source: vendor/gzip/1.3.11/unlzw.c

Last change on this file was 3325, checked in by bird, 18 years ago

gzip 1.3.11
File size: 8.6 KB
RevLine 
[3325]1/* unlzw.c -- decompress files in LZW format.
2 * The code in this file is directly derived from the public domain 'compress'
3 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
4 * Ken Turkowski, Dave Mack and Peter Jannesen.
5 *
6 * This is a temporary version which will be rewritten in some future version
7 * to accommodate in-memory decompression.
8 */
9
10#ifdef RCSID
11static char rcsid[] = "$Id: unlzw.c,v 1.5 2006/12/11 18:54:39 eggert Exp $";
12#endif
13
14#include <config.h>
15#include "tailor.h"
16
17#ifdef HAVE_UNISTD_H
18# include <unistd.h>
19#endif
20#ifdef HAVE_FCNTL_H
21# include <fcntl.h>
22#endif
23
24#include "gzip.h"
25#include "lzw.h"
26
27typedef unsigned char char_type;
28typedef long code_int;
29typedef unsigned long count_int;
30typedef unsigned short count_short;
31typedef unsigned long cmp_code_int;
32
33#define MAXCODE(n) (1L << (n))
34
35#ifndef REGISTERS
36# define REGISTERS 2
37#endif
38#define REG1
39#define REG2
40#define REG3
41#define REG4
42#define REG5
43#define REG6
44#define REG7
45#define REG8
46#define REG9
47#define REG10
48#define REG11
49#define REG12
50#define REG13
51#define REG14
52#define REG15
53#define REG16
54#if REGISTERS >= 1
55# undef REG1
56# define REG1 register
57#endif
58#if REGISTERS >= 2
59# undef REG2
60# define REG2 register
61#endif
62#if REGISTERS >= 3
63# undef REG3
64# define REG3 register
65#endif
66#if REGISTERS >= 4
67# undef REG4
68# define REG4 register
69#endif
70#if REGISTERS >= 5
71# undef REG5
72# define REG5 register
73#endif
74#if REGISTERS >= 6
75# undef REG6
76# define REG6 register
77#endif
78#if REGISTERS >= 7
79# undef REG7
80# define REG7 register
81#endif
82#if REGISTERS >= 8
83# undef REG8
84# define REG8 register
85#endif
86#if REGISTERS >= 9
87# undef REG9
88# define REG9 register
89#endif
90#if REGISTERS >= 10
91# undef REG10
92# define REG10 register
93#endif
94#if REGISTERS >= 11
95# undef REG11
96# define REG11 register
97#endif
98#if REGISTERS >= 12
99# undef REG12
100# define REG12 register
101#endif
102#if REGISTERS >= 13
103# undef REG13
104# define REG13 register
105#endif
106#if REGISTERS >= 14
107# undef REG14
108# define REG14 register
109#endif
110#if REGISTERS >= 15
111# undef REG15
112# define REG15 register
113#endif
114#if REGISTERS >= 16
115# undef REG16
116# define REG16 register
117#endif
118
119#ifndef BYTEORDER
120# define BYTEORDER 0000
121#endif
122
123#ifndef NOALLIGN
124# define NOALLIGN 0
125#endif
126
127
128union bytes {
129 long word;
130 struct {
131#if BYTEORDER == 4321
132 char_type b1;
133 char_type b2;
134 char_type b3;
135 char_type b4;
136#else
137#if BYTEORDER == 1234
138 char_type b4;
139 char_type b3;
140 char_type b2;
141 char_type b1;
142#else
143# undef BYTEORDER
144 int dummy;
145#endif
146#endif
147 } bytes;
148};
149
150#if BYTEORDER == 4321 && NOALLIGN == 1
151# define input(b,o,c,n,m){ \
152 (c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x7))&(m); \
153 (o) += (n); \
154 }
155#else
156# define input(b,o,c,n,m){ \
157 REG1 char_type *p = &(b)[(o)>>3]; \
158 (c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
159 ((long)(p[2])<<16))>>((o)&0x7))&(m); \
160 (o) += (n); \
161 }
162#endif
163
164#ifndef MAXSEG_64K
165 /* DECLARE(ush, tab_prefix, (1<<BITS)); -- prefix code */
166# define tab_prefixof(i) tab_prefix[i]
167# define clear_tab_prefixof() memzero(tab_prefix, 256);
168#else
169 /* DECLARE(ush, tab_prefix0, (1<<(BITS-1)); -- prefix for even codes */
170 /* DECLARE(ush, tab_prefix1, (1<<(BITS-1)); -- prefix for odd codes */
171 ush *tab_prefix[2];
172# define tab_prefixof(i) tab_prefix[(i)&1][(i)>>1]
173# define clear_tab_prefixof() \
174 memzero(tab_prefix0, 128), \
175 memzero(tab_prefix1, 128);
176#endif
177#define de_stack ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
178#define tab_suffixof(i) tab_suffix[i]
179
180int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
181
182/* ============================================================================
183 * Decompress in to out. This routine adapts to the codes in the
184 * file building the "string" table on-the-fly; requiring no table to
185 * be stored in the compressed file.
186 * IN assertions: the buffer inbuf contains already the beginning of
187 * the compressed data, from offsets iptr to insize-1 included.
188 * The magic header has already been checked and skipped.
189 * bytes_in and bytes_out have been initialized.
190 */
191int unlzw(in, out)
192 int in, out; /* input and output file descriptors */
193{
194 REG2 char_type *stackp;
195 REG3 code_int code;
196 REG4 int finchar;
197 REG5 code_int oldcode;
198 REG6 code_int incode;
199 REG7 long inbits;
200 REG8 long posbits;
201 REG9 int outpos;
202/* REG10 int insize; (global) */
203 REG11 unsigned bitmask;
204 REG12 code_int free_ent;
205 REG13 code_int maxcode;
206 REG14 code_int maxmaxcode;
207 REG15 int n_bits;
208 REG16 int rsize;
209
210#ifdef MAXSEG_64K
211 tab_prefix[0] = tab_prefix0;
212 tab_prefix[1] = tab_prefix1;
213#endif
214 maxbits = get_byte();
215 block_mode = maxbits & BLOCK_MODE;
216 if ((maxbits & LZW_RESERVED) != 0) {
217 WARN((stderr, "\n%s: %s: warning, unknown flags 0x%x\n",
218 program_name, ifname, maxbits & LZW_RESERVED));
219 }
220 maxbits &= BIT_MASK;
221 maxmaxcode = MAXCODE(maxbits);
222
223 if (maxbits > BITS) {
224 fprintf(stderr,
225 "\n%s: %s: compressed with %d bits, can only handle %d bits\n",
226 program_name, ifname, maxbits, BITS);
227 exit_code = ERROR;
228 return ERROR;
229 }
230 rsize = insize;
231 maxcode = MAXCODE(n_bits = INIT_BITS)-1;
232 bitmask = (1<<n_bits)-1;
233 oldcode = -1;
234 finchar = 0;
235 outpos = 0;
236 posbits = inptr<<3;
237
238 free_ent = ((block_mode) ? FIRST : 256);
239
240 clear_tab_prefixof(); /* Initialize the first 256 entries in the table. */
241
242 for (code = 255 ; code >= 0 ; --code) {
243 tab_suffixof(code) = (char_type)code;
244 }
245 do {
246 REG1 int i;
247 int e;
248 int o;
249
250 resetbuf:
251 e = insize-(o = (posbits>>3));
252
253 for (i = 0 ; i < e ; ++i) {
254 inbuf[i] = inbuf[i+o];
255 }
256 insize = e;
257 posbits = 0;
258
259 if (insize < INBUF_EXTRA) {
260 rsize = read_buffer (in, (char *) inbuf + insize, INBUFSIZ);
261 if (rsize == -1) {
262 read_error();
263 }
264 insize += rsize;
265 bytes_in += (off_t)rsize;
266 }
267 inbits = ((rsize != 0) ? ((long)insize - insize%n_bits)<<3 :
268 ((long)insize<<3)-(n_bits-1));
269
270 while (inbits > posbits) {
271 if (free_ent > maxcode) {
272 posbits = ((posbits-1) +
273 ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
274 ++n_bits;
275 if (n_bits == maxbits) {
276 maxcode = maxmaxcode;
277 } else {
278 maxcode = MAXCODE(n_bits)-1;
279 }
280 bitmask = (1<<n_bits)-1;
281 goto resetbuf;
282 }
283 input(inbuf,posbits,code,n_bits,bitmask);
284 Tracev((stderr, "%d ", code));
285
286 if (oldcode == -1) {
287 if (256 <= code)
288 gzip_error ("corrupt input.");
289 outbuf[outpos++] = (char_type)(finchar = (int)(oldcode=code));
290 continue;
291 }
292 if (code == CLEAR && block_mode) {
293 clear_tab_prefixof();
294 free_ent = FIRST - 1;
295 posbits = ((posbits-1) +
296 ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
297 maxcode = MAXCODE(n_bits = INIT_BITS)-1;
298 bitmask = (1<<n_bits)-1;
299 goto resetbuf;
300 }
301 incode = code;
302 stackp = de_stack;
303
304 if (code >= free_ent) { /* Special case for KwKwK string. */
305 if (code > free_ent) {
306#ifdef DEBUG
307 char_type *p;
308
309 posbits -= n_bits;
310 p = &inbuf[posbits>>3];
311 fprintf(stderr,
312 "code:%ld free_ent:%ld n_bits:%d insize:%u\n",
313 code, free_ent, n_bits, insize);
314 fprintf(stderr,
315 "posbits:%ld inbuf:%02X %02X %02X %02X %02X\n",
316 posbits, p[-1],p[0],p[1],p[2],p[3]);
317#endif
318 if (!test && outpos > 0) {
319 write_buf(out, (char*)outbuf, outpos);
320 bytes_out += (off_t)outpos;
321 }
322 gzip_error (to_stdout
323 ? "corrupt input."
324 : "corrupt input. Use zcat to recover some data.");
325 }
326 *--stackp = (char_type)finchar;
327 code = oldcode;
328 }
329
330 while ((cmp_code_int)code >= (cmp_code_int)256) {
331 /* Generate output characters in reverse order */
332 *--stackp = tab_suffixof(code);
333 code = tab_prefixof(code);
334 }
335 *--stackp = (char_type)(finchar = tab_suffixof(code));
336
337 /* And put them out in forward order */
338 {
339 REG1 int i;
340
341 if (outpos+(i = (de_stack-stackp)) >= OUTBUFSIZ) {
342 do {
343 if (i > OUTBUFSIZ-outpos) i = OUTBUFSIZ-outpos;
344
345 if (i > 0) {
346 memcpy(outbuf+outpos, stackp, i);
347 outpos += i;
348 }
349 if (outpos >= OUTBUFSIZ) {
350 if (!test) {
351 write_buf(out, (char*)outbuf, outpos);
352 bytes_out += (off_t)outpos;
353 }
354 outpos = 0;
355 }
356 stackp+= i;
357 } while ((i = (de_stack-stackp)) > 0);
358 } else {
359 memcpy(outbuf+outpos, stackp, i);
360 outpos += i;
361 }
362 }
363
364 if ((code = free_ent) < maxmaxcode) { /* Generate the new entry. */
365
366 tab_prefixof(code) = (unsigned short)oldcode;
367 tab_suffixof(code) = (char_type)finchar;
368 free_ent = code+1;
369 }
370 oldcode = incode; /* Remember previous code. */
371 }
372 } while (rsize != 0);
373
374 if (!test && outpos > 0) {
375 write_buf(out, (char*)outbuf, outpos);
376 bytes_out += (off_t)outpos;
377 }
378 return OK;
379}
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