/* inflate.c -- zlib interface to inflate modules
* Copyright (C) 1995-1998 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#include <linux/zutil.h>
#include "infblock.h"
#include "infutil.h"
int zlib_inflateSync(
z_streamp z
)
{
uInt n; /* number of bytes to look at */
Byte *p; /* pointer to bytes */
uInt m; /* number of marker bytes found in a row */
uLong r, w; /* temporaries to save total_in and total_out */
/* set up */
if (z == NULL || z->state == NULL)
return Z_STREAM_ERROR;
if (z->state->mode != I_BAD)
{
z->state->mode = I_BAD;
z->state->sub.marker = 0;
}
if ((n = z->avail_in) == 0)
return Z_BUF_ERROR;
p = z->next_in;
m = z->state->sub.marker;
/* search */
while (n && m < 4)
{
static const Byte mark[4] = {0, 0, 0xff, 0xff};
if (*p == mark[m])
m++;
else if (*p)
m = 0;
else
m = 4 - m;
p++, n--;
}
/* restore */
z->total_in += p - z->next_in;
z->next_in = p;
z->avail_in = n;
z->state->sub.marker = m;
/* return no joy or set up to restart on a new block */
if (m != 4)
return Z_DATA_ERROR;
r = z->total_in; w = z->total_out;
zlib_inflateReset(z);
z->total_in = r; z->total_out = w;
z->state->mode = BLOCKS;
return Z_OK;
}
/* Returns true if inflate is currently at the end of a block generated
* by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
* implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
* but removes the length bytes of the resulting empty stored block. When
* decompressing, PPP checks that at the end of input packet, inflate is
* waiting for these length bytes.
*/
int zlib_inflateSyncPoint(
z_streamp z
)
{
if (z == NULL || z->state == NULL || z->state->blocks == NULL)
return Z_STREAM_ERROR;
return zlib_inflate_blocks_sync_point(z->state->blocks);
}
/*
* This subroutine adds the data at next_in/avail_in to the output history
* without performing any output. The output buffer must be "caught up";
* i.e. no pending output (hence s->read equals s->write), and the state must
* be BLOCKS (i.e. we should be willing to see the start of a series of
* BLOCKS). On exit, the output will also be caught up, and the checksum
* will have been updated if need be.
*/
static int zlib_inflate_addhistory(inflate_blocks_statef *s,
z_stream *z)
{
uLong b; /* bit buffer */ /* NOT USED HERE */
uInt k; /* bits in bit buffer */ /* NOT USED HERE */
uInt t; /* temporary storage */
Byte *p; /* input data pointer */
uInt n; /* bytes available there */
Byte *q; /* output window write pointer */
uInt m; /* bytes to end of window or read pointer */
if (s->read != s->write)
return Z_STREAM_ERROR;
if (s->mode != TYPE)
return Z_DATA_ERROR;
/* we're ready to rock */
LOAD
/* while there is input ready, copy to output buffer, moving
* pointers as needed.
*/
while (n) {
t = n; /* how many to do */
/* is there room until end of buffer? */
if (t > m) t = m;
/* update check information */
if (s->checkfn != NULL)
s->check = (*s->checkfn)(s->check, q, t);
memcpy(q, p, t);
q += t;
p += t;
n -= t;
z->total_out += t;
s->read = q; /* drag read pointer forward */
/* WWRAP */ /* expand WWRAP macro by hand to handle s->read */
if (q == s->end) {
s->read = q = s->window;
m = WAVAIL;
}
}
UPDATE
return Z_OK;
}
/*
* This subroutine adds the data at next_in/avail_in to the output history
* without performing any output. The output buffer must be "caught up";
* i.e. no pending output (hence s->read equals s->write), and the state must
* be BLOCKS (i.e. we should be willing to see the start of a series of
* BLOCKS). On exit, the output will also be caught up, and the checksum
* will have been updated if need be.
*/
int zlib_inflateIncomp(
z_stream *z
)
{
if (z->state->mode != BLOCKS)
return Z_DATA_ERROR;
return zlib_inflate_addhistory(z->state->blocks, z);
}
