparent; /* 1 if input file is not a .gz file    */
	char     mode;        /* 'w' or 'r'                           */
	long     startpos;    /* start of compressed data in file     */
	                      /* (header skipped)                     */
} _gz_stream;

/* Macros for getting two-byte and four-byte header values. */
#define SH(p) ((unsigned short)(unsigned char)((p)[0]) | \
			   ((unsigned short)(unsigned char)((p)[1]) << 8))
#define LG(p) ((unsigned long)(SH(p)) | ((unsigned long)(SH((p)+2)) << 16))

#define tolow(c)  (isupper(c) ? (c) - 'A' + 'a' : (c))
	
static char *
__strlwr(char *s)
{
	char *t;

	for (t = s; *t; t++)
		*t = tolow(*t);

	return s;
}

/*
 * XXX I am almost certain that this function is wrong!
 */
static long
__getTotalFileSize(FILE *fp)
{
	long bytesIn;
	long bytesOut = -1L;
	
	bytesIn = (long)gzseek(fp, (off_t)(-8), SEEK_END);
	
	if (bytesIn != -1L)
	{
		unsigned char buf[8];
		bytesIn += 8L;

		if (fread((char *)buf, sizeof(unsigned char),
				  sizeof(buf), fp) != sizeof(buf))
		{
			return -1; /* Read error. */
		}
		
		bytesOut = LG(buf + 4);
	}
	
	return bytesOut;
}

/* XXX zlib's tailor.h does more than this. */
#define MAX_SUFFIX 30

/* XXX BAD BAD BAD! Don't assume, check in configure.in! */
#define PATH_SEP '/'
#define MAX_PATH_LEN 260

static char *
__getSuffix(char *name)
{
	int nlen, slen;
	char suffix[MAX_SUFFIX + 3]; /* last chars of name,
	                                forced to lower case. */
	static char *knownSuffixes[] =
	{
		".gz", ".z", ".taz", ".tgz", "-gz", "-z", "_z", "z", NULL
	};
	char **suf = knownSuffixes;

	/* XXX Strip a version number from the filename here! */

	nlen = strlen(name);

	if (nlen < MAX_SUFFIX + 2)
		strcpy(suffix, name);
	else
		strcpy(suffix, name + nlen - MAX_SUFFIX - 2);

	__strlwr(suffix);
	slen = strlen(suffix);

	do
	{
		int s = strlen(*suf);

		if (slen > s && suffix[slen - s - 1] != PATH_SEP &&
			!strcmp(suffix + slen - s, *suf))
		{
			return name + nlen - s;
		}
	}
	while (*++suf != NULL);

	return NULL;
}

static char *
__makeOutputFilename(const char *ifname)
{
	char ofname[MAX_PATH_LEN];
	char *suff;  /* ofname z suffix */

	if (ifname == NULL)
		return strdup("unknown");

	strcpy(ofname, ifname);

	/* Strip a version number if any and get the gzip suffix if present: */
	suff = __getSuffix(ofname);

	if (suff == NULL)
	{
		return strdup(ofname);

		/* return NULL; */
	}

	/* Make a special case for .tgz and .taz: */
	__strlwr(suff);

	if (!strcmp(suff, ".tgz") || !strcmp(suff, ".taz"))
		strcpy(suff, ".tar");
	else
		*suff = '\0';  /* strip the z suffix */

	return strdup(ofname);
}

#endif /* _MOD_ZLIB_UTILS_H_ */