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/* inflate.c -- zlib interface to inflate modules
* Copyright (C) 1995 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#include "zutil.h"
#include "infblock.h"
struct inflate_blocks_state {int dummy;}; /* for buggy compilers */
/* inflate private state */
struct internal_state {
/* mode */
enum {
METHOD, /* waiting for method byte */
FLAG, /* waiting for flag byte */
START, /* make new blocks state */
BLOCKS, /* decompressing blocks */
CHECK4, /* four check bytes to go */
CHECK3, /* three check bytes to go */
CHECK2, /* two check bytes to go */
CHECK1, /* one check byte to go */
DONE, /* finished check, done */
ERROR} /* got an error--stay here */
mode; /* current inflate mode */
int no_header;
uInt w_size; /* LZ77 window size (32K by default) */
uInt w_bits; /* log2(w_size) (8..16) */
/* mode dependent information */
union {
uInt method; /* if FLAGS, method byte */
struct inflate_blocks_state
*blocks; /* if BLOCKS, current state */
struct {
uLong was; /* computed check value */
uLong need; /* stream check value */
} check; /* if CHECK, check values to compare */
} sub; /* submode */
};
int inflateInit (strm)
z_stream *strm;
{
return inflateInit2(strm, WBITS);
}
int inflateInit2(z, windowBits)
z_stream *z;
int windowBits;
{
if (z == Z_NULL)
return Z_STREAM_ERROR;
if (z->zalloc == Z_NULL) z->zalloc = zcalloc;
if (z->zfree == Z_NULL) z->zfree = zcfree;
z->total_in = z->total_out = 0;
z->msg = Z_NULL;
if ((z->state = (struct internal_state *)
ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
return Z_MEM_ERROR;
z->state->mode = METHOD;
z->state->no_header = 0;
if (windowBits < 0) { /* undocumented feature: no zlib header */
windowBits = - windowBits;
z->state->no_header = 1;
z->state->sub.method = DEFLATED;
z->state->mode = START;
}
if (windowBits < 8 || windowBits > 15) {
inflateEnd(z);
return Z_STREAM_ERROR;
}
z->state->w_bits = windowBits;
z->state->w_size = 1<<windowBits;
return Z_OK;
}
#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)
int inflate(z, f)
z_stream *z;
int f;
{
int r;
uInt b;
uLong c;
if (z == Z_NULL || z->next_in == Z_NULL)
return Z_STREAM_ERROR;
r = Z_BUF_ERROR;
while (1) switch (z->state->mode)
{
case METHOD:
if (z->avail_in == 0) return r; r = Z_OK;
if (((z->state->sub.method = NEXTBYTE) & 0xf != DEFLATED))
{
z->state->mode = ERROR;
z->msg = "unknown compression method";
return Z_DATA_ERROR;
}
if ((z->state->sub.method >> 4) > z->state->w_bits)
{
z->state->mode = ERROR;
z->msg = "invalid window size";
return Z_DATA_ERROR;
}
z->state->mode = FLAG;
case FLAG:
if (z->avail_in == 0) return r; r = Z_OK;
if ((b = NEXTBYTE) & 0x20)
{
z->state->mode = ERROR;
z->msg = "invalid reserved bit";
return Z_DATA_ERROR;
}
if (((z->state->sub.method << 8) + b) % 31)
{
z->state->mode = ERROR;
z->msg = "incorrect header check";
return Z_DATA_ERROR;
}
z->state->mode = START;
case START:
if ((z->state->sub.blocks = inflate_blocks_new(z,z->state->w_size))
== Z_NULL)
return Z_MEM_ERROR;
z->state->mode = BLOCKS;
case BLOCKS:
if ((r = inflate_blocks(z->state->sub.blocks, z, r)) != Z_STREAM_END)
return r;
inflate_blocks_free(z->state->sub.blocks, z, &c, &r);
if (z->state->no_header) {
z->state->mode = DONE;
return Z_STREAM_END;
}
z->state->sub.check.was = c;
if (r != -1)
{
z->state->sub.check.need = (uLong)r << 24;
z->state->mode = CHECK3;
r = Z_OK;
break;
}
r = Z_OK;
z->state->mode = CHECK4;
case CHECK4:
if (z->avail_in == 0) return r; r = Z_OK;
z->state->sub.check.need = (uLong)NEXTBYTE << 24;
z->state->mode = CHECK3;
case CHECK3:
if (z->avail_in == 0) return r; r = Z_OK;
z->state->sub.check.need += (uLong)NEXTBYTE << 16;
z->state->mode = CHECK2;
case CHECK2:
if (z->avail_in == 0) return r; r = Z_OK;
z->state->sub.check.need += (uLong)NEXTBYTE << 8;
z->state->mode = CHECK1;
case CHECK1:
if (z->avail_in == 0) return r; r = Z_OK;
z->state->sub.check.need += (uLong)NEXTBYTE;
if (z->state->sub.check.was != z->state->sub.check.need)
{
z->state->mode = ERROR;
z->msg = "incorrect data check";
return Z_DATA_ERROR;
}
z->state->mode = DONE;
case DONE:
return Z_STREAM_END;
case ERROR:
return Z_DATA_ERROR;
default:
return Z_STREAM_ERROR;
}
}
int inflateEnd(z)
z_stream *z;
{
uLong c;
int e;
if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
return Z_STREAM_ERROR;
if (z->state->mode == BLOCKS)
inflate_blocks_free(z->state->sub.blocks, z, &c, &e);
ZFREE(z, z->state);
z->state = Z_NULL;
return Z_OK;
}
/* inflateSync not implemented yet--this just consumes input */
int inflateSync(z)
z_stream *z;
{
if (z == Z_NULL) return Z_STREAM_ERROR;
if (z->avail_in == 0) return Z_BUF_ERROR;
do {
z->total_in++;
} while (--z->avail_in);
return Z_DATA_ERROR;
}
/* inflateReset not fully implemented yet--this frees and reallocates */
int inflateReset(z)
z_stream *z;
{
int r;
if ((r = inflateEnd(z)) != Z_OK)
return r;
return inflateInit(z);
}
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