/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1998-2011 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * sfio pzip discipline
 */

#include "pzlib.h"

#include <sfdcbzip.h>

#define GZ_MAGIC_1	0x1f		/* 1st gzip magic char		*/
#define GZ_MAGIC_2	0x8b		/* 2nd gzip magic char		*/
#define LZ_MAGIC_2	0x9d		/* 2nd lzw magic char		*/

#define PZ_GZ_MAGOFF	10		/* compressed magic offset	*/
#define PZ_GZ_MAGIC_1	0x92		/* 1st compressed magic char	*/
#define PZ_GZ_MAGIC_2	0x17		/* 2nd compressed magic char	*/

typedef struct
{
	Sfdisc_t	sfdisc;		/* sfio discipline		*/
	Pzdisc_t	disc;		/* pzip discipline		*/
	Pz_t*		pz;		/* pz handle			*/
	Sfio_t*		io;		/* real pzwrite stream		*/
} Sfpzip_t;

/*
 * pzip exception handler
 * free on close
 */

static int
sfpzexcept(Sfio_t* sp, int op, void* val, Sfdisc_t* dp)
{
	register Sfpzip_t*	pz = (Sfpzip_t*)dp;
	int			r;

	NoP(sp);
	switch (op)
	{
	case SF_ATEXIT:
		sfdisc(sp, SF_POPDISC);
		return 0;
	case SF_CLOSING:
	case SF_DPOP:
	case SF_FINAL:
		if (pz->pz)
		{
			pz->pz->flags &= ~PZ_STREAM;
			r = pzclose(pz->pz);
			pz->pz = 0;
		}
		else
			r = 0;
		if (op != SF_CLOSING)
			free(dp);
		return r;
	case SF_DBUFFER:
		return 1;
	case SF_SYNC:
		return val ? 0 : pzsync(pz->pz);
	case SFPZ_HANDLE:
		return (*((Pz_t**)val) = pz->pz) ? 1 : -1;
	}
	return 0;
}

/*
 * sfio pzip discipline read
 */

static ssize_t
sfpzread(Sfio_t* fp, Void_t* buf, size_t size, Sfdisc_t* dp)
{
	register Sfpzip_t*	pz = (Sfpzip_t*)dp;

	return pzread(pz->pz, buf, size);
}

/*
 * sfio pzip discipline write
 */

static ssize_t
sfpzwrite(Sfio_t* fp, const Void_t* buf, size_t size, Sfdisc_t* dp)
{
	register Sfpzip_t*	pz = (Sfpzip_t*)dp;

	return pzwrite(pz->pz, pz->io, buf, size);
}

/*
 * create and push the sfio pzip discipline
 *
 * (flags&PZ_STAT) return
 *	>0	is a pzip file
 *	 0	not a pzip file
 *	<0	error
 * otherwise flags have pzopen() semantics and return
 *	>0	discipline pushed (one or more of { pzip gzip lzw })
 *	 0	discipline not needed
 *	<0	error
 */

int
sfdcpzip(Sfio_t* sp, const char* path, unsigned long flags, Pzdisc_t* disc)
{
	Sfio_t*		io;
	Sfpzip_t*	pz;
	Pz_t*		oz;

	if (flags & PZ_HANDLE)
	{
		oz = (Pz_t*)sp;
		sp = oz->io;
	}
	else
		oz = 0;
	if (sfset(sp, 0, 0) & SF_WRITE)
	{
		if (flags & PZ_STAT)
			return -1;
	}
	else if (!(flags & PZ_FORCE))
	{
		unsigned char*	s;
		int		r;
		int		m1;
		int		m2;

		if (!(r = sfset(sp, 0, 0) & SF_SHARE))
			sfset(sp, SF_SHARE, 1);
		s = (unsigned char*)sfreserve(sp, PZ_GZ_MAGOFF + 2, 1);
		if (!r)
			sfset(sp, SF_SHARE, 0);
		if (!s)
			return -1;
		m1 = s[0];
		m2 = s[1];
		r = m1 == PZ_MAGIC_1 && m2 == PZ_MAGIC_2 && s[2] > 0 && s[3] < 10 ||
		    m1 == GZ_MAGIC_1 && m2 == GZ_MAGIC_2 &&
		    s[PZ_GZ_MAGOFF] == PZ_GZ_MAGIC_1 && s[PZ_GZ_MAGOFF+1] == PZ_GZ_MAGIC_2;
		sfread(sp, s, 0);
		if (flags & PZ_STAT)
			return r;
		if (!r)
		{
			if (!(flags & PZ_NOGZIP))
			{
				if (m1 == GZ_MAGIC_1)
				{
					if (m2 == GZ_MAGIC_2)
						r = sfdcgzip(sp, (flags & PZ_CRC) ? 0 : SFGZ_NOCRC);
					else if (m2 == LZ_MAGIC_2)
						r = sfdclzw(sp, 0);
				}
				else if (m1 == 'B' && m2 == 'Z' && s[2] == 'h' && s[3] >= '1' && s[3] <= '9')
					r = sfdcbzip(sp, 0);
			}
			return r;
		}
		sfsync(sp);
	}
	if (!(io = sfnew(NiL, NiL, SF_UNBOUND, sffileno(sp), (sfset(sp, 0, 0) & (SF_READ|SF_WRITE)))))
		return -1;
	if (!(pz = newof(0, Sfpzip_t, 1, 0)))
	{
		io->_file = -1;
		sfclose(io);
		return -1;
	}
	pz->disc.version = PZ_VERSION;
	flags &= ~(PZ_READ|PZ_WRITE|PZ_STAT|PZ_STREAM|PZ_INTERNAL);
	flags |= PZ_PUSHED|PZ_STREAM|((sfset(sp, 0, 0) & SF_READ) ? PZ_READ : PZ_WRITE);
	if (oz && (oz->flags & PZ_WRITE))
		flags |= PZ_DELAY;
	if (disc)
	{
		pz->disc.errorf = disc->errorf;
		pz->disc.window = disc->window;
		pz->disc.options = disc->options;
		pz->disc.partition = disc->partition;
		if (disc->splitf)
			flags |= PZ_ACCEPT;
	}
	if (!(pz->pz = pzopen(&pz->disc, (char*)io, flags)) || (sp->_file = open("/dev/null", 0)) < 0)
	{
		io->_file = -1;
		sfclose(io);
		free(pz);
		return -1;
	}
	if (path)
		pz->pz->path = path;
	pz->sfdisc.exceptf = sfpzexcept;
	if (flags & PZ_WRITE)
	{
		pz->sfdisc.writef = sfpzwrite;
		pz->io = io;
	}
	else
		pz->sfdisc.readf = sfpzread;
	sfset(sp, SF_SHARE|SF_PUBLIC, 0);
	if (sfdisc(sp, &pz->sfdisc) != &pz->sfdisc)
	{
		close(sp->_file);
		sp->_file = io->_file;
		sfseek(sp, sftell(io), SEEK_SET);
		io->_file = -1;
		pzclose(pz->pz);
		free(pz);
		return -1;
	}
	if (oz)
		oz->flags |= pz->pz->flags & PZ_INTERNAL;
	return 1;
}