source: MondoRescue/branches/3.2/mindi-busybox/archival/libunarchive/decompress_uncompress.c

Last change on this file was 1765, checked in by Bruno Cornec, 16 years ago

Update to busybox 1.7.2
File size: 7.7 KB
Line 
1/* vi: set sw=4 ts=4: */
2#include "libbb.h"
3
4/* uncompress for busybox -- (c) 2002 Robert Griebl
5 *
6 * based on the original compress42.c source
7 * (see disclaimer below)
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
29/* Default input buffer size */
30#define IBUFSIZ 2048
31
32/* Default output buffer size */
33#define OBUFSIZ 2048
34
35/* Defines for third byte of header */
36#define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
37 /* Masks 0x20 and 0x40 are free. */
38 /* I think 0x20 should mean that there is */
39 /* a fourth header byte (for expansion). */
40#define BLOCK_MODE 0x80 /* Block compression if table is full and */
41 /* compression rate is dropping flush tables */
42 /* the next two codes should not be changed lightly, as they must not */
43 /* lie within the contiguous general code space. */
44#define FIRST 257 /* first free entry */
45#define CLEAR 256 /* table clear output code */
46
47#define INIT_BITS 9 /* initial number of bits/code */
48
49
50/* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
51#define HBITS 17 /* 50% occupancy */
52#define HSIZE (1<<HBITS)
53#define HMASK (HSIZE-1) /* unused */
54#define HPRIME 9941 /* unused */
55#define BITS 16
56#define BITS_STR "16"
57#undef MAXSEG_64K /* unused */
58#define MAXCODE(n) (1L << (n))
59
60#define htabof(i) htab[i]
61#define codetabof(i) codetab[i]
62#define tab_prefixof(i) codetabof(i)
63#define tab_suffixof(i) ((unsigned char *)(htab))[i]
64#define de_stack ((unsigned char *)&(htab[HSIZE-1]))
65#define clear_tab_prefixof() memset(codetab, 0, 256)
66
67/*
68 * Decompress stdin to stdout. This routine adapts to the codes in the
69 * file building the "string" table on-the-fly; requiring no table to
70 * be stored in the compressed file.
71 */
72
73USE_DESKTOP(long long) int
74uncompress(int fd_in, int fd_out)
75{
76 USE_DESKTOP(long long total_written = 0;)
77 USE_DESKTOP(long long) int retval = -1;
78 unsigned char *stackp;
79 long code;
80 int finchar;
81 long oldcode;
82 long incode;
83 int inbits;
84 int posbits;
85 int outpos;
86 int insize;
87 int bitmask;
88 long free_ent;
89 long maxcode;
90 long maxmaxcode;
91 int n_bits;
92 int rsize = 0;
93 unsigned char *inbuf; /* were eating insane amounts of stack - */
94 unsigned char *outbuf; /* bad for some embedded targets */
95 unsigned char *htab;
96 unsigned short *codetab;
97
98 /* Hmm, these were statics - why?! */
99 /* user settable max # bits/code */
100 int maxbits; /* = BITS; */
101 /* block compress mode -C compatible with 2.0 */
102 int block_mode; /* = BLOCK_MODE; */
103
104 inbuf = xzalloc(IBUFSIZ + 64);
105 outbuf = xzalloc(OBUFSIZ + 2048);
106 htab = xzalloc(HSIZE); /* wsn't zeroed out before, maybe can xmalloc? */
107 codetab = xzalloc(HSIZE * sizeof(codetab[0]));
108
109 insize = 0;
110
111 /* xread isn't good here, we have to return - caller may want
112 * to do some cleanup (e.g. delete incomplete unpacked file etc) */
113 if (full_read(fd_in, inbuf, 1) != 1) {
114 bb_error_msg("short read");
115 goto err;
116 }
117
118 maxbits = inbuf[0] & BIT_MASK;
119 block_mode = inbuf[0] & BLOCK_MODE;
120 maxmaxcode = MAXCODE(maxbits);
121
122 if (maxbits > BITS) {
123 bb_error_msg("compressed with %d bits, can only handle "
124 BITS_STR" bits", maxbits);
125 goto err;
126 }
127
128 n_bits = INIT_BITS;
129 maxcode = MAXCODE(INIT_BITS) - 1;
130 bitmask = (1 << INIT_BITS) - 1;
131 oldcode = -1;
132 finchar = 0;
133 outpos = 0;
134 posbits = 0 << 3;
135
136 free_ent = ((block_mode) ? FIRST : 256);
137
138 /* As above, initialize the first 256 entries in the table. */
139 /*clear_tab_prefixof(); - done by xzalloc */
140
141 for (code = 255; code >= 0; --code) {
142 tab_suffixof(code) = (unsigned char) code;
143 }
144
145 do {
146 resetbuf:
147 {
148 int i;
149 int e;
150 int o;
151
152 o = posbits >> 3;
153 e = insize - o;
154
155 for (i = 0; i < e; ++i)
156 inbuf[i] = inbuf[i + o];
157
158 insize = e;
159 posbits = 0;
160 }
161
162 if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
163 rsize = safe_read(fd_in, inbuf + insize, IBUFSIZ);
164//error check??
165 insize += rsize;
166 }
167
168 inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
169 (insize << 3) - (n_bits - 1));
170
171 while (inbits > posbits) {
172 if (free_ent > maxcode) {
173 posbits =
174 ((posbits - 1) +
175 ((n_bits << 3) -
176 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
177 ++n_bits;
178 if (n_bits == maxbits) {
179 maxcode = maxmaxcode;
180 } else {
181 maxcode = MAXCODE(n_bits) - 1;
182 }
183 bitmask = (1 << n_bits) - 1;
184 goto resetbuf;
185 }
186 {
187 unsigned char *p = &inbuf[posbits >> 3];
188
189 code = ((((long) (p[0])) | ((long) (p[1]) << 8) |
190 ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
191 }
192 posbits += n_bits;
193
194
195 if (oldcode == -1) {
196 oldcode = code;
197 finchar = (int) oldcode;
198 outbuf[outpos++] = (unsigned char) finchar;
199 continue;
200 }
201
202 if (code == CLEAR && block_mode) {
203 clear_tab_prefixof();
204 free_ent = FIRST - 1;
205 posbits =
206 ((posbits - 1) +
207 ((n_bits << 3) -
208 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
209 n_bits = INIT_BITS;
210 maxcode = MAXCODE(INIT_BITS) - 1;
211 bitmask = (1 << INIT_BITS) - 1;
212 goto resetbuf;
213 }
214
215 incode = code;
216 stackp = de_stack;
217
218 /* Special case for KwKwK string. */
219 if (code >= free_ent) {
220 if (code > free_ent) {
221 unsigned char *p;
222
223 posbits -= n_bits;
224 p = &inbuf[posbits >> 3];
225
226 bb_error_msg
227 ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
228 insize, posbits, p[-1], p[0], p[1], p[2], p[3],
229 (posbits & 07));
230 bb_error_msg("uncompress: corrupt input");
231 goto err;
232 }
233
234 *--stackp = (unsigned char) finchar;
235 code = oldcode;
236 }
237
238 /* Generate output characters in reverse order */
239 while ((long) code >= (long) 256) {
240 *--stackp = tab_suffixof(code);
241 code = tab_prefixof(code);
242 }
243
244 finchar = tab_suffixof(code);
245 *--stackp = (unsigned char) finchar;
246
247 /* And put them out in forward order */
248 {
249 int i;
250
251 i = de_stack - stackp;
252 if (outpos + i >= OBUFSIZ) {
253 do {
254 if (i > OBUFSIZ - outpos) {
255 i = OBUFSIZ - outpos;
256 }
257
258 if (i > 0) {
259 memcpy(outbuf + outpos, stackp, i);
260 outpos += i;
261 }
262
263 if (outpos >= OBUFSIZ) {
264 full_write(fd_out, outbuf, outpos);
265//error check??
266 USE_DESKTOP(total_written += outpos;)
267 outpos = 0;
268 }
269 stackp += i;
270 i = de_stack - stackp;
271 } while (i > 0);
272 } else {
273 memcpy(outbuf + outpos, stackp, i);
274 outpos += i;
275 }
276 }
277
278 /* Generate the new entry. */
279 code = free_ent;
280 if (code < maxmaxcode) {
281 tab_prefixof(code) = (unsigned short) oldcode;
282 tab_suffixof(code) = (unsigned char) finchar;
283 free_ent = code + 1;
284 }
285
286 /* Remember previous code. */
287 oldcode = incode;
288 }
289
290 } while (rsize > 0);
291
292 if (outpos > 0) {
293 full_write(fd_out, outbuf, outpos);
294//error check??
295 USE_DESKTOP(total_written += outpos;)
296 }
297
298 retval = USE_DESKTOP(total_written) + 0;
299 err:
300 free(inbuf);
301 free(outbuf);
302 free(htab);
303 free(codetab);
304 return retval;
305}
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