1 /* $NetBSD: zuncompress.c,v 1.11 2011/08/16 13:55:02 joerg Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (c) 1985, 1986, 1992, 1993
7 * The Regents of the University of California. All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * Diomidis Spinellis and James A. Woods, derived from original
11 * work by Spencer Thomas and Joseph Orost.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * from: NetBSD: zopen.c,v 1.8 2003/08/07 11:13:29 agc Exp
38 */
39
40 /* This file is #included by gzip.c */
41
42 static int zread(void *, char *, int);
43
44 #define tab_prefixof(i) (zs->zs_codetab[i])
45 #define tab_suffixof(i) ((char_type *)(zs->zs_htab))[i]
46 #define de_stack ((char_type *)&tab_suffixof(1 << BITS))
47
48 #define BITS 16 /* Default bits. */
49 #define HSIZE 69001 /* 95% occupancy */ /* XXX may not need HSIZE */
50 #define BIT_MASK 0x1f /* Defines for third byte of header. */
51 #define BLOCK_MASK 0x80
52 #define CHECK_GAP 10000 /* Ratio check interval. */
53 #define BUFSIZE (64 * 1024)
54
55 /*
56 * Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
57 * a fourth header byte (for expansion).
58 */
59 #define INIT_BITS 9 /* Initial number of bits/code. */
60
61 /*
62 * the next two codes should not be changed lightly, as they must not
63 * lie within the contiguous general code space.
64 */
65 #define FIRST 257 /* First free entry. */
66 #define CLEAR 256 /* Table clear output code. */
67
68
69 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
70
71 typedef long code_int;
72 typedef long count_int;
73 typedef u_char char_type;
74
75 static char_type magic_header[] =
76 {'\037', '\235'}; /* 1F 9D */
77
78 static char_type rmask[9] =
79 {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
80
81 static off_t total_compressed_bytes;
82 static size_t compressed_prelen;
83 static char *compressed_pre;
84
85 struct s_zstate {
86 FILE *zs_fp; /* File stream for I/O */
87 char zs_mode; /* r or w */
88 enum {
89 S_START, S_MIDDLE, S_EOF
90 } zs_state; /* State of computation */
91 int zs_n_bits; /* Number of bits/code. */
92 int zs_maxbits; /* User settable max # bits/code. */
93 code_int zs_maxcode; /* Maximum code, given n_bits. */
94 code_int zs_maxmaxcode; /* Should NEVER generate this code. */
95 count_int zs_htab [HSIZE];
96 u_short zs_codetab [HSIZE];
97 code_int zs_hsize; /* For dynamic table sizing. */
98 code_int zs_free_ent; /* First unused entry. */
99 /*
100 * Block compression parameters -- after all codes are used up,
101 * and compression rate changes, start over.
102 */
103 int zs_block_compress;
104 int zs_clear_flg;
105 long zs_ratio;
106 count_int zs_checkpoint;
107 int zs_offset;
108 long zs_in_count; /* Length of input. */
109 long zs_bytes_out; /* Length of compressed output. */
110 long zs_out_count; /* # of codes output (for debugging). */
111 char_type zs_buf[BITS];
112 union {
113 struct {
114 long zs_fcode;
115 code_int zs_ent;
116 code_int zs_hsize_reg;
117 int zs_hshift;
118 } w; /* Write parameters */
119 struct {
120 char_type *zs_stackp;
121 int zs_finchar;
122 code_int zs_code, zs_oldcode, zs_incode;
123 int zs_roffset, zs_size;
124 char_type zs_gbuf[BITS];
125 } r; /* Read parameters */
126 } u;
127 };
128
129 static code_int getcode(struct s_zstate *zs);
130
131 static off_t
zuncompress(FILE * in,FILE * out,char * pre,size_t prelen,off_t * compressed_bytes)132 zuncompress(FILE *in, FILE *out, char *pre, size_t prelen,
133 off_t *compressed_bytes)
134 {
135 off_t bin, bout = 0;
136 char *buf;
137
138 buf = malloc(BUFSIZE);
139 if (buf == NULL)
140 return -1;
141
142 /* XXX */
143 compressed_prelen = prelen;
144 if (prelen != 0)
145 compressed_pre = pre;
146 else
147 compressed_pre = NULL;
148
149 while ((bin = fread(buf, 1, BUFSIZE, in)) != 0) {
150 if (tflag == 0 && (off_t)fwrite(buf, 1, bin, out) != bin) {
151 free(buf);
152 return -1;
153 }
154 bout += bin;
155 }
156
157 if (compressed_bytes)
158 *compressed_bytes = total_compressed_bytes;
159
160 free(buf);
161 return bout;
162 }
163
164 static int
zclose(void * zs)165 zclose(void *zs)
166 {
167 free(zs);
168 /* We leave the caller to close the fd passed to zdopen() */
169 return 0;
170 }
171
172 FILE *
zdopen(int fd)173 zdopen(int fd)
174 {
175 struct s_zstate *zs;
176
177 if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL)
178 return (NULL);
179
180 zs->zs_state = S_START;
181
182 /* XXX we can get rid of some of these */
183 zs->zs_hsize = HSIZE; /* For dynamic table sizing. */
184 zs->zs_free_ent = 0; /* First unused entry. */
185 zs->zs_block_compress = BLOCK_MASK;
186 zs->zs_clear_flg = 0; /* XXX we calloc()'d this structure why = 0? */
187 zs->zs_ratio = 0;
188 zs->zs_checkpoint = CHECK_GAP;
189 zs->zs_in_count = 1; /* Length of input. */
190 zs->zs_out_count = 0; /* # of codes output (for debugging). */
191 zs->u.r.zs_roffset = 0;
192 zs->u.r.zs_size = 0;
193
194 /*
195 * Layering compress on top of stdio in order to provide buffering,
196 * and ensure that reads and write work with the data specified.
197 */
198 if ((zs->zs_fp = fdopen(fd, "r")) == NULL) {
199 free(zs);
200 return NULL;
201 }
202
203 return funopen(zs, zread, NULL, NULL, zclose);
204 }
205
206 /*
207 * Decompress read. This routine adapts to the codes in the file building
208 * the "string" table on-the-fly; requiring no table to be stored in the
209 * compressed file. The tables used herein are shared with those of the
210 * compress() routine. See the definitions above.
211 */
212 static int
zread(void * cookie,char * rbp,int num)213 zread(void *cookie, char *rbp, int num)
214 {
215 u_int count, i;
216 struct s_zstate *zs;
217 u_char *bp, header[3];
218
219 if (num == 0)
220 return (0);
221
222 zs = cookie;
223 count = num;
224 bp = (u_char *)rbp;
225 switch (zs->zs_state) {
226 case S_START:
227 zs->zs_state = S_MIDDLE;
228 break;
229 case S_MIDDLE:
230 goto middle;
231 case S_EOF:
232 goto eof;
233 }
234
235 /* Check the magic number */
236 for (i = 0; i < 3 && compressed_prelen; i++, compressed_prelen--)
237 header[i] = *compressed_pre++;
238
239 if (fread(header + i, 1, sizeof(header) - i, zs->zs_fp) !=
240 sizeof(header) - i ||
241 memcmp(header, magic_header, sizeof(magic_header)) != 0) {
242 errno = EFTYPE;
243 return (-1);
244 }
245 total_compressed_bytes = 0;
246 zs->zs_maxbits = header[2]; /* Set -b from file. */
247 zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK;
248 zs->zs_maxbits &= BIT_MASK;
249 zs->zs_maxmaxcode = 1L << zs->zs_maxbits;
250 if (zs->zs_maxbits > BITS || zs->zs_maxbits < 12) {
251 errno = EFTYPE;
252 return (-1);
253 }
254 /* As above, initialize the first 256 entries in the table. */
255 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS);
256 for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0; zs->u.r.zs_code--) {
257 tab_prefixof(zs->u.r.zs_code) = 0;
258 tab_suffixof(zs->u.r.zs_code) = (char_type) zs->u.r.zs_code;
259 }
260 zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256;
261
262 zs->u.r.zs_oldcode = -1;
263 zs->u.r.zs_stackp = de_stack;
264
265 while ((zs->u.r.zs_code = getcode(zs)) > -1) {
266
267 if ((zs->u.r.zs_code == CLEAR) && zs->zs_block_compress) {
268 for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0;
269 zs->u.r.zs_code--)
270 tab_prefixof(zs->u.r.zs_code) = 0;
271 zs->zs_clear_flg = 1;
272 zs->zs_free_ent = FIRST;
273 zs->u.r.zs_oldcode = -1;
274 continue;
275 }
276 zs->u.r.zs_incode = zs->u.r.zs_code;
277
278 /* Special case for KwKwK string. */
279 if (zs->u.r.zs_code >= zs->zs_free_ent) {
280 if (zs->u.r.zs_code > zs->zs_free_ent ||
281 zs->u.r.zs_oldcode == -1) {
282 /* Bad stream. */
283 errno = EFTYPE;
284 return (-1);
285 }
286 *zs->u.r.zs_stackp++ = zs->u.r.zs_finchar;
287 zs->u.r.zs_code = zs->u.r.zs_oldcode;
288 }
289 /*
290 * The above condition ensures that code < free_ent.
291 * The construction of tab_prefixof in turn guarantees that
292 * each iteration decreases code and therefore stack usage is
293 * bound by 1 << BITS - 256.
294 */
295
296 /* Generate output characters in reverse order. */
297 while (zs->u.r.zs_code >= 256) {
298 *zs->u.r.zs_stackp++ = tab_suffixof(zs->u.r.zs_code);
299 zs->u.r.zs_code = tab_prefixof(zs->u.r.zs_code);
300 }
301 *zs->u.r.zs_stackp++ = zs->u.r.zs_finchar = tab_suffixof(zs->u.r.zs_code);
302
303 /* And put them out in forward order. */
304 middle: do {
305 if (count-- == 0)
306 return (num);
307 *bp++ = *--zs->u.r.zs_stackp;
308 } while (zs->u.r.zs_stackp > de_stack);
309
310 /* Generate the new entry. */
311 if ((zs->u.r.zs_code = zs->zs_free_ent) < zs->zs_maxmaxcode &&
312 zs->u.r.zs_oldcode != -1) {
313 tab_prefixof(zs->u.r.zs_code) = (u_short) zs->u.r.zs_oldcode;
314 tab_suffixof(zs->u.r.zs_code) = zs->u.r.zs_finchar;
315 zs->zs_free_ent = zs->u.r.zs_code + 1;
316 }
317
318 /* Remember previous code. */
319 zs->u.r.zs_oldcode = zs->u.r.zs_incode;
320 }
321 zs->zs_state = S_EOF;
322 eof: return (num - count);
323 }
324
325 /*-
326 * Read one code from the standard input. If EOF, return -1.
327 * Inputs:
328 * stdin
329 * Outputs:
330 * code or -1 is returned.
331 */
332 static code_int
getcode(struct s_zstate * zs)333 getcode(struct s_zstate *zs)
334 {
335 code_int gcode;
336 int r_off, bits, i;
337 char_type *bp;
338
339 bp = zs->u.r.zs_gbuf;
340 if (zs->zs_clear_flg > 0 || zs->u.r.zs_roffset >= zs->u.r.zs_size ||
341 zs->zs_free_ent > zs->zs_maxcode) {
342 /*
343 * If the next entry will be too big for the current gcode
344 * size, then we must increase the size. This implies reading
345 * a new buffer full, too.
346 */
347 if (zs->zs_free_ent > zs->zs_maxcode) {
348 zs->zs_n_bits++;
349 if (zs->zs_n_bits == zs->zs_maxbits) /* Won't get any bigger now. */
350 zs->zs_maxcode = zs->zs_maxmaxcode;
351 else
352 zs->zs_maxcode = MAXCODE(zs->zs_n_bits);
353 }
354 if (zs->zs_clear_flg > 0) {
355 zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS);
356 zs->zs_clear_flg = 0;
357 }
358 /* XXX */
359 for (i = 0; i < zs->zs_n_bits && compressed_prelen; i++, compressed_prelen--)
360 zs->u.r.zs_gbuf[i] = *compressed_pre++;
361 zs->u.r.zs_size = fread(zs->u.r.zs_gbuf + i, 1, zs->zs_n_bits - i, zs->zs_fp);
362 zs->u.r.zs_size += i;
363 if (zs->u.r.zs_size <= 0) /* End of file. */
364 return (-1);
365 zs->u.r.zs_roffset = 0;
366
367 total_compressed_bytes += zs->u.r.zs_size;
368
369 /* Round size down to integral number of codes. */
370 zs->u.r.zs_size = (zs->u.r.zs_size << 3) - (zs->zs_n_bits - 1);
371 }
372 r_off = zs->u.r.zs_roffset;
373 bits = zs->zs_n_bits;
374
375 /* Get to the first byte. */
376 bp += (r_off >> 3);
377 r_off &= 7;
378
379 /* Get first part (low order bits). */
380 gcode = (*bp++ >> r_off);
381 bits -= (8 - r_off);
382 r_off = 8 - r_off; /* Now, roffset into gcode word. */
383
384 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
385 if (bits >= 8) {
386 gcode |= *bp++ << r_off;
387 r_off += 8;
388 bits -= 8;
389 }
390
391 /* High order bits. */
392 gcode |= (*bp & rmask[bits]) << r_off;
393 zs->u.r.zs_roffset += zs->zs_n_bits;
394
395 return (gcode);
396 }
397
398