Annotation of embedaddon/rsync/zlib/inflate.c, revision 1.1.1.2

1.1       misho       1: /* inflate.c -- zlib decompression
1.1.1.2 ! misho       2:  * Copyright (C) 1995-2012 Mark Adler
1.1       misho       3:  * For conditions of distribution and use, see copyright notice in zlib.h
                      4:  */
                      5: 
                      6: /*
                      7:  * Change history:
                      8:  *
                      9:  * 1.2.beta0    24 Nov 2002
                     10:  * - First version -- complete rewrite of inflate to simplify code, avoid
                     11:  *   creation of window when not needed, minimize use of window when it is
                     12:  *   needed, make inffast.c even faster, implement gzip decoding, and to
                     13:  *   improve code readability and style over the previous zlib inflate code
                     14:  *
                     15:  * 1.2.beta1    25 Nov 2002
                     16:  * - Use pointers for available input and output checking in inffast.c
                     17:  * - Remove input and output counters in inffast.c
                     18:  * - Change inffast.c entry and loop from avail_in >= 7 to >= 6
                     19:  * - Remove unnecessary second byte pull from length extra in inffast.c
                     20:  * - Unroll direct copy to three copies per loop in inffast.c
                     21:  *
                     22:  * 1.2.beta2    4 Dec 2002
                     23:  * - Change external routine names to reduce potential conflicts
                     24:  * - Correct filename to inffixed.h for fixed tables in inflate.c
                     25:  * - Make hbuf[] unsigned char to match parameter type in inflate.c
                     26:  * - Change strm->next_out[-state->offset] to *(strm->next_out - state->offset)
                     27:  *   to avoid negation problem on Alphas (64 bit) in inflate.c
                     28:  *
                     29:  * 1.2.beta3    22 Dec 2002
                     30:  * - Add comments on state->bits assertion in inffast.c
                     31:  * - Add comments on op field in inftrees.h
                     32:  * - Fix bug in reuse of allocated window after inflateReset()
                     33:  * - Remove bit fields--back to byte structure for speed
                     34:  * - Remove distance extra == 0 check in inflate_fast()--only helps for lengths
                     35:  * - Change post-increments to pre-increments in inflate_fast(), PPC biased?
                     36:  * - Add compile time option, POSTINC, to use post-increments instead (Intel?)
                     37:  * - Make MATCH copy in inflate() much faster for when inflate_fast() not used
                     38:  * - Use local copies of stream next and avail values, as well as local bit
                     39:  *   buffer and bit count in inflate()--for speed when inflate_fast() not used
                     40:  *
                     41:  * 1.2.beta4    1 Jan 2003
                     42:  * - Split ptr - 257 statements in inflate_table() to avoid compiler warnings
                     43:  * - Move a comment on output buffer sizes from inffast.c to inflate.c
                     44:  * - Add comments in inffast.c to introduce the inflate_fast() routine
                     45:  * - Rearrange window copies in inflate_fast() for speed and simplification
                     46:  * - Unroll last copy for window match in inflate_fast()
                     47:  * - Use local copies of window variables in inflate_fast() for speed
1.1.1.2 ! misho      48:  * - Pull out common wnext == 0 case for speed in inflate_fast()
1.1       misho      49:  * - Make op and len in inflate_fast() unsigned for consistency
                     50:  * - Add FAR to lcode and dcode declarations in inflate_fast()
                     51:  * - Simplified bad distance check in inflate_fast()
                     52:  * - Added inflateBackInit(), inflateBack(), and inflateBackEnd() in new
                     53:  *   source file infback.c to provide a call-back interface to inflate for
                     54:  *   programs like gzip and unzip -- uses window as output buffer to avoid
                     55:  *   window copying
                     56:  *
                     57:  * 1.2.beta5    1 Jan 2003
                     58:  * - Improved inflateBack() interface to allow the caller to provide initial
                     59:  *   input in strm.
                     60:  * - Fixed stored blocks bug in inflateBack()
                     61:  *
                     62:  * 1.2.beta6    4 Jan 2003
                     63:  * - Added comments in inffast.c on effectiveness of POSTINC
                     64:  * - Typecasting all around to reduce compiler warnings
                     65:  * - Changed loops from while (1) or do {} while (1) to for (;;), again to
                     66:  *   make compilers happy
                     67:  * - Changed type of window in inflateBackInit() to unsigned char *
                     68:  *
                     69:  * 1.2.beta7    27 Jan 2003
                     70:  * - Changed many types to unsigned or unsigned short to avoid warnings
                     71:  * - Added inflateCopy() function
                     72:  *
                     73:  * 1.2.0        9 Mar 2003
                     74:  * - Changed inflateBack() interface to provide separate opaque descriptors
                     75:  *   for the in() and out() functions
                     76:  * - Changed inflateBack() argument and in_func typedef to swap the length
                     77:  *   and buffer address return values for the input function
                     78:  * - Check next_in and next_out for Z_NULL on entry to inflate()
                     79:  *
                     80:  * The history for versions after 1.2.0 are in ChangeLog in zlib distribution.
                     81:  */
                     82: 
                     83: #include "zutil.h"
                     84: #include "inftrees.h"
                     85: #include "inflate.h"
                     86: #include "inffast.h"
                     87: 
                     88: #ifdef MAKEFIXED
                     89: #  ifndef BUILDFIXED
                     90: #    define BUILDFIXED
                     91: #  endif
                     92: #endif
                     93: 
                     94: /* function prototypes */
                     95: local void fixedtables OF((struct inflate_state FAR *state));
1.1.1.2 ! misho      96: local int updatewindow OF((z_streamp strm, const unsigned char FAR *end,
        !            97:                            unsigned copy));
1.1       misho      98: #ifdef BUILDFIXED
                     99:    void makefixed OF((void));
                    100: #endif
1.1.1.2 ! misho     101: local unsigned syncsearch OF((unsigned FAR *have, const unsigned char FAR *buf,
1.1       misho     102:                               unsigned len));
                    103: 
1.1.1.2 ! misho     104: int ZEXPORT inflateResetKeep(strm)
1.1       misho     105: z_streamp strm;
                    106: {
                    107:     struct inflate_state FAR *state;
                    108: 
                    109:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                    110:     state = (struct inflate_state FAR *)strm->state;
                    111:     strm->total_in = strm->total_out = state->total = 0;
                    112:     strm->msg = Z_NULL;
1.1.1.2 ! misho     113:     if (state->wrap)        /* to support ill-conceived Java test suite */
        !           114:         strm->adler = state->wrap & 1;
1.1       misho     115:     state->mode = HEAD;
                    116:     state->last = 0;
                    117:     state->havedict = 0;
                    118:     state->dmax = 32768U;
                    119:     state->head = Z_NULL;
                    120:     state->hold = 0;
                    121:     state->bits = 0;
                    122:     state->lencode = state->distcode = state->next = state->codes;
1.1.1.2 ! misho     123:     state->sane = 1;
        !           124:     state->back = -1;
1.1       misho     125:     Tracev((stderr, "inflate: reset\n"));
                    126:     return Z_OK;
                    127: }
                    128: 
1.1.1.2 ! misho     129: int ZEXPORT inflateReset(strm)
1.1       misho     130: z_streamp strm;
                    131: {
                    132:     struct inflate_state FAR *state;
                    133: 
                    134:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                    135:     state = (struct inflate_state FAR *)strm->state;
1.1.1.2 ! misho     136:     state->wsize = 0;
        !           137:     state->whave = 0;
        !           138:     state->wnext = 0;
        !           139:     return inflateResetKeep(strm);
        !           140: }
        !           141: 
        !           142: int ZEXPORT inflateReset2(strm, windowBits)
        !           143: z_streamp strm;
        !           144: int windowBits;
        !           145: {
        !           146:     int wrap;
        !           147:     struct inflate_state FAR *state;
        !           148: 
        !           149:     /* get the state */
        !           150:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
        !           151:     state = (struct inflate_state FAR *)strm->state;
        !           152: 
        !           153:     /* extract wrap request from windowBits parameter */
        !           154:     if (windowBits < 0) {
        !           155:         wrap = 0;
        !           156:         windowBits = -windowBits;
        !           157:     }
        !           158:     else {
        !           159:         wrap = (windowBits >> 4) + 1;
        !           160: #ifdef GUNZIP
        !           161:         if (windowBits < 48)
        !           162:             windowBits &= 15;
        !           163: #endif
        !           164:     }
        !           165: 
        !           166:     /* set number of window bits, free window if different */
        !           167:     if (windowBits && (windowBits < 8 || windowBits > 15))
        !           168:         return Z_STREAM_ERROR;
        !           169:     if (state->window != Z_NULL && state->wbits != (unsigned)windowBits) {
        !           170:         ZFREE(strm, state->window);
        !           171:         state->window = Z_NULL;
        !           172:     }
        !           173: 
        !           174:     /* update state and reset the rest of it */
        !           175:     state->wrap = wrap;
        !           176:     state->wbits = (unsigned)windowBits;
        !           177:     return inflateReset(strm);
1.1       misho     178: }
                    179: 
                    180: int ZEXPORT inflateInit2_(strm, windowBits, version, stream_size)
                    181: z_streamp strm;
                    182: int windowBits;
                    183: const char *version;
                    184: int stream_size;
                    185: {
1.1.1.2 ! misho     186:     int ret;
1.1       misho     187:     struct inflate_state FAR *state;
                    188: 
                    189:     if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
                    190:         stream_size != (int)(sizeof(z_stream)))
                    191:         return Z_VERSION_ERROR;
                    192:     if (strm == Z_NULL) return Z_STREAM_ERROR;
                    193:     strm->msg = Z_NULL;                 /* in case we return an error */
                    194:     if (strm->zalloc == (alloc_func)0) {
1.1.1.2 ! misho     195: #ifdef Z_SOLO
        !           196:         return Z_STREAM_ERROR;
        !           197: #else
1.1       misho     198:         strm->zalloc = zcalloc;
                    199:         strm->opaque = (voidpf)0;
1.1.1.2 ! misho     200: #endif
1.1       misho     201:     }
1.1.1.2 ! misho     202:     if (strm->zfree == (free_func)0)
        !           203: #ifdef Z_SOLO
        !           204:         return Z_STREAM_ERROR;
        !           205: #else
        !           206:         strm->zfree = zcfree;
        !           207: #endif
1.1       misho     208:     state = (struct inflate_state FAR *)
                    209:             ZALLOC(strm, 1, sizeof(struct inflate_state));
                    210:     if (state == Z_NULL) return Z_MEM_ERROR;
                    211:     Tracev((stderr, "inflate: allocated\n"));
                    212:     strm->state = (struct internal_state FAR *)state;
1.1.1.2 ! misho     213:     state->window = Z_NULL;
        !           214:     ret = inflateReset2(strm, windowBits);
        !           215:     if (ret != Z_OK) {
1.1       misho     216:         ZFREE(strm, state);
                    217:         strm->state = Z_NULL;
                    218:     }
1.1.1.2 ! misho     219:     return ret;
1.1       misho     220: }
                    221: 
                    222: int ZEXPORT inflateInit_(strm, version, stream_size)
                    223: z_streamp strm;
                    224: const char *version;
                    225: int stream_size;
                    226: {
                    227:     return inflateInit2_(strm, DEF_WBITS, version, stream_size);
                    228: }
                    229: 
1.1.1.2 ! misho     230: int ZEXPORT inflatePrime(strm, bits, value)
        !           231: z_streamp strm;
        !           232: int bits;
        !           233: int value;
        !           234: {
        !           235:     struct inflate_state FAR *state;
        !           236: 
        !           237:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
        !           238:     state = (struct inflate_state FAR *)strm->state;
        !           239:     if (bits < 0) {
        !           240:         state->hold = 0;
        !           241:         state->bits = 0;
        !           242:         return Z_OK;
        !           243:     }
        !           244:     if (bits > 16 || state->bits + bits > 32) return Z_STREAM_ERROR;
        !           245:     value &= (1L << bits) - 1;
        !           246:     state->hold += value << state->bits;
        !           247:     state->bits += bits;
        !           248:     return Z_OK;
        !           249: }
        !           250: 
1.1       misho     251: /*
                    252:    Return state with length and distance decoding tables and index sizes set to
                    253:    fixed code decoding.  Normally this returns fixed tables from inffixed.h.
                    254:    If BUILDFIXED is defined, then instead this routine builds the tables the
                    255:    first time it's called, and returns those tables the first time and
                    256:    thereafter.  This reduces the size of the code by about 2K bytes, in
                    257:    exchange for a little execution time.  However, BUILDFIXED should not be
                    258:    used for threaded applications, since the rewriting of the tables and virgin
                    259:    may not be thread-safe.
                    260:  */
                    261: local void fixedtables(state)
                    262: struct inflate_state FAR *state;
                    263: {
                    264: #ifdef BUILDFIXED
                    265:     static int virgin = 1;
                    266:     static code *lenfix, *distfix;
                    267:     static code fixed[544];
                    268: 
                    269:     /* build fixed huffman tables if first call (may not be thread safe) */
                    270:     if (virgin) {
                    271:         unsigned sym, bits;
                    272:         static code *next;
                    273: 
                    274:         /* literal/length table */
                    275:         sym = 0;
                    276:         while (sym < 144) state->lens[sym++] = 8;
                    277:         while (sym < 256) state->lens[sym++] = 9;
                    278:         while (sym < 280) state->lens[sym++] = 7;
                    279:         while (sym < 288) state->lens[sym++] = 8;
                    280:         next = fixed;
                    281:         lenfix = next;
                    282:         bits = 9;
                    283:         inflate_table(LENS, state->lens, 288, &(next), &(bits), state->work);
                    284: 
                    285:         /* distance table */
                    286:         sym = 0;
                    287:         while (sym < 32) state->lens[sym++] = 5;
                    288:         distfix = next;
                    289:         bits = 5;
                    290:         inflate_table(DISTS, state->lens, 32, &(next), &(bits), state->work);
                    291: 
                    292:         /* do this just once */
                    293:         virgin = 0;
                    294:     }
                    295: #else /* !BUILDFIXED */
                    296: #   include "inffixed.h"
                    297: #endif /* BUILDFIXED */
                    298:     state->lencode = lenfix;
                    299:     state->lenbits = 9;
                    300:     state->distcode = distfix;
                    301:     state->distbits = 5;
                    302: }
                    303: 
                    304: #ifdef MAKEFIXED
                    305: #include <stdio.h>
                    306: 
                    307: /*
                    308:    Write out the inffixed.h that is #include'd above.  Defining MAKEFIXED also
                    309:    defines BUILDFIXED, so the tables are built on the fly.  makefixed() writes
                    310:    those tables to stdout, which would be piped to inffixed.h.  A small program
                    311:    can simply call makefixed to do this:
                    312: 
                    313:     void makefixed(void);
                    314: 
                    315:     int main(void)
                    316:     {
                    317:         makefixed();
                    318:         return 0;
                    319:     }
                    320: 
                    321:    Then that can be linked with zlib built with MAKEFIXED defined and run:
                    322: 
                    323:     a.out > inffixed.h
                    324:  */
                    325: void makefixed()
                    326: {
                    327:     unsigned low, size;
                    328:     struct inflate_state state;
                    329: 
                    330:     fixedtables(&state);
                    331:     puts("    /* inffixed.h -- table for decoding fixed codes");
                    332:     puts("     * Generated automatically by makefixed().");
                    333:     puts("     */");
                    334:     puts("");
                    335:     puts("    /* WARNING: this file should *not* be used by applications.");
                    336:     puts("       It is part of the implementation of this library and is");
                    337:     puts("       subject to change. Applications should only use zlib.h.");
                    338:     puts("     */");
                    339:     puts("");
                    340:     size = 1U << 9;
                    341:     printf("    static const code lenfix[%u] = {", size);
                    342:     low = 0;
                    343:     for (;;) {
                    344:         if ((low % 7) == 0) printf("\n        ");
1.1.1.2 ! misho     345:         printf("{%u,%u,%d}", (low & 127) == 99 ? 64 : state.lencode[low].op,
        !           346:                state.lencode[low].bits, state.lencode[low].val);
1.1       misho     347:         if (++low == size) break;
                    348:         putchar(',');
                    349:     }
                    350:     puts("\n    };");
                    351:     size = 1U << 5;
                    352:     printf("\n    static const code distfix[%u] = {", size);
                    353:     low = 0;
                    354:     for (;;) {
                    355:         if ((low % 6) == 0) printf("\n        ");
                    356:         printf("{%u,%u,%d}", state.distcode[low].op, state.distcode[low].bits,
                    357:                state.distcode[low].val);
                    358:         if (++low == size) break;
                    359:         putchar(',');
                    360:     }
                    361:     puts("\n    };");
                    362: }
                    363: #endif /* MAKEFIXED */
                    364: 
                    365: /*
                    366:    Update the window with the last wsize (normally 32K) bytes written before
                    367:    returning.  If window does not exist yet, create it.  This is only called
                    368:    when a window is already in use, or when output has been written during this
                    369:    inflate call, but the end of the deflate stream has not been reached yet.
                    370:    It is also called to create a window for dictionary data when a dictionary
                    371:    is loaded.
                    372: 
                    373:    Providing output buffers larger than 32K to inflate() should provide a speed
                    374:    advantage, since only the last 32K of output is copied to the sliding window
                    375:    upon return from inflate(), and since all distances after the first 32K of
                    376:    output will fall in the output data, making match copies simpler and faster.
                    377:    The advantage may be dependent on the size of the processor's data caches.
                    378:  */
1.1.1.2 ! misho     379: local int updatewindow(strm, end, copy)
1.1       misho     380: z_streamp strm;
1.1.1.2 ! misho     381: const Bytef *end;
        !           382: unsigned copy;
1.1       misho     383: {
                    384:     struct inflate_state FAR *state;
1.1.1.2 ! misho     385:     unsigned dist;
1.1       misho     386: 
                    387:     state = (struct inflate_state FAR *)strm->state;
                    388: 
                    389:     /* if it hasn't been done already, allocate space for the window */
                    390:     if (state->window == Z_NULL) {
                    391:         state->window = (unsigned char FAR *)
                    392:                         ZALLOC(strm, 1U << state->wbits,
                    393:                                sizeof(unsigned char));
                    394:         if (state->window == Z_NULL) return 1;
                    395:     }
                    396: 
                    397:     /* if window not in use yet, initialize */
                    398:     if (state->wsize == 0) {
                    399:         state->wsize = 1U << state->wbits;
1.1.1.2 ! misho     400:         state->wnext = 0;
1.1       misho     401:         state->whave = 0;
                    402:     }
                    403: 
                    404:     /* copy state->wsize or less output bytes into the circular window */
                    405:     if (copy >= state->wsize) {
1.1.1.2 ! misho     406:         zmemcpy(state->window, end - state->wsize, state->wsize);
        !           407:         state->wnext = 0;
1.1       misho     408:         state->whave = state->wsize;
                    409:     }
                    410:     else {
1.1.1.2 ! misho     411:         dist = state->wsize - state->wnext;
1.1       misho     412:         if (dist > copy) dist = copy;
1.1.1.2 ! misho     413:         zmemcpy(state->window + state->wnext, end - copy, dist);
1.1       misho     414:         copy -= dist;
                    415:         if (copy) {
1.1.1.2 ! misho     416:             zmemcpy(state->window, end - copy, copy);
        !           417:             state->wnext = copy;
1.1       misho     418:             state->whave = state->wsize;
                    419:         }
                    420:         else {
1.1.1.2 ! misho     421:             state->wnext += dist;
        !           422:             if (state->wnext == state->wsize) state->wnext = 0;
1.1       misho     423:             if (state->whave < state->wsize) state->whave += dist;
                    424:         }
                    425:     }
                    426:     return 0;
                    427: }
                    428: 
                    429: /* Macros for inflate(): */
                    430: 
                    431: /* check function to use adler32() for zlib or crc32() for gzip */
                    432: #ifdef GUNZIP
                    433: #  define UPDATE(check, buf, len) \
                    434:     (state->flags ? crc32(check, buf, len) : adler32(check, buf, len))
                    435: #else
                    436: #  define UPDATE(check, buf, len) adler32(check, buf, len)
                    437: #endif
                    438: 
                    439: /* check macros for header crc */
                    440: #ifdef GUNZIP
                    441: #  define CRC2(check, word) \
                    442:     do { \
                    443:         hbuf[0] = (unsigned char)(word); \
                    444:         hbuf[1] = (unsigned char)((word) >> 8); \
                    445:         check = crc32(check, hbuf, 2); \
                    446:     } while (0)
                    447: 
                    448: #  define CRC4(check, word) \
                    449:     do { \
                    450:         hbuf[0] = (unsigned char)(word); \
                    451:         hbuf[1] = (unsigned char)((word) >> 8); \
                    452:         hbuf[2] = (unsigned char)((word) >> 16); \
                    453:         hbuf[3] = (unsigned char)((word) >> 24); \
                    454:         check = crc32(check, hbuf, 4); \
                    455:     } while (0)
                    456: #endif
                    457: 
                    458: /* Load registers with state in inflate() for speed */
                    459: #define LOAD() \
                    460:     do { \
                    461:         put = strm->next_out; \
                    462:         left = strm->avail_out; \
                    463:         next = strm->next_in; \
                    464:         have = strm->avail_in; \
                    465:         hold = state->hold; \
                    466:         bits = state->bits; \
                    467:     } while (0)
                    468: 
                    469: /* Restore state from registers in inflate() */
                    470: #define RESTORE() \
                    471:     do { \
                    472:         strm->next_out = put; \
                    473:         strm->avail_out = left; \
                    474:         strm->next_in = next; \
                    475:         strm->avail_in = have; \
                    476:         state->hold = hold; \
                    477:         state->bits = bits; \
                    478:     } while (0)
                    479: 
                    480: /* Clear the input bit accumulator */
                    481: #define INITBITS() \
                    482:     do { \
                    483:         hold = 0; \
                    484:         bits = 0; \
                    485:     } while (0)
                    486: 
                    487: /* Get a byte of input into the bit accumulator, or return from inflate()
                    488:    if there is no input available. */
                    489: #define PULLBYTE() \
                    490:     do { \
                    491:         if (have == 0) goto inf_leave; \
                    492:         have--; \
                    493:         hold += (unsigned long)(*next++) << bits; \
                    494:         bits += 8; \
                    495:     } while (0)
                    496: 
                    497: /* Assure that there are at least n bits in the bit accumulator.  If there is
                    498:    not enough available input to do that, then return from inflate(). */
                    499: #define NEEDBITS(n) \
                    500:     do { \
                    501:         while (bits < (unsigned)(n)) \
                    502:             PULLBYTE(); \
                    503:     } while (0)
                    504: 
                    505: /* Return the low n bits of the bit accumulator (n < 16) */
                    506: #define BITS(n) \
                    507:     ((unsigned)hold & ((1U << (n)) - 1))
                    508: 
                    509: /* Remove n bits from the bit accumulator */
                    510: #define DROPBITS(n) \
                    511:     do { \
                    512:         hold >>= (n); \
                    513:         bits -= (unsigned)(n); \
                    514:     } while (0)
                    515: 
                    516: /* Remove zero to seven bits as needed to go to a byte boundary */
                    517: #define BYTEBITS() \
                    518:     do { \
                    519:         hold >>= bits & 7; \
                    520:         bits -= bits & 7; \
                    521:     } while (0)
                    522: 
                    523: /*
                    524:    inflate() uses a state machine to process as much input data and generate as
                    525:    much output data as possible before returning.  The state machine is
                    526:    structured roughly as follows:
                    527: 
                    528:     for (;;) switch (state) {
                    529:     ...
                    530:     case STATEn:
                    531:         if (not enough input data or output space to make progress)
                    532:             return;
                    533:         ... make progress ...
                    534:         state = STATEm;
                    535:         break;
                    536:     ...
                    537:     }
                    538: 
                    539:    so when inflate() is called again, the same case is attempted again, and
                    540:    if the appropriate resources are provided, the machine proceeds to the
                    541:    next state.  The NEEDBITS() macro is usually the way the state evaluates
                    542:    whether it can proceed or should return.  NEEDBITS() does the return if
                    543:    the requested bits are not available.  The typical use of the BITS macros
                    544:    is:
                    545: 
                    546:         NEEDBITS(n);
                    547:         ... do something with BITS(n) ...
                    548:         DROPBITS(n);
                    549: 
                    550:    where NEEDBITS(n) either returns from inflate() if there isn't enough
                    551:    input left to load n bits into the accumulator, or it continues.  BITS(n)
                    552:    gives the low n bits in the accumulator.  When done, DROPBITS(n) drops
                    553:    the low n bits off the accumulator.  INITBITS() clears the accumulator
                    554:    and sets the number of available bits to zero.  BYTEBITS() discards just
                    555:    enough bits to put the accumulator on a byte boundary.  After BYTEBITS()
                    556:    and a NEEDBITS(8), then BITS(8) would return the next byte in the stream.
                    557: 
                    558:    NEEDBITS(n) uses PULLBYTE() to get an available byte of input, or to return
                    559:    if there is no input available.  The decoding of variable length codes uses
                    560:    PULLBYTE() directly in order to pull just enough bytes to decode the next
                    561:    code, and no more.
                    562: 
                    563:    Some states loop until they get enough input, making sure that enough
                    564:    state information is maintained to continue the loop where it left off
                    565:    if NEEDBITS() returns in the loop.  For example, want, need, and keep
                    566:    would all have to actually be part of the saved state in case NEEDBITS()
                    567:    returns:
                    568: 
                    569:     case STATEw:
                    570:         while (want < need) {
                    571:             NEEDBITS(n);
                    572:             keep[want++] = BITS(n);
                    573:             DROPBITS(n);
                    574:         }
                    575:         state = STATEx;
                    576:     case STATEx:
                    577: 
                    578:    As shown above, if the next state is also the next case, then the break
                    579:    is omitted.
                    580: 
                    581:    A state may also return if there is not enough output space available to
                    582:    complete that state.  Those states are copying stored data, writing a
                    583:    literal byte, and copying a matching string.
                    584: 
                    585:    When returning, a "goto inf_leave" is used to update the total counters,
                    586:    update the check value, and determine whether any progress has been made
                    587:    during that inflate() call in order to return the proper return code.
                    588:    Progress is defined as a change in either strm->avail_in or strm->avail_out.
                    589:    When there is a window, goto inf_leave will update the window with the last
                    590:    output written.  If a goto inf_leave occurs in the middle of decompression
                    591:    and there is no window currently, goto inf_leave will create one and copy
                    592:    output to the window for the next call of inflate().
                    593: 
                    594:    In this implementation, the flush parameter of inflate() only affects the
                    595:    return code (per zlib.h).  inflate() always writes as much as possible to
                    596:    strm->next_out, given the space available and the provided input--the effect
                    597:    documented in zlib.h of Z_SYNC_FLUSH.  Furthermore, inflate() always defers
                    598:    the allocation of and copying into a sliding window until necessary, which
                    599:    provides the effect documented in zlib.h for Z_FINISH when the entire input
                    600:    stream available.  So the only thing the flush parameter actually does is:
                    601:    when flush is set to Z_FINISH, inflate() cannot return Z_OK.  Instead it
                    602:    will return Z_BUF_ERROR if it has not reached the end of the stream.
                    603:  */
                    604: 
                    605: int ZEXPORT inflate(strm, flush)
                    606: z_streamp strm;
                    607: int flush;
                    608: {
                    609:     struct inflate_state FAR *state;
1.1.1.2 ! misho     610:     z_const unsigned char FAR *next;    /* next input */
1.1       misho     611:     unsigned char FAR *put;     /* next output */
                    612:     unsigned have, left;        /* available input and output */
                    613:     unsigned long hold;         /* bit buffer */
                    614:     unsigned bits;              /* bits in bit buffer */
                    615:     unsigned in, out;           /* save starting available input and output */
                    616:     unsigned copy;              /* number of stored or match bytes to copy */
                    617:     unsigned char FAR *from;    /* where to copy match bytes from */
1.1.1.2 ! misho     618:     code here;                  /* current decoding table entry */
1.1       misho     619:     code last;                  /* parent table entry */
                    620:     unsigned len;               /* length to copy for repeats, bits to drop */
                    621:     int ret;                    /* return code */
                    622: #ifdef GUNZIP
                    623:     unsigned char hbuf[4];      /* buffer for gzip header crc calculation */
                    624: #endif
                    625:     static const unsigned short order[19] = /* permutation of code lengths */
                    626:         {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
                    627: 
                    628:     if (strm == Z_NULL || strm->state == Z_NULL || strm->next_out == Z_NULL ||
                    629:         (strm->next_in == Z_NULL && strm->avail_in != 0))
                    630:         return Z_STREAM_ERROR;
                    631: 
                    632:     state = (struct inflate_state FAR *)strm->state;
                    633:     if (state->mode == TYPE) state->mode = TYPEDO;      /* skip check */
                    634:     LOAD();
                    635:     in = have;
                    636:     out = left;
                    637:     ret = Z_OK;
                    638:     for (;;)
                    639:         switch (state->mode) {
                    640:         case HEAD:
                    641:             if (state->wrap == 0) {
                    642:                 state->mode = TYPEDO;
                    643:                 break;
                    644:             }
                    645:             NEEDBITS(16);
                    646: #ifdef GUNZIP
                    647:             if ((state->wrap & 2) && hold == 0x8b1f) {  /* gzip header */
                    648:                 state->check = crc32(0L, Z_NULL, 0);
                    649:                 CRC2(state->check, hold);
                    650:                 INITBITS();
                    651:                 state->mode = FLAGS;
                    652:                 break;
                    653:             }
                    654:             state->flags = 0;           /* expect zlib header */
                    655:             if (state->head != Z_NULL)
                    656:                 state->head->done = -1;
                    657:             if (!(state->wrap & 1) ||   /* check if zlib header allowed */
                    658: #else
                    659:             if (
                    660: #endif
                    661:                 ((BITS(8) << 8) + (hold >> 8)) % 31) {
                    662:                 strm->msg = (char *)"incorrect header check";
                    663:                 state->mode = BAD;
                    664:                 break;
                    665:             }
                    666:             if (BITS(4) != Z_DEFLATED) {
                    667:                 strm->msg = (char *)"unknown compression method";
                    668:                 state->mode = BAD;
                    669:                 break;
                    670:             }
                    671:             DROPBITS(4);
                    672:             len = BITS(4) + 8;
1.1.1.2 ! misho     673:             if (state->wbits == 0)
        !           674:                 state->wbits = len;
        !           675:             else if (len > state->wbits) {
1.1       misho     676:                 strm->msg = (char *)"invalid window size";
                    677:                 state->mode = BAD;
                    678:                 break;
                    679:             }
                    680:             state->dmax = 1U << len;
                    681:             Tracev((stderr, "inflate:   zlib header ok\n"));
                    682:             strm->adler = state->check = adler32(0L, Z_NULL, 0);
                    683:             state->mode = hold & 0x200 ? DICTID : TYPE;
                    684:             INITBITS();
                    685:             break;
                    686: #ifdef GUNZIP
                    687:         case FLAGS:
                    688:             NEEDBITS(16);
                    689:             state->flags = (int)(hold);
                    690:             if ((state->flags & 0xff) != Z_DEFLATED) {
                    691:                 strm->msg = (char *)"unknown compression method";
                    692:                 state->mode = BAD;
                    693:                 break;
                    694:             }
                    695:             if (state->flags & 0xe000) {
                    696:                 strm->msg = (char *)"unknown header flags set";
                    697:                 state->mode = BAD;
                    698:                 break;
                    699:             }
                    700:             if (state->head != Z_NULL)
                    701:                 state->head->text = (int)((hold >> 8) & 1);
                    702:             if (state->flags & 0x0200) CRC2(state->check, hold);
                    703:             INITBITS();
                    704:             state->mode = TIME;
                    705:            /* FALL THROUGH */
                    706:         case TIME:
                    707:             NEEDBITS(32);
                    708:             if (state->head != Z_NULL)
                    709:                 state->head->time = hold;
                    710:             if (state->flags & 0x0200) CRC4(state->check, hold);
                    711:             INITBITS();
                    712:             state->mode = OS;
                    713:            /* FALL THROUGH */
                    714:         case OS:
                    715:             NEEDBITS(16);
                    716:             if (state->head != Z_NULL) {
                    717:                 state->head->xflags = (int)(hold & 0xff);
                    718:                 state->head->os = (int)(hold >> 8);
                    719:             }
                    720:             if (state->flags & 0x0200) CRC2(state->check, hold);
                    721:             INITBITS();
                    722:             state->mode = EXLEN;
                    723:            /* FALL THROUGH */
                    724:         case EXLEN:
                    725:             if (state->flags & 0x0400) {
                    726:                 NEEDBITS(16);
                    727:                 state->length = (unsigned)(hold);
                    728:                 if (state->head != Z_NULL)
                    729:                     state->head->extra_len = (unsigned)hold;
                    730:                 if (state->flags & 0x0200) CRC2(state->check, hold);
                    731:                 INITBITS();
                    732:             }
                    733:             else if (state->head != Z_NULL)
                    734:                 state->head->extra = Z_NULL;
                    735:             state->mode = EXTRA;
                    736:            /* FALL THROUGH */
                    737:         case EXTRA:
                    738:             if (state->flags & 0x0400) {
                    739:                 copy = state->length;
                    740:                 if (copy > have) copy = have;
                    741:                 if (copy) {
                    742:                     if (state->head != Z_NULL &&
                    743:                         state->head->extra != Z_NULL) {
                    744:                         len = state->head->extra_len - state->length;
                    745:                         zmemcpy(state->head->extra + len, next,
                    746:                                 len + copy > state->head->extra_max ?
                    747:                                 state->head->extra_max - len : copy);
                    748:                     }
                    749:                     if (state->flags & 0x0200)
                    750:                         state->check = crc32(state->check, next, copy);
                    751:                     have -= copy;
                    752:                     next += copy;
                    753:                     state->length -= copy;
                    754:                 }
                    755:                 if (state->length) goto inf_leave;
                    756:             }
                    757:             state->length = 0;
                    758:             state->mode = NAME;
                    759:            /* FALL THROUGH */
                    760:         case NAME:
                    761:             if (state->flags & 0x0800) {
                    762:                 if (have == 0) goto inf_leave;
                    763:                 copy = 0;
                    764:                 do {
                    765:                     len = (unsigned)(next[copy++]);
                    766:                     if (state->head != Z_NULL &&
                    767:                             state->head->name != Z_NULL &&
                    768:                             state->length < state->head->name_max)
                    769:                         state->head->name[state->length++] = len;
                    770:                 } while (len && copy < have);
                    771:                 if (state->flags & 0x0200)
                    772:                     state->check = crc32(state->check, next, copy);
                    773:                 have -= copy;
                    774:                 next += copy;
                    775:                 if (len) goto inf_leave;
                    776:             }
                    777:             else if (state->head != Z_NULL)
                    778:                 state->head->name = Z_NULL;
                    779:             state->length = 0;
                    780:             state->mode = COMMENT;
                    781:            /* FALL THROUGH */
                    782:         case COMMENT:
                    783:             if (state->flags & 0x1000) {
                    784:                 if (have == 0) goto inf_leave;
                    785:                 copy = 0;
                    786:                 do {
                    787:                     len = (unsigned)(next[copy++]);
                    788:                     if (state->head != Z_NULL &&
                    789:                             state->head->comment != Z_NULL &&
                    790:                             state->length < state->head->comm_max)
                    791:                         state->head->comment[state->length++] = len;
                    792:                 } while (len && copy < have);
                    793:                 if (state->flags & 0x0200)
                    794:                     state->check = crc32(state->check, next, copy);
                    795:                 have -= copy;
                    796:                 next += copy;
                    797:                 if (len) goto inf_leave;
                    798:             }
                    799:             else if (state->head != Z_NULL)
                    800:                 state->head->comment = Z_NULL;
                    801:             state->mode = HCRC;
                    802:            /* FALL THROUGH */
                    803:         case HCRC:
                    804:             if (state->flags & 0x0200) {
                    805:                 NEEDBITS(16);
                    806:                 if (hold != (state->check & 0xffff)) {
                    807:                     strm->msg = (char *)"header crc mismatch";
                    808:                     state->mode = BAD;
                    809:                     break;
                    810:                 }
                    811:                 INITBITS();
                    812:             }
                    813:             if (state->head != Z_NULL) {
                    814:                 state->head->hcrc = (int)((state->flags >> 9) & 1);
                    815:                 state->head->done = 1;
                    816:             }
                    817:             strm->adler = state->check = crc32(0L, Z_NULL, 0);
                    818:             state->mode = TYPE;
                    819:             break;
                    820: #endif
                    821:         case DICTID:
                    822:             NEEDBITS(32);
1.1.1.2 ! misho     823:             strm->adler = state->check = ZSWAP32(hold);
1.1       misho     824:             INITBITS();
                    825:             state->mode = DICT;
                    826:            /* FALL THROUGH */
                    827:         case DICT:
                    828:             if (state->havedict == 0) {
                    829:                 RESTORE();
                    830:                 return Z_NEED_DICT;
                    831:             }
                    832:             strm->adler = state->check = adler32(0L, Z_NULL, 0);
                    833:             state->mode = TYPE;
                    834:            /* FALL THROUGH */
                    835:         case TYPE:
1.1.1.2 ! misho     836:             if (flush == Z_BLOCK || flush == Z_TREES) goto inf_leave;
1.1       misho     837:            /* FALL THROUGH */
                    838:         case TYPEDO:
                    839:             if (state->last) {
                    840:                 BYTEBITS();
                    841:                 state->mode = CHECK;
                    842:                 break;
                    843:             }
                    844:             NEEDBITS(3);
                    845:             state->last = BITS(1);
                    846:             DROPBITS(1);
                    847:             switch (BITS(2)) {
                    848:             case 0:                             /* stored block */
                    849:                 Tracev((stderr, "inflate:     stored block%s\n",
                    850:                         state->last ? " (last)" : ""));
                    851:                 state->mode = STORED;
                    852:                 break;
                    853:             case 1:                             /* fixed block */
                    854:                 fixedtables(state);
                    855:                 Tracev((stderr, "inflate:     fixed codes block%s\n",
                    856:                         state->last ? " (last)" : ""));
1.1.1.2 ! misho     857:                 state->mode = LEN_;             /* decode codes */
        !           858:                 if (flush == Z_TREES) {
        !           859:                     DROPBITS(2);
        !           860:                     goto inf_leave;
        !           861:                 }
1.1       misho     862:                 break;
                    863:             case 2:                             /* dynamic block */
                    864:                 Tracev((stderr, "inflate:     dynamic codes block%s\n",
                    865:                         state->last ? " (last)" : ""));
                    866:                 state->mode = TABLE;
                    867:                 break;
                    868:             case 3:
                    869:                 strm->msg = (char *)"invalid block type";
                    870:                 state->mode = BAD;
                    871:             }
                    872:             DROPBITS(2);
                    873:             break;
                    874:         case STORED:
                    875:             BYTEBITS();                         /* go to byte boundary */
                    876:             NEEDBITS(32);
                    877:             if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
                    878:                 strm->msg = (char *)"invalid stored block lengths";
                    879:                 state->mode = BAD;
                    880:                 break;
                    881:             }
                    882:             state->length = (unsigned)hold & 0xffff;
                    883:             Tracev((stderr, "inflate:       stored length %u\n",
                    884:                     state->length));
                    885:             INITBITS();
1.1.1.2 ! misho     886:             state->mode = COPY_;
        !           887:             if (flush == Z_TREES) goto inf_leave;
        !           888:         case COPY_:
1.1       misho     889:             state->mode = COPY;
                    890:            /* FALL THROUGH */
                    891:         case COPY:
                    892:             copy = state->length;
                    893:             if (copy) {
                    894:                 if (copy > have) copy = have;
                    895:                 if (copy > left) copy = left;
                    896:                 if (copy == 0) goto inf_leave;
                    897:                 zmemcpy(put, next, copy);
                    898:                 have -= copy;
                    899:                 next += copy;
                    900:                 left -= copy;
                    901:                 put += copy;
                    902:                 state->length -= copy;
                    903:                 break;
                    904:             }
                    905:             Tracev((stderr, "inflate:       stored end\n"));
                    906:             state->mode = TYPE;
                    907:             break;
                    908:         case TABLE:
                    909:             NEEDBITS(14);
                    910:             state->nlen = BITS(5) + 257;
                    911:             DROPBITS(5);
                    912:             state->ndist = BITS(5) + 1;
                    913:             DROPBITS(5);
                    914:             state->ncode = BITS(4) + 4;
                    915:             DROPBITS(4);
                    916: #ifndef PKZIP_BUG_WORKAROUND
                    917:             if (state->nlen > 286 || state->ndist > 30) {
                    918:                 strm->msg = (char *)"too many length or distance symbols";
                    919:                 state->mode = BAD;
                    920:                 break;
                    921:             }
                    922: #endif
                    923:             Tracev((stderr, "inflate:       table sizes ok\n"));
                    924:             state->have = 0;
                    925:             state->mode = LENLENS;
                    926:            /* FALL THROUGH */
                    927:         case LENLENS:
                    928:             while (state->have < state->ncode) {
                    929:                 NEEDBITS(3);
                    930:                 state->lens[order[state->have++]] = (unsigned short)BITS(3);
                    931:                 DROPBITS(3);
                    932:             }
                    933:             while (state->have < 19)
                    934:                 state->lens[order[state->have++]] = 0;
                    935:             state->next = state->codes;
1.1.1.2 ! misho     936:             state->lencode = (const code FAR *)(state->next);
1.1       misho     937:             state->lenbits = 7;
                    938:             ret = inflate_table(CODES, state->lens, 19, &(state->next),
                    939:                                 &(state->lenbits), state->work);
                    940:             if (ret) {
                    941:                 strm->msg = (char *)"invalid code lengths set";
                    942:                 state->mode = BAD;
                    943:                 break;
                    944:             }
                    945:             Tracev((stderr, "inflate:       code lengths ok\n"));
                    946:             state->have = 0;
                    947:             state->mode = CODELENS;
                    948:            /* FALL THROUGH */
                    949:         case CODELENS:
                    950:             while (state->have < state->nlen + state->ndist) {
                    951:                 for (;;) {
1.1.1.2 ! misho     952:                     here = state->lencode[BITS(state->lenbits)];
        !           953:                     if ((unsigned)(here.bits) <= bits) break;
1.1       misho     954:                     PULLBYTE();
                    955:                 }
1.1.1.2 ! misho     956:                 if (here.val < 16) {
        !           957:                     DROPBITS(here.bits);
        !           958:                     state->lens[state->have++] = here.val;
1.1       misho     959:                 }
                    960:                 else {
1.1.1.2 ! misho     961:                     if (here.val == 16) {
        !           962:                         NEEDBITS(here.bits + 2);
        !           963:                         DROPBITS(here.bits);
1.1       misho     964:                         if (state->have == 0) {
                    965:                             strm->msg = (char *)"invalid bit length repeat";
                    966:                             state->mode = BAD;
                    967:                             break;
                    968:                         }
                    969:                         len = state->lens[state->have - 1];
                    970:                         copy = 3 + BITS(2);
                    971:                         DROPBITS(2);
                    972:                     }
1.1.1.2 ! misho     973:                     else if (here.val == 17) {
        !           974:                         NEEDBITS(here.bits + 3);
        !           975:                         DROPBITS(here.bits);
1.1       misho     976:                         len = 0;
                    977:                         copy = 3 + BITS(3);
                    978:                         DROPBITS(3);
                    979:                     }
                    980:                     else {
1.1.1.2 ! misho     981:                         NEEDBITS(here.bits + 7);
        !           982:                         DROPBITS(here.bits);
1.1       misho     983:                         len = 0;
                    984:                         copy = 11 + BITS(7);
                    985:                         DROPBITS(7);
                    986:                     }
                    987:                     if (state->have + copy > state->nlen + state->ndist) {
                    988:                         strm->msg = (char *)"invalid bit length repeat";
                    989:                         state->mode = BAD;
                    990:                         break;
                    991:                     }
                    992:                     while (copy--)
                    993:                         state->lens[state->have++] = (unsigned short)len;
                    994:                 }
                    995:             }
                    996: 
                    997:             /* handle error breaks in while */
                    998:             if (state->mode == BAD) break;
                    999: 
1.1.1.2 ! misho    1000:             /* check for end-of-block code (better have one) */
        !          1001:             if (state->lens[256] == 0) {
        !          1002:                 strm->msg = (char *)"invalid code -- missing end-of-block";
        !          1003:                 state->mode = BAD;
        !          1004:                 break;
        !          1005:             }
        !          1006: 
        !          1007:             /* build code tables -- note: do not change the lenbits or distbits
        !          1008:                values here (9 and 6) without reading the comments in inftrees.h
        !          1009:                concerning the ENOUGH constants, which depend on those values */
1.1       misho    1010:             state->next = state->codes;
1.1.1.2 ! misho    1011:             state->lencode = (const code FAR *)(state->next);
1.1       misho    1012:             state->lenbits = 9;
                   1013:             ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
                   1014:                                 &(state->lenbits), state->work);
                   1015:             if (ret) {
                   1016:                 strm->msg = (char *)"invalid literal/lengths set";
                   1017:                 state->mode = BAD;
                   1018:                 break;
                   1019:             }
1.1.1.2 ! misho    1020:             state->distcode = (const code FAR *)(state->next);
1.1       misho    1021:             state->distbits = 6;
                   1022:             ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
                   1023:                             &(state->next), &(state->distbits), state->work);
                   1024:             if (ret) {
                   1025:                 strm->msg = (char *)"invalid distances set";
                   1026:                 state->mode = BAD;
                   1027:                 break;
                   1028:             }
                   1029:             Tracev((stderr, "inflate:       codes ok\n"));
1.1.1.2 ! misho    1030:             state->mode = LEN_;
        !          1031:             if (flush == Z_TREES) goto inf_leave;
        !          1032:            /* FALL THROUGH */
        !          1033:         case LEN_:
1.1       misho    1034:             state->mode = LEN;
                   1035:            /* FALL THROUGH */
                   1036:         case LEN:
                   1037:             if (have >= 6 && left >= 258) {
                   1038:                 RESTORE();
                   1039:                 inflate_fast(strm, out);
                   1040:                 LOAD();
1.1.1.2 ! misho    1041:                 if (state->mode == TYPE)
        !          1042:                     state->back = -1;
1.1       misho    1043:                 break;
                   1044:             }
1.1.1.2 ! misho    1045:             state->back = 0;
1.1       misho    1046:             for (;;) {
1.1.1.2 ! misho    1047:                 here = state->lencode[BITS(state->lenbits)];
        !          1048:                 if ((unsigned)(here.bits) <= bits) break;
1.1       misho    1049:                 PULLBYTE();
                   1050:             }
1.1.1.2 ! misho    1051:             if (here.op && (here.op & 0xf0) == 0) {
        !          1052:                 last = here;
1.1       misho    1053:                 for (;;) {
1.1.1.2 ! misho    1054:                     here = state->lencode[last.val +
1.1       misho    1055:                             (BITS(last.bits + last.op) >> last.bits)];
1.1.1.2 ! misho    1056:                     if ((unsigned)(last.bits + here.bits) <= bits) break;
1.1       misho    1057:                     PULLBYTE();
                   1058:                 }
                   1059:                 DROPBITS(last.bits);
1.1.1.2 ! misho    1060:                 state->back += last.bits;
1.1       misho    1061:             }
1.1.1.2 ! misho    1062:             DROPBITS(here.bits);
        !          1063:             state->back += here.bits;
        !          1064:             state->length = (unsigned)here.val;
        !          1065:             if ((int)(here.op) == 0) {
        !          1066:                 Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
1.1       misho    1067:                         "inflate:         literal '%c'\n" :
1.1.1.2 ! misho    1068:                         "inflate:         literal 0x%02x\n", here.val));
1.1       misho    1069:                 state->mode = LIT;
                   1070:                 break;
                   1071:             }
1.1.1.2 ! misho    1072:             if (here.op & 32) {
1.1       misho    1073:                 Tracevv((stderr, "inflate:         end of block\n"));
1.1.1.2 ! misho    1074:                 state->back = -1;
1.1       misho    1075:                 state->mode = TYPE;
                   1076:                 break;
                   1077:             }
1.1.1.2 ! misho    1078:             if (here.op & 64) {
1.1       misho    1079:                 strm->msg = (char *)"invalid literal/length code";
                   1080:                 state->mode = BAD;
                   1081:                 break;
                   1082:             }
1.1.1.2 ! misho    1083:             state->extra = (unsigned)(here.op) & 15;
1.1       misho    1084:             state->mode = LENEXT;
                   1085:            /* FALL THROUGH */
                   1086:         case LENEXT:
                   1087:             if (state->extra) {
                   1088:                 NEEDBITS(state->extra);
                   1089:                 state->length += BITS(state->extra);
                   1090:                 DROPBITS(state->extra);
1.1.1.2 ! misho    1091:                 state->back += state->extra;
1.1       misho    1092:             }
                   1093:             Tracevv((stderr, "inflate:         length %u\n", state->length));
1.1.1.2 ! misho    1094:             state->was = state->length;
1.1       misho    1095:             state->mode = DIST;
                   1096:            /* FALL THROUGH */
                   1097:         case DIST:
                   1098:             for (;;) {
1.1.1.2 ! misho    1099:                 here = state->distcode[BITS(state->distbits)];
        !          1100:                 if ((unsigned)(here.bits) <= bits) break;
1.1       misho    1101:                 PULLBYTE();
                   1102:             }
1.1.1.2 ! misho    1103:             if ((here.op & 0xf0) == 0) {
        !          1104:                 last = here;
1.1       misho    1105:                 for (;;) {
1.1.1.2 ! misho    1106:                     here = state->distcode[last.val +
1.1       misho    1107:                             (BITS(last.bits + last.op) >> last.bits)];
1.1.1.2 ! misho    1108:                     if ((unsigned)(last.bits + here.bits) <= bits) break;
1.1       misho    1109:                     PULLBYTE();
                   1110:                 }
                   1111:                 DROPBITS(last.bits);
1.1.1.2 ! misho    1112:                 state->back += last.bits;
1.1       misho    1113:             }
1.1.1.2 ! misho    1114:             DROPBITS(here.bits);
        !          1115:             state->back += here.bits;
        !          1116:             if (here.op & 64) {
1.1       misho    1117:                 strm->msg = (char *)"invalid distance code";
                   1118:                 state->mode = BAD;
                   1119:                 break;
                   1120:             }
1.1.1.2 ! misho    1121:             state->offset = (unsigned)here.val;
        !          1122:             state->extra = (unsigned)(here.op) & 15;
1.1       misho    1123:             state->mode = DISTEXT;
                   1124:            /* FALL THROUGH */
                   1125:         case DISTEXT:
                   1126:             if (state->extra) {
                   1127:                 NEEDBITS(state->extra);
                   1128:                 state->offset += BITS(state->extra);
                   1129:                 DROPBITS(state->extra);
1.1.1.2 ! misho    1130:                 state->back += state->extra;
1.1       misho    1131:             }
                   1132: #ifdef INFLATE_STRICT
                   1133:             if (state->offset > state->dmax) {
                   1134:                 strm->msg = (char *)"invalid distance too far back";
                   1135:                 state->mode = BAD;
                   1136:                 break;
                   1137:             }
                   1138: #endif
                   1139:             Tracevv((stderr, "inflate:         distance %u\n", state->offset));
                   1140:             state->mode = MATCH;
                   1141:            /* FALL THROUGH */
                   1142:         case MATCH:
                   1143:             if (left == 0) goto inf_leave;
                   1144:             copy = out - left;
                   1145:             if (state->offset > copy) {         /* copy from window */
                   1146:                 copy = state->offset - copy;
1.1.1.2 ! misho    1147:                 if (copy > state->whave) {
        !          1148:                     if (state->sane) {
        !          1149:                         strm->msg = (char *)"invalid distance too far back";
        !          1150:                         state->mode = BAD;
        !          1151:                         break;
        !          1152:                     }
        !          1153: #ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
        !          1154:                     Trace((stderr, "inflate.c too far\n"));
        !          1155:                     copy -= state->whave;
        !          1156:                     if (copy > state->length) copy = state->length;
        !          1157:                     if (copy > left) copy = left;
        !          1158:                     left -= copy;
        !          1159:                     state->length -= copy;
        !          1160:                     do {
        !          1161:                         *put++ = 0;
        !          1162:                     } while (--copy);
        !          1163:                     if (state->length == 0) state->mode = LEN;
        !          1164:                     break;
        !          1165: #endif
        !          1166:                 }
        !          1167:                 if (copy > state->wnext) {
        !          1168:                     copy -= state->wnext;
1.1       misho    1169:                     from = state->window + (state->wsize - copy);
                   1170:                 }
                   1171:                 else
1.1.1.2 ! misho    1172:                     from = state->window + (state->wnext - copy);
1.1       misho    1173:                 if (copy > state->length) copy = state->length;
                   1174:             }
                   1175:             else {                              /* copy from output */
                   1176:                 from = put - state->offset;
                   1177:                 copy = state->length;
                   1178:             }
                   1179:             if (copy > left) copy = left;
                   1180:             left -= copy;
                   1181:             state->length -= copy;
                   1182:             do {
                   1183:                 *put++ = *from++;
                   1184:             } while (--copy);
                   1185:             if (state->length == 0) state->mode = LEN;
                   1186:             break;
                   1187:         case LIT:
                   1188:             if (left == 0) goto inf_leave;
                   1189:             *put++ = (unsigned char)(state->length);
                   1190:             left--;
                   1191:             state->mode = LEN;
                   1192:             break;
                   1193:         case CHECK:
                   1194:             if (state->wrap) {
                   1195:                 NEEDBITS(32);
                   1196:                 out -= left;
                   1197:                 strm->total_out += out;
                   1198:                 state->total += out;
                   1199:                 if (out)
                   1200:                     strm->adler = state->check =
                   1201:                         UPDATE(state->check, put - out, out);
                   1202:                 out = left;
                   1203:                 if ((
                   1204: #ifdef GUNZIP
                   1205:                      state->flags ? hold :
                   1206: #endif
1.1.1.2 ! misho    1207:                      ZSWAP32(hold)) != state->check) {
1.1       misho    1208:                     strm->msg = (char *)"incorrect data check";
                   1209:                     state->mode = BAD;
                   1210:                     break;
                   1211:                 }
                   1212:                 INITBITS();
                   1213:                 Tracev((stderr, "inflate:   check matches trailer\n"));
                   1214:             }
                   1215: #ifdef GUNZIP
                   1216:             state->mode = LENGTH;
                   1217:            /* FALL THROUGH */
                   1218:         case LENGTH:
                   1219:             if (state->wrap && state->flags) {
                   1220:                 NEEDBITS(32);
                   1221:                 if (hold != (state->total & 0xffffffffUL)) {
                   1222:                     strm->msg = (char *)"incorrect length check";
                   1223:                     state->mode = BAD;
                   1224:                     break;
                   1225:                 }
                   1226:                 INITBITS();
                   1227:                 Tracev((stderr, "inflate:   length matches trailer\n"));
                   1228:             }
                   1229: #endif
                   1230:             state->mode = DONE;
                   1231:            /* FALL THROUGH */
                   1232:         case DONE:
                   1233:             ret = Z_STREAM_END;
                   1234:             goto inf_leave;
                   1235:         case BAD:
                   1236:             ret = Z_DATA_ERROR;
                   1237:             goto inf_leave;
                   1238:         case MEM:
                   1239:             return Z_MEM_ERROR;
                   1240:         case SYNC:
                   1241:         default:
                   1242:             return Z_STREAM_ERROR;
                   1243:         }
                   1244: 
                   1245:     /*
                   1246:        Return from inflate(), updating the total counts and the check value.
                   1247:        If there was no progress during the inflate() call, return a buffer
                   1248:        error.  Call updatewindow() to create and/or update the window state.
                   1249:        Note: a memory error from inflate() is non-recoverable.
                   1250:      */
                   1251:   inf_leave:
                   1252:     RESTORE();
1.1.1.2 ! misho    1253:     if (state->wsize || (out != strm->avail_out && state->mode < BAD &&
        !          1254:             (state->mode < CHECK || flush != Z_FINISH)))
        !          1255:         if (updatewindow(strm, strm->next_out, out - strm->avail_out)) {
1.1       misho    1256:             state->mode = MEM;
                   1257:             return Z_MEM_ERROR;
                   1258:         }
                   1259:     in -= strm->avail_in;
                   1260:     out -= strm->avail_out;
                   1261:     strm->total_in += in;
                   1262:     strm->total_out += out;
                   1263:     state->total += out;
                   1264:     if (state->wrap && out)
                   1265:         strm->adler = state->check =
                   1266:             UPDATE(state->check, strm->next_out - out, out);
                   1267:     strm->data_type = state->bits + (state->last ? 64 : 0) +
1.1.1.2 ! misho    1268:                       (state->mode == TYPE ? 128 : 0) +
        !          1269:                       (state->mode == LEN_ || state->mode == COPY_ ? 256 : 0);
1.1       misho    1270:     if (((in == 0 && out == 0) || flush == Z_FINISH) && ret == Z_OK)
                   1271:         ret = Z_BUF_ERROR;
                   1272:     return ret;
                   1273: }
                   1274: 
                   1275: int ZEXPORT inflateEnd(strm)
                   1276: z_streamp strm;
                   1277: {
                   1278:     struct inflate_state FAR *state;
                   1279:     if (strm == Z_NULL || strm->state == Z_NULL || strm->zfree == (free_func)0)
                   1280:         return Z_STREAM_ERROR;
                   1281:     state = (struct inflate_state FAR *)strm->state;
                   1282:     if (state->window != Z_NULL) ZFREE(strm, state->window);
                   1283:     ZFREE(strm, strm->state);
                   1284:     strm->state = Z_NULL;
                   1285:     Tracev((stderr, "inflate: end\n"));
                   1286:     return Z_OK;
                   1287: }
                   1288: 
1.1.1.2 ! misho    1289: int ZEXPORT inflateGetDictionary(strm, dictionary, dictLength)
        !          1290: z_streamp strm;
        !          1291: Bytef *dictionary;
        !          1292: uInt *dictLength;
        !          1293: {
        !          1294:     struct inflate_state FAR *state;
        !          1295: 
        !          1296:     /* check state */
        !          1297:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
        !          1298:     state = (struct inflate_state FAR *)strm->state;
        !          1299: 
        !          1300:     /* copy dictionary */
        !          1301:     if (state->whave && dictionary != Z_NULL) {
        !          1302:         zmemcpy(dictionary, state->window + state->wnext,
        !          1303:                 state->whave - state->wnext);
        !          1304:         zmemcpy(dictionary + state->whave - state->wnext,
        !          1305:                 state->window, state->wnext);
        !          1306:     }
        !          1307:     if (dictLength != Z_NULL)
        !          1308:         *dictLength = state->whave;
        !          1309:     return Z_OK;
        !          1310: }
        !          1311: 
1.1       misho    1312: int ZEXPORT inflateSetDictionary(strm, dictionary, dictLength)
                   1313: z_streamp strm;
                   1314: const Bytef *dictionary;
                   1315: uInt dictLength;
                   1316: {
                   1317:     struct inflate_state FAR *state;
1.1.1.2 ! misho    1318:     unsigned long dictid;
        !          1319:     int ret;
1.1       misho    1320: 
                   1321:     /* check state */
                   1322:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                   1323:     state = (struct inflate_state FAR *)strm->state;
                   1324:     if (state->wrap != 0 && state->mode != DICT)
                   1325:         return Z_STREAM_ERROR;
                   1326: 
1.1.1.2 ! misho    1327:     /* check for correct dictionary identifier */
1.1       misho    1328:     if (state->mode == DICT) {
1.1.1.2 ! misho    1329:         dictid = adler32(0L, Z_NULL, 0);
        !          1330:         dictid = adler32(dictid, dictionary, dictLength);
        !          1331:         if (dictid != state->check)
1.1       misho    1332:             return Z_DATA_ERROR;
                   1333:     }
                   1334: 
1.1.1.2 ! misho    1335:     /* copy dictionary to window using updatewindow(), which will amend the
        !          1336:        existing dictionary if appropriate */
        !          1337:     ret = updatewindow(strm, dictionary + dictLength, dictLength);
        !          1338:     if (ret) {
1.1       misho    1339:         state->mode = MEM;
                   1340:         return Z_MEM_ERROR;
                   1341:     }
                   1342:     state->havedict = 1;
                   1343:     Tracev((stderr, "inflate:   dictionary set\n"));
                   1344:     return Z_OK;
                   1345: }
                   1346: 
                   1347: int ZEXPORT inflateGetHeader(strm, head)
                   1348: z_streamp strm;
                   1349: gz_headerp head;
                   1350: {
                   1351:     struct inflate_state FAR *state;
                   1352: 
                   1353:     /* check state */
                   1354:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                   1355:     state = (struct inflate_state FAR *)strm->state;
                   1356:     if ((state->wrap & 2) == 0) return Z_STREAM_ERROR;
                   1357: 
                   1358:     /* save header structure */
                   1359:     state->head = head;
                   1360:     head->done = 0;
                   1361:     return Z_OK;
                   1362: }
                   1363: 
                   1364: /*
                   1365:    Search buf[0..len-1] for the pattern: 0, 0, 0xff, 0xff.  Return when found
                   1366:    or when out of input.  When called, *have is the number of pattern bytes
                   1367:    found in order so far, in 0..3.  On return *have is updated to the new
                   1368:    state.  If on return *have equals four, then the pattern was found and the
                   1369:    return value is how many bytes were read including the last byte of the
                   1370:    pattern.  If *have is less than four, then the pattern has not been found
                   1371:    yet and the return value is len.  In the latter case, syncsearch() can be
                   1372:    called again with more data and the *have state.  *have is initialized to
                   1373:    zero for the first call.
                   1374:  */
                   1375: local unsigned syncsearch(have, buf, len)
                   1376: unsigned FAR *have;
1.1.1.2 ! misho    1377: const unsigned char FAR *buf;
1.1       misho    1378: unsigned len;
                   1379: {
                   1380:     unsigned got;
                   1381:     unsigned next;
                   1382: 
                   1383:     got = *have;
                   1384:     next = 0;
                   1385:     while (next < len && got < 4) {
                   1386:         if ((int)(buf[next]) == (got < 2 ? 0 : 0xff))
                   1387:             got++;
                   1388:         else if (buf[next])
                   1389:             got = 0;
                   1390:         else
                   1391:             got = 4 - got;
                   1392:         next++;
                   1393:     }
                   1394:     *have = got;
                   1395:     return next;
                   1396: }
                   1397: 
                   1398: int ZEXPORT inflateSync(strm)
                   1399: z_streamp strm;
                   1400: {
                   1401:     unsigned len;               /* number of bytes to look at or looked at */
                   1402:     unsigned long in, out;      /* temporary to save total_in and total_out */
                   1403:     unsigned char buf[4];       /* to restore bit buffer to byte string */
                   1404:     struct inflate_state FAR *state;
                   1405: 
                   1406:     /* check parameters */
                   1407:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                   1408:     state = (struct inflate_state FAR *)strm->state;
                   1409:     if (strm->avail_in == 0 && state->bits < 8) return Z_BUF_ERROR;
                   1410: 
                   1411:     /* if first time, start search in bit buffer */
                   1412:     if (state->mode != SYNC) {
                   1413:         state->mode = SYNC;
                   1414:         state->hold <<= state->bits & 7;
                   1415:         state->bits -= state->bits & 7;
                   1416:         len = 0;
                   1417:         while (state->bits >= 8) {
                   1418:             buf[len++] = (unsigned char)(state->hold);
                   1419:             state->hold >>= 8;
                   1420:             state->bits -= 8;
                   1421:         }
                   1422:         state->have = 0;
                   1423:         syncsearch(&(state->have), buf, len);
                   1424:     }
                   1425: 
                   1426:     /* search available input */
                   1427:     len = syncsearch(&(state->have), strm->next_in, strm->avail_in);
                   1428:     strm->avail_in -= len;
                   1429:     strm->next_in += len;
                   1430:     strm->total_in += len;
                   1431: 
                   1432:     /* return no joy or set up to restart inflate() on a new block */
                   1433:     if (state->have != 4) return Z_DATA_ERROR;
                   1434:     in = strm->total_in;  out = strm->total_out;
                   1435:     inflateReset(strm);
                   1436:     strm->total_in = in;  strm->total_out = out;
                   1437:     state->mode = TYPE;
                   1438:     return Z_OK;
                   1439: }
                   1440: 
                   1441: /*
                   1442:    Returns true if inflate is currently at the end of a block generated by
                   1443:    Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
                   1444:    implementation to provide an additional safety check. PPP uses
                   1445:    Z_SYNC_FLUSH but removes the length bytes of the resulting empty stored
                   1446:    block. When decompressing, PPP checks that at the end of input packet,
                   1447:    inflate is waiting for these length bytes.
                   1448:  */
                   1449: int ZEXPORT inflateSyncPoint(strm)
                   1450: z_streamp strm;
                   1451: {
                   1452:     struct inflate_state FAR *state;
                   1453: 
                   1454:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
                   1455:     state = (struct inflate_state FAR *)strm->state;
                   1456:     return state->mode == STORED && state->bits == 0;
                   1457: }
                   1458: 
                   1459: int ZEXPORT inflateCopy(dest, source)
                   1460: z_streamp dest;
                   1461: z_streamp source;
                   1462: {
                   1463:     struct inflate_state FAR *state;
                   1464:     struct inflate_state FAR *copy;
                   1465:     unsigned char FAR *window;
                   1466:     unsigned wsize;
                   1467: 
                   1468:     /* check input */
                   1469:     if (dest == Z_NULL || source == Z_NULL || source->state == Z_NULL ||
                   1470:         source->zalloc == (alloc_func)0 || source->zfree == (free_func)0)
                   1471:         return Z_STREAM_ERROR;
                   1472:     state = (struct inflate_state FAR *)source->state;
                   1473: 
                   1474:     /* allocate space */
                   1475:     copy = (struct inflate_state FAR *)
                   1476:            ZALLOC(source, 1, sizeof(struct inflate_state));
                   1477:     if (copy == Z_NULL) return Z_MEM_ERROR;
                   1478:     window = Z_NULL;
                   1479:     if (state->window != Z_NULL) {
                   1480:         window = (unsigned char FAR *)
                   1481:                  ZALLOC(source, 1U << state->wbits, sizeof(unsigned char));
                   1482:         if (window == Z_NULL) {
                   1483:             ZFREE(source, copy);
                   1484:             return Z_MEM_ERROR;
                   1485:         }
                   1486:     }
                   1487: 
                   1488:     /* copy state */
1.1.1.2 ! misho    1489:     zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
        !          1490:     zmemcpy((voidpf)copy, (voidpf)state, sizeof(struct inflate_state));
1.1       misho    1491:     if (state->lencode >= state->codes &&
                   1492:         state->lencode <= state->codes + ENOUGH - 1) {
                   1493:         copy->lencode = copy->codes + (state->lencode - state->codes);
                   1494:         copy->distcode = copy->codes + (state->distcode - state->codes);
                   1495:     }
                   1496:     copy->next = copy->codes + (state->next - state->codes);
                   1497:     if (window != Z_NULL) {
                   1498:         wsize = 1U << state->wbits;
                   1499:         zmemcpy(window, state->window, wsize);
                   1500:     }
                   1501:     copy->window = window;
                   1502:     dest->state = (struct internal_state FAR *)copy;
                   1503:     return Z_OK;
                   1504: }
1.1.1.2 ! misho    1505: 
        !          1506: int ZEXPORT inflateUndermine(strm, subvert)
        !          1507: z_streamp strm;
        !          1508: int subvert;
        !          1509: {
        !          1510:     struct inflate_state FAR *state;
        !          1511: 
        !          1512:     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
        !          1513:     state = (struct inflate_state FAR *)strm->state;
        !          1514:     state->sane = !subvert;
        !          1515: #ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
        !          1516:     return Z_OK;
        !          1517: #else
        !          1518:     state->sane = 1;
        !          1519:     return Z_DATA_ERROR;
        !          1520: #endif
        !          1521: }
        !          1522: 
        !          1523: long ZEXPORT inflateMark(strm)
        !          1524: z_streamp strm;
        !          1525: {
        !          1526:     struct inflate_state FAR *state;
        !          1527: 
        !          1528:     if (strm == Z_NULL || strm->state == Z_NULL) return -1L << 16;
        !          1529:     state = (struct inflate_state FAR *)strm->state;
        !          1530:     return ((long)(state->back) << 16) +
        !          1531:         (state->mode == COPY ? state->length :
        !          1532:             (state->mode == MATCH ? state->was - state->length : 0));
        !          1533: }

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