usr.bin/gzip/zuncompress.c

43 #define	tab_prefixof(i)	(zs->zs_codetab[i])
44 #define	tab_suffixof(i)	((char_type *)(zs->zs_htab))[i]
128 static code_int	getcode(struct s_zstate *zs);
164 zclose(void *zs)
166 	free(zs);
174 	struct s_zstate *zs;
176 	if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL)
179 	zs->zs_state = S_START;
182 	zs->zs_hsize = HSIZE;			/* For dynamic table sizing. */
183 	zs->zs_free_ent = 0;			/* First unused entry. */
184 	zs->zs_block_compress = BLOCK_MASK;
185 	zs->zs_clear_flg = 0;			/* XXX we calloc()'d this structure why = 0? */
186 	zs->zs_ratio = 0;
187 	zs->zs_checkpoint = CHECK_GAP;
188 	zs->zs_in_count = 1;			/* Length of input. */
189 	zs->zs_out_count = 0;			/* # of codes output (for debugging). */
190 	zs->u.r.zs_roffset = 0;
191 	zs->u.r.zs_size = 0;
197 	if ((zs->zs_fp = fdopen(fd, "r")) == NULL) {
198 		free(zs);
202 	return funopen(zs, zread, NULL, NULL, zclose);
215 	struct s_zstate *zs;
221 	zs = cookie;
224 	switch (zs->zs_state) {
226 		zs->zs_state = S_MIDDLE;
238 	if (fread(header + i, 1, sizeof(header) - i, zs->zs_fp) !=
245 	zs->zs_maxbits = header[2];	/* Set -b from file. */
246 	zs->zs_block_compress = zs->zs_maxbits & BLOCK_MASK;
247 	zs->zs_maxbits &= BIT_MASK;
248 	zs->zs_maxmaxcode = 1L << zs->zs_maxbits;
249 	if (zs->zs_maxbits > BITS || zs->zs_maxbits < 12) {
254 	zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS);
255 	for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0; zs->u.r.zs_code--) {
256 		tab_prefixof(zs->u.r.zs_code) = 0;
257 		tab_suffixof(zs->u.r.zs_code) = (char_type) zs->u.r.zs_code;
259 	zs->zs_free_ent = zs->zs_block_compress ? FIRST : 256;
261 	zs->u.r.zs_oldcode = -1;
262 	zs->u.r.zs_stackp = de_stack;
264 	while ((zs->u.r.zs_code = getcode(zs)) > -1) {
266 		if ((zs->u.r.zs_code == CLEAR) && zs->zs_block_compress) {
267 			for (zs->u.r.zs_code = 255; zs->u.r.zs_code >= 0;
268 			    zs->u.r.zs_code--)
269 				tab_prefixof(zs->u.r.zs_code) = 0;
270 			zs->zs_clear_flg = 1;
271 			zs->zs_free_ent = FIRST;
272 			zs->u.r.zs_oldcode = -1;
275 		zs->u.r.zs_incode = zs->u.r.zs_code;
278 		if (zs->u.r.zs_code >= zs->zs_free_ent) {
279 			if (zs->u.r.zs_code > zs->zs_free_ent ||
280 			    zs->u.r.zs_oldcode == -1) {
285 			*zs->u.r.zs_stackp++ = zs->u.r.zs_finchar;
286 			zs->u.r.zs_code = zs->u.r.zs_oldcode;
296 		while (zs->u.r.zs_code >= 256) {
297 			*zs->u.r.zs_stackp++ = tab_suffixof(zs->u.r.zs_code);
298 			zs->u.r.zs_code = tab_prefixof(zs->u.r.zs_code);
300 		*zs->u.r.zs_stackp++ = zs->u.r.zs_finchar = tab_suffixof(zs->u.r.zs_code);
306 			*bp++ = *--zs->u.r.zs_stackp;
307 		} while (zs->u.r.zs_stackp > de_stack);
310 		if ((zs->u.r.zs_code = zs->zs_free_ent) < zs->zs_maxmaxcode &&
311 		    zs->u.r.zs_oldcode != -1) {
312 			tab_prefixof(zs->u.r.zs_code) = (u_short) zs->u.r.zs_oldcode;
313 			tab_suffixof(zs->u.r.zs_code) = zs->u.r.zs_finchar;
314 			zs->zs_free_ent = zs->u.r.zs_code + 1;
318 		zs->u.r.zs_oldcode = zs->u.r.zs_incode;
320 	zs->zs_state = S_EOF;
332 getcode(struct s_zstate *zs)
338 	bp = zs->u.r.zs_gbuf;
339 	if (zs->zs_clear_flg > 0 || zs->u.r.zs_roffset >= zs->u.r.zs_size ||
340 	    zs->zs_free_ent > zs->zs_maxcode) {
346 		if (zs->zs_free_ent > zs->zs_maxcode) {
347 			zs->zs_n_bits++;
348 			if (zs->zs_n_bits == zs->zs_maxbits)	/* Won't get any bigger now. */
349 				zs->zs_maxcode = zs->zs_maxmaxcode;
351 				zs->zs_maxcode = MAXCODE(zs->zs_n_bits);
353 		if (zs->zs_clear_flg > 0) {
354 			zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS);
355 			zs->zs_clear_flg = 0;
358 		for (i = 0; i < zs->zs_n_bits && compressed_prelen; i++, compressed_prelen--)
359 			zs->u.r.zs_gbuf[i] = *compressed_pre++;
360 		zs->u.r.zs_size = fread(zs->u.r.zs_gbuf + i, 1, zs->zs_n_bits - i, zs->zs_fp);
361 		zs->u.r.zs_size += i;
362 		if (zs->u.r.zs_size <= 0)			/* End of file. */
364 		zs->u.r.zs_roffset = 0;
366 		total_compressed_bytes += zs->u.r.zs_size;
369 		zs->u.r.zs_size = (zs->u.r.zs_size << 3) - (zs->zs_n_bits - 1);
371 	r_off = zs->u.r.zs_roffset;
372 	bits = zs->zs_n_bits;
392 	zs->u.r.zs_roffset += zs->zs_n_bits;