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