gzread.c revision 00fb66d0b1488e4ca655906f82b27eb2ccc3e309
1/* gzread.c -- zlib functions for reading gzip files 2 * Copyright (C) 2004, 2005, 2010, 2011 Mark Adler 3 * For conditions of distribution and use, see copyright notice in zlib.h 4 */ 5 6#include "gzguts.h" 7 8/* Local functions */ 9local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *)); 10local int gz_avail OF((gz_statep)); 11local int gz_look OF((gz_statep)); 12local int gz_decomp OF((gz_statep)); 13local int gz_fetch OF((gz_statep)); 14local int gz_skip OF((gz_statep, z_off64_t)); 15 16/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from 17 state->fd, and update state->eof, state->err, and state->msg as appropriate. 18 This function needs to loop on read(), since read() is not guaranteed to 19 read the number of bytes requested, depending on the type of descriptor. */ 20local int gz_load(state, buf, len, have) 21 gz_statep state; 22 unsigned char *buf; 23 unsigned len; 24 unsigned *have; 25{ 26 int ret; 27 28 *have = 0; 29 do { 30 ret = read(state->fd, buf + *have, len - *have); 31 if (ret <= 0) 32 break; 33 *have += ret; 34 } while (*have < len); 35 if (ret < 0) { 36 gz_error(state, Z_ERRNO, zstrerror()); 37 return -1; 38 } 39 if (ret == 0) 40 state->eof = 1; 41 return 0; 42} 43 44/* Load up input buffer and set eof flag if last data loaded -- return -1 on 45 error, 0 otherwise. Note that the eof flag is set when the end of the input 46 file is reached, even though there may be unused data in the buffer. Once 47 that data has been used, no more attempts will be made to read the file. 48 If strm->avail_in != 0, then the current data is moved to the beginning of 49 the input buffer, and then the remainder of the buffer is loaded with the 50 available data from the input file. */ 51local int gz_avail(state) 52 gz_statep state; 53{ 54 unsigned got; 55 z_streamp strm = &(state->strm); 56 57 if (state->err != Z_OK && state->err != Z_BUF_ERROR) 58 return -1; 59 if (state->eof == 0) { 60 if (strm->avail_in) 61 memmove(state->in, strm->next_in, strm->avail_in); 62 if (gz_load(state, state->in + strm->avail_in, 63 state->size - strm->avail_in, &got) == -1) 64 return -1; 65 strm->avail_in += got; 66 strm->next_in = state->in; 67 } 68 return 0; 69} 70 71/* Look for gzip header, set up for inflate or copy. state->x.have must be 0. 72 If this is the first time in, allocate required memory. state->how will be 73 left unchanged if there is no more input data available, will be set to COPY 74 if there is no gzip header and direct copying will be performed, or it will 75 be set to GZIP for decompression. If direct copying, then leftover input 76 data from the input buffer will be copied to the output buffer. In that 77 case, all further file reads will be directly to either the output buffer or 78 a user buffer. If decompressing, the inflate state will be initialized. 79 gz_look() will return 0 on success or -1 on failure. */ 80local int gz_look(state) 81 gz_statep state; 82{ 83 z_streamp strm = &(state->strm); 84 85 /* allocate read buffers and inflate memory */ 86 if (state->size == 0) { 87 /* allocate buffers */ 88 state->in = malloc(state->want); 89 state->out = malloc(state->want << 1); 90 if (state->in == NULL || state->out == NULL) { 91 if (state->out != NULL) 92 free(state->out); 93 if (state->in != NULL) 94 free(state->in); 95 gz_error(state, Z_MEM_ERROR, "out of memory"); 96 return -1; 97 } 98 state->size = state->want; 99 100 /* allocate inflate memory */ 101 state->strm.zalloc = Z_NULL; 102 state->strm.zfree = Z_NULL; 103 state->strm.opaque = Z_NULL; 104 state->strm.avail_in = 0; 105 state->strm.next_in = Z_NULL; 106 if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) { /* gunzip */ 107 free(state->out); 108 free(state->in); 109 state->size = 0; 110 gz_error(state, Z_MEM_ERROR, "out of memory"); 111 return -1; 112 } 113 } 114 115 /* get at least the magic bytes in the input buffer */ 116 if (strm->avail_in < 2) { 117 if (gz_avail(state) == -1) 118 return -1; 119 if (strm->avail_in == 0) 120 return 0; 121 } 122 123 /* look for gzip magic bytes -- if there, do gzip decoding (note: there is 124 a logical dilemma here when considering the case of a partially written 125 gzip file, to wit, if a single 31 byte is written, then we cannot tell 126 whether this is a single-byte file, or just a partially written gzip 127 file -- for here we assume that if a gzip file is being written, then 128 the header will be written in a single operation, so that reading a 129 single byte is sufficient indication that it is not a gzip file) */ 130 if (strm->avail_in > 1 && 131 strm->next_in[0] == 31 && strm->next_in[1] == 139) { 132 inflateReset(strm); 133 state->how = GZIP; 134 state->direct = 0; 135 return 0; 136 } 137 138 /* no gzip header -- if we were decoding gzip before, then this is trailing 139 garbage. Ignore the trailing garbage and finish. */ 140 if (state->direct == 0) { 141 strm->avail_in = 0; 142 state->eof = 1; 143 state->x.have = 0; 144 return 0; 145 } 146 147 /* doing raw i/o, copy any leftover input to output -- this assumes that 148 the output buffer is larger than the input buffer, which also assures 149 space for gzungetc() */ 150 state->x.next = state->out; 151 if (strm->avail_in) { 152 memcpy(state->x.next, strm->next_in, strm->avail_in); 153 state->x.have = strm->avail_in; 154 strm->avail_in = 0; 155 } 156 state->how = COPY; 157 state->direct = 1; 158 return 0; 159} 160 161/* Decompress from input to the provided next_out and avail_out in the state. 162 On return, state->x.have and state->x.next point to the just decompressed 163 data. If the gzip stream completes, state->how is reset to LOOK to look for 164 the next gzip stream or raw data, once state->x.have is depleted. Returns 0 165 on success, -1 on failure. */ 166local int gz_decomp(state) 167 gz_statep state; 168{ 169 int ret = Z_OK; 170 unsigned had; 171 z_streamp strm = &(state->strm); 172 173 /* fill output buffer up to end of deflate stream */ 174 had = strm->avail_out; 175 do { 176 /* get more input for inflate() */ 177 if (strm->avail_in == 0 && gz_avail(state) == -1) 178 return -1; 179 if (strm->avail_in == 0) { 180 gz_error(state, Z_BUF_ERROR, "unexpected end of file"); 181 break; 182 } 183 184 /* decompress and handle errors */ 185 ret = inflate(strm, Z_NO_FLUSH); 186 if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) { 187 gz_error(state, Z_STREAM_ERROR, 188 "internal error: inflate stream corrupt"); 189 return -1; 190 } 191 if (ret == Z_MEM_ERROR) { 192 gz_error(state, Z_MEM_ERROR, "out of memory"); 193 return -1; 194 } 195 if (ret == Z_DATA_ERROR) { /* deflate stream invalid */ 196 gz_error(state, Z_DATA_ERROR, 197 strm->msg == NULL ? "compressed data error" : strm->msg); 198 return -1; 199 } 200 } while (strm->avail_out && ret != Z_STREAM_END); 201 202 /* update available output */ 203 state->x.have = had - strm->avail_out; 204 state->x.next = strm->next_out - state->x.have; 205 206 /* if the gzip stream completed successfully, look for another */ 207 if (ret == Z_STREAM_END) 208 state->how = LOOK; 209 210 /* good decompression */ 211 return 0; 212} 213 214/* Fetch data and put it in the output buffer. Assumes state->x.have is 0. 215 Data is either copied from the input file or decompressed from the input 216 file depending on state->how. If state->how is LOOK, then a gzip header is 217 looked for to determine whether to copy or decompress. Returns -1 on error, 218 otherwise 0. gz_fetch() will leave state->how as COPY or GZIP unless the 219 end of the input file has been reached and all data has been processed. */ 220local int gz_fetch(state) 221 gz_statep state; 222{ 223 z_streamp strm = &(state->strm); 224 225 do { 226 switch(state->how) { 227 case LOOK: /* -> LOOK, COPY (only if never GZIP), or GZIP */ 228 if (gz_look(state) == -1) 229 return -1; 230 if (state->how == LOOK) 231 return 0; 232 break; 233 case COPY: /* -> COPY */ 234 if (gz_load(state, state->out, state->size << 1, &(state->x.have)) 235 == -1) 236 return -1; 237 state->x.next = state->out; 238 return 0; 239 case GZIP: /* -> GZIP or LOOK (if end of gzip stream) */ 240 strm->avail_out = state->size << 1; 241 strm->next_out = state->out; 242 if (gz_decomp(state) == -1) 243 return -1; 244 } 245 } while (state->x.have == 0 && (!state->eof || strm->avail_in)); 246 return 0; 247} 248 249/* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */ 250local int gz_skip(state, len) 251 gz_statep state; 252 z_off64_t len; 253{ 254 unsigned n; 255 256 /* skip over len bytes or reach end-of-file, whichever comes first */ 257 while (len) 258 /* skip over whatever is in output buffer */ 259 if (state->x.have) { 260 n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ? 261 (unsigned)len : state->x.have; 262 state->x.have -= n; 263 state->x.next += n; 264 state->x.pos += n; 265 len -= n; 266 } 267 268 /* output buffer empty -- return if we're at the end of the input */ 269 else if (state->eof && state->strm.avail_in == 0) 270 break; 271 272 /* need more data to skip -- load up output buffer */ 273 else { 274 /* get more output, looking for header if required */ 275 if (gz_fetch(state) == -1) 276 return -1; 277 } 278 return 0; 279} 280 281/* -- see zlib.h -- */ 282int ZEXPORT gzread(file, buf, len) 283 gzFile file; 284 voidp buf; 285 unsigned len; 286{ 287 unsigned got, n; 288 gz_statep state; 289 z_streamp strm; 290 291 /* get internal structure */ 292 if (file == NULL) 293 return -1; 294 state = (gz_statep)file; 295 strm = &(state->strm); 296 297 /* check that we're reading and that there's no (serious) error */ 298 if (state->mode != GZ_READ || 299 (state->err != Z_OK && state->err != Z_BUF_ERROR)) 300 return -1; 301 302 /* since an int is returned, make sure len fits in one, otherwise return 303 with an error (this avoids the flaw in the interface) */ 304 if ((int)len < 0) { 305 gz_error(state, Z_DATA_ERROR, "requested length does not fit in int"); 306 return -1; 307 } 308 309 /* if len is zero, avoid unnecessary operations */ 310 if (len == 0) 311 return 0; 312 313 /* process a skip request */ 314 if (state->seek) { 315 state->seek = 0; 316 if (gz_skip(state, state->skip) == -1) 317 return -1; 318 } 319 320 /* get len bytes to buf, or less than len if at the end */ 321 got = 0; 322 do { 323 /* first just try copying data from the output buffer */ 324 if (state->x.have) { 325 n = state->x.have > len ? len : state->x.have; 326 memcpy(buf, state->x.next, n); 327 state->x.next += n; 328 state->x.have -= n; 329 } 330 331 /* output buffer empty -- return if we're at the end of the input */ 332 else if (state->eof && strm->avail_in == 0) { 333 state->past = 1; /* tried to read past end */ 334 break; 335 } 336 337 /* need output data -- for small len or new stream load up our output 338 buffer */ 339 else if (state->how == LOOK || len < (state->size << 1)) { 340 /* get more output, looking for header if required */ 341 if (gz_fetch(state) == -1) 342 return -1; 343 continue; /* no progress yet -- go back to memcpy() above */ 344 /* the copy above assures that we will leave with space in the 345 output buffer, allowing at least one gzungetc() to succeed */ 346 } 347 348 /* large len -- read directly into user buffer */ 349 else if (state->how == COPY) { /* read directly */ 350 if (gz_load(state, buf, len, &n) == -1) 351 return -1; 352 } 353 354 /* large len -- decompress directly into user buffer */ 355 else { /* state->how == GZIP */ 356 strm->avail_out = len; 357 strm->next_out = buf; 358 if (gz_decomp(state) == -1) 359 return -1; 360 n = state->x.have; 361 state->x.have = 0; 362 } 363 364 /* update progress */ 365 len -= n; 366 buf = (char *)buf + n; 367 got += n; 368 state->x.pos += n; 369 } while (len); 370 371 /* return number of bytes read into user buffer (will fit in int) */ 372 return (int)got; 373} 374 375/* -- see zlib.h -- */ 376int ZEXPORT gzgetc_(file) 377 gzFile file; 378{ 379 int ret; 380 unsigned char buf[1]; 381 gz_statep state; 382 383 /* get internal structure */ 384 if (file == NULL) 385 return -1; 386 state = (gz_statep)file; 387 388 /* check that we're reading and that there's no (serious) error */ 389 if (state->mode != GZ_READ || 390 (state->err != Z_OK && state->err != Z_BUF_ERROR)) 391 return -1; 392 393 /* try output buffer (no need to check for skip request) */ 394 if (state->x.have) { 395 state->x.have--; 396 state->x.pos++; 397 return *(state->x.next)++; 398 } 399 400 /* nothing there -- try gzread() */ 401 ret = gzread(file, buf, 1); 402 return ret < 1 ? -1 : buf[0]; 403} 404 405#undef gzgetc 406int ZEXPORT gzgetc(file) 407gzFile file; 408{ 409 return gzgetc_(file); 410} 411 412/* -- see zlib.h -- */ 413int ZEXPORT gzungetc(c, file) 414 int c; 415 gzFile file; 416{ 417 gz_statep state; 418 419 /* get internal structure */ 420 if (file == NULL) 421 return -1; 422 state = (gz_statep)file; 423 424 /* check that we're reading and that there's no (serious) error */ 425 if (state->mode != GZ_READ || 426 (state->err != Z_OK && state->err != Z_BUF_ERROR)) 427 return -1; 428 429 /* process a skip request */ 430 if (state->seek) { 431 state->seek = 0; 432 if (gz_skip(state, state->skip) == -1) 433 return -1; 434 } 435 436 /* can't push EOF */ 437 if (c < 0) 438 return -1; 439 440 /* if output buffer empty, put byte at end (allows more pushing) */ 441 if (state->x.have == 0) { 442 state->x.have = 1; 443 state->x.next = state->out + (state->size << 1) - 1; 444 state->x.next[0] = c; 445 state->x.pos--; 446 state->past = 0; 447 return c; 448 } 449 450 /* if no room, give up (must have already done a gzungetc()) */ 451 if (state->x.have == (state->size << 1)) { 452 gz_error(state, Z_DATA_ERROR, "out of room to push characters"); 453 return -1; 454 } 455 456 /* slide output data if needed and insert byte before existing data */ 457 if (state->x.next == state->out) { 458 unsigned char *src = state->out + state->x.have; 459 unsigned char *dest = state->out + (state->size << 1); 460 while (src > state->out) 461 *--dest = *--src; 462 state->x.next = dest; 463 } 464 state->x.have++; 465 state->x.next--; 466 state->x.next[0] = c; 467 state->x.pos--; 468 state->past = 0; 469 return c; 470} 471 472/* -- see zlib.h -- */ 473char * ZEXPORT gzgets(file, buf, len) 474 gzFile file; 475 char *buf; 476 int len; 477{ 478 unsigned left, n; 479 char *str; 480 unsigned char *eol; 481 gz_statep state; 482 483 /* check parameters and get internal structure */ 484 if (file == NULL || buf == NULL || len < 1) 485 return NULL; 486 state = (gz_statep)file; 487 488 /* check that we're reading and that there's no (serious) error */ 489 if (state->mode != GZ_READ || 490 (state->err != Z_OK && state->err != Z_BUF_ERROR)) 491 return NULL; 492 493 /* process a skip request */ 494 if (state->seek) { 495 state->seek = 0; 496 if (gz_skip(state, state->skip) == -1) 497 return NULL; 498 } 499 500 /* copy output bytes up to new line or len - 1, whichever comes first -- 501 append a terminating zero to the string (we don't check for a zero in 502 the contents, let the user worry about that) */ 503 str = buf; 504 left = (unsigned)len - 1; 505 if (left) do { 506 /* assure that something is in the output buffer */ 507 if (state->x.have == 0 && gz_fetch(state) == -1) 508 return NULL; /* error */ 509 if (state->x.have == 0) { /* end of file */ 510 state->past = 1; /* read past end */ 511 break; /* return what we have */ 512 } 513 514 /* look for end-of-line in current output buffer */ 515 n = state->x.have > left ? left : state->x.have; 516 eol = memchr(state->x.next, '\n', n); 517 if (eol != NULL) 518 n = (unsigned)(eol - state->x.next) + 1; 519 520 /* copy through end-of-line, or remainder if not found */ 521 memcpy(buf, state->x.next, n); 522 state->x.have -= n; 523 state->x.next += n; 524 state->x.pos += n; 525 left -= n; 526 buf += n; 527 } while (left && eol == NULL); 528 529 /* return terminated string, or if nothing, end of file */ 530 if (buf == str) 531 return NULL; 532 buf[0] = 0; 533 return str; 534} 535 536/* -- see zlib.h -- */ 537int ZEXPORT gzdirect(file) 538 gzFile file; 539{ 540 gz_statep state; 541 542 /* get internal structure */ 543 if (file == NULL) 544 return 0; 545 state = (gz_statep)file; 546 547 /* if the state is not known, but we can find out, then do so (this is 548 mainly for right after a gzopen() or gzdopen()) */ 549 if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0) 550 (void)gz_look(state); 551 552 /* return 1 if transparent, 0 if processing a gzip stream */ 553 return state->direct; 554} 555 556/* -- see zlib.h -- */ 557int ZEXPORT gzclose_r(file) 558 gzFile file; 559{ 560 int ret, err; 561 gz_statep state; 562 563 /* get internal structure */ 564 if (file == NULL) 565 return Z_STREAM_ERROR; 566 state = (gz_statep)file; 567 568 /* check that we're reading */ 569 if (state->mode != GZ_READ) 570 return Z_STREAM_ERROR; 571 572 /* free memory and close file */ 573 if (state->size) { 574 inflateEnd(&(state->strm)); 575 free(state->out); 576 free(state->in); 577 } 578 err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK; 579 gz_error(state, Z_OK, NULL); 580 free(state->path); 581 ret = close(state->fd); 582 free(state); 583 return ret ? Z_ERRNO : err; 584} 585