summaryrefslogtreecommitdiffstats
path: root/lib/zlib_inflate/inflate_sync.c
blob: 61411ff89d6160da831df3ac73bbd2f551b75c8e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
/* 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"

#if 0
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;
}
#endif  /*  0  */


/* 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.
 */
#if 0
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);
}
#endif  /*  0  */

/*
 * 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);
}
OpenPOWER on IntegriCloud