alpar@9: /* infback.c -- inflate using a call-back interface
alpar@9:  * Copyright (C) 1995-2009 Mark Adler
alpar@9:  * For conditions of distribution and use, see copyright notice in zlib.h
alpar@9:  */
alpar@9: 
alpar@9: /*
alpar@9:    This code is largely copied from inflate.c.  Normally either infback.o or
alpar@9:    inflate.o would be linked into an application--not both.  The interface
alpar@9:    with inffast.c is retained so that optimized assembler-coded versions of
alpar@9:    inflate_fast() can be used with either inflate.c or infback.c.
alpar@9:  */
alpar@9: 
alpar@9: #include "zutil.h"
alpar@9: #include "inftrees.h"
alpar@9: #include "inflate.h"
alpar@9: #include "inffast.h"
alpar@9: 
alpar@9: /* function prototypes */
alpar@9: local void fixedtables OF((struct inflate_state FAR *state));
alpar@9: 
alpar@9: /*
alpar@9:    strm provides memory allocation functions in zalloc and zfree, or
alpar@9:    Z_NULL to use the library memory allocation functions.
alpar@9: 
alpar@9:    windowBits is in the range 8..15, and window is a user-supplied
alpar@9:    window and output buffer that is 2**windowBits bytes.
alpar@9:  */
alpar@9: int ZEXPORT inflateBackInit_(strm, windowBits, window, version, stream_size)
alpar@9: z_streamp strm;
alpar@9: int windowBits;
alpar@9: unsigned char FAR *window;
alpar@9: const char *version;
alpar@9: int stream_size;
alpar@9: {
alpar@9:     struct inflate_state FAR *state;
alpar@9: 
alpar@9:     if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
alpar@9:         stream_size != (int)(sizeof(z_stream)))
alpar@9:         return Z_VERSION_ERROR;
alpar@9:     if (strm == Z_NULL || window == Z_NULL ||
alpar@9:         windowBits < 8 || windowBits > 15)
alpar@9:         return Z_STREAM_ERROR;
alpar@9:     strm->msg = Z_NULL;                 /* in case we return an error */
alpar@9:     if (strm->zalloc == (alloc_func)0) {
alpar@9:         strm->zalloc = zcalloc;
alpar@9:         strm->opaque = (voidpf)0;
alpar@9:     }
alpar@9:     if (strm->zfree == (free_func)0) strm->zfree = zcfree;
alpar@9:     state = (struct inflate_state FAR *)ZALLOC(strm, 1,
alpar@9:                                                sizeof(struct inflate_state));
alpar@9:     if (state == Z_NULL) return Z_MEM_ERROR;
alpar@9:     Tracev((stderr, "inflate: allocated\n"));
alpar@9:     strm->state = (struct internal_state FAR *)state;
alpar@9:     state->dmax = 32768U;
alpar@9:     state->wbits = windowBits;
alpar@9:     state->wsize = 1U << windowBits;
alpar@9:     state->window = window;
alpar@9:     state->wnext = 0;
alpar@9:     state->whave = 0;
alpar@9:     return Z_OK;
alpar@9: }
alpar@9: 
alpar@9: /*
alpar@9:    Return state with length and distance decoding tables and index sizes set to
alpar@9:    fixed code decoding.  Normally this returns fixed tables from inffixed.h.
alpar@9:    If BUILDFIXED is defined, then instead this routine builds the tables the
alpar@9:    first time it's called, and returns those tables the first time and
alpar@9:    thereafter.  This reduces the size of the code by about 2K bytes, in
alpar@9:    exchange for a little execution time.  However, BUILDFIXED should not be
alpar@9:    used for threaded applications, since the rewriting of the tables and virgin
alpar@9:    may not be thread-safe.
alpar@9:  */
alpar@9: local void fixedtables(state)
alpar@9: struct inflate_state FAR *state;
alpar@9: {
alpar@9: #ifdef BUILDFIXED
alpar@9:     static int virgin = 1;
alpar@9:     static code *lenfix, *distfix;
alpar@9:     static code fixed[544];
alpar@9: 
alpar@9:     /* build fixed huffman tables if first call (may not be thread safe) */
alpar@9:     if (virgin) {
alpar@9:         unsigned sym, bits;
alpar@9:         static code *next;
alpar@9: 
alpar@9:         /* literal/length table */
alpar@9:         sym = 0;
alpar@9:         while (sym < 144) state->lens[sym++] = 8;
alpar@9:         while (sym < 256) state->lens[sym++] = 9;
alpar@9:         while (sym < 280) state->lens[sym++] = 7;
alpar@9:         while (sym < 288) state->lens[sym++] = 8;
alpar@9:         next = fixed;
alpar@9:         lenfix = next;
alpar@9:         bits = 9;
alpar@9:         inflate_table(LENS, state->lens, 288, &(next), &(bits), state->work);
alpar@9: 
alpar@9:         /* distance table */
alpar@9:         sym = 0;
alpar@9:         while (sym < 32) state->lens[sym++] = 5;
alpar@9:         distfix = next;
alpar@9:         bits = 5;
alpar@9:         inflate_table(DISTS, state->lens, 32, &(next), &(bits), state->work);
alpar@9: 
alpar@9:         /* do this just once */
alpar@9:         virgin = 0;
alpar@9:     }
alpar@9: #else /* !BUILDFIXED */
alpar@9: #   include "inffixed.h"
alpar@9: #endif /* BUILDFIXED */
alpar@9:     state->lencode = lenfix;
alpar@9:     state->lenbits = 9;
alpar@9:     state->distcode = distfix;
alpar@9:     state->distbits = 5;
alpar@9: }
alpar@9: 
alpar@9: /* Macros for inflateBack(): */
alpar@9: 
alpar@9: /* Load returned state from inflate_fast() */
alpar@9: #define LOAD() \
alpar@9:     do { \
alpar@9:         put = strm->next_out; \
alpar@9:         left = strm->avail_out; \
alpar@9:         next = strm->next_in; \
alpar@9:         have = strm->avail_in; \
alpar@9:         hold = state->hold; \
alpar@9:         bits = state->bits; \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Set state from registers for inflate_fast() */
alpar@9: #define RESTORE() \
alpar@9:     do { \
alpar@9:         strm->next_out = put; \
alpar@9:         strm->avail_out = left; \
alpar@9:         strm->next_in = next; \
alpar@9:         strm->avail_in = have; \
alpar@9:         state->hold = hold; \
alpar@9:         state->bits = bits; \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Clear the input bit accumulator */
alpar@9: #define INITBITS() \
alpar@9:     do { \
alpar@9:         hold = 0; \
alpar@9:         bits = 0; \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Assure that some input is available.  If input is requested, but denied,
alpar@9:    then return a Z_BUF_ERROR from inflateBack(). */
alpar@9: #define PULL() \
alpar@9:     do { \
alpar@9:         if (have == 0) { \
alpar@9:             have = in(in_desc, &next); \
alpar@9:             if (have == 0) { \
alpar@9:                 next = Z_NULL; \
alpar@9:                 ret = Z_BUF_ERROR; \
alpar@9:                 goto inf_leave; \
alpar@9:             } \
alpar@9:         } \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Get a byte of input into the bit accumulator, or return from inflateBack()
alpar@9:    with an error if there is no input available. */
alpar@9: #define PULLBYTE() \
alpar@9:     do { \
alpar@9:         PULL(); \
alpar@9:         have--; \
alpar@9:         hold += (unsigned long)(*next++) << bits; \
alpar@9:         bits += 8; \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Assure that there are at least n bits in the bit accumulator.  If there is
alpar@9:    not enough available input to do that, then return from inflateBack() with
alpar@9:    an error. */
alpar@9: #define NEEDBITS(n) \
alpar@9:     do { \
alpar@9:         while (bits < (unsigned)(n)) \
alpar@9:             PULLBYTE(); \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Return the low n bits of the bit accumulator (n < 16) */
alpar@9: #define BITS(n) \
alpar@9:     ((unsigned)hold & ((1U << (n)) - 1))
alpar@9: 
alpar@9: /* Remove n bits from the bit accumulator */
alpar@9: #define DROPBITS(n) \
alpar@9:     do { \
alpar@9:         hold >>= (n); \
alpar@9:         bits -= (unsigned)(n); \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Remove zero to seven bits as needed to go to a byte boundary */
alpar@9: #define BYTEBITS() \
alpar@9:     do { \
alpar@9:         hold >>= bits & 7; \
alpar@9:         bits -= bits & 7; \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /* Assure that some output space is available, by writing out the window
alpar@9:    if it's full.  If the write fails, return from inflateBack() with a
alpar@9:    Z_BUF_ERROR. */
alpar@9: #define ROOM() \
alpar@9:     do { \
alpar@9:         if (left == 0) { \
alpar@9:             put = state->window; \
alpar@9:             left = state->wsize; \
alpar@9:             state->whave = left; \
alpar@9:             if (out(out_desc, put, left)) { \
alpar@9:                 ret = Z_BUF_ERROR; \
alpar@9:                 goto inf_leave; \
alpar@9:             } \
alpar@9:         } \
alpar@9:     } while (0)
alpar@9: 
alpar@9: /*
alpar@9:    strm provides the memory allocation functions and window buffer on input,
alpar@9:    and provides information on the unused input on return.  For Z_DATA_ERROR
alpar@9:    returns, strm will also provide an error message.
alpar@9: 
alpar@9:    in() and out() are the call-back input and output functions.  When
alpar@9:    inflateBack() needs more input, it calls in().  When inflateBack() has
alpar@9:    filled the window with output, or when it completes with data in the
alpar@9:    window, it calls out() to write out the data.  The application must not
alpar@9:    change the provided input until in() is called again or inflateBack()
alpar@9:    returns.  The application must not change the window/output buffer until
alpar@9:    inflateBack() returns.
alpar@9: 
alpar@9:    in() and out() are called with a descriptor parameter provided in the
alpar@9:    inflateBack() call.  This parameter can be a structure that provides the
alpar@9:    information required to do the read or write, as well as accumulated
alpar@9:    information on the input and output such as totals and check values.
alpar@9: 
alpar@9:    in() should return zero on failure.  out() should return non-zero on
alpar@9:    failure.  If either in() or out() fails, than inflateBack() returns a
alpar@9:    Z_BUF_ERROR.  strm->next_in can be checked for Z_NULL to see whether it
alpar@9:    was in() or out() that caused in the error.  Otherwise,  inflateBack()
alpar@9:    returns Z_STREAM_END on success, Z_DATA_ERROR for an deflate format
alpar@9:    error, or Z_MEM_ERROR if it could not allocate memory for the state.
alpar@9:    inflateBack() can also return Z_STREAM_ERROR if the input parameters
alpar@9:    are not correct, i.e. strm is Z_NULL or the state was not initialized.
alpar@9:  */
alpar@9: int ZEXPORT inflateBack(strm, in, in_desc, out, out_desc)
alpar@9: z_streamp strm;
alpar@9: in_func in;
alpar@9: void FAR *in_desc;
alpar@9: out_func out;
alpar@9: void FAR *out_desc;
alpar@9: {
alpar@9:     struct inflate_state FAR *state;
alpar@9:     unsigned char FAR *next;    /* next input */
alpar@9:     unsigned char FAR *put;     /* next output */
alpar@9:     unsigned have, left;        /* available input and output */
alpar@9:     unsigned long hold;         /* bit buffer */
alpar@9:     unsigned bits;              /* bits in bit buffer */
alpar@9:     unsigned copy;              /* number of stored or match bytes to copy */
alpar@9:     unsigned char FAR *from;    /* where to copy match bytes from */
alpar@9:     code here;                  /* current decoding table entry */
alpar@9:     code last;                  /* parent table entry */
alpar@9:     unsigned len;               /* length to copy for repeats, bits to drop */
alpar@9:     int ret;                    /* return code */
alpar@9:     static const unsigned short order[19] = /* permutation of code lengths */
alpar@9:         {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
alpar@9: 
alpar@9:     /* Check that the strm exists and that the state was initialized */
alpar@9:     if (strm == Z_NULL || strm->state == Z_NULL)
alpar@9:         return Z_STREAM_ERROR;
alpar@9:     state = (struct inflate_state FAR *)strm->state;
alpar@9: 
alpar@9:     /* Reset the state */
alpar@9:     strm->msg = Z_NULL;
alpar@9:     state->mode = TYPE;
alpar@9:     state->last = 0;
alpar@9:     state->whave = 0;
alpar@9:     next = strm->next_in;
alpar@9:     have = next != Z_NULL ? strm->avail_in : 0;
alpar@9:     hold = 0;
alpar@9:     bits = 0;
alpar@9:     put = state->window;
alpar@9:     left = state->wsize;
alpar@9: 
alpar@9:     /* Inflate until end of block marked as last */
alpar@9:     for (;;)
alpar@9:         switch (state->mode) {
alpar@9:         case TYPE:
alpar@9:             /* determine and dispatch block type */
alpar@9:             if (state->last) {
alpar@9:                 BYTEBITS();
alpar@9:                 state->mode = DONE;
alpar@9:                 break;
alpar@9:             }
alpar@9:             NEEDBITS(3);
alpar@9:             state->last = BITS(1);
alpar@9:             DROPBITS(1);
alpar@9:             switch (BITS(2)) {
alpar@9:             case 0:                             /* stored block */
alpar@9:                 Tracev((stderr, "inflate:     stored block%s\n",
alpar@9:                         state->last ? " (last)" : ""));
alpar@9:                 state->mode = STORED;
alpar@9:                 break;
alpar@9:             case 1:                             /* fixed block */
alpar@9:                 fixedtables(state);
alpar@9:                 Tracev((stderr, "inflate:     fixed codes block%s\n",
alpar@9:                         state->last ? " (last)" : ""));
alpar@9:                 state->mode = LEN;              /* decode codes */
alpar@9:                 break;
alpar@9:             case 2:                             /* dynamic block */
alpar@9:                 Tracev((stderr, "inflate:     dynamic codes block%s\n",
alpar@9:                         state->last ? " (last)" : ""));
alpar@9:                 state->mode = TABLE;
alpar@9:                 break;
alpar@9:             case 3:
alpar@9:                 strm->msg = (char *)"invalid block type";
alpar@9:                 state->mode = BAD;
alpar@9:             }
alpar@9:             DROPBITS(2);
alpar@9:             break;
alpar@9: 
alpar@9:         case STORED:
alpar@9:             /* get and verify stored block length */
alpar@9:             BYTEBITS();                         /* go to byte boundary */
alpar@9:             NEEDBITS(32);
alpar@9:             if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
alpar@9:                 strm->msg = (char *)"invalid stored block lengths";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             state->length = (unsigned)hold & 0xffff;
alpar@9:             Tracev((stderr, "inflate:       stored length %u\n",
alpar@9:                     state->length));
alpar@9:             INITBITS();
alpar@9: 
alpar@9:             /* copy stored block from input to output */
alpar@9:             while (state->length != 0) {
alpar@9:                 copy = state->length;
alpar@9:                 PULL();
alpar@9:                 ROOM();
alpar@9:                 if (copy > have) copy = have;
alpar@9:                 if (copy > left) copy = left;
alpar@9:                 zmemcpy(put, next, copy);
alpar@9:                 have -= copy;
alpar@9:                 next += copy;
alpar@9:                 left -= copy;
alpar@9:                 put += copy;
alpar@9:                 state->length -= copy;
alpar@9:             }
alpar@9:             Tracev((stderr, "inflate:       stored end\n"));
alpar@9:             state->mode = TYPE;
alpar@9:             break;
alpar@9: 
alpar@9:         case TABLE:
alpar@9:             /* get dynamic table entries descriptor */
alpar@9:             NEEDBITS(14);
alpar@9:             state->nlen = BITS(5) + 257;
alpar@9:             DROPBITS(5);
alpar@9:             state->ndist = BITS(5) + 1;
alpar@9:             DROPBITS(5);
alpar@9:             state->ncode = BITS(4) + 4;
alpar@9:             DROPBITS(4);
alpar@9: #ifndef PKZIP_BUG_WORKAROUND
alpar@9:             if (state->nlen > 286 || state->ndist > 30) {
alpar@9:                 strm->msg = (char *)"too many length or distance symbols";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9: #endif
alpar@9:             Tracev((stderr, "inflate:       table sizes ok\n"));
alpar@9: 
alpar@9:             /* get code length code lengths (not a typo) */
alpar@9:             state->have = 0;
alpar@9:             while (state->have < state->ncode) {
alpar@9:                 NEEDBITS(3);
alpar@9:                 state->lens[order[state->have++]] = (unsigned short)BITS(3);
alpar@9:                 DROPBITS(3);
alpar@9:             }
alpar@9:             while (state->have < 19)
alpar@9:                 state->lens[order[state->have++]] = 0;
alpar@9:             state->next = state->codes;
alpar@9:             state->lencode = (code const FAR *)(state->next);
alpar@9:             state->lenbits = 7;
alpar@9:             ret = inflate_table(CODES, state->lens, 19, &(state->next),
alpar@9:                                 &(state->lenbits), state->work);
alpar@9:             if (ret) {
alpar@9:                 strm->msg = (char *)"invalid code lengths set";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             Tracev((stderr, "inflate:       code lengths ok\n"));
alpar@9: 
alpar@9:             /* get length and distance code code lengths */
alpar@9:             state->have = 0;
alpar@9:             while (state->have < state->nlen + state->ndist) {
alpar@9:                 for (;;) {
alpar@9:                     here = state->lencode[BITS(state->lenbits)];
alpar@9:                     if ((unsigned)(here.bits) <= bits) break;
alpar@9:                     PULLBYTE();
alpar@9:                 }
alpar@9:                 if (here.val < 16) {
alpar@9:                     NEEDBITS(here.bits);
alpar@9:                     DROPBITS(here.bits);
alpar@9:                     state->lens[state->have++] = here.val;
alpar@9:                 }
alpar@9:                 else {
alpar@9:                     if (here.val == 16) {
alpar@9:                         NEEDBITS(here.bits + 2);
alpar@9:                         DROPBITS(here.bits);
alpar@9:                         if (state->have == 0) {
alpar@9:                             strm->msg = (char *)"invalid bit length repeat";
alpar@9:                             state->mode = BAD;
alpar@9:                             break;
alpar@9:                         }
alpar@9:                         len = (unsigned)(state->lens[state->have - 1]);
alpar@9:                         copy = 3 + BITS(2);
alpar@9:                         DROPBITS(2);
alpar@9:                     }
alpar@9:                     else if (here.val == 17) {
alpar@9:                         NEEDBITS(here.bits + 3);
alpar@9:                         DROPBITS(here.bits);
alpar@9:                         len = 0;
alpar@9:                         copy = 3 + BITS(3);
alpar@9:                         DROPBITS(3);
alpar@9:                     }
alpar@9:                     else {
alpar@9:                         NEEDBITS(here.bits + 7);
alpar@9:                         DROPBITS(here.bits);
alpar@9:                         len = 0;
alpar@9:                         copy = 11 + BITS(7);
alpar@9:                         DROPBITS(7);
alpar@9:                     }
alpar@9:                     if (state->have + copy > state->nlen + state->ndist) {
alpar@9:                         strm->msg = (char *)"invalid bit length repeat";
alpar@9:                         state->mode = BAD;
alpar@9:                         break;
alpar@9:                     }
alpar@9:                     while (copy--)
alpar@9:                         state->lens[state->have++] = (unsigned short)len;
alpar@9:                 }
alpar@9:             }
alpar@9: 
alpar@9:             /* handle error breaks in while */
alpar@9:             if (state->mode == BAD) break;
alpar@9: 
alpar@9:             /* check for end-of-block code (better have one) */
alpar@9:             if (state->lens[256] == 0) {
alpar@9:                 strm->msg = (char *)"invalid code -- missing end-of-block";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9: 
alpar@9:             /* build code tables -- note: do not change the lenbits or distbits
alpar@9:                values here (9 and 6) without reading the comments in inftrees.h
alpar@9:                concerning the ENOUGH constants, which depend on those values */
alpar@9:             state->next = state->codes;
alpar@9:             state->lencode = (code const FAR *)(state->next);
alpar@9:             state->lenbits = 9;
alpar@9:             ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
alpar@9:                                 &(state->lenbits), state->work);
alpar@9:             if (ret) {
alpar@9:                 strm->msg = (char *)"invalid literal/lengths set";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             state->distcode = (code const FAR *)(state->next);
alpar@9:             state->distbits = 6;
alpar@9:             ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
alpar@9:                             &(state->next), &(state->distbits), state->work);
alpar@9:             if (ret) {
alpar@9:                 strm->msg = (char *)"invalid distances set";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             Tracev((stderr, "inflate:       codes ok\n"));
alpar@9:             state->mode = LEN;
alpar@9: 
alpar@9:         case LEN:
alpar@9:             /* use inflate_fast() if we have enough input and output */
alpar@9:             if (have >= 6 && left >= 258) {
alpar@9:                 RESTORE();
alpar@9:                 if (state->whave < state->wsize)
alpar@9:                     state->whave = state->wsize - left;
alpar@9:                 inflate_fast(strm, state->wsize);
alpar@9:                 LOAD();
alpar@9:                 break;
alpar@9:             }
alpar@9: 
alpar@9:             /* get a literal, length, or end-of-block code */
alpar@9:             for (;;) {
alpar@9:                 here = state->lencode[BITS(state->lenbits)];
alpar@9:                 if ((unsigned)(here.bits) <= bits) break;
alpar@9:                 PULLBYTE();
alpar@9:             }
alpar@9:             if (here.op && (here.op & 0xf0) == 0) {
alpar@9:                 last = here;
alpar@9:                 for (;;) {
alpar@9:                     here = state->lencode[last.val +
alpar@9:                             (BITS(last.bits + last.op) >> last.bits)];
alpar@9:                     if ((unsigned)(last.bits + here.bits) <= bits) break;
alpar@9:                     PULLBYTE();
alpar@9:                 }
alpar@9:                 DROPBITS(last.bits);
alpar@9:             }
alpar@9:             DROPBITS(here.bits);
alpar@9:             state->length = (unsigned)here.val;
alpar@9: 
alpar@9:             /* process literal */
alpar@9:             if (here.op == 0) {
alpar@9:                 Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
alpar@9:                         "inflate:         literal '%c'\n" :
alpar@9:                         "inflate:         literal 0x%02x\n", here.val));
alpar@9:                 ROOM();
alpar@9:                 *put++ = (unsigned char)(state->length);
alpar@9:                 left--;
alpar@9:                 state->mode = LEN;
alpar@9:                 break;
alpar@9:             }
alpar@9: 
alpar@9:             /* process end of block */
alpar@9:             if (here.op & 32) {
alpar@9:                 Tracevv((stderr, "inflate:         end of block\n"));
alpar@9:                 state->mode = TYPE;
alpar@9:                 break;
alpar@9:             }
alpar@9: 
alpar@9:             /* invalid code */
alpar@9:             if (here.op & 64) {
alpar@9:                 strm->msg = (char *)"invalid literal/length code";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9: 
alpar@9:             /* length code -- get extra bits, if any */
alpar@9:             state->extra = (unsigned)(here.op) & 15;
alpar@9:             if (state->extra != 0) {
alpar@9:                 NEEDBITS(state->extra);
alpar@9:                 state->length += BITS(state->extra);
alpar@9:                 DROPBITS(state->extra);
alpar@9:             }
alpar@9:             Tracevv((stderr, "inflate:         length %u\n", state->length));
alpar@9: 
alpar@9:             /* get distance code */
alpar@9:             for (;;) {
alpar@9:                 here = state->distcode[BITS(state->distbits)];
alpar@9:                 if ((unsigned)(here.bits) <= bits) break;
alpar@9:                 PULLBYTE();
alpar@9:             }
alpar@9:             if ((here.op & 0xf0) == 0) {
alpar@9:                 last = here;
alpar@9:                 for (;;) {
alpar@9:                     here = state->distcode[last.val +
alpar@9:                             (BITS(last.bits + last.op) >> last.bits)];
alpar@9:                     if ((unsigned)(last.bits + here.bits) <= bits) break;
alpar@9:                     PULLBYTE();
alpar@9:                 }
alpar@9:                 DROPBITS(last.bits);
alpar@9:             }
alpar@9:             DROPBITS(here.bits);
alpar@9:             if (here.op & 64) {
alpar@9:                 strm->msg = (char *)"invalid distance code";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             state->offset = (unsigned)here.val;
alpar@9: 
alpar@9:             /* get distance extra bits, if any */
alpar@9:             state->extra = (unsigned)(here.op) & 15;
alpar@9:             if (state->extra != 0) {
alpar@9:                 NEEDBITS(state->extra);
alpar@9:                 state->offset += BITS(state->extra);
alpar@9:                 DROPBITS(state->extra);
alpar@9:             }
alpar@9:             if (state->offset > state->wsize - (state->whave < state->wsize ?
alpar@9:                                                 left : 0)) {
alpar@9:                 strm->msg = (char *)"invalid distance too far back";
alpar@9:                 state->mode = BAD;
alpar@9:                 break;
alpar@9:             }
alpar@9:             Tracevv((stderr, "inflate:         distance %u\n", state->offset));
alpar@9: 
alpar@9:             /* copy match from window to output */
alpar@9:             do {
alpar@9:                 ROOM();
alpar@9:                 copy = state->wsize - state->offset;
alpar@9:                 if (copy < left) {
alpar@9:                     from = put + copy;
alpar@9:                     copy = left - copy;
alpar@9:                 }
alpar@9:                 else {
alpar@9:                     from = put - state->offset;
alpar@9:                     copy = left;
alpar@9:                 }
alpar@9:                 if (copy > state->length) copy = state->length;
alpar@9:                 state->length -= copy;
alpar@9:                 left -= copy;
alpar@9:                 do {
alpar@9:                     *put++ = *from++;
alpar@9:                 } while (--copy);
alpar@9:             } while (state->length != 0);
alpar@9:             break;
alpar@9: 
alpar@9:         case DONE:
alpar@9:             /* inflate stream terminated properly -- write leftover output */
alpar@9:             ret = Z_STREAM_END;
alpar@9:             if (left < state->wsize) {
alpar@9:                 if (out(out_desc, state->window, state->wsize - left))
alpar@9:                     ret = Z_BUF_ERROR;
alpar@9:             }
alpar@9:             goto inf_leave;
alpar@9: 
alpar@9:         case BAD:
alpar@9:             ret = Z_DATA_ERROR;
alpar@9:             goto inf_leave;
alpar@9: 
alpar@9:         default:                /* can't happen, but makes compilers happy */
alpar@9:             ret = Z_STREAM_ERROR;
alpar@9:             goto inf_leave;
alpar@9:         }
alpar@9: 
alpar@9:     /* Return unused input */
alpar@9:   inf_leave:
alpar@9:     strm->next_in = next;
alpar@9:     strm->avail_in = have;
alpar@9:     return ret;
alpar@9: }
alpar@9: 
alpar@9: int ZEXPORT inflateBackEnd(strm)
alpar@9: z_streamp strm;
alpar@9: {
alpar@9:     if (strm == Z_NULL || strm->state == Z_NULL || strm->zfree == (free_func)0)
alpar@9:         return Z_STREAM_ERROR;
alpar@9:     ZFREE(strm, strm->state);
alpar@9:     strm->state = Z_NULL;
alpar@9:     Tracev((stderr, "inflate: end\n"));
alpar@9:     return Z_OK;
alpar@9: }