cread.c revision 1.2
1 /* $NetBSD: cread.c,v 1.2 2002/02/24 20:51:07 leo Exp $ */ 2 3 /* 4 * Copyright (c) 1996 5 * Matthias Drochner. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed for the NetBSD Project 18 * by Matthias Drochner. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 * 33 */ 34 35 /* 36 * Support for compressed bootfiles (only read) 37 * 38 * - provides copen(), cclose(), cread(), clseek(). 39 * - compression parts stripped from zlib:gzio.c 40 * - copied from libsa with small modifications for my MiNT environment. 41 * Note that everything in the 'tostools' hierarchy is made to function 42 * in my local MiNT environment. 43 */ 44 45 /* gzio.c -- IO on .gz files 46 * Copyright (C) 1995-1996 Jean-loup Gailly. 47 * For conditions of distribution and use, see copyright notice in zlib.h 48 */ 49 50 #define _CREAD_C /* Turn of open/close/read redefines */ 51 52 #include <unistd.h> 53 #include <string.h> 54 #include <memory.h> 55 #include <fcntl.h> 56 #include <errno.h> 57 #include <zlib.h> 58 #include <cread.h> 59 60 #define __P(proto) proto 61 #define SOPEN_MAX 1 62 63 64 #define EOF (-1) /* needed by compression code */ 65 66 #ifdef SAVE_MEMORY 67 #define Z_BUFSIZE 1024 68 #else 69 #define Z_BUFSIZE 32*1024 70 #endif 71 72 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */ 73 74 /* gzip flag byte */ 75 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */ 76 #define HEAD_CRC 0x02 /* bit 1 set: header CRC present */ 77 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */ 78 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */ 79 #define COMMENT 0x10 /* bit 4 set: file comment present */ 80 #define RESERVED 0xE0 /* bits 5..7: reserved */ 81 82 static struct sd { 83 z_stream stream; 84 int z_err; /* error code for last stream operation */ 85 int z_eof; /* set if end of input file */ 86 int fd; 87 unsigned char *inbuf; /* input buffer */ 88 unsigned long crc; /* crc32 of uncompressed data */ 89 int compressed; /* 1 if input file is a .gz file */ 90 } *ss[SOPEN_MAX]; 91 92 static int get_byte __P((struct sd *)); 93 static unsigned long getLong __P((struct sd *)); 94 static void check_header __P((struct sd *)); 95 96 /* XXX - find suitable headerf ile for these: */ 97 void *zcalloc __P((void *, unsigned int, unsigned int)); 98 void zcfree __P((void *, void *)); 99 void zmemcpy __P((unsigned char *, unsigned char *, unsigned int)); 100 101 102 /* 103 * compression utilities 104 */ 105 106 void * 107 zcalloc (opaque, items, size) 108 void *opaque; 109 unsigned items; 110 unsigned size; 111 { 112 return(malloc(items * size)); 113 } 114 115 void 116 zcfree (opaque, ptr) 117 void *opaque; 118 void *ptr; 119 { 120 free(ptr); 121 } 122 123 void 124 zmemcpy(dest, source, len) 125 unsigned char *dest; 126 unsigned char *source; 127 unsigned int len; 128 { 129 bcopy(source, dest, len); 130 } 131 132 static int 133 get_byte(s) 134 struct sd *s; 135 { 136 if (s->z_eof) 137 return (EOF); 138 139 if (s->stream.avail_in == 0) { 140 int got; 141 142 errno = 0; 143 got = cread(s->fd, s->inbuf, Z_BUFSIZE); 144 if (got <= 0) { 145 s->z_eof = 1; 146 if (errno) s->z_err = Z_ERRNO; 147 return EOF; 148 } 149 s->stream.avail_in = got; 150 s->stream.next_in = s->inbuf; 151 } 152 s->stream.avail_in--; 153 return *(s->stream.next_in)++; 154 } 155 156 static unsigned long 157 getLong (s) 158 struct sd *s; 159 { 160 unsigned long x = (unsigned long)get_byte(s); 161 int c; 162 163 x += ((unsigned long)get_byte(s)) << 8; 164 x += ((unsigned long)get_byte(s)) << 16; 165 c = get_byte(s); 166 if (c == EOF) 167 s->z_err = Z_DATA_ERROR; 168 x += ((unsigned long)c)<<24; 169 return x; 170 } 171 172 static void 173 check_header(s) 174 struct sd *s; 175 { 176 int method; /* method byte */ 177 int flags; /* flags byte */ 178 unsigned int len; 179 int c; 180 181 /* Check the gzip magic header */ 182 for (len = 0; len < 2; len++) { 183 c = get_byte(s); 184 if (c == gz_magic[len]) 185 continue; 186 if ((c == EOF) && (len == 0)) { 187 /* 188 * We must not change s->compressed if we are at EOF; 189 * we may have come to the end of a gzipped file and be 190 * check to see if another gzipped file is concatenated 191 * to this one. If one isn't, we still need to be able 192 * to lseek on this file as a compressed file. 193 */ 194 return; 195 } 196 s->compressed = 0; 197 if (c != EOF) { 198 s->stream.avail_in++; 199 s->stream.next_in--; 200 } 201 s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END; 202 return; 203 } 204 s->compressed = 1; 205 method = get_byte(s); 206 flags = get_byte(s); 207 if (method != Z_DEFLATED || (flags & RESERVED) != 0) { 208 s->z_err = Z_DATA_ERROR; 209 return; 210 } 211 212 /* Discard time, xflags and OS code: */ 213 for (len = 0; len < 6; len++) 214 (void)get_byte(s); 215 216 if ((flags & EXTRA_FIELD) != 0) { 217 /* skip the extra field */ 218 len = (unsigned int)get_byte(s); 219 len += ((unsigned int)get_byte(s)) << 8; 220 /* len is garbage if EOF but the loop below will quit anyway */ 221 while (len-- != 0 && get_byte(s) != EOF) /*void*/; 222 } 223 if ((flags & ORIG_NAME) != 0) { 224 /* skip the original file name */ 225 while ((c = get_byte(s)) != 0 && c != EOF) /*void*/; 226 } 227 if ((flags & COMMENT) != 0) { 228 /* skip the .gz file comment */ 229 while ((c = get_byte(s)) != 0 && c != EOF) /*void*/; 230 } 231 if ((flags & HEAD_CRC) != 0) { /* skip the header crc */ 232 for (len = 0; len < 2; len++) 233 (void)get_byte(s); 234 } 235 s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK; 236 } 237 238 /* 239 * new open(), close(), read(), lseek() 240 */ 241 242 int 243 copen(fname, mode) 244 const char *fname; 245 int mode; 246 { 247 int fd; 248 struct sd *s = 0; 249 250 if ( ((fd = open(fname, mode)) == -1) || (mode != O_RDONLY) ) 251 /* compression only for read */ 252 return(fd); 253 254 ss[fd] = s = malloc(sizeof(struct sd)); 255 if (s == 0) 256 goto errout; 257 bzero(s, sizeof(struct sd)); 258 259 if (inflateInit2(&(s->stream), -15) != Z_OK) 260 goto errout; 261 262 s->stream.next_in = s->inbuf = (unsigned char*)malloc(Z_BUFSIZE); 263 if (s->inbuf == 0) { 264 inflateEnd(&(s->stream)); 265 goto errout; 266 } 267 268 s->fd = fd; 269 check_header(s); /* skip the .gz header */ 270 return(fd); 271 272 errout: 273 if (s != 0) 274 free(s); 275 close(fd); 276 return (-1); 277 } 278 279 int 280 cclose(fd) 281 int fd; 282 { 283 struct sd *s; 284 285 s = ss[fd]; 286 287 inflateEnd(&(s->stream)); 288 289 free(s->inbuf); 290 free(s); 291 292 return (close(fd)); 293 } 294 295 size_t 296 cread(fd, buf, len) 297 int fd; 298 void *buf; 299 size_t len; 300 { 301 struct sd *s; 302 unsigned char *start = buf; /* starting point for crc computation */ 303 304 s = ss[fd]; 305 306 if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) 307 return (-1); 308 if (s->z_err == Z_STREAM_END) 309 return (0); /* EOF */ 310 311 s->stream.next_out = buf; 312 s->stream.avail_out = len; 313 314 while (s->stream.avail_out != 0) { 315 316 if (s->compressed == 0) { 317 /* Copy first the lookahead bytes: */ 318 unsigned int n = s->stream.avail_in; 319 if (n > s->stream.avail_out) 320 n = s->stream.avail_out; 321 if (n > 0) { 322 zmemcpy(s->stream.next_out, 323 s->stream.next_in, n); 324 s->stream.next_out += n; 325 s->stream.next_in += n; 326 s->stream.avail_out -= n; 327 s->stream.avail_in -= n; 328 } 329 if (s->stream.avail_out > 0) { 330 int got; 331 got = read(s->fd, s->stream.next_out, 332 s->stream.avail_out); 333 if (got == -1) 334 return (got); 335 s->stream.avail_out -= got; 336 } 337 return (int)(len - s->stream.avail_out); 338 } 339 340 if (s->stream.avail_in == 0 && !s->z_eof) { 341 int got; 342 errno = 0; 343 got = read(fd, s->inbuf, Z_BUFSIZE); 344 if (got <= 0) { 345 s->z_eof = 1; 346 if (errno) { 347 s->z_err = Z_ERRNO; 348 break; 349 } 350 } 351 s->stream.avail_in = got; 352 s->stream.next_in = s->inbuf; 353 } 354 355 s->z_err = inflate(&(s->stream), Z_NO_FLUSH); 356 357 if (s->z_err == Z_STREAM_END) { 358 /* Check CRC and original size */ 359 s->crc = crc32(s->crc, start, (unsigned int) 360 (s->stream.next_out - start)); 361 start = s->stream.next_out; 362 363 if (getLong(s) != s->crc || 364 getLong(s) != s->stream.total_out) { 365 366 s->z_err = Z_DATA_ERROR; 367 } else { 368 /* Check for concatenated .gz files: */ 369 check_header(s); 370 if (s->z_err == Z_OK) { 371 inflateReset(&(s->stream)); 372 s->crc = crc32(0L, Z_NULL, 0); 373 } 374 } 375 } 376 if (s->z_err != Z_OK || s->z_eof) 377 break; 378 } 379 380 s->crc = crc32(s->crc, start, 381 (unsigned int)(s->stream.next_out - start)); 382 383 return (int)(len - s->stream.avail_out); 384 } 385 386 off_t 387 clseek(fd, offset, where) 388 int fd; 389 off_t offset; 390 int where; 391 { 392 struct sd *s; 393 394 s = ss[fd]; 395 396 if(s->compressed == 0) { 397 off_t res = lseek(fd, offset, where); 398 if (res != (off_t)-1) { 399 /* make sure the lookahead buffer is invalid */ 400 s->stream.avail_in = 0; 401 } 402 return (res); 403 } 404 405 switch(where) { 406 case SEEK_CUR: 407 offset += s->stream.total_out; 408 case SEEK_SET: 409 /* if seek backwards, simply start from the beginning */ 410 if (offset < s->stream.total_out) { 411 off_t res; 412 void *sav_inbuf; 413 414 res = lseek(fd, 0, SEEK_SET); 415 if(res == (off_t)-1) 416 return(res); 417 /* ??? perhaps fallback to close / open */ 418 419 inflateEnd(&(s->stream)); 420 421 sav_inbuf = s->inbuf; /* don't allocate again */ 422 bzero(s, sizeof(struct sd)); /* this resets total_out to 0! */ 423 424 inflateInit2(&(s->stream), -15); 425 s->stream.next_in = s->inbuf = sav_inbuf; 426 427 s->fd = fd; 428 check_header(s); /* skip the .gz header */ 429 } 430 431 /* to seek forwards, throw away data */ 432 if (offset > s->stream.total_out) { 433 off_t toskip = offset - s->stream.total_out; 434 435 while (toskip > 0) { 436 #define DUMMYBUFSIZE 256 437 char dummybuf[DUMMYBUFSIZE]; 438 off_t len = toskip; 439 if (len > DUMMYBUFSIZE) len = DUMMYBUFSIZE; 440 if (cread(fd, dummybuf, len) != len) { 441 errno = EINVAL; 442 return ((off_t)-1); 443 } 444 toskip -= len; 445 } 446 } 447 #ifdef DEBUG 448 if (offset != s->stream.total_out) 449 panic("lseek compressed"); 450 #endif 451 return (offset); 452 case SEEK_END: 453 errno = EINVAL; 454 break; 455 default: 456 errno = EINVAL; 457 } 458 459 return((off_t)-1); 460 } 461
Indexes created Mon Sep 29 03:10:08 GMT 2025