Category : C Source Code
Archive : LZPIPE.ZIP
Filename : DISZIP.C
Output of file : DISZIP.C contained in archive : LZPIPE.ZIP
* (funzip.c & inflate.c files) which are written and
* gracefully put into public domain by Mark Adler.
* You can find original texts in Info-Zip 'unzip' distribution.
*/
/*#define PKZIP_BUG_WORKAROUND*/
#include
#include "modern.h"
#include "stdinc.h"
#ifdef MODERN
# include
#else
char *malloc();
#endif
#include "zipdefs.h"
#include "lzpipe.h"
#include "crc32.h"
#ifndef max
# define max(a,b) (((a) > (b)) ? (a) : (b))
#endif
#define AT_EOF 0x80 /* End of data achieved */
#define INITED 0x40 /* Header processed */
#define METHOD 0x03 /* Inflate method mask */
#define IBEGIN 0x20 /* Trees (or stored length) processed */
#define ICFLAG 0x10 /* Copy pending */
static uch zipstate = 0;
#ifdef LZFILE
static FILE *zip_inp_port = NULL;
# define readbyte() getc(zip_inp_port)
# define nextbyte() getc(zip_inp_port)
#else
static int (*zip_inp_port)__ARGS__((void)) = (int(*)())0;
# define readbyte() (*zip_inp_port)()
# define nextbyte() (*zip_inp_port)()
#endif
#define PF_CRYPT 1 /* PKWare flag fields */
#define PF_ATEOF 8
#define PF_ERROR 0x1ff0
#define GF_ASCII 1 /* GNU flag fields */
#define GF_CONT 2
#define GF_EXTRA 4
#define GF_FNAME 8
#define GF_COMMENT 0x10
#define GF_CRYPT 0x20
#define GF_ERROR 0xC0
static char ziptype = 0;
static ush zipflags, zmethod;
static ulg crc32val, srcsize;
static uch *slide = (uch*)0;
static ulg outsiz; /* total bytes written to out */
static char *outbuf;
static ush outpos; /* output posiztion in slide */
/*
Inflate deflated (PKZIP's method 8 compressed) data. The compression
method searches for as much of the current string of bytes (up to a
length of 258) in the previous 32K bytes. If it doesn't find any
matches (of at least length 3), it codes the next byte. Otherwise, it
codes the length of the matched string and its distance backwards from
the current position. There is a single Huffman code that codes both
single bytes (called "literals") and match lengths. A second Huffman
code codes the distance information, which follows a length code. Each
length or distance code actually represents a base value and a number
of "extra" (sometimes zero) bits to get to add to the base value. At
the end of each deflated block is a special end-of-block (EOB) literal/
length code. The decoding process is basically: get a literal/length
code; if EOB then done; if a literal, emit the decoded byte; if a
length then get the distance and emit the referred-to bytes from the
sliding window of previously emitted data.
There are (currently) three kinds of inflate blocks: stored, fixed, and
dynamic. The compressor outputs a chunk of data at a time, and decides
which method to use on a chunk-by-chunk basis. A chunk might typically
be 32K to 64K, uncompressed. If the chunk is uncompressible, then the
"stored" method is used. In this case, the bytes are simply stored as
is, eight bits per byte, with none of the above coding. The bytes are
preceded by a count, since there is no longer an EOB code.
If the data is compressible, then either the fixed or dynamic methods
are used. In the dynamic method, the compressed data is preceded by
an encoding of the literal/length and distance Huffman codes that are
to be used to decode this block. The representation is itself Huffman
coded, and so is preceded by a description of that code. These code
descriptions take up a little space, and so for small blocks, there is
a predefined set of codes, called the fixed codes. The fixed method is
used if the block ends up smaller that way (usually for quite small
chunks), otherwise the dynamic method is used. In the latter case, the
codes are customized to the probabilities in the current block, and so
can code it much better than the pre-determined fixed codes can.
The Huffman codes themselves are decoded using a mutli-level table
lookup, in order to maximize the speed of decoding plus the speed of
building the decoding tables. See the comments below that precede the
lbits and dbits tuning parameters.
*/
/*
Notes beyond the 1.93a appnote.txt:
1. Distance pointers never point before the beginning of the output
stream.
2. Distance pointers can point back across blocks, up to 32k away.
3. There is an implied maximum of 7 bits for the bit length table and
15 bits for the actual data.
4. If only one code exists, then it is encoded using one bit. (Zero
would be more efficient, but perhaps a little confusing.) If two
codes exist, they are coded using one bit each (0 and 1).
5. There is no way of sending zero distance codes--a dummy must be
sent if there are none. (History: a pre 2.0 version of PKZIP would
store blocks with no distance codes, but this was discovered to be
too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
zero distance codes, which is sent as one code of zero bits in
length.
6. There are up to 286 literal/length codes. Code 256 represents the
end-of-block. Note however that the static length tree defines
288 codes just to fill out the Huffman codes. Codes 286 and 287
cannot be used though, since there is no length base or extra bits
defined for them. Similarily, there are up to 30 distance codes.
However, static trees define 32 codes (all 5 bits) to fill out the
Huffman codes, but the last two had better not show up in the data.
7. Unzip can check dynamic Huffman blocks for complete code sets.
The exception is that a single code would not be complete (see #4).
8. The five bits following the block type is really the number of
literal codes sent minus 257.
9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
(1+6+6). Therefore, to output three times the length, you output
three codes (1+1+1), whereas to output four times the same length,
you only need two codes (1+3). Hmm.
10. In the tree reconstruction algorithm, Code = Code + Increment
only if BitLength(i) is not zero. (Pretty obvious.)
11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
12. Note: length code 284 can represent 227-258, but length code 285
really is 258. The last length deserves its own, short code
since it gets used a lot in very redundant files. The length
258 is special since 258 - 3 (the min match length) is 255.
13. The literal/length and distance code bit lengths are read as a
single stream of lengths. It is possible (and advantageous) for
a repeat code (16, 17, or 18) to go across the boundary between
the two sets of lengths.
*/
/* Huffman code lookup table entry--this entry is four bytes for machines
that have 16-bit pointers (e.g. PC's in the small or medium model).
Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
means that v is a literal, 16 < e < 32 means that v is a pointer to
the next table, which codes e - 16 bits, and lastly e == 99 indicates
an unused code. If a code with e == 99 is looked up, this implies an
error in the data. */
#define EOB 15
#define LITERAL 16
#define BAD 99
typedef struct _huft {
uch e; /* number of extra bits or operation */
uch b; /* number of bits in this code or subcode */
union {
ush n; /* literal, length base, or distance base */
struct _huft *t; /* pointer to next level of table */
} v;
} huft;
/* Function prototypes */
static void huft_free __ARGS__((huft **));
static int huft_build __ARGS__((unsigned *, unsigned, unsigned, ush *, ush *,
huft **, int *));
static void copyout __ARGS__((void));
static ush getbits __ARGS__((ush));
static int decode __ARGS__((unsigned *, huft *, int));
static int inflate_codes __ARGS__((huft *, huft *, int, int, unsigned));
static int inflate_dynamic __ARGS__((unsigned));
static int inflate_fixed __ARGS__((unsigned));
static int inflate_stored __ARGS__((unsigned));
static ush getsh __ARGS__((void));
static ulg getlg __ARGS__((void));
static int skip __ARGS__((int));
/* The inflate algorithm uses a sliding 32K byte window on the uncompressed
stream to find repeated byte strings. This is implemented here as a
circular buffer. The index is updated simply by incrementing and then
and'ing with 0x7fff (32K-1). */
/* It is left to other modules to supply the 32K area. It is assumed
to be usable as if it were declared "uch slide[32768];" or as just
"uch *slide;" and then malloc'ed in the latter case. The definition
must be in unzip.h, included above. */
unsigned wp; /* current position in slide */
/* Tables for deflate from PKZIP's appnote.txt. */
static unsigned border[] = { /* Order of the bit length code lengths */
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
static ush cplens[] = { /* Copy lengths for literal codes 257..285 */
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
/* note: see note #13 above about the 258 in this list. */
static ush cplext[] = { /* Extra bits for literal codes 257..285 */
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
static ush cpdist[] = { /* Copy offsets for distance codes 0..29 */
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
8193, 12289, 16385, 24577};
static ush cpdext[] = { /* Extra bits for distance codes */
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
12, 12, 13, 13};
/* Macros for inflate() bit peeking and grabbing.
The usage is:
NEEDBITS(j)
x = b & mask_bits[j];
DUMPBITS(j)
where NEEDBITS makes sure that b has at least j bits in it, and
DUMPBITS removes the bits from b. The macros use the variable k
for the number of bits in b. Normally, b and k are register
variables for speed, and are initialized at the begining of a
routine that uses these macros from a global bit buffer and count.
If we assume that EOB will be the longest code, then we will never
ask for bits with NEEDBITS that are beyond the end of the stream.
So, NEEDBITS should not read any more bytes than are needed to
meet the request. Then no bytes need to be "returned" to the buffer
at the end of the last block.
However, this assumption is not true for fixed blocks--the EOB code
is 7 bits, but the other literal/length codes can be 8 or 9 bits.
(The EOB code is shorter than other codes becuase fixed blocks are
generally short. So, while a block always has an EOB, many other
literal/length codes have a significantly lower probability of
showing up at all.) However, by making the first table have a
lookup of seven bits, the EOB code will be found in that first
lookup, and so will not require that too many bits be pulled from
the stream.
*/
static ulg bb; /* bit buffer */
static unsigned bk; /* bits in bit buffer */
#define NEEDBITS(n) {while(k<(n)){b|=((ulg)nextbyte())<
/* A reasonable optimization for 16-bits computers */
#define NEEDTINY(n) {if(k<(n)){b|=(unsigned)nextbyte()<
static ush mask_bits[] = {
0x0000,
0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
};
/*
Huffman code decoding is performed using a multi-level table lookup.
The fastest way to decode is to simply build a lookup table whose
size is determined by the longest code. However, the time it takes
to build this table can also be a factor if the data being decoded
is not very long. The most common codes are necessarily the
shortest codes, so those codes dominate the decoding time, and hence
the speed. The idea is you can have a shorter table that decodes the
shorter, more probable codes, and then point to subsidiary tables for
the longer codes. The time it costs to decode the longer codes is
then traded against the time it takes to make longer tables.
This results of this trade are in the variables lbits and dbits
below. lbits is the number of bits the first level table for literal/
length codes can decode in one step, and dbits is the same thing for
the distance codes. Subsequent tables are also less than or equal to
those sizes. These values may be adjusted either when all of the
codes are shorter than that, in which case the longest code length in
bits is used, or when the shortest code is *longer* than the requested
table size, in which case the length of the shortest code in bits is
used.
There are two different values for the two tables, since they code a
different number of possibilities each. The literal/length table
codes 286 possible values, or in a flat code, a little over eight
bits. The distance table codes 30 possible values, or a little less
than five bits, flat. The optimum values for speed end up being
about one bit more than those, so lbits is 8+1 and dbits is 5+1.
The optimum values may differ though from machine to machine, and
possibly even between compilers. Your mileage may vary.
*/
#if 0
int lbits = 9; /* bits in base literal/length lookup table */
int dbits = 6; /* bits in base distance lookup table */
#else
#define lbits 9
#define dbits 6
#endif
static void huft_free(t)
huft **t; /* table to free */
/* Free the malloc'ed tables built by huft_build(), which makes a linked
list of the tables it made, with the links in a dummy first entry of
each table. */
{
register huft *p, *q;
/* Go through linked list, freeing from the malloced (t[-1]) address. */
p = *t;
while (p) {
q = (--p)->v.t;
free(p);
p = q;
}
*t = NULL;
}
/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
#define BMAX 16 /* maximum bit length of any code (16 for explode) */
#define N_MAX 288 /* maximum number of codes in any set */
#ifdef DEBUG
unsigned hufts; /* track memory usage */
#endif
static int huft_build(b, n, s, d, e, t, m)
unsigned *b; /* code lengths in bits (all assumed <= BMAX) */
unsigned n; /* number of codes (assumed <= N_MAX) */
unsigned s; /* number of simple-valued codes (0..s-1) */
ush *d; /* list of base values for non-simple codes */
ush *e; /* list of extra bits for non-simple codes */
huft **t; /* result: starting table */
int *m; /* maximum lookup bits, returns actual */
/* Given a list of code lengths and a maximum table size, make a set of
tables to decode that set of codes. Return zero on success, one if
the given code set is incomplete (the tables are still built in this
case), two if the input is invalid (all zero length codes or an
oversubscribed set of lengths), and three if not enough memory. */
{
unsigned a; /* counter for codes of length k */
unsigned c[BMAX+1]; /* bit length count table */
unsigned f; /* i repeats in table every f entries */
int g; /* maximum code length */
int h; /* table level */
register unsigned i; /* counter, current code */
register unsigned j; /* counter */
register int k; /* number of bits in current code */
int l; /* bits per table (returned in m) */
register unsigned *p; /* pointer into c[], b[], or v[] */
register huft *q; /* points to current table */
huft r; /* table entry for structure assignment */
huft *u[BMAX]; /* table stack */
unsigned v[N_MAX]; /* values in order of bit length */
register int w; /* bits before this table == (l * h) */
unsigned x[BMAX+1]; /* bit offsets, then code stack */
unsigned *xp; /* pointer into x */
int y; /* number of dummy codes added */
unsigned z; /* number of entries in current table */
/* Generate counts for each bit length */
for (i=0; i<=BMAX; i++) c[i] = 0;
p = b; i = n;
do {
c[*p++]++; /* assume all entries <= BMAX */
} while (--i);
if (c[0] == n) { /* null input--all zero length codes */
*t = (huft *)NULL;
*m = 0;
return 0;
}
/* Find minimum and maximum length, bound *m by those */
l = *m;
for (j = 1; j <= BMAX && !c[j]; j++);
k = j; /* minimum code length */
if ((unsigned)l < j) l = j;
for (i = BMAX; i && !c[i]; i--);
g = i; /* maximum code length */
if ((unsigned)l > i) l = i;
*m = l;
/* Adjust last length count to fill out codes, if needed */
for (y = 1 << j; j < i; j++, y <<= 1)
if ((y -= c[j]) < 0) return 2; /* bad input: more codes than bits */
if ((y -= c[i]) < 0) return 2;
c[i] += y;
/* Generate starting offsets into the value table for each length */
x[1] = j = 0;
p = c + 1; xp = x + 2;
while (--i) { /* note that i == g from above */
*xp++ = (j += *p++);
}
/* Make a table of values in order of bit lengths */
p = b; i = 0;
do {
if ((j = *p++) != 0) v[x[j]++] = i;
} while (++i < n);
/* Generate the Huffman codes and for each, make the table entries */
x[0] = i = 0; /* first Huffman code is zero */
p = v; /* grab values in bit order */
h = -1; /* no tables yet--level -1 */
w = -l; /* bits decoded == (l * h) */
u[0] = (huft *)NULL; /* just to keep compilers happy */
q = (huft *)NULL; /* ditto */
z = 0; /* ditto */
/* go through the bit lengths (k already is bits in shortest code) */
for (; k <= g; k++) {
a = c[k];
while (a--) {
/* here i is the Huffman code of length k bits for value *p */
/* make tables up to required level */
while (k > w + l) {
h++;
w += l; /* previous table always l bits */
/* compute minimum size table less than or equal to l bits */
z = (z = g - w) > (unsigned)l ? l : z; /* upper limit on table size */
if ((f = 1 << (j = k - w)) > a + 1) { /* try a k-w bit table */
f -= a + 1; /* too few codes for k-w bit table */
xp = c + k; /* deduct codes from patterns left */
while (++j < z) { /* try smaller tables up to z bits */
if ((f <<= 1) <= *++xp)
break; /* enough codes to use up j bits */
f -= *xp; /* else deduct codes from patterns */
}
}
z = 1 << j; /* table entries for j-bit table */
/* allocate and link in new table */
q = (huft *)malloc((z + 1)*sizeof(huft));
if (!q) {/* not enough memory */
if (h) huft_free(u); return (lzerror=ZNOMEM, ERROR);
}
#ifdef DEBUG
hufts += z + 1; /* track memory usage */
#endif
*t = q + 1; /* link to list for huft_free() */
*(t = &(q->v.t)) = (huft *)NULL;
u[h] = ++q; /* table starts after link */
/* connect to last table, if there is one */
if (h) {
x[h] = i; /* save pattern for backing up */
r.b = (uch)l; /* bits to dump before this table */
r.e = (uch)(16 + j); /* bits in this table */
r.v.t = q; /* pointer to this table */
j = i >> (w - l); /* (get around Turbo C bug) */
u[h-1][j] = r; /* connect to last table */
}
}
/* set up table entry in r */
r.b = (uch)(k - w);
if (p >= v + n) {
r.e = 99; /* out of values--invalid code */
} else if (*p < s) {
r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */
r.v.n = *p++; /* simple code is just the value */
} else {
r.e = (uch)e[*p - s]; /* non-simple--look up in lists */
r.v.n = d[*p++ - s];
}
/* fill code-like entries with r */
f = 1 << (k - w);
for (j = i >> w; j < z; j += f) q[j] = r;
/* backwards increment the k-bit code i */
for (j = 1 << (k - 1); i & j; j >>= 1) i ^= j;
i ^= j;
/* backup over finished tables */
while ((i & ((1 << w) - 1)) != x[h]) {
h--; /* don't need to update q */
w -= l;
}
}
}
/* Return true (1) if we were given an incomplete table */
return y != 0 && g != 1;
}
static void copyout()
{
register unsigned length;
if ((length = wp - outpos) != 0) {
updcrc(slide+outpos, length);
#ifdef NOMEMCPY
while (length--) *outbuf++ = (char)slide[outpos++];
#else
(void)memcpy(outbuf, slide+outpos, length);
outbuf += length;
outpos += length;
#endif
outsiz += length;
}
}
static ush getbits(n)
ush n; /* number of bits to get */
{
register ulg b; /* bit buffer */
register unsigned k; /* number of bits in bit buffer */
register unsigned j;
/* make local copies of globals */
b = bb; k = bk;
NEEDBITS(n);
j = (unsigned)b & mask_bits[n];
DUMPBITS(n);
/* restore the globals from the locals */
bk = k; bb = b;
return j;
}
static int decode(np, t, bn)
unsigned *np; /* decoded value */
huft *t; /* tree to decode */
int bn; /* bits number */
/* Returns number of extra bits (BAD on error). */
{
register unsigned e; /* table entry flag */
register ulg b; /* bit buffer */
register unsigned k; /* number of bits in bit buffer */
/* make local copies of globals */
b = bb; k = bk;
NEEDBITS((unsigned)bn)
t += ((unsigned)b & mask_bits[bn]);
while ((e = t->e) > 16) {
if (e == BAD) goto end;
DUMPBITS(t->b)
e -= 16;
NEEDBITS(e)
t = t->v.t + ((unsigned)b & mask_bits[e]);
}
DUMPBITS(t->b)
*np = t->v.n;
/* restore the globals from the locals */
bk = k; bb = b;
end:
return e;
}
static huft *tl = NULL; /* literal/length code table */
static huft *td = NULL; /* distance code table */
static int bl; /* lookup bits for tl */
static int bd; /* lookup bits for td */
static int inflate_codes(tl, td, bl, bd, length)
huft *tl, *td; /* literal/length and distance decoder tables */
int bl, bd; /* number of bits decoded by tl[] and td[] */
unsigned length;
/* inflate (decompress) the codes in a deflated (compressed) block.
Return an number of bytes decompressed or ERROR. */
{
register unsigned i;
register unsigned e; /* number of extra bits */
static unsigned n,d; /* length and index for copy */
for (i=0; i
if ((e = decode(&n, tl, bl)) == BAD)
return (lzerror=ZMOULD, ERROR);
if (e == LITERAL) {
slide[wp++] = (uch)n;
if (wp >= WSIZE) {
copyout(); outpos = wp = 0;
}
++i;
continue;
}
if (e == EOB) {
/* clear all unneccesary flags & exit */
zipstate &= AT_EOF|INITED; break;
}
/* Length code encountered, get length of block to copy */
n += getbits(e);
/* decode distance of block to copy */
if ((e = decode(&d, td, bd)) == BAD)
return (lzerror=ZMOULD, ERROR);
d = wp - (d + getbits(e));
}
zipstate &= ~ICFLAG;
/* do the copy */
do {
d &= WSIZE-1;
if ((e = WSIZE - max(d,wp)) > n) e = n;
if (i+e > length) {
zipstate |= ICFLAG; e = length-i;
}
i += e;
n -= e;
#ifndef NOMEMCPY
if (wp - d >= e) {/* (this test assumes unsigned comparison) */
memcpy(slide + wp, slide + d, e);
wp += e;
d += e;
} else /* do it slow to avoid memcpy() overlap */
#endif /* !NOMEMCPY */
do slide[wp++] = slide[d++]; while (--e);
if (wp >= WSIZE) {
copyout(); outpos = wp = 0;
}
} while (n && !(zipstate & ICFLAG));
}
copyout();
return i;
}
static int inflate_dynamic(length)
unsigned length;
/* decompress an inflated type 2 (dynamic Huffman codes) block. */
/* Returns number of bytes decompressed or ERROR. */
{
register i;
if (!(zipstate & IBEGIN)) {
unsigned j;
unsigned l; /* last length */
unsigned m; /* mask for bit lengths table */
unsigned n; /* number of lengths to get */
unsigned nb; /* number of bit length codes */
unsigned nl; /* number of literal/length codes */
unsigned nd; /* number of distance codes */
#ifdef PKZIP_BUG_WORKAROUND
unsigned ll[288+32]; /* literal/length and distance code lengths */
#else
unsigned ll[286+30]; /* literal/length and distance code lengths */
#endif
register ulg b; /* bit buffer */
register unsigned k; /* number of bits in bit buffer */
/* make local bit buffer */ b = bb; k = bk;
/* read in table lengths */
NEEDTINY(5)
nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */
DUMPTINY(5)
NEEDTINY(5)
nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */
DUMPTINY(5)
NEEDTINY(4)
nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */
DUMPTINY(4)
#ifdef PKZIP_BUG_WORKAROUND
if (nl > 288 || nd > 32)
#else
if (nl > 286 || nd > 30)
#endif
return (lzerror=ZMOULD, ERROR); /* bad lengths */
/* read in bit-length-code lengths */
for (j = 0; j < nb; j++) {
NEEDTINY(3)
ll[border[j]] = (unsigned)b & 7;
DUMPTINY(3)
}
for (; j < 19; j++) ll[border[j]] = 0;
/* build decoding table for trees--single level, 7 bit lookup */
bl = 7;
if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) {
if (i != ERROR) /* all save memory lack */ lzerror = ZMOULD;
if (i == TRUE) /* incomplete code set */ huft_free(&tl);
return ERROR;
}
/* read in literal and distance code lengths */
n = nl + nd;
m = mask_bits[bl];
i = l = 0;
while ((unsigned)i < n) {
NEEDBITS((unsigned)bl)
j = (td = tl + ((unsigned)b & m))->b;
DUMPBITS(j)
j = td->v.n;
if (j < 16) { /* length of code in bits (0..15) */
ll[i++] = l = j; /* save last length in l */
} else {
if (j == 16) {/* repeat last length 3 to 6 times */
NEEDTINY(2)
j = 3 + ((unsigned)b & 3);
DUMPTINY(2)
} else {
l = 0;
if (j == 17) {/* 3 to 10 zero length codes */
NEEDTINY(3)
j = 3 + ((unsigned)b & 7);
DUMPTINY(3)
} else {/* j == 18: 11 to 138 zero length codes */
NEEDTINY(7)
j = 11 + ((unsigned)b & 0x7f);
DUMPTINY(7)
}
}
if ((unsigned)i + j > n) return (lzerror=ZMOULD, ERROR);
while (j--) ll[i++] = l;
}
}
/* free decoding table for trees */
huft_free(&tl);
/* restore the global bit buffer */
bb = b;
bk = k;
/* build the decoding tables for literal/length and distance codes */
bl = lbits;
if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) {
if (i != ERROR) /* all save memory lack */ lzerror = ZMOULD;
if (i == TRUE) /* incomplete literal tree */ huft_free(&tl);
return ERROR;
}
bd = dbits;
if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) {
#ifndef PKZIP_BUG_WORKAROUND
if (i == TRUE) huft_free(&td); /* incomplete distance tree */
#else
if (i != TRUE)
#endif
{
huft_free(&tl);
if (i != ERROR) lzerror = ZMOULD;
return ERROR;
}
}
zipstate |= IBEGIN;
}
i = inflate_codes(tl, td, bl, bd, length);
if (i == ERROR || !(zipstate & IBEGIN)) {
huft_free(&tl); huft_free(&td);
}
return i;
}
static int inflate_fixed(length)
unsigned length;
/* decompress an inflated type 1 (fixed Huffman codes) block. We should
either replace this with a custom decoder, or at least precompute the
Huffman tables. */
/* Returns number of bytes decompressed or ERROR. */
{
register i;
if (!(zipstate & IBEGIN)) {
unsigned l[288]; /* length list for huft_build */
i = 0;
/* set up literal table; make a complete, but wrong code set */
do l[i] = 8; while (++i < 144);
do l[i] = 9; while (++i < 256);
do l[i] = 7; while (++i < 280);
do l[i] = 8; while (++i < 288);
bl = 7;
if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
if (i != ERROR) /* all save memory lack */ lzerror = ZERROR;
if (i == TRUE) /* incomplete code set */ huft_free(&tl);
return ERROR;
}
/* set up distance table */
for (i=0; i<30; i++) l[i] = 5; /* make an incomplete code set */
bd = 5;
if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) & ~1) {
if (i != ERROR) lzerror = ZERROR;
huft_free(&tl);
return ERROR;
}
}
i = inflate_codes(tl, td, bl, bd, length);
if (i == ERROR || !(zipstate & IBEGIN)) {
huft_free(&tl); huft_free(&td);
}
return i;
}
static int inflate_stored(length)
unsigned length;
/* "decompress" an inflated type 0 (stored) block. */
/* Returns number of bytes restored or ERROR. */
{
static unsigned n; /* number of bytes to copy */
register unsigned i;
if (!(zipstate & IBEGIN)) {
if (bk > 7) /* fail to align bit buffer */
return (lzerror=ZERROR, ERROR);
/* go to byte boundary */
bb = 0; /* bit buffer */
bk = 0; /* number of bits in bit buffer */
/* get the length and its complement */
n = nextbyte(); n |= nextbyte() << 8;
i = nextbyte(); i |= nextbyte() << 8;
if (n != (i ^ 0xffff)) /* data error */
return (lzerror=ZMOULD, ERROR);
}
/* read and output the "compressed" data */
for (i=0; i
/* End of block - clear method and other unneccesary flags */
zipstate &= AT_EOF|INITED;
break;
}
slide[wp++] = (uch)nextbyte();
if (wp >= WSIZE) {
copyout(); outpos = wp = 0;
}
}
copyout();
return i;
}
static int skip(n)
register int n;
{
while (n--) if (readbyte()==EOF) return EOF; return 0;
}
static ush getsh()
{
register ush i; i = readbyte(); return i | (readbyte() << 8);
}
static ulg getlg()
{
register ush i; i = getsh(); return i | ((ulg)getsh() << 16);
}
int unzalloc()
{
if (!slide) slide = (uch*)malloc(WSIZE); return !slide;
}
int unzopen(inp_port, ztype)
#ifdef LZFILE
FILE *inp_port;
#else
int (*inp_port)__ARGS__((void));
#endif
int ztype;
{
lzerror = 0;
if (unzalloc()) return (lzerror = ZNOMEM);
zip_inp_port = inp_port;
zipstate = 0;
ziptype = ztype;
outsiz = 0L;
/* Initialise CRC calculations */
crcbegin();
/* Initialise deflate */
wp = 0; bb = 0; bk = 0;
outpos = 0;
return 0;
}
int unzread(buffer, length)
char *buffer; unsigned length;
{
register i;
register unsigned j, k;
register ulg b;
if (!(zipstate & INITED)) {/* Read and decode header */
if (!slide || !zip_inp_port) return (lzerror = ZNOPEN, ERROR);
/* Check for zip type */
k = getsh();
if (ziptype == ZIP_PKW) {
if (k != GZIP_MAGIC) return ZMAGIC;
} else if (ziptype == ZIP_GNU) {
if (k!=PKW_01_MAGIC || getsh()!=PKW_23_MAGIC) return ZMAGIC;
} else {
if (k==PKW_01_MAGIC && getsh()==PKW_23_MAGIC) ziptype=ZIP_PKW;
else if (k == GZIP_MAGIC) ziptype=ZIP_GNU;
else return ZMAGIC;
}
/* Decode header */
if (ziptype == ZIP_GNU) {
zmethod = readbyte();
if ((zipflags = readbyte()) & (GF_ERROR|GF_CRYPT|GF_CONT))
return ZUNSUP;
/* Skip file time, extra flags and OS type */
if (skip(6)) return ZHDEOF;
#if 0
if (zipflags & GF_CONT) {
/* Skip the part number */ if (skip(2)) return ZHDEOF;
}
#endif
if (zipflags & GF_EXTRA) {/* Skip the extra field */
k = getsh(); if (skip(k)) return ZHDEOF;
}
if (zipflags & GF_FNAME) {/* Skip the file name */
do if ((i=readbyte()) == EOF) return ZHDEOF; while (i);
}
if (zipflags & GF_COMMENT) {/* Skip comment */
do if ((i=readbyte()) == EOF) return ZHDEOF; while (i);
}
} else {/* PKWARE */
if (skip(2)) return ZHDEOF; /* version to extract */
if ((zipflags = getsh()) & (PF_ERROR|PF_CRYPT)) return ZUNSUP;
zmethod = getsh();
if (skip(4)) return ZHDEOF; /* skip file time/date */
crc32val = getlg();
(void) getlg(); /* Ignore packed size */
srcsize = getlg();
k = getsh(); /* file name length */
j = getsh(); /* extra field length */
if (/* header length */30L + k + j > 65535L || skip(k+j))
return ZHDEOF;
}
/* Header decoded */
zipstate |= INITED;
}
if (zmethod == DEFLATED) {
outbuf = buffer;
j = 0;
do {
if (!(zipstate & METHOD)) {
if (zipstate & AT_EOF) break;
/* make local bit buffer */
b = bb; k = bk;
/* read in last block bit */
NEEDTINY(1)
if ((int)b & 1) zipstate |= AT_EOF;
DUMPTINY(1)
/* read in block type */
NEEDTINY(2)
if ((i = ((int)b & 3) + 1) & ~METHOD)
return (lzerror=ZMOULD, ERROR);
DUMPTINY(2)
zipstate |= i;
/* restore the global bit buffer */
bb = b; bk = k;
}
k = length - j;
switch (zipstate & METHOD) {
case 3 : i = inflate_dynamic(k); break;
case 2 : i = inflate_fixed (k); break;
case 1 : i = inflate_stored (k); break;
default: lzerror = ZMOULD; return ERROR;
}
if (i == ERROR) return i;
} while ((i || !(zipstate & AT_EOF)) && (j+=i) < length);
return j;
}
#if 0
else if (ziptype == Z_PKW && zmethod == STORED) ;
#endif
lzerror = ZUNSUP;
return ERROR;
}
void unzfree()
{
if (slide) { free(slide); slide = (uch*)0; }
if (tl) huft_free(&tl);
if (td) huft_free(&td);
}
int unzclose()
{
int k = ERROR; /* return value */
int i = 0; /* bytes rest */
lzerror = ZNOPEN;
if (!slide || !zip_inp_port || !(zipstate & INITED)) goto end;
if (!(zipstate & AT_EOF)) {
/* Indicate warning message */ k = (lzerror=ZNOEOF); goto end;
}
if (zipstate & METHOD) {
char b[16]; register j;
/* skip the rest of data */
while ((j=unzread(b, sizeof(b))) == sizeof(b)) i += j;
if (j == ERROR) goto end;
}
if (ziptype == ZIP_GNU) {
crc32val = getlg();
srcsize = getlg();
} else if (ziptype == ZIP_PKW) {
if (zipflags & PF_ATEOF) {
crc32val = getlg();
(void) getlg(); /* Ignore packed size */
srcsize = getlg();
}
} else {
lzerror = ZNOPEN; goto end;
}
if (outsiz != srcsize) {
lzerror = ZBADSZ; goto end;
}
if (crc32val != getcrc()) {
lzerror = BADCRC; goto end;
}
if (ziptype == ZIP_PKW) {
register ulg l;
/* Test for end of archive */
if ((l = getlg()) != PKW_CENTRAL) {
/* Indicate warning message */
k = (lzerror = l==PKW_MAGIC ? ZNOEOF : ZMOULD);
goto end;
}
}
k = 0; /* Indicate normal close */
if (i) k = (lzerror = ZNOEOF);
end:
unzfree();
zipstate = 0;
zip_inp_port = NULL;
return k;
}
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/