1 /* vi: set sw=4 ts=4: */
2 /* uncompress for busybox -- (c) 2002 Robert Griebl
4 * based on the original compress42.c source
5 * (see disclaimer below)
8 /* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
11 * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
12 * Jim McKie (decvax!mcvax!jim)
13 * Steve Davies (decvax!vax135!petsd!peora!srd)
14 * Ken Turkowski (decvax!decwrl!turtlevax!ken)
15 * James A. Woods (decvax!ihnp4!ames!jaw)
16 * Joe Orost (decvax!vax135!petsd!joe)
17 * Dave Mack (csu@alembic.acs.com)
18 * Peter Jannesen, Network Communication Systems
21 * marc@suse.de : a small security fix for a buffer overflow
23 * [... History snipped ...]
28 #include "bb_archive.h"
31 /* Default input buffer size */
34 /* Default output buffer size */
37 /* Defines for third byte of header */
38 #define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
39 /* Masks 0x20 and 0x40 are free. */
40 /* I think 0x20 should mean that there is */
41 /* a fourth header byte (for expansion). */
42 #define BLOCK_MODE 0x80 /* Block compression if table is full and */
43 /* compression rate is dropping flush tables */
44 /* the next two codes should not be changed lightly, as they must not */
45 /* lie within the contiguous general code space. */
46 #define FIRST 257 /* first free entry */
47 #define CLEAR 256 /* table clear output code */
49 #define INIT_BITS 9 /* initial number of bits/code */
52 /* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
53 #define HBITS 17 /* 50% occupancy */
54 #define HSIZE (1<<HBITS)
55 #define HMASK (HSIZE-1) /* unused */
56 #define HPRIME 9941 /* unused */
59 #undef MAXSEG_64K /* unused */
60 #define MAXCODE(n) (1L << (n))
62 #define htabof(i) htab[i]
63 #define codetabof(i) codetab[i]
64 #define tab_prefixof(i) codetabof(i)
65 #define tab_suffixof(i) ((unsigned char *)(htab))[i]
66 #define de_stack ((unsigned char *)&(htab[HSIZE-1]))
67 #define clear_tab_prefixof() memset(codetab, 0, 256)
70 * Decompress stdin to stdout. This routine adapts to the codes in the
71 * file building the "string" table on-the-fly; requiring no table to
72 * be stored in the compressed file.
75 IF_DESKTOP(long long) int FAST_FUNC
76 unpack_Z_stream(transformer_state_t *xstate)
78 IF_DESKTOP(long long total_written = 0;)
79 IF_DESKTOP(long long) int retval = -1;
80 unsigned char *stackp;
94 unsigned char *inbuf; /* were eating insane amounts of stack - */
95 unsigned char *outbuf; /* bad for some embedded targets */
97 unsigned short *codetab;
99 /* Hmm, these were statics - why?! */
100 /* user settable max # bits/code */
101 int maxbits; /* = BITS; */
102 /* block compress mode -C compatible with 2.0 */
103 int block_mode; /* = BLOCK_MODE; */
105 if (check_signature16(xstate, COMPRESS_MAGIC))
108 inbuf = xzalloc(IBUFSIZ + 64);
109 outbuf = xzalloc(OBUFSIZ + 2048);
110 htab = xzalloc(HSIZE); /* wasn't zeroed out before, maybe can xmalloc? */
111 codetab = xzalloc(HSIZE * sizeof(codetab[0]));
115 /* xread isn't good here, we have to return - caller may want
116 * to do some cleanup (e.g. delete incomplete unpacked file etc) */
117 if (full_read(xstate->src_fd, inbuf, 1) != 1) {
118 bb_error_msg("short read");
122 maxbits = inbuf[0] & BIT_MASK;
123 block_mode = inbuf[0] & BLOCK_MODE;
124 maxmaxcode = MAXCODE(maxbits);
126 if (maxbits > BITS) {
127 bb_error_msg("compressed with %d bits, can only handle "
128 BITS_STR" bits", maxbits);
133 maxcode = MAXCODE(INIT_BITS) - 1;
134 bitmask = (1 << INIT_BITS) - 1;
140 free_ent = ((block_mode) ? FIRST : 256);
142 /* As above, initialize the first 256 entries in the table. */
143 /*clear_tab_prefixof(); - done by xzalloc */
147 for (i = 255; i >= 0; --i)
148 tab_suffixof(i) = (unsigned char) i;
161 for (i = 0; i < e; ++i)
162 inbuf[i] = inbuf[i + o];
168 if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
169 rsize = safe_read(xstate->src_fd, inbuf + insize, IBUFSIZ);
171 bb_error_msg_and_die(bb_msg_read_error);
175 inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
176 (insize << 3) - (n_bits - 1));
178 while (inbits > posbits) {
181 if (free_ent > maxcode) {
185 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
187 if (n_bits == maxbits) {
188 maxcode = maxmaxcode;
190 maxcode = MAXCODE(n_bits) - 1;
192 bitmask = (1 << n_bits) - 1;
196 unsigned char *p = &inbuf[posbits >> 3];
198 | ((long) (p[1]) << 8)
199 | ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
205 bb_error_msg_and_die("corrupted data"); /* %ld", code); */
207 finchar = (int) oldcode;
208 outbuf[outpos++] = (unsigned char) finchar;
212 if (code == CLEAR && block_mode) {
213 clear_tab_prefixof();
214 free_ent = FIRST - 1;
218 (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
220 maxcode = MAXCODE(INIT_BITS) - 1;
221 bitmask = (1 << INIT_BITS) - 1;
228 /* Special case for KwKwK string. */
229 if (code >= free_ent) {
230 if (code > free_ent) {
235 p = &inbuf[posbits >> 3];
237 ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
238 insize, posbits, p[-1], p[0], p[1], p[2], p[3],
241 bb_error_msg("corrupted data");
245 *--stackp = (unsigned char) finchar;
249 /* Generate output characters in reverse order */
250 while (code >= 256) {
251 if (stackp <= &htabof(0))
252 bb_error_msg_and_die("corrupted data");
253 *--stackp = tab_suffixof(code);
254 code = tab_prefixof(code);
257 finchar = tab_suffixof(code);
258 *--stackp = (unsigned char) finchar;
260 /* And put them out in forward order */
264 i = de_stack - stackp;
265 if (outpos + i >= OBUFSIZ) {
267 if (i > OBUFSIZ - outpos) {
268 i = OBUFSIZ - outpos;
272 memcpy(outbuf + outpos, stackp, i);
276 if (outpos >= OBUFSIZ) {
277 xtransformer_write(xstate, outbuf, outpos);
278 IF_DESKTOP(total_written += outpos;)
282 i = de_stack - stackp;
285 memcpy(outbuf + outpos, stackp, i);
290 /* Generate the new entry. */
291 if (free_ent < maxmaxcode) {
292 tab_prefixof(free_ent) = (unsigned short) oldcode;
293 tab_suffixof(free_ent) = (unsigned char) finchar;
297 /* Remember previous code. */
303 xtransformer_write(xstate, outbuf, outpos);
304 IF_DESKTOP(total_written += outpos;)
307 retval = IF_DESKTOP(total_written) + 0;