inflate.c

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    unsigned ll[288+32];/* literal/length and distance code lengths */
#else
    unsigned ll[286+30];/* literal/length and distance code lengths */
#endif
    static unsigned border[] = {  /* Order of the bit length code lengths */
	16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
    BITS_SAVE;

    reuse_mblock(&decoder->pool);

    /* read in table lengths */
    NEEDBITS(5);
    nl = 257 + GETBITS(5);	/* number of literal/length codes */
    DUMPBITS(5);
    NEEDBITS(5);
    nd = 1 + GETBITS(5);	/* number of distance codes */
    DUMPBITS(5);
    NEEDBITS(4);
    nb = 4 + GETBITS(4);	/* number of bit length codes */
    DUMPBITS(4);
#ifdef PKZIP_BUG_WORKAROUND
    if(nl > 288 || nd > 32)
#else
    if(nl > 286 || nd > 30)
#endif
    {
	BITS_RESTORE;
	return -1;		/* bad lengths */
    }

    /* read in bit-length-code lengths */
    for(j = 0; j < nb; j++)
    {
	NEEDBITS(3);
	ll[border[j]] = GETBITS(3);
	DUMPBITS(3);
    }
    for(; j < 19; j++)
	ll[border[j]] = 0;

    /* build decoding table for trees--single level, 7 bit lookup */
    bl = 7;
    if((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl, &decoder->pool)) != 0)
    {
	reuse_mblock(&decoder->pool);
	BITS_RESTORE;
	return -1;		/* incomplete code set */
    }

    /* read in literal and distance code lengths */
    n = nl + nd;
    i = l = 0;
    while((unsigned)i < n)
    {
	NEEDBITS((unsigned)bl);
	j = (td = tl + (GETBITS(bl)))->b;
	DUMPBITS(j);
	j = td->v.n;
	if(j < 16)		/* length of code in bits (0..15) */
	    ll[i++] = l = j;	/* save last length in l */
	else if(j == 16)	/* repeat last length 3 to 6 times */
	{
	    NEEDBITS(2);
	    j = 3 + GETBITS(2);
	    DUMPBITS(2);
	    if((unsigned)i + j > n)
	    {
		BITS_RESTORE;
		return -1;
	    }
	    while(j--)
		ll[i++] = l;
	}
	else if(j == 17)	/* 3 to 10 zero length codes */
	{
	    NEEDBITS(3);
	    j = 3 + GETBITS(3);
	    DUMPBITS(3);
	    if((unsigned)i + j > n)
	    {
		BITS_RESTORE;
		return -1;
	    }
	    while(j--)
		ll[i++] = 0;
	    l = 0;
	}
	else			/* j == 18: 11 to 138 zero length codes */
	{
	    NEEDBITS(7);
	    j = 11 + GETBITS(7);
	    DUMPBITS(7);
	    if((unsigned)i + j > n)
	    {
		BITS_RESTORE;
		return -1;
	    }
	    while(j--)
		ll[i++] = 0;
	    l = 0;
	}
    }

    BITS_RESTORE;

    /* free decoding table for trees */
    reuse_mblock(&decoder->pool);

    /* build the decoding tables for literal/length and distance codes */
    bl = lbits;
    i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl, &decoder->pool);
    if(bl == 0)			      /* no literals or lengths */
      i = 1;
    if(i)
    {
	if(i == 1)
	    fprintf(stderr, " incomplete literal tree\n");
	reuse_mblock(&decoder->pool);
	return -1;		/* incomplete code set */
    }
    bd = dbits;
    i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd, &decoder->pool);
    if(bd == 0 && nl > 257)    /* lengths but no distances */
    {
	fprintf(stderr, " incomplete distance tree\n");
	reuse_mblock(&decoder->pool);
	return -1;
    }

    if(i == 1) {
#ifdef PKZIP_BUG_WORKAROUND
	i = 0;
#else
	fprintf(stderr, " incomplete distance tree\n");
#endif
    }
    if(i)
    {
	reuse_mblock(&decoder->pool);
	return -1;
    }

    /* decompress until an end-of-block code */
    decoder->tl = tl;
    decoder->td = td;
    decoder->bl = bl;
    decoder->bd = bd;

    i = inflate_codes(decoder, buff, size);

    if(i == -1) /* error */
    {
	reuse_mblock(&decoder->pool);
	return -1;
    }

    /* free the decoding tables, return */
    return i;
}

local void inflate_start(InflateHandler decoder)
/* initialize window, bit buffer */
{
    decoder->wp = 0;
    decoder->bit_buf = 0;
    decoder->bit_len = 0;
    decoder->insize = decoder->inptr = 0;
    decoder->fixed_td = decoder->fixed_tl = NULL;
    decoder->method = -1;
    decoder->eof = 0;
    decoder->copy_leng = decoder->copy_dist = 0;
    decoder->tl = NULL;

    init_mblock(&decoder->pool);
}

/*ARGSUSED*/
static long default_read_func(char *buf, long size, void *v)
{
    return (long)fread(buf, 1, size, stdin);
}

InflateHandler open_inflate_handler(
    long (* read_func)(char *buf, long size, void *user_val),
    void *user_val)
{
    InflateHandler decoder;

    decoder = (InflateHandler)
	malloc(sizeof(struct _InflateHandler));
    inflate_start(decoder);
    decoder->user_val = user_val;
    if(read_func == NULL)
	decoder->read_func = default_read_func;
    else
	decoder->read_func = read_func;
    return decoder;
}

void close_inflate_handler(InflateHandler decoder)
{
    if(decoder->fixed_tl != NULL)
    {
	huft_free(decoder->fixed_td);
	huft_free(decoder->fixed_tl);
	decoder->fixed_td = decoder->fixed_tl = NULL;
    }
    reuse_mblock(&decoder->pool);
    free(decoder);
}

/* decompress an inflated entry */
long zip_inflate(
    InflateHandler decoder,
    char *buff,
    long size)
{
    long n, i;

    n = 0;
    while(n < size)
    {
	if(decoder->eof && decoder->method == -1)
	    return n;

	if(decoder->copy_leng > 0)
	{
	    unsigned l, w, d;

	    l = decoder->copy_leng;
	    w = decoder->wp;
	    if(decoder->method != STORED_BLOCK)
	    {
		/* STATIC_TREES or DYN_TREES */
		d = decoder->copy_dist;
		while(l > 0 && n < size)
		{
		    l--;
		    d &= WSIZE - 1;
		    w &= WSIZE - 1;
		    buff[n++] = decoder->slide[w++] = decoder->slide[d++];
		}
		decoder->copy_dist = d;
	    }
	    else /* STATIC_TREES or DYN_TREES */
	    {
		BITS_SAVE;
		while(l > 0 && n < size)
		{
		    l--;
		    w &= WSIZE - 1;
		    NEEDBITS(8);
		    buff[n++] = decoder->slide[w++] = (uch)GETBITS(8);
		    DUMPBITS(8);
		}
		BITS_RESTORE;
		if(l == 0)
		    decoder->method = -1; /* done */
	    }
	    decoder->copy_leng = l;
	    decoder->wp = w;
	    if(n == size)
		return n;
	}

	if(decoder->method == -1)
	{
	    BITS_SAVE;
	    if(decoder->eof)
	    {
		BITS_RESTORE;
		break;
	    }
	    /* read in last block bit */
	    NEEDBITS(1);
	    if(GETBITS(1))
		decoder->eof = 1;
	    DUMPBITS(1);

	    /* read in block type */
	    NEEDBITS(2);
	    decoder->method = (int)GETBITS(2);
	    DUMPBITS(2);
	    decoder->tl = NULL;
	    decoder->copy_leng = 0;
	    BITS_RESTORE;
	}

	switch(decoder->method)
	{
	  case STORED_BLOCK:
	    i = inflate_stored(decoder, buff + n, size - n);
	    break;

	  case STATIC_TREES:
	    if(decoder->tl != NULL)
		i = inflate_codes(decoder, buff + n, size - n);
	    else
		i = inflate_fixed(decoder, buff + n, size - n);
	    break;

	  case DYN_TREES:
	    if(decoder->tl != NULL)
		i = inflate_codes(decoder, buff + n, size - n);
	    else
		i = inflate_dynamic(decoder, buff + n, size - n);
	    break;

	  default: /* error */
	    i = -1;
	    break;
	}

	if(i == -1)
	{
	    if(decoder->eof)
		return 0;
	    return -1; /* error */
	}
	n += i;
    }
    return n;
}

/* ===========================================================================
 * Fill the input buffer. This is called only when the buffer is empty.
 */
local int fill_inbuf(InflateHandler decoder)
{
    int len;

    /* Read as much as possible */
    decoder->insize = 0;
    errno = 0;
    do {
	len = decoder->read_func((char*)decoder->inbuf + decoder->insize,
				 (long)(INBUFSIZ - decoder->insize),
				 decoder->user_val);
	if(len == 0 || len == EOF) break;
	decoder->insize += len;
    } while(decoder->insize < INBUFSIZ);

    if(decoder->insize == 0)
	return EOF;
    decoder->inptr = 1;
    return decoder->inbuf[0];
}