lib/zlib_inflate/inflate_sync.c

   1 /* inflate.c -- zlib interface to inflate modules
   2  * Copyright (C) 1995-1998 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 #include <linux/zutil.h>
   7 #include "infblock.h"
   8 #include "infutil.h"
   9
  10 #if 0
  11 int zlib_inflateSync(
  12         z_streamp z
  13 )
  14 {
  15   uInt n;       /* number of bytes to look at */
  16   Byte *p;      /* pointer to bytes */
  17   uInt m;       /* number of marker bytes found in a row */
  18   uLong r, w;   /* temporaries to save total_in and total_out */
  19
  20   /* set up */
  21   if (z == NULL || z->state == NULL)
  22     return Z_STREAM_ERROR;
  23   if (z->state->mode != I_BAD)
  24   {
  25     z->state->mode = I_BAD;
  26     z->state->sub.marker = 0;
  27   }
  28   if ((n = z->avail_in) == 0)
  29     return Z_BUF_ERROR;
  30   p = z->next_in;
  31   m = z->state->sub.marker;
  32
  33   /* search */
  34   while (n && m < 4)
  35   {
  36     static const Byte mark[4] = {0, 0, 0xff, 0xff};
  37     if (*p == mark[m])
  38       m++;
  39     else if (*p)
  40       m = 0;
  41     else
  42       m = 4 - m;
  43     p++, n--;
  44   }
  45
  46   /* restore */
  47   z->total_in += p - z->next_in;
  48   z->next_in = p;
  49   z->avail_in = n;
  50   z->state->sub.marker = m;
  51
  52   /* return no joy or set up to restart on a new block */
  53   if (m != 4)
  54     return Z_DATA_ERROR;
  55   r = z->total_in;  w = z->total_out;
  56   zlib_inflateReset(z);
  57   z->total_in = r;  z->total_out = w;
  58   z->state->mode = BLOCKS;
  59   return Z_OK;
  60 }
  61 #endif  /*  0  */
  62
  63
  64 /* Returns true if inflate is currently at the end of a block generated
  65  * by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
  66  * implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
  67  * but removes the length bytes of the resulting empty stored block. When
  68  * decompressing, PPP checks that at the end of input packet, inflate is
  69  * waiting for these length bytes.
  70  */
  71 #if 0
  72 int zlib_inflateSyncPoint(
  73         z_streamp z
  74 )
  75 {
  76   if (z == NULL || z->state == NULL || z->state->blocks == NULL)
  77     return Z_STREAM_ERROR;
  78   return zlib_inflate_blocks_sync_point(z->state->blocks);
  79 }
  80 #endif  /*  0  */
  81
  82 /*
  83  * This subroutine adds the data at next_in/avail_in to the output history
  84  * without performing any output.  The output buffer must be "caught up";
  85  * i.e. no pending output (hence s->read equals s->write), and the state must
  86  * be BLOCKS (i.e. we should be willing to see the start of a series of
  87  * BLOCKS).  On exit, the output will also be caught up, and the checksum
  88  * will have been updated if need be.
  89  */
  90 static int zlib_inflate_addhistory(inflate_blocks_statef *s,
  91                                       z_stream              *z)
  92 {
  93     uLong b;              /* bit buffer */  /* NOT USED HERE */
  94     uInt k;               /* bits in bit buffer */ /* NOT USED HERE */
  95     uInt t;               /* temporary storage */
  96     Byte *p;              /* input data pointer */
  97     uInt n;               /* bytes available there */
  98     Byte *q;              /* output window write pointer */
  99     uInt m;               /* bytes to end of window or read pointer */
 100
 101     if (s->read != s->write)
 102         return Z_STREAM_ERROR;
 103     if (s->mode != TYPE)
 104         return Z_DATA_ERROR;
 105
 106     /* we're ready to rock */
 107     LOAD
 108     /* while there is input ready, copy to output buffer, moving
 109      * pointers as needed.
 110      */
 111     while (n) {
 112         t = n;  /* how many to do */
 113         /* is there room until end of buffer? */
 114         if (t > m) t = m;
 115         /* update check information */
 116         if (s->checkfn != NULL)
 117             s->check = (*s->checkfn)(s->check, q, t);
 118         memcpy(q, p, t);
 119         q += t;
 120         p += t;
 121         n -= t;
 122         z->total_out += t;
 123         s->read = q;    /* drag read pointer forward */
 124 /*      WWRAP  */       /* expand WWRAP macro by hand to handle s->read */
 125         if (q == s->end) {
 126             s->read = q = s->window;
 127             m = WAVAIL;
 128         }
 129     }
 130     UPDATE
 131     return Z_OK;
 132 }
 133
 134
 135 /*
 136  * This subroutine adds the data at next_in/avail_in to the output history
 137  * without performing any output.  The output buffer must be "caught up";
 138  * i.e. no pending output (hence s->read equals s->write), and the state must
 139  * be BLOCKS (i.e. we should be willing to see the start of a series of
 140  * BLOCKS).  On exit, the output will also be caught up, and the checksum
 141  * will have been updated if need be.
 142  */
 143
 144 int zlib_inflateIncomp(
 145         z_stream *z
 146
 147 )
 148 {
 149     if (z->state->mode != BLOCKS)
 150         return Z_DATA_ERROR;
 151     return zlib_inflate_addhistory(z->state->blocks, z);
 152 }