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 */
|
---|
67 | static int block_mode = BLOCK_MODE;
|
---|
68 |
|
---|
69 | /* user settable max # bits/code */
|
---|
70 | static 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 |
|
---|
88 | int 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 | }
|
---|