source: MondoRescue/trunk/mindi-busybox/archival/libunarchive/decompress_uncompress.c@ 904

Last change on this file since 904 was 904, checked in by Bruno Cornec, 18 years ago

merge -r890:902 $SVN_M/branches/stable
File size: 7.0 KB
Line 
1#include "libbb.h"
2
3/* uncompress for busybox -- (c) 2002 Robert Griebl
4 *
5 * based on the original compress42.c source
6 * (see disclaimer below)
7 */
8
9
10/* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
11 *
12 * Authors:
13 * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
14 * Jim McKie (decvax!mcvax!jim)
15 * Steve Davies (decvax!vax135!petsd!peora!srd)
16 * Ken Turkowski (decvax!decwrl!turtlevax!ken)
17 * James A. Woods (decvax!ihnp4!ames!jaw)
18 * Joe Orost (decvax!vax135!petsd!joe)
19 * Dave Mack (csu@alembic.acs.com)
20 * Peter Jannesen, Network Communication Systems
21 * (peter@ncs.nl)
22 *
23 * marc@suse.de : a small security fix for a buffer overflow
24 *
25 * [... History snipped ...]
26 *
27 */
28#include <stdio.h>
29#include <string.h>
30#include <unistd.h>
31
32/* Default input buffer size */
33#define IBUFSIZ 2048
34
35/* Default output buffer size */
36#define OBUFSIZ 2048
37
38/* Defines for third byte of header */
39#define MAGIC_1 (char_type)'\037' /* First byte of compressed file */
40#define MAGIC_2 (char_type)'\235' /* Second byte of compressed file */
41#define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
42 /* Masks 0x20 and 0x40 are free. */
43 /* I think 0x20 should mean that there is */
44 /* a fourth header byte (for expansion). */
45#define BLOCK_MODE 0x80 /* Block compresssion if table is full and */
46 /* compression rate is dropping flush tables */
47 /* the next two codes should not be changed lightly, as they must not */
48 /* lie within the contiguous general code space. */
49#define FIRST 257 /* first free entry */
50#define CLEAR 256 /* table clear output code */
51
52#define INIT_BITS 9 /* initial number of bits/code */
53
54
55/* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
56#define FAST
57
58#define HBITS 17 /* 50% occupancy */
59#define HSIZE (1<<HBITS)
60#define HMASK (HSIZE-1)
61#define HPRIME 9941
62#define BITS 16
63#undef MAXSEG_64K
64#define MAXCODE(n) (1L << (n))
65
66/* Block compress mode -C compatible with 2.0 */
67static int block_mode = BLOCK_MODE;
68
69/* user settable max # bits/code */
70static int maxbits = BITS;
71
72#define htabof(i) htab[i]
73#define codetabof(i) codetab[i]
74#define tab_prefixof(i) codetabof(i)
75#define tab_suffixof(i) ((unsigned char *)(htab))[i]
76#define de_stack ((unsigned char *)&(htab[HSIZE-1]))
77#define clear_htab() memset(htab, -1, HSIZE)
78#define clear_tab_prefixof() memset(codetab, 0, 256);
79
80
81/*
82 * Decompress stdin to stdout. This routine adapts to the codes in the
83 * file building the "string" table on-the-fly; requiring no table to
84 * be stored in the compressed file. The tables used herein are shared
85 * with those of the compress() routine. See the definitions above.
86 */
87
88int uncompress(int fd_in, int fd_out)
89{
90 unsigned char *stackp;
91 long int code;
92 int finchar;
93 long int oldcode;
94 long int incode;
95 int inbits;
96 int posbits;
97 int outpos;
98 int insize;
99 int bitmask;
100 long int free_ent;
101 long int maxcode;
102 long int maxmaxcode;
103 int n_bits;
104 int rsize = 0;
105 RESERVE_CONFIG_UBUFFER(inbuf, IBUFSIZ + 64);
106 RESERVE_CONFIG_UBUFFER(outbuf, OBUFSIZ + 2048);
107 unsigned char htab[HSIZE];
108 unsigned short codetab[HSIZE];
109 memset(inbuf, 0, IBUFSIZ + 64);
110 memset(outbuf, 0, OBUFSIZ + 2048);
111
112 insize = 0;
113
114 inbuf[0] = bb_xread_char(fd_in);
115
116 maxbits = inbuf[0] & BIT_MASK;
117 block_mode = inbuf[0] & BLOCK_MODE;
118 maxmaxcode = MAXCODE(maxbits);
119
120 if (maxbits > BITS) {
121 bb_error_msg("compressed with %d bits, can only handle %d bits", maxbits,
122 BITS);
123 return -1;
124 }
125
126 maxcode = MAXCODE(n_bits = INIT_BITS) - 1;
127 bitmask = (1 << n_bits) - 1;
128 oldcode = -1;
129 finchar = 0;
130 outpos = 0;
131 posbits = 0 << 3;
132
133 free_ent = ((block_mode) ? FIRST : 256);
134
135 /* As above, initialize the first 256 entries in the table. */
136 clear_tab_prefixof();
137
138 for (code = 255; code >= 0; --code) {
139 tab_suffixof(code) = (unsigned char) code;
140 }
141
142 do {
143 resetbuf:;
144 {
145 int i;
146 int e;
147 int o;
148
149 e = insize - (o = (posbits >> 3));
150
151 for (i = 0; i < e; ++i)
152 inbuf[i] = inbuf[i + o];
153
154 insize = e;
155 posbits = 0;
156 }
157
158 if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
159 rsize = safe_read(fd_in, inbuf + insize, IBUFSIZ);
160 insize += rsize;
161 }
162
163 inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
164 (insize << 3) - (n_bits - 1));
165
166 while (inbits > posbits) {
167 if (free_ent > maxcode) {
168 posbits =
169 ((posbits - 1) +
170 ((n_bits << 3) -
171 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
172 ++n_bits;
173 if (n_bits == maxbits) {
174 maxcode = maxmaxcode;
175 } else {
176 maxcode = MAXCODE(n_bits) - 1;
177 }
178 bitmask = (1 << n_bits) - 1;
179 goto resetbuf;
180 }
181 {
182 unsigned char *p = &inbuf[posbits >> 3];
183
184 code =
185 ((((long) (p[0])) | ((long) (p[1]) << 8) |
186 ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
187 }
188 posbits += n_bits;
189
190
191 if (oldcode == -1) {
192 outbuf[outpos++] = (unsigned char) (finchar =
193 (int) (oldcode = code));
194 continue;
195 }
196
197 if (code == CLEAR && block_mode) {
198 clear_tab_prefixof();
199 free_ent = FIRST - 1;
200 posbits =
201 ((posbits - 1) +
202 ((n_bits << 3) -
203 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
204 maxcode = MAXCODE(n_bits = INIT_BITS) - 1;
205 bitmask = (1 << n_bits) - 1;
206 goto resetbuf;
207 }
208
209 incode = code;
210 stackp = de_stack;
211
212 /* Special case for KwKwK string. */
213 if (code >= free_ent) {
214 if (code > free_ent) {
215 unsigned char *p;
216
217 posbits -= n_bits;
218 p = &inbuf[posbits >> 3];
219
220 bb_error_msg
221 ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
222 insize, posbits, p[-1], p[0], p[1], p[2], p[3],
223 (posbits & 07));
224 bb_error_msg("uncompress: corrupt input");
225 return -1;
226 }
227
228 *--stackp = (unsigned char) finchar;
229 code = oldcode;
230 }
231
232 /* Generate output characters in reverse order */
233 while ((long int) code >= (long int) 256) {
234 *--stackp = tab_suffixof(code);
235 code = tab_prefixof(code);
236 }
237
238 *--stackp = (unsigned char) (finchar = tab_suffixof(code));
239
240 /* And put them out in forward order */
241 {
242 int i;
243
244 if (outpos + (i = (de_stack - stackp)) >= OBUFSIZ) {
245 do {
246 if (i > OBUFSIZ - outpos) {
247 i = OBUFSIZ - outpos;
248 }
249
250 if (i > 0) {
251 memcpy(outbuf + outpos, stackp, i);
252 outpos += i;
253 }
254
255 if (outpos >= OBUFSIZ) {
256 write(fd_out, outbuf, outpos);
257 outpos = 0;
258 }
259 stackp += i;
260 } while ((i = (de_stack - stackp)) > 0);
261 } else {
262 memcpy(outbuf + outpos, stackp, i);
263 outpos += i;
264 }
265 }
266
267 /* Generate the new entry. */
268 if ((code = free_ent) < maxmaxcode) {
269 tab_prefixof(code) = (unsigned short) oldcode;
270 tab_suffixof(code) = (unsigned char) finchar;
271 free_ent = code + 1;
272 }
273
274 /* Remember previous code. */
275 oldcode = incode;
276 }
277
278 } while (rsize > 0);
279
280 if (outpos > 0) {
281 write(fd_out, outbuf, outpos);
282 }
283
284 RELEASE_CONFIG_BUFFER(inbuf);
285 RELEASE_CONFIG_BUFFER(outbuf);
286 return 0;
287}
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