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1.1 root 1: /*
2: puff.c
3: Copyright (C) 2002-2004 Mark Adler, all rights reserved
4: version 1.8, 9 Jan 2004
5:
6: This software is provided 'as-is', without any express or implied
7: warranty. In no event will the author be held liable for any damages
8: arising from the use of this software.
9:
10: Permission is granted to anyone to use this software for any purpose,
11: including commercial applications, and to alter it and redistribute it
12: freely, subject to the following restrictions:
13:
14: 1. The origin of this software must not be misrepresented; you must not
15: claim that you wrote the original software. If you use this software
16: in a product, an acknowledgment in the product documentation would be
17: appreciated but is not required.
18: 2. Altered source versions must be plainly marked as such, and must not be
19: misrepresented as being the original software.
20: 3. This notice may not be removed or altered from any source distribution.
21:
22: Mark Adler [email protected]
23: */
24:
25: /* Adapted by TrueCrypt Foundation */
26:
27:
28: #define local static /* for local function definitions */
29: #define NIL ((unsigned char *)0) /* for no output option */
30:
31: /*
32: * Maximums for allocations and loops. It is not useful to change these --
33: * they are fixed by the deflate format.
34: */
35: #define MAXBITS 15 /* maximum bits in a code */
36: #define MAXLCODES 286 /* maximum number of literal/length codes */
37: #define MAXDCODES 30 /* maximum number of distance codes */
38: #define MAXCODES (MAXLCODES+MAXDCODES) /* maximum codes lengths to read */
39: #define FIXLCODES 288 /* number of fixed literal/length codes */
40:
41: /* input and output state */
42: struct state {
43: /* output state */
44: unsigned char *out; /* output buffer */
45: unsigned int outlen; /* available space at out */
46: unsigned int outcnt; /* bytes written to out so far */
47:
48: /* input state */
49: unsigned char *in; /* input buffer */
50: unsigned int incnt; /* bytes read so far */
51: int bitbuf; /* bit buffer */
52: int bitcnt; /* number of bits in bit buffer */
53: };
54:
55:
56: local int bits(struct state *s, int need)
57: {
58: long val; /* bit accumulator (can use up to 20 bits) */
59:
60: /* load at least need bits into val */
61: val = s->bitbuf;
62: while (s->bitcnt < need) {
63: val |= (long)(s->in[s->incnt++]) << s->bitcnt; /* load eight bits */
64: s->bitcnt += 8;
65: }
66:
67: /* drop need bits and update buffer, always zero to seven bits left */
68: s->bitbuf = (int)(val >> need);
69: s->bitcnt -= need;
70:
71: /* return need bits, zeroing the bits above that */
72: return (int)(val & ((1L << need) - 1));
73: }
74:
75:
76: local int stored(struct state *s)
77: {
78: unsigned len; /* length of stored block */
79:
80: /* discard leftover bits from current byte (assumes s->bitcnt < 8) */
81: s->bitbuf = 0;
82: s->bitcnt = 0;
83:
84: /* get length and check against its one's complement */
85: len = s->in[s->incnt++];
86: len |= s->in[s->incnt++] << 8;
87: if (s->in[s->incnt++] != (~len & 0xff) ||
88: s->in[s->incnt++] != ((~len >> 8) & 0xff))
89: return -2; /* didn't match complement! */
90:
91: /* copy len bytes from in to out */
92: if (s->out != NIL) {
93: if (s->outcnt + len > s->outlen)
94: return 1; /* not enough output space */
95: while (len--)
96: s->out[s->outcnt++] = s->in[s->incnt++];
97: }
98: else { /* just scanning */
99: s->outcnt += len;
100: s->incnt += len;
101: }
102:
103: /* done with a valid stored block */
104: return 0;
105: }
106:
107:
108: struct huffman {
109: short *count; /* number of symbols of each length */
110: short *symbol; /* canonically ordered symbols */
111: };
112:
113:
114: #ifdef SLOW
115: local int decode(struct state *s, struct huffman *h)
116: {
117: int len; /* current number of bits in code */
118: int code; /* len bits being decoded */
119: int first; /* first code of length len */
120: int count; /* number of codes of length len */
121: int index; /* index of first code of length len in symbol table */
122:
123: code = first = index = 0;
124: for (len = 1; len <= MAXBITS; len++) {
125: code |= bits(s, 1); /* get next bit */
126: count = h->count[len];
127: if (code < first + count) /* if length len, return symbol */
128: return h->symbol[index + (code - first)];
129: index += count; /* else update for next length */
130: first += count;
131: first <<= 1;
132: code <<= 1;
133: }
134: return -9; /* ran out of codes */
135: }
136:
137: /*
138: * A faster version of decode() for real applications of this code. It's not
139: * as readable, but it makes puff() twice as fast. And it only makes the code
140: * a few percent larger.
141: */
142: #else /* !SLOW */
143: local int decode(struct state *s, struct huffman *h)
144: {
145: int len; /* current number of bits in code */
146: int code; /* len bits being decoded */
147: int first; /* first code of length len */
148: int count; /* number of codes of length len */
149: int index; /* index of first code of length len in symbol table */
150: int bitbuf; /* bits from stream */
151: int left; /* bits left in next or left to process */
152: short *next; /* next number of codes */
153:
154: bitbuf = s->bitbuf;
155: left = s->bitcnt;
156: code = first = index = 0;
157: len = 1;
158: next = h->count + 1;
159: while (1) {
160: while (left--) {
161: code |= bitbuf & 1;
162: bitbuf >>= 1;
163: count = *next++;
164: if (code < first + count) { /* if length len, return symbol */
165: s->bitbuf = bitbuf;
166: s->bitcnt = (s->bitcnt - len) & 7;
167: return h->symbol[index + (code - first)];
168: }
169: index += count; /* else update for next length */
170: first += count;
171: first <<= 1;
172: code <<= 1;
173: len++;
174: }
175: left = (MAXBITS+1) - len;
176: if (left == 0) break;
177: bitbuf = s->in[s->incnt++];
178: if (left > 8) left = 8;
179: }
180: return -9; /* ran out of codes */
181: }
182: #endif /* SLOW */
183:
184:
185: local int construct(struct huffman *h, short *length, int n)
186: {
187: int symbol; /* current symbol when stepping through length[] */
188: int len; /* current length when stepping through h->count[] */
189: int left; /* number of possible codes left of current length */
190: short offs[MAXBITS+1]; /* offsets in symbol table for each length */
191:
192: /* count number of codes of each length */
193: for (len = 0; len <= MAXBITS; len++)
194: h->count[len] = 0;
195: for (symbol = 0; symbol < n; symbol++)
196: (h->count[length[symbol]])++; /* assumes lengths are within bounds */
197: if (h->count[0] == n) /* no codes! */
198: return 0; /* complete, but decode() will fail */
199:
200: /* check for an over-subscribed or incomplete set of lengths */
201: left = 1; /* one possible code of zero length */
202: for (len = 1; len <= MAXBITS; len++) {
203: left <<= 1; /* one more bit, double codes left */
204: left -= h->count[len]; /* deduct count from possible codes */
205: if (left < 0) return left; /* over-subscribed--return negative */
206: } /* left > 0 means incomplete */
207:
208: /* generate offsets into symbol table for each length for sorting */
209: offs[1] = 0;
210: for (len = 1; len < MAXBITS; len++)
211: offs[len + 1] = offs[len] + h->count[len];
212:
213: /*
214: * put symbols in table sorted by length, by symbol order within each
215: * length
216: */
217: for (symbol = 0; symbol < n; symbol++)
218: if (length[symbol] != 0)
219: h->symbol[offs[length[symbol]]++] = symbol;
220:
221: /* return zero for complete set, positive for incomplete set */
222: return left;
223: }
224:
225:
226: local int codes(struct state *s,
227: struct huffman *lencode,
228: struct huffman *distcode)
229: {
230: int symbol; /* decoded symbol */
231: int len; /* length for copy */
232: unsigned dist; /* distance for copy */
233: static const short lens[29] = { /* Size base for length codes 257..285 */
234: 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
235: 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
236: static const short lext[29] = { /* Extra bits for length codes 257..285 */
237: 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
238: 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
239: static const short dists[30] = { /* Offset base for distance codes 0..29 */
240: 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
241: 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
242: 8193, 12289, 16385, 24577};
243: static const short dext[30] = { /* Extra bits for distance codes 0..29 */
244: 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
245: 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
246: 12, 12, 13, 13};
247:
248: /* decode literals and length/distance pairs */
249: do {
250: symbol = decode(s, lencode);
251: if (symbol < 0) return symbol; /* invalid symbol */
252: if (symbol < 256) { /* literal: symbol is the byte */
253: /* write out the literal */
254: if (s->out != NIL) {
255: if (s->outcnt == s->outlen) return 1;
256: s->out[s->outcnt] = symbol;
257: }
258: s->outcnt++;
259: }
260: else if (symbol > 256) { /* length */
261: /* get and compute length */
262: symbol -= 257;
263: if (symbol >= 29) return -9; /* invalid fixed code */
264: len = lens[symbol] + bits(s, lext[symbol]);
265:
266: /* get and check distance */
267: symbol = decode(s, distcode);
268: if (symbol < 0) return symbol; /* invalid symbol */
269: dist = dists[symbol] + bits(s, dext[symbol]);
270: if (dist > s->outcnt)
271: return -10; /* distance too far back */
272:
273: /* copy length bytes from distance bytes back */
274: if (s->out != NIL) {
275: if (s->outcnt + len > s->outlen) return 1;
276: while (len--) {
277: s->out[s->outcnt] = s->out[s->outcnt - dist];
278: s->outcnt++;
279: }
280: }
281: else
282: s->outcnt += len;
283: }
284: } while (symbol != 256); /* end of block symbol */
285:
286: /* done with a valid fixed or dynamic block */
287: return 0;
288: }
289:
290:
291: local int fixed(struct state *s)
292: {
293: static int virgin = 1;
294: static short lencnt[MAXBITS+1], lensym[FIXLCODES];
295: static short distcnt[MAXBITS+1], distsym[MAXDCODES];
296: static struct huffman lencode = {lencnt, lensym};
297: static struct huffman distcode = {distcnt, distsym};
298:
299: /* build fixed huffman tables if first call (may not be thread safe) */
300: if (virgin) {
301: int symbol;
302: short lengths[FIXLCODES];
303:
304: /* literal/length table */
305: for (symbol = 0; symbol < 144; symbol++)
306: lengths[symbol] = 8;
307: for (; symbol < 256; symbol++)
308: lengths[symbol] = 9;
309: for (; symbol < 280; symbol++)
310: lengths[symbol] = 7;
311: for (; symbol < FIXLCODES; symbol++)
312: lengths[symbol] = 8;
313: construct(&lencode, lengths, FIXLCODES);
314:
315: /* distance table */
316: for (symbol = 0; symbol < MAXDCODES; symbol++)
317: lengths[symbol] = 5;
318: construct(&distcode, lengths, MAXDCODES);
319:
320: /* do this just once */
321: virgin = 0;
322: }
323:
324: /* decode data until end-of-block code */
325: return codes(s, &lencode, &distcode);
326: }
327:
328:
329: local int dynamic(struct state *s)
330: {
331: int nlen, ndist, ncode; /* number of lengths in descriptor */
332: int index; /* index of lengths[] */
333: int err; /* construct() return value */
334: short lengths[MAXCODES]; /* descriptor code lengths */
335: short lencnt[MAXBITS+1], lensym[MAXLCODES]; /* lencode memory */
336: short distcnt[MAXBITS+1], distsym[MAXDCODES]; /* distcode memory */
337: struct huffman lencode = {lencnt, lensym}; /* length code */
338: struct huffman distcode = {distcnt, distsym}; /* distance code */
339: static const short order[19] = /* permutation of code length codes */
340: {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
341:
342: /* get number of lengths in each table, check lengths */
343: nlen = bits(s, 5) + 257;
344: ndist = bits(s, 5) + 1;
345: ncode = bits(s, 4) + 4;
346: if (nlen > MAXLCODES || ndist > MAXDCODES)
347: return -3; /* bad counts */
348:
349: /* read code length code lengths (really), missing lengths are zero */
350: for (index = 0; index < ncode; index++)
351: lengths[order[index]] = bits(s, 3);
352: for (; index < 19; index++)
353: lengths[order[index]] = 0;
354:
355: /* build huffman table for code lengths codes (use lencode temporarily) */
356: err = construct(&lencode, lengths, 19);
357: if (err != 0) return -4; /* require complete code set here */
358:
359: /* read length/literal and distance code length tables */
360: index = 0;
361: while (index < nlen + ndist) {
362: int symbol; /* decoded value */
363: int len; /* last length to repeat */
364:
365: symbol = decode(s, &lencode);
366: if (symbol < 16) /* length in 0..15 */
367: lengths[index++] = symbol;
368: else { /* repeat instruction */
369: len = 0; /* assume repeating zeros */
370: if (symbol == 16) { /* repeat last length 3..6 times */
371: if (index == 0) return -5; /* no last length! */
372: len = lengths[index - 1]; /* last length */
373: symbol = 3 + bits(s, 2);
374: }
375: else if (symbol == 17) /* repeat zero 3..10 times */
376: symbol = 3 + bits(s, 3);
377: else /* == 18, repeat zero 11..138 times */
378: symbol = 11 + bits(s, 7);
379: if (index + symbol > nlen + ndist)
380: return -6; /* too many lengths! */
381: while (symbol--) /* repeat last or zero symbol times */
382: lengths[index++] = len;
383: }
384: }
385:
386: /* build huffman table for literal/length codes */
387: err = construct(&lencode, lengths, nlen);
388: if (err < 0 || (err > 0 && nlen - lencode.count[0] != 1))
389: return -7; /* only allow incomplete codes if just one code */
390:
391: /* build huffman table for distance codes */
392: err = construct(&distcode, lengths + nlen, ndist);
393: if (err < 0 || (err > 0 && ndist - distcode.count[0] != 1))
394: return -8; /* only allow incomplete codes if just one code */
395:
396: /* decode data until end-of-block code */
397: return codes(s, &lencode, &distcode);
398: }
399:
400:
401: void _acrtused () { }
402:
403: // Decompress deflated data
404: int far main (
405: unsigned char *dest, /* pointer to destination pointer */
406: unsigned int destlen, /* amount of output space */
407: unsigned char *source) /* pointer to source data pointer */
408: {
409: struct state s; /* input/output state */
410: int last, type; /* block information */
411: int err; /* return value */
412:
413: /* initialize output state */
414: s.out = dest;
415: s.outlen = destlen; /* ignored if dest is NIL */
416: s.outcnt = 0;
417:
418: /* initialize input state */
419: s.in = source;
420: s.incnt = 0;
421: s.bitbuf = 0;
422: s.bitcnt = 0;
423:
424: /* process blocks until last block or error */
425: do {
426: last = bits(&s, 1); /* one if last block */
427: type = bits(&s, 2); /* block type 0..3 */
428: err = type == 0 ? stored(&s) :
429: (type == 1 ? fixed(&s) :
430: (type == 2 ? dynamic(&s) :
431: -1)); /* type == 3, invalid */
432: if (err != 0) break; /* return with error */
433: } while (!last);
434:
435: return err;
436: }
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