cread.c revision 1.1
1 /* $NetBSD: cread.c,v 1.1 2001/10/11 07:07:42 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 #include <unistd.h> 51 #include <string.h> 52 #include <memory.h> 53 #include <fcntl.h> 54 #include <errno.h> 55 #include <zlib.h> 56 57 #define __P(proto) proto 58 #define SOPEN_MAX 1 59 60 61 #define EOF (-1) /* needed by compression code */ 62 63 #ifdef SAVE_MEMORY 64 #define Z_BUFSIZE 1024 65 #else 66 #define Z_BUFSIZE 32*1024 67 #endif 68 69 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */ 70 71 /* gzip flag byte */ 72 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */ 73 #define HEAD_CRC 0x02 /* bit 1 set: header CRC present */ 74 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */ 75 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */ 76 #define COMMENT 0x10 /* bit 4 set: file comment present */ 77 #define RESERVED 0xE0 /* bits 5..7: reserved */ 78 79 static struct sd { 80 z_stream stream; 81 int z_err; /* error code for last stream operation */ 82 int z_eof; /* set if end of input file */ 83 int fd; 84 unsigned char *inbuf; /* input buffer */ 85 unsigned long crc; /* crc32 of uncompressed data */ 86 int compressed; /* 1 if input file is a .gz file */ 87 } *ss[SOPEN_MAX]; 88 89 static int get_byte __P((struct sd *)); 90 static unsigned long getLong __P((struct sd *)); 91 static void check_header __P((struct sd *)); 92 93 /* XXX - find suitable headerf ile for these: */ 94 void *zcalloc __P((void *, unsigned int, unsigned int)); 95 void zcfree __P((void *, void *)); 96 void zmemcpy __P((unsigned char *, unsigned char *, unsigned int)); 97 98 99 /* 100 * compression utilities 101 */ 102 103 void * 104 zcalloc (opaque, items, size) 105 void *opaque; 106 unsigned items; 107 unsigned size; 108 { 109 return(malloc(items * size)); 110 } 111 112 void 113 zcfree (opaque, ptr) 114 void *opaque; 115 void *ptr; 116 { 117 free(ptr); 118 } 119 120 void 121 zmemcpy(dest, source, len) 122 unsigned char *dest; 123 unsigned char *source; 124 unsigned int len; 125 { 126 bcopy(source, dest, len); 127 } 128 129 static int 130 get_byte(s) 131 struct sd *s; 132 { 133 if (s->z_eof) 134 return (EOF); 135 136 if (s->stream.avail_in == 0) { 137 int got; 138 139 errno = 0; 140 got = cread(s->fd, s->inbuf, Z_BUFSIZE); 141 if (got <= 0) { 142 s->z_eof = 1; 143 if (errno) s->z_err = Z_ERRNO; 144 return EOF; 145 } 146 s->stream.avail_in = got; 147 s->stream.next_in = s->inbuf; 148 } 149 s->stream.avail_in--; 150 return *(s->stream.next_in)++; 151 } 152 153 static unsigned long 154 getLong (s) 155 struct sd *s; 156 { 157 unsigned long x = (unsigned long)get_byte(s); 158 int c; 159 160 x += ((unsigned long)get_byte(s)) << 8; 161 x += ((unsigned long)get_byte(s)) << 16; 162 c = get_byte(s); 163 if (c == EOF) 164 s->z_err = Z_DATA_ERROR; 165 x += ((unsigned long)c)<<24; 166 return x; 167 } 168 169 static void 170 check_header(s) 171 struct sd *s; 172 { 173 int method; /* method byte */ 174 int flags; /* flags byte */ 175 unsigned int len; 176 int c; 177 178 /* Check the gzip magic header */ 179 for (len = 0; len < 2; len++) { 180 c = get_byte(s); 181 if (c == gz_magic[len]) 182 continue; 183 if ((c == EOF) && (len == 0)) { 184 /* 185 * We must not change s->compressed if we are at EOF; 186 * we may have come to the end of a gzipped file and be 187 * check to see if another gzipped file is concatenated 188 * to this one. If one isn't, we still need to be able 189 * to lseek on this file as a compressed file. 190 */ 191 return; 192 } 193 s->compressed = 0; 194 if (c != EOF) { 195 s->stream.avail_in++; 196 s->stream.next_in--; 197 } 198 s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END; 199 return; 200 } 201 s->compressed = 1; 202 method = get_byte(s); 203 flags = get_byte(s); 204 if (method != Z_DEFLATED || (flags & RESERVED) != 0) { 205 s->z_err = Z_DATA_ERROR; 206 return; 207 } 208 209 /* Discard time, xflags and OS code: */ 210 for (len = 0; len < 6; len++) 211 (void)get_byte(s); 212 213 if ((flags & EXTRA_FIELD) != 0) { 214 /* skip the extra field */ 215 len = (unsigned int)get_byte(s); 216 len += ((unsigned int)get_byte(s)) << 8; 217 /* len is garbage if EOF but the loop below will quit anyway */ 218 while (len-- != 0 && get_byte(s) != EOF) /*void*/; 219 } 220 if ((flags & ORIG_NAME) != 0) { 221 /* skip the original file name */ 222 while ((c = get_byte(s)) != 0 && c != EOF) /*void*/; 223 } 224 if ((flags & COMMENT) != 0) { 225 /* skip the .gz file comment */ 226 while ((c = get_byte(s)) != 0 && c != EOF) /*void*/; 227 } 228 if ((flags & HEAD_CRC) != 0) { /* skip the header crc */ 229 for (len = 0; len < 2; len++) 230 (void)get_byte(s); 231 } 232 s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK; 233 } 234 235 /* 236 * new open(), close(), read(), lseek() 237 */ 238 239 int 240 copen(fname, mode) 241 const char *fname; 242 int mode; 243 { 244 int fd; 245 struct sd *s = 0; 246 247 if ( ((fd = open(fname, mode)) == -1) || (mode != O_RDONLY) ) 248 /* compression only for read */ 249 return(fd); 250 251 ss[fd] = s = malloc(sizeof(struct sd)); 252 if (s == 0) 253 goto errout; 254 bzero(s, sizeof(struct sd)); 255 256 if (inflateInit2(&(s->stream), -15) != Z_OK) 257 goto errout; 258 259 s->stream.next_in = s->inbuf = (unsigned char*)malloc(Z_BUFSIZE); 260 if (s->inbuf == 0) { 261 inflateEnd(&(s->stream)); 262 goto errout; 263 } 264 265 s->fd = fd; 266 check_header(s); /* skip the .gz header */ 267 return(fd); 268 269 errout: 270 if (s != 0) 271 free(s); 272 close(fd); 273 return (-1); 274 } 275 276 int 277 cclose(fd) 278 int fd; 279 { 280 struct sd *s; 281 282 s = ss[fd]; 283 284 inflateEnd(&(s->stream)); 285 286 free(s->inbuf); 287 free(s); 288 289 return (close(fd)); 290 } 291 292 size_t 293 cread(fd, buf, len) 294 int fd; 295 void *buf; 296 size_t len; 297 { 298 struct sd *s; 299 unsigned char *start = buf; /* starting point for crc computation */ 300 301 s = ss[fd]; 302 303 if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) 304 return (-1); 305 if (s->z_err == Z_STREAM_END) 306 return (0); /* EOF */ 307 308 s->stream.next_out = buf; 309 s->stream.avail_out = len; 310 311 while (s->stream.avail_out != 0) { 312 313 if (s->compressed == 0) { 314 /* Copy first the lookahead bytes: */ 315 unsigned int n = s->stream.avail_in; 316 if (n > s->stream.avail_out) 317 n = s->stream.avail_out; 318 if (n > 0) { 319 zmemcpy(s->stream.next_out, 320 s->stream.next_in, n); 321 s->stream.next_out += n; 322 s->stream.next_in += n; 323 s->stream.avail_out -= n; 324 s->stream.avail_in -= n; 325 } 326 if (s->stream.avail_out > 0) { 327 int got; 328 got = read(s->fd, s->stream.next_out, 329 s->stream.avail_out); 330 if (got == -1) 331 return (got); 332 s->stream.avail_out -= got; 333 } 334 return (int)(len - s->stream.avail_out); 335 } 336 337 if (s->stream.avail_in == 0 && !s->z_eof) { 338 int got; 339 errno = 0; 340 got = read(fd, s->inbuf, Z_BUFSIZE); 341 if (got <= 0) { 342 s->z_eof = 1; 343 if (errno) { 344 s->z_err = Z_ERRNO; 345 break; 346 } 347 } 348 s->stream.avail_in = got; 349 s->stream.next_in = s->inbuf; 350 } 351 352 s->z_err = inflate(&(s->stream), Z_NO_FLUSH); 353 354 if (s->z_err == Z_STREAM_END) { 355 /* Check CRC and original size */ 356 s->crc = crc32(s->crc, start, (unsigned int) 357 (s->stream.next_out - start)); 358 start = s->stream.next_out; 359 360 if (getLong(s) != s->crc || 361 getLong(s) != s->stream.total_out) { 362 363 s->z_err = Z_DATA_ERROR; 364 } else { 365 /* Check for concatenated .gz files: */ 366 check_header(s); 367 if (s->z_err == Z_OK) { 368 inflateReset(&(s->stream)); 369 s->crc = crc32(0L, Z_NULL, 0); 370 } 371 } 372 } 373 if (s->z_err != Z_OK || s->z_eof) 374 break; 375 } 376 377 s->crc = crc32(s->crc, start, 378 (unsigned int)(s->stream.next_out - start)); 379 380 return (int)(len - s->stream.avail_out); 381 } 382 383 off_t 384 clseek(fd, offset, where) 385 int fd; 386 off_t offset; 387 int where; 388 { 389 struct sd *s; 390 391 s = ss[fd]; 392 393 if(s->compressed == 0) { 394 off_t res = lseek(fd, offset, where); 395 if (res != (off_t)-1) { 396 /* make sure the lookahead buffer is invalid */ 397 s->stream.avail_in = 0; 398 } 399 return (res); 400 } 401 402 switch(where) { 403 case SEEK_CUR: 404 offset += s->stream.total_out; 405 case SEEK_SET: 406 /* if seek backwards, simply start from the beginning */ 407 if (offset < s->stream.total_out) { 408 off_t res; 409 void *sav_inbuf; 410 411 res = lseek(fd, 0, SEEK_SET); 412 if(res == (off_t)-1) 413 return(res); 414 /* ??? perhaps fallback to close / open */ 415 416 inflateEnd(&(s->stream)); 417 418 sav_inbuf = s->inbuf; /* don't allocate again */ 419 bzero(s, sizeof(struct sd)); /* this resets total_out to 0! */ 420 421 inflateInit2(&(s->stream), -15); 422 s->stream.next_in = s->inbuf = sav_inbuf; 423 424 s->fd = fd; 425 check_header(s); /* skip the .gz header */ 426 } 427 428 /* to seek forwards, throw away data */ 429 if (offset > s->stream.total_out) { 430 off_t toskip = offset - s->stream.total_out; 431 432 while (toskip > 0) { 433 #define DUMMYBUFSIZE 256 434 char dummybuf[DUMMYBUFSIZE]; 435 off_t len = toskip; 436 if (len > DUMMYBUFSIZE) len = DUMMYBUFSIZE; 437 if (cread(fd, dummybuf, len) != len) { 438 errno = EINVAL; 439 return ((off_t)-1); 440 } 441 toskip -= len; 442 } 443 } 444 #ifdef DEBUG 445 if (offset != s->stream.total_out) 446 panic("lseek compressed"); 447 #endif 448 return (offset); 449 case SEEK_END: 450 errno = EINVAL; 451 break; 452 default: 453 errno = EINVAL; 454 } 455 456 return((off_t)-1); 457 } 458
Indexes created Mon Sep 29 03:10:08 GMT 2025