usr/src/boot/lib/libz/gzread.c

   1 /* gzread.c -- zlib functions for reading gzip files
   2  * Copyright (C) 2004, 2005, 2010, 2011, 2012, 2013 Mark Adler
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  */
   5
   6 /* $FreeBSD$ */
   7
   8 #include "gzguts.h"
   9 #include <unistd.h>
  10
  11 /* Local functions */
  12 local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
  13 local int gz_avail OF((gz_statep));
  14 local int gz_look OF((gz_statep));
  15 local int gz_decomp OF((gz_statep));
  16 local int gz_fetch OF((gz_statep));
  17 local int gz_skip OF((gz_statep, z_off64_t));
  18
  19 /* Use read() to load a buffer -- return -1 on error, otherwise 0.  Read from
  20    state->fd, and update state->eof, state->err, and state->msg as appropriate.
  21    This function needs to loop on read(), since read() is not guaranteed to
  22    read the number of bytes requested, depending on the type of descriptor. */
  23 local int gz_load(state, buf, len, have)
  24     gz_statep state;
  25     unsigned char *buf;
  26     unsigned len;
  27     unsigned *have;
  28 {
  29     int ret;
  30
  31     *have = 0;
  32     do {
  33         ret = read(state->fd, buf + *have, len - *have);
  34         if (ret <= 0)
  35             break;
  36         *have += ret;
  37     } while (*have < len);
  38     if (ret < 0) {
  39         gz_error(state, Z_ERRNO, zstrerror());
  40         return -1;
  41     }
  42     if (ret == 0)
  43         state->eof = 1;
  44     return 0;
  45 }
  46
  47 /* Load up input buffer and set eof flag if last data loaded -- return -1 on
  48    error, 0 otherwise.  Note that the eof flag is set when the end of the input
  49    file is reached, even though there may be unused data in the buffer.  Once
  50    that data has been used, no more attempts will be made to read the file.
  51    If strm->avail_in != 0, then the current data is moved to the beginning of
  52    the input buffer, and then the remainder of the buffer is loaded with the
  53    available data from the input file. */
  54 local int gz_avail(state)
  55     gz_statep state;
  56 {
  57     unsigned got;
  58     z_streamp strm = &(state->strm);
  59
  60     if (state->err != Z_OK && state->err != Z_BUF_ERROR)
  61         return -1;
  62     if (state->eof == 0) {
  63         if (strm->avail_in) {       /* copy what's there to the start */
  64             unsigned char *p = state->in;
  65             unsigned const char *q = strm->next_in;
  66             unsigned n = strm->avail_in;
  67             do {
  68                 *p++ = *q++;
  69             } while (--n);
  70         }
  71         if (gz_load(state, state->in + strm->avail_in,
  72                     state->size - strm->avail_in, &got) == -1)
  73             return -1;
  74         strm->avail_in += got;
  75         strm->next_in = state->in;
  76     }
  77     return 0;
  78 }
  79
  80 /* Look for gzip header, set up for inflate or copy.  state->x.have must be 0.
  81    If this is the first time in, allocate required memory.  state->how will be
  82    left unchanged if there is no more input data available, will be set to COPY
  83    if there is no gzip header and direct copying will be performed, or it will
  84    be set to GZIP for decompression.  If direct copying, then leftover input
  85    data from the input buffer will be copied to the output buffer.  In that
  86    case, all further file reads will be directly to either the output buffer or
  87    a user buffer.  If decompressing, the inflate state will be initialized.
  88    gz_look() will return 0 on success or -1 on failure. */
  89 local int gz_look(state)
  90     gz_statep state;
  91 {
  92     z_streamp strm = &(state->strm);
  93
  94     /* allocate read buffers and inflate memory */
  95     if (state->size == 0) {
  96         /* allocate buffers */
  97         state->in = (unsigned char *)malloc(state->want);
  98         state->out = (unsigned char *)malloc(state->want << 1);
  99         if (state->in == NULL || state->out == NULL) {
 100             if (state->out != NULL)
 101                 free(state->out);
 102             if (state->in != NULL)
 103                 free(state->in);
 104             gz_error(state, Z_MEM_ERROR, "out of memory");
 105             return -1;
 106         }
 107         state->size = state->want;
 108
 109         /* allocate inflate memory */
 110         state->strm.zalloc = Z_NULL;
 111         state->strm.zfree = Z_NULL;
 112         state->strm.opaque = Z_NULL;
 113         state->strm.avail_in = 0;
 114         state->strm.next_in = Z_NULL;
 115         if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) {    /* gunzip */
 116             free(state->out);
 117             free(state->in);
 118             state->size = 0;
 119             gz_error(state, Z_MEM_ERROR, "out of memory");
 120             return -1;
 121         }
 122     }
 123
 124     /* get at least the magic bytes in the input buffer */
 125     if (strm->avail_in < 2) {
 126         if (gz_avail(state) == -1)
 127             return -1;
 128         if (strm->avail_in == 0)
 129             return 0;
 130     }
 131
 132     /* look for gzip magic bytes -- if there, do gzip decoding (note: there is
 133        a logical dilemma here when considering the case of a partially written
 134        gzip file, to wit, if a single 31 byte is written, then we cannot tell
 135        whether this is a single-byte file, or just a partially written gzip
 136        file -- for here we assume that if a gzip file is being written, then
 137        the header will be written in a single operation, so that reading a
 138        single byte is sufficient indication that it is not a gzip file) */
 139     if (strm->avail_in > 1 &&
 140             strm->next_in[0] == 31 && strm->next_in[1] == 139) {
 141         inflateReset(strm);
 142         state->how = GZIP;
 143         state->direct = 0;
 144         return 0;
 145     }
 146
 147     /* no gzip header -- if we were decoding gzip before, then this is trailing
 148        garbage.  Ignore the trailing garbage and finish. */
 149     if (state->direct == 0) {
 150         strm->avail_in = 0;
 151         state->eof = 1;
 152         state->x.have = 0;
 153         return 0;
 154     }
 155
 156     /* doing raw i/o, copy any leftover input to output -- this assumes that
 157        the output buffer is larger than the input buffer, which also assures
 158        space for gzungetc() */
 159     state->x.next = state->out;
 160     if (strm->avail_in) {
 161         memcpy(state->x.next, strm->next_in, strm->avail_in);
 162         state->x.have = strm->avail_in;
 163         strm->avail_in = 0;
 164     }
 165     state->how = COPY;
 166     state->direct = 1;
 167     return 0;
 168 }
 169
 170 /* Decompress from input to the provided next_out and avail_out in the state.
 171    On return, state->x.have and state->x.next point to the just decompressed
 172    data.  If the gzip stream completes, state->how is reset to LOOK to look for
 173    the next gzip stream or raw data, once state->x.have is depleted.  Returns 0
 174    on success, -1 on failure. */
 175 local int gz_decomp(state)
 176     gz_statep state;
 177 {
 178     int ret = Z_OK;
 179     unsigned had;
 180     z_streamp strm = &(state->strm);
 181
 182     /* fill output buffer up to end of deflate stream */
 183     had = strm->avail_out;
 184     do {
 185         /* get more input for inflate() */
 186         if (strm->avail_in == 0 && gz_avail(state) == -1)
 187             return -1;
 188         if (strm->avail_in == 0) {
 189             gz_error(state, Z_BUF_ERROR, "unexpected end of file");
 190             break;
 191         }
 192
 193         /* decompress and handle errors */
 194         ret = inflate(strm, Z_NO_FLUSH);
 195         if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
 196             gz_error(state, Z_STREAM_ERROR,
 197                      "internal error: inflate stream corrupt");
 198             return -1;
 199         }
 200         if (ret == Z_MEM_ERROR) {
 201             gz_error(state, Z_MEM_ERROR, "out of memory");
 202             return -1;
 203         }
 204         if (ret == Z_DATA_ERROR) {              /* deflate stream invalid */
 205             gz_error(state, Z_DATA_ERROR,
 206                      strm->msg == NULL ? "compressed data error" : strm->msg);
 207             return -1;
 208         }
 209     } while (strm->avail_out && ret != Z_STREAM_END);
 210
 211     /* update available output */
 212     state->x.have = had - strm->avail_out;
 213     state->x.next = strm->next_out - state->x.have;
 214
 215     /* if the gzip stream completed successfully, look for another */
 216     if (ret == Z_STREAM_END)
 217         state->how = LOOK;
 218
 219     /* good decompression */
 220     return 0;
 221 }
 222
 223 /* Fetch data and put it in the output buffer.  Assumes state->x.have is 0.
 224    Data is either copied from the input file or decompressed from the input
 225    file depending on state->how.  If state->how is LOOK, then a gzip header is
 226    looked for to determine whether to copy or decompress.  Returns -1 on error,
 227    otherwise 0.  gz_fetch() will leave state->how as COPY or GZIP unless the
 228    end of the input file has been reached and all data has been processed.  */
 229 local int gz_fetch(state)
 230     gz_statep state;
 231 {
 232     z_streamp strm = &(state->strm);
 233
 234     do {
 235         switch(state->how) {
 236         case LOOK:      /* -> LOOK, COPY (only if never GZIP), or GZIP */
 237             if (gz_look(state) == -1)
 238                 return -1;
 239             if (state->how == LOOK)
 240                 return 0;
 241             break;
 242         case COPY:      /* -> COPY */
 243             if (gz_load(state, state->out, state->size << 1, &(state->x.have))
 244                     == -1)
 245                 return -1;
 246             state->x.next = state->out;
 247             return 0;
 248         case GZIP:      /* -> GZIP or LOOK (if end of gzip stream) */
 249             strm->avail_out = state->size << 1;
 250             strm->next_out = state->out;
 251             if (gz_decomp(state) == -1)
 252                 return -1;
 253         }
 254     } while (state->x.have == 0 && (!state->eof || strm->avail_in));
 255     return 0;
 256 }
 257
 258 /* Skip len uncompressed bytes of output.  Return -1 on error, 0 on success. */
 259 local int gz_skip(state, len)
 260     gz_statep state;
 261     z_off64_t len;
 262 {
 263     unsigned n;
 264
 265     /* skip over len bytes or reach end-of-file, whichever comes first */
 266     while (len)
 267         /* skip over whatever is in output buffer */
 268         if (state->x.have) {
 269             n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
 270                 (unsigned)len : state->x.have;
 271             state->x.have -= n;
 272             state->x.next += n;
 273             state->x.pos += n;
 274             len -= n;
 275         }
 276
 277         /* output buffer empty -- return if we're at the end of the input */
 278         else if (state->eof && state->strm.avail_in == 0)
 279             break;
 280
 281         /* need more data to skip -- load up output buffer */
 282         else {
 283             /* get more output, looking for header if required */
 284             if (gz_fetch(state) == -1)
 285                 return -1;
 286         }
 287     return 0;
 288 }
 289
 290 /* -- see zlib.h -- */
 291 int ZEXPORT gzread(file, buf, len)
 292     gzFile file;
 293     voidp buf;
 294     unsigned len;
 295 {
 296     unsigned got, n;
 297     gz_statep state;
 298     z_streamp strm;
 299
 300     /* get internal structure */
 301     if (file == NULL)
 302         return -1;
 303     state = (gz_statep)file;
 304     strm = &(state->strm);
 305
 306     /* check that we're reading and that there's no (serious) error */
 307     if (state->mode != GZ_READ ||
 308             (state->err != Z_OK && state->err != Z_BUF_ERROR))
 309         return -1;
 310
 311     /* since an int is returned, make sure len fits in one, otherwise return
 312        with an error (this avoids the flaw in the interface) */
 313     if ((int)len < 0) {
 314         gz_error(state, Z_DATA_ERROR, "requested length does not fit in int");
 315         return -1;
 316     }
 317
 318     /* if len is zero, avoid unnecessary operations */
 319     if (len == 0)
 320         return 0;
 321
 322     /* process a skip request */
 323     if (state->seek) {
 324         state->seek = 0;
 325         if (gz_skip(state, state->skip) == -1)
 326             return -1;
 327     }
 328
 329     /* get len bytes to buf, or less than len if at the end */
 330     got = 0;
 331     do {
 332         /* first just try copying data from the output buffer */
 333         if (state->x.have) {
 334             n = state->x.have > len ? len : state->x.have;
 335             memcpy(buf, state->x.next, n);
 336             state->x.next += n;
 337             state->x.have -= n;
 338         }
 339
 340         /* output buffer empty -- return if we're at the end of the input */
 341         else if (state->eof && strm->avail_in == 0) {
 342             state->past = 1;        /* tried to read past end */
 343             break;
 344         }
 345
 346         /* need output data -- for small len or new stream load up our output
 347            buffer */
 348         else if (state->how == LOOK || len < (state->size << 1)) {
 349             /* get more output, looking for header if required */
 350             if (gz_fetch(state) == -1)
 351                 return -1;
 352             continue;       /* no progress yet -- go back to copy above */
 353             /* the copy above assures that we will leave with space in the
 354                output buffer, allowing at least one gzungetc() to succeed */
 355         }
 356
 357         /* large len -- read directly into user buffer */
 358         else if (state->how == COPY) {      /* read directly */
 359             if (gz_load(state, (unsigned char *)buf, len, &n) == -1)
 360                 return -1;
 361         }
 362
 363         /* large len -- decompress directly into user buffer */
 364         else {  /* state->how == GZIP */
 365             strm->avail_out = len;
 366             strm->next_out = (unsigned char *)buf;
 367             if (gz_decomp(state) == -1)
 368                 return -1;
 369             n = state->x.have;
 370             state->x.have = 0;
 371         }
 372
 373         /* update progress */
 374         len -= n;
 375         buf = (char *)buf + n;
 376         got += n;
 377         state->x.pos += n;
 378     } while (len);
 379
 380     /* return number of bytes read into user buffer (will fit in int) */
 381     return (int)got;
 382 }
 383
 384 /* -- see zlib.h -- */
 385 #ifdef Z_PREFIX_SET
 386 #  undef z_gzgetc
 387 #else
 388 #  undef gzgetc
 389 #endif
 390 int ZEXPORT gzgetc(file)
 391     gzFile file;
 392 {
 393     int ret;
 394     unsigned char buf[1];
 395     gz_statep state;
 396
 397     /* get internal structure */
 398     if (file == NULL)
 399         return -1;
 400     state = (gz_statep)file;
 401
 402     /* check that we're reading and that there's no (serious) error */
 403     if (state->mode != GZ_READ ||
 404         (state->err != Z_OK && state->err != Z_BUF_ERROR))
 405         return -1;
 406
 407     /* try output buffer (no need to check for skip request) */
 408     if (state->x.have) {
 409         state->x.have--;
 410         state->x.pos++;
 411         return *(state->x.next)++;
 412     }
 413
 414     /* nothing there -- try gzread() */
 415     ret = gzread(file, buf, 1);
 416     return ret < 1 ? -1 : buf[0];
 417 }
 418
 419 int ZEXPORT gzgetc_(file)
 420 gzFile file;
 421 {
 422     return gzgetc(file);
 423 }
 424
 425 /* -- see zlib.h -- */
 426 int ZEXPORT gzungetc(c, file)
 427     int c;
 428     gzFile file;
 429 {
 430     gz_statep state;
 431
 432     /* get internal structure */
 433     if (file == NULL)
 434         return -1;
 435     state = (gz_statep)file;
 436
 437     /* check that we're reading and that there's no (serious) error */
 438     if (state->mode != GZ_READ ||
 439         (state->err != Z_OK && state->err != Z_BUF_ERROR))
 440         return -1;
 441
 442     /* process a skip request */
 443     if (state->seek) {
 444         state->seek = 0;
 445         if (gz_skip(state, state->skip) == -1)
 446             return -1;
 447     }
 448
 449     /* can't push EOF */
 450     if (c < 0)
 451         return -1;
 452
 453     /* if output buffer empty, put byte at end (allows more pushing) */
 454     if (state->x.have == 0) {
 455         state->x.have = 1;
 456         state->x.next = state->out + (state->size << 1) - 1;
 457         state->x.next[0] = c;
 458         state->x.pos--;
 459         state->past = 0;
 460         return c;
 461     }
 462
 463     /* if no room, give up (must have already done a gzungetc()) */
 464     if (state->x.have == (state->size << 1)) {
 465         gz_error(state, Z_DATA_ERROR, "out of room to push characters");
 466         return -1;
 467     }
 468
 469     /* slide output data if needed and insert byte before existing data */
 470     if (state->x.next == state->out) {
 471         unsigned char *src = state->out + state->x.have;
 472         unsigned char *dest = state->out + (state->size << 1);
 473         while (src > state->out)
 474             *--dest = *--src;
 475         state->x.next = dest;
 476     }
 477     state->x.have++;
 478     state->x.next--;
 479     state->x.next[0] = c;
 480     state->x.pos--;
 481     state->past = 0;
 482     return c;
 483 }
 484
 485 /* -- see zlib.h -- */
 486 char * ZEXPORT gzgets(file, buf, len)
 487     gzFile file;
 488     char *buf;
 489     int len;
 490 {
 491     unsigned left, n;
 492     char *str;
 493     unsigned char *eol;
 494     gz_statep state;
 495
 496     /* check parameters and get internal structure */
 497     if (file == NULL || buf == NULL || len < 1)
 498         return NULL;
 499     state = (gz_statep)file;
 500
 501     /* check that we're reading and that there's no (serious) error */
 502     if (state->mode != GZ_READ ||
 503         (state->err != Z_OK && state->err != Z_BUF_ERROR))
 504         return NULL;
 505
 506     /* process a skip request */
 507     if (state->seek) {
 508         state->seek = 0;
 509         if (gz_skip(state, state->skip) == -1)
 510             return NULL;
 511     }
 512
 513     /* copy output bytes up to new line or len - 1, whichever comes first --
 514        append a terminating zero to the string (we don't check for a zero in
 515        the contents, let the user worry about that) */
 516     str = buf;
 517     left = (unsigned)len - 1;
 518     if (left) do {
 519         /* assure that something is in the output buffer */
 520         if (state->x.have == 0 && gz_fetch(state) == -1)
 521             return NULL;                /* error */
 522         if (state->x.have == 0) {       /* end of file */
 523             state->past = 1;            /* read past end */
 524             break;                      /* return what we have */
 525         }
 526
 527         /* look for end-of-line in current output buffer */
 528         n = state->x.have > left ? left : state->x.have;
 529         eol = (unsigned char *)memchr(state->x.next, '\n', n);
 530         if (eol != NULL)
 531             n = (unsigned)(eol - state->x.next) + 1;
 532
 533         /* copy through end-of-line, or remainder if not found */
 534         memcpy(buf, state->x.next, n);
 535         state->x.have -= n;
 536         state->x.next += n;
 537         state->x.pos += n;
 538         left -= n;
 539         buf += n;
 540     } while (left && eol == NULL);
 541
 542     /* return terminated string, or if nothing, end of file */
 543     if (buf == str)
 544         return NULL;
 545     buf[0] = 0;
 546     return str;
 547 }
 548
 549 /* -- see zlib.h -- */
 550 int ZEXPORT gzdirect(file)
 551     gzFile file;
 552 {
 553     gz_statep state;
 554
 555     /* get internal structure */
 556     if (file == NULL)
 557         return 0;
 558     state = (gz_statep)file;
 559
 560     /* if the state is not known, but we can find out, then do so (this is
 561        mainly for right after a gzopen() or gzdopen()) */
 562     if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
 563         (void)gz_look(state);
 564
 565     /* return 1 if transparent, 0 if processing a gzip stream */
 566     return state->direct;
 567 }
 568
 569 /* -- see zlib.h -- */
 570 int ZEXPORT gzclose_r(file)
 571     gzFile file;
 572 {
 573     int ret, err;
 574     gz_statep state;
 575
 576     /* get internal structure */
 577     if (file == NULL)
 578         return Z_STREAM_ERROR;
 579     state = (gz_statep)file;
 580
 581     /* check that we're reading */
 582     if (state->mode != GZ_READ)
 583         return Z_STREAM_ERROR;
 584
 585     /* free memory and close file */
 586     if (state->size) {
 587         inflateEnd(&(state->strm));
 588         free(state->out);
 589         free(state->in);
 590     }
 591     err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
 592     gz_error(state, Z_OK, NULL);
 593     free(state->path);
 594     ret = close(state->fd);
 595     free(state);
 596     return ret ? Z_ERRNO : err;
 597 }