harvey/sys/src/9/w/pxeload/inflate.c

/*
 * This file is part of the UCB release of Plan 9. It is subject to the license
 * terms in the LICENSE file found in the top-level directory of this
 * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
 * part of the UCB release of Plan 9, including this file, may be copied,
 * modified, propagated, or distributed except according to the terms contained
 * in the LICENSE file.
 */

#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include <flate.h>

typedef struct Biobuf	Biobuf;

struct Biobuf
{
	uint8_t *bp;
	uint8_t *p;
	uint8_t *ep;
};

static int	header(Biobuf*);
static int	trailer(Biobuf*, Biobuf*);
static int	getc(void*);
static uint32_t	offset(Biobuf*);
static int	crcwrite(void *out, void *buf, int n);
static uint32_t	get4(Biobuf *b);
static uint32_t	Boffset(Biobuf *bp);

/* GZIP flags */
enum {
	Ftext=		(1<<0),
	Fhcrc=		(1<<1),
	Fextra=		(1<<2),
	Fname=		(1<<3),
	Fcomment=	(1<<4),

	GZCRCPOLY	= 0xedb88320UL,
};

static uint32_t	*crctab;
static uint32_t	crc;

extern void diff(char*);	//XXX
int
gunzip(uint8_t *out, int outn, uint8_t *in, int inn)
{
	Biobuf bin, bout;
	int err;

	crc = 0;
	crctab = mkcrctab(GZCRCPOLY);
	err = inflateinit();
	if(err != FlateOk)
		print("inflateinit failed: %s\n", flateerr(err));

	bin.bp = bin.p = in;
	bin.ep = in+inn;
	bout.bp = bout.p = out;
	bout.ep = out+outn;

	err = header(&bin);
	if(err != FlateOk)
		return err;

	err = inflate(&bout, crcwrite, &bin, getc);
	if(err != FlateOk)
		print("inflate failed: %s\n", flateerr(err));

	err = trailer(&bout, &bin);
	if(err != FlateOk)
		return err;

	return Boffset(&bout);
}

static int
header(Biobuf *bin)
{
	int i, flag;

	if(getc(bin) != 0x1f || getc(bin) != 0x8b){
		print("bad magic\n");
		return FlateCorrupted;
	}
	if(getc(bin) != 8){
		print("unknown compression type\n");
		return FlateCorrupted;
	}

	flag = getc(bin);

	/* mod time */
	get4(bin);

	/* extra flags */
	getc(bin);

	/* OS type */
	getc(bin);

	if(flag & Fextra)
		for(i=getc(bin); i>0; i--)
			getc(bin);

	/* name */
	if(flag&Fname)
		while(getc(bin) != 0)
			;

	/* comment */
	if(flag&Fcomment)
		while(getc(bin) != 0)
			;

	/* crc16 */
	if(flag&Fhcrc) {
		getc(bin);
		getc(bin);
	}

	return FlateOk;
}

static int
trailer(Biobuf *bout, Biobuf *bin)
{
	/* crc32 */
	if(crc != get4(bin)){
		print("crc mismatch\n");
		return FlateCorrupted;
	}

	/* length */
	if(get4(bin) != Boffset(bout)){
		print("bad output len\n");
		return FlateCorrupted;
	}
	return FlateOk;
}

static uint32_t
get4(Biobuf *b)
{
	uint32_t v;
	int i, c;

	v = 0;
	for(i = 0; i < 4; i++){
		c = getc(b);
		v |= c << (i * 8);
	}
	return v;
}

static int
getc(void *in)
{
	Biobuf *bp = in;

//	if((bp->p - bp->bp) % 10000 == 0)
//		print(".");
	if(bp->p >= bp->ep)
		return -1;
	return *bp->p++;
}

static uint32_t
Boffset(Biobuf *bp)
{
	return bp->p - bp->bp;
}

static int
crcwrite(void *out, void *buf, int n)
{
	Biobuf *bp;
	int nn;

	crc = blockcrc(crctab, crc, buf, n);
	bp = out;
	nn = n;
	if(nn > bp->ep-bp->p)
		nn = bp->ep-bp->p;
	if(nn > 0)
		memmove(bp->p, buf, nn);
	bp->p += n;
	return n;
}

#undef malloc
#undef free

void *
malloc(uint32_t n)
{
	return ialloc(n, 8);
}

void
free(void *)
{
}