/src/gstreamer/subprojects/zlib-1.3.2/infback.c

Source
/* infback.c -- inflate using a call-back interface
 * Copyright (C) 1995-2026 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/*
   This code is largely copied from inflate.c.  Normally either infback.o or
   inflate.o would be linked into an application--not both.  The interface
   with inffast.c is retained so that optimized assembler-coded versions of
   inflate_fast() can be used with either inflate.c or infback.c.
 */

#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"

/*
   strm provides memory allocation functions in zalloc and zfree, or
   Z_NULL to use the library memory allocation functions.

   windowBits is in the range 8..15, and window is a user-supplied
   window and output buffer that is 2**windowBits bytes.
 */
int ZEXPORT inflateBackInit_(z_streamp strm, int windowBits,
                             unsigned char FAR *window, const char *version,
                             int stream_size) {
    struct inflate_state FAR *state;

    if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
        stream_size != (int)(sizeof(z_stream)))
        return Z_VERSION_ERROR;
    if (strm == Z_NULL || window == Z_NULL ||
        windowBits < 8 || windowBits > 15)
        return Z_STREAM_ERROR;
    strm->msg = Z_NULL;                 /* in case we return an error */
    if (strm->zalloc == (alloc_func)0) {
#ifdef Z_SOLO
        return Z_STREAM_ERROR;
#else
        strm->zalloc = zcalloc;
        strm->opaque = (voidpf)0;
#endif
    }
    if (strm->zfree == (free_func)0)
#ifdef Z_SOLO
        return Z_STREAM_ERROR;
#else
        strm->zfree = zcfree;
#endif
    state = (struct inflate_state FAR *)ZALLOC(strm, 1,
                                               sizeof(struct inflate_state));
    if (state == Z_NULL) return Z_MEM_ERROR;
    Tracev((stderr, "inflate: allocated\n"));
    strm->state = (struct internal_state FAR *)state;
    state->dmax = 32768U;
    state->wbits = (uInt)windowBits;
    state->wsize = 1U << windowBits;
    state->window = window;
    state->wnext = 0;
    state->whave = 0;
    state->sane = 1;
    return Z_OK;
}

/* Macros for inflateBack(): */

/* Load returned state from inflate_fast() */
#define LOAD() \
    do { \
        put = strm->next_out; \
        left = strm->avail_out; \
        next = strm->next_in; \
        have = strm->avail_in; \
        hold = state->hold; \
        bits = state->bits; \
    } while (0)

/* Set state from registers for inflate_fast() */
#define RESTORE() \
    do { \
        strm->next_out = put; \
        strm->avail_out = left; \
        strm->next_in = next; \
        strm->avail_in = have; \
        state->hold = hold; \
        state->bits = bits; \
    } while (0)

/* Clear the input bit accumulator */
#define INITBITS() \
    do { \
        hold = 0; \
        bits = 0; \
    } while (0)

/* Assure that some input is available.  If input is requested, but denied,
   then return a Z_BUF_ERROR from inflateBack(). */
#define PULL() \
    do { \
        if (have == 0) { \
            have = in(in_desc, &next); \
            if (have == 0) { \
                next = Z_NULL; \
                ret = Z_BUF_ERROR; \
                goto inf_leave; \
            } \
        } \
    } while (0)

/* Get a byte of input into the bit accumulator, or return from inflateBack()
   with an error if there is no input available. */
#define PULLBYTE() \
    do { \
        PULL(); \
        have--; \
        hold += (unsigned long)(*next++) << bits; \
        bits += 8; \
    } while (0)

/* Assure that there are at least n bits in the bit accumulator.  If there is
   not enough available input to do that, then return from inflateBack() with
   an error. */
#define NEEDBITS(n) \
    do { \
        while (bits < (unsigned)(n)) \
            PULLBYTE(); \
    } while (0)

/* Return the low n bits of the bit accumulator (n < 16) */
#define BITS(n) \
    ((unsigned)hold & ((1U << (n)) - 1))

/* Remove n bits from the bit accumulator */
#define DROPBITS(n) \
    do { \
        hold >>= (n); \
        bits -= (unsigned)(n); \
    } while (0)

/* Remove zero to seven bits as needed to go to a byte boundary */
#define BYTEBITS() \
    do { \
        hold >>= bits & 7; \
        bits -= bits & 7; \
    } while (0)

/* Assure that some output space is available, by writing out the window
   if it's full.  If the write fails, return from inflateBack() with a
   Z_BUF_ERROR. */
#define ROOM() \
    do { \
        if (left == 0) { \
            put = state->window; \
            left = state->wsize; \
            state->whave = left; \
            if (out(out_desc, put, left)) { \
                ret = Z_BUF_ERROR; \
                goto inf_leave; \
            } \
        } \
    } while (0)

/*
   strm provides the memory allocation functions and window buffer on input,
   and provides information on the unused input on return.  For Z_DATA_ERROR
   returns, strm will also provide an error message.

   in() and out() are the call-back input and output functions.  When
   inflateBack() needs more input, it calls in().  When inflateBack() has
   filled the window with output, or when it completes with data in the
   window, it calls out() to write out the data.  The application must not
   change the provided input until in() is called again or inflateBack()
   returns.  The application must not change the window/output buffer until
   inflateBack() returns.

   in() and out() are called with a descriptor parameter provided in the
   inflateBack() call.  This parameter can be a structure that provides the
   information required to do the read or write, as well as accumulated
   information on the input and output such as totals and check values.

   in() should return zero on failure.  out() should return non-zero on
   failure.  If either in() or out() fails, than inflateBack() returns a
   Z_BUF_ERROR.  strm->next_in can be checked for Z_NULL to see whether it
   was in() or out() that caused in the error.  Otherwise,  inflateBack()
   returns Z_STREAM_END on success, Z_DATA_ERROR for an deflate format
   error, or Z_MEM_ERROR if it could not allocate memory for the state.
   inflateBack() can also return Z_STREAM_ERROR if the input parameters
   are not correct, i.e. strm is Z_NULL or the state was not initialized.
 */
int ZEXPORT inflateBack(z_streamp strm, in_func in, void FAR *in_desc,
                        out_func out, void FAR *out_desc) {
    struct inflate_state FAR *state;
    z_const unsigned char FAR *next;    /* next input */
    unsigned char FAR *put;     /* next output */
    unsigned have, left;        /* available input and output */
    unsigned long hold;         /* bit buffer */
    unsigned bits;              /* bits in bit buffer */
    unsigned copy;              /* number of stored or match bytes to copy */
    unsigned char FAR *from;    /* where to copy match bytes from */
    code here;                  /* current decoding table entry */
    code last;                  /* parent table entry */
    unsigned len;               /* length to copy for repeats, bits to drop */
    int ret;                    /* return code */
    static const unsigned short order[19] = /* permutation of code lengths */
        {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};

    /* Check that the strm exists and that the state was initialized */
    if (strm == Z_NULL || strm->state == Z_NULL)
        return Z_STREAM_ERROR;
    state = (struct inflate_state FAR *)strm->state;

    /* Reset the state */
    strm->msg = Z_NULL;
    state->mode = TYPE;
    state->last = 0;
    state->whave = 0;
    next = strm->next_in;
    have = next != Z_NULL ? strm->avail_in : 0;
    hold = 0;
    bits = 0;
    put = state->window;
    left = state->wsize;

    /* Inflate until end of block marked as last */
    for (;;)
        switch (state->mode) {
        case TYPE:
            /* determine and dispatch block type */
            if (state->last) {
                BYTEBITS();
                state->mode = DONE;
                break;
            }
            NEEDBITS(3);
            state->last = BITS(1);
            DROPBITS(1);
            switch (BITS(2)) {
            case 0:                             /* stored block */
                Tracev((stderr, "inflate:     stored block%s\n",
                        state->last ? " (last)" : ""));
                state->mode = STORED;
                break;
            case 1:                             /* fixed block */
                inflate_fixed(state);
                Tracev((stderr, "inflate:     fixed codes block%s\n",
                        state->last ? " (last)" : ""));
                state->mode = LEN;              /* decode codes */
                break;
            case 2:                             /* dynamic block */
                Tracev((stderr, "inflate:     dynamic codes block%s\n",
                        state->last ? " (last)" : ""));
                state->mode = TABLE;
                break;
            default:
                strm->msg = (z_const char *)"invalid block type";
                state->mode = BAD;
            }
            DROPBITS(2);
            break;

        case STORED:
            /* get and verify stored block length */
            BYTEBITS();                         /* go to byte boundary */
            NEEDBITS(32);
            if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
                strm->msg = (z_const char *)"invalid stored block lengths";
                state->mode = BAD;
                break;
            }
            state->length = (unsigned)hold & 0xffff;
            Tracev((stderr, "inflate:       stored length %u\n",
                    state->length));
            INITBITS();

            /* copy stored block from input to output */
            while (state->length != 0) {
                copy = state->length;
                PULL();
                ROOM();
                if (copy > have) copy = have;
                if (copy > left) copy = left;
                zmemcpy(put, next, copy);
                have -= copy;
                next += copy;
                left -= copy;
                put += copy;
                state->length -= copy;
            }
            Tracev((stderr, "inflate:       stored end\n"));
            state->mode = TYPE;
            break;

        case TABLE:
            /* get dynamic table entries descriptor */
            NEEDBITS(14);
            state->nlen = BITS(5) + 257;
            DROPBITS(5);
            state->ndist = BITS(5) + 1;
            DROPBITS(5);
            state->ncode = BITS(4) + 4;
            DROPBITS(4);
#ifndef PKZIP_BUG_WORKAROUND
            if (state->nlen > 286 || state->ndist > 30) {
                strm->msg = (z_const char *)
                    "too many length or distance symbols";
                state->mode = BAD;
                break;
            }
#endif
            Tracev((stderr, "inflate:       table sizes ok\n"));

            /* get code length code lengths (not a typo) */
            state->have = 0;
            while (state->have < state->ncode) {
                NEEDBITS(3);
                state->lens[order[state->have++]] = (unsigned short)BITS(3);
                DROPBITS(3);
            }
            while (state->have < 19)
                state->lens[order[state->have++]] = 0;
            state->next = state->codes;
            state->lencode = (code const FAR *)(state->next);
            state->lenbits = 7;
            ret = inflate_table(CODES, state->lens, 19, &(state->next),
                                &(state->lenbits), state->work);
            if (ret) {
                strm->msg = (z_const char *)"invalid code lengths set";
                state->mode = BAD;
                break;
            }
            Tracev((stderr, "inflate:       code lengths ok\n"));

            /* get length and distance code code lengths */
            state->have = 0;
            while (state->have < state->nlen + state->ndist) {
                for (;;) {
                    here = state->lencode[BITS(state->lenbits)];
                    if ((unsigned)(here.bits) <= bits) break;
                    PULLBYTE();
                }
                if (here.val < 16) {
                    DROPBITS(here.bits);
                    state->lens[state->have++] = here.val;
                }
                else {
                    if (here.val == 16) {
                        NEEDBITS(here.bits + 2);
                        DROPBITS(here.bits);
                        if (state->have == 0) {
                            strm->msg = (z_const char *)
                                "invalid bit length repeat";
                            state->mode = BAD;
                            break;
                        }
                        len = (unsigned)(state->lens[state->have - 1]);
                        copy = 3 + BITS(2);
                        DROPBITS(2);
                    }
                    else if (here.val == 17) {
                        NEEDBITS(here.bits + 3);
                        DROPBITS(here.bits);
                        len = 0;
                        copy = 3 + BITS(3);
                        DROPBITS(3);
                    }
                    else {
                        NEEDBITS(here.bits + 7);
                        DROPBITS(here.bits);
                        len = 0;
                        copy = 11 + BITS(7);
                        DROPBITS(7);
                    }
                    if (state->have + copy > state->nlen + state->ndist) {
                        strm->msg = (z_const char *)
                            "invalid bit length repeat";
                        state->mode = BAD;
                        break;
                    }
                    while (copy--)
                        state->lens[state->have++] = (unsigned short)len;
                }
            }

            /* handle error breaks in while */
            if (state->mode == BAD) break;

            /* check for end-of-block code (better have one) */
            if (state->lens[256] == 0) {
                strm->msg = (z_const char *)
                    "invalid code -- missing end-of-block";
                state->mode = BAD;
                break;
            }

            /* build code tables -- note: do not change the lenbits or distbits
               values here (9 and 6) without reading the comments in inftrees.h
               concerning the ENOUGH constants, which depend on those values */
            state->next = state->codes;
            state->lencode = (code const FAR *)(state->next);
            state->lenbits = 9;
            ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
                                &(state->lenbits), state->work);
            if (ret) {
                strm->msg = (z_const char *)"invalid literal/lengths set";
                state->mode = BAD;
                break;
            }
            state->distcode = (code const FAR *)(state->next);
            state->distbits = 6;
            ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
                            &(state->next), &(state->distbits), state->work);
            if (ret) {
                strm->msg = (z_const char *)"invalid distances set";
                state->mode = BAD;
                break;
            }
            Tracev((stderr, "inflate:       codes ok\n"));
            state->mode = LEN;
                /* fallthrough */

        case LEN:
            /* use inflate_fast() if we have enough input and output */
            if (have >= 6 && left >= 258) {
                RESTORE();
                if (state->whave < state->wsize)
                    state->whave = state->wsize - left;
                inflate_fast(strm, state->wsize);
                LOAD();
                break;
            }

            /* get a literal, length, or end-of-block code */
            for (;;) {
                here = state->lencode[BITS(state->lenbits)];
                if ((unsigned)(here.bits) <= bits) break;
                PULLBYTE();
            }
            if (here.op && (here.op & 0xf0) == 0) {
                last = here;
                for (;;) {
                    here = state->lencode[last.val +
                            (BITS(last.bits + last.op) >> last.bits)];
                    if ((unsigned)(last.bits + here.bits) <= bits) break;
                    PULLBYTE();
                }
                DROPBITS(last.bits);
            }
            DROPBITS(here.bits);
            state->length = (unsigned)here.val;

            /* process literal */
            if (here.op == 0) {
                Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
                        "inflate:         literal '%c'\n" :
                        "inflate:         literal 0x%02x\n", here.val));
                ROOM();
                *put++ = (unsigned char)(state->length);
                left--;
                state->mode = LEN;
                break;
            }

            /* process end of block */
            if (here.op & 32) {
                Tracevv((stderr, "inflate:         end of block\n"));
                state->mode = TYPE;
                break;
            }

            /* invalid code */
            if (here.op & 64) {
                strm->msg = (z_const char *)"invalid literal/length code";
                state->mode = BAD;
                break;
            }

            /* length code -- get extra bits, if any */
            state->extra = (unsigned)(here.op) & 15;
            if (state->extra != 0) {
                NEEDBITS(state->extra);
                state->length += BITS(state->extra);
                DROPBITS(state->extra);
            }
            Tracevv((stderr, "inflate:         length %u\n", state->length));

            /* get distance code */
            for (;;) {
                here = state->distcode[BITS(state->distbits)];
                if ((unsigned)(here.bits) <= bits) break;
                PULLBYTE();
            }
            if ((here.op & 0xf0) == 0) {
                last = here;
                for (;;) {
                    here = state->distcode[last.val +
                            (BITS(last.bits + last.op) >> last.bits)];
                    if ((unsigned)(last.bits + here.bits) <= bits) break;
                    PULLBYTE();
                }
                DROPBITS(last.bits);
            }
            DROPBITS(here.bits);
            if (here.op & 64) {
                strm->msg = (z_const char *)"invalid distance code";
                state->mode = BAD;
                break;
            }
            state->offset = (unsigned)here.val;

            /* get distance extra bits, if any */
            state->extra = (unsigned)(here.op) & 15;
            if (state->extra != 0) {
                NEEDBITS(state->extra);
                state->offset += BITS(state->extra);
                DROPBITS(state->extra);
            }
            if (state->offset > state->wsize - (state->whave < state->wsize ?
                                                left : 0)) {
                strm->msg = (z_const char *)"invalid distance too far back";
                state->mode = BAD;
                break;
            }
            Tracevv((stderr, "inflate:         distance %u\n", state->offset));

            /* copy match from window to output */
            do {
                ROOM();
                copy = state->wsize - state->offset;
                if (copy < left) {
                    from = put + copy;
                    copy = left - copy;
                }
                else {
                    from = put - state->offset;
                    copy = left;
                }
                if (copy > state->length) copy = state->length;
                state->length -= copy;
                left -= copy;
                do {
                    *put++ = *from++;
                } while (--copy);
            } while (state->length != 0);
            break;

        case DONE:
            /* inflate stream terminated properly */
            ret = Z_STREAM_END;
            goto inf_leave;

        case BAD:
            ret = Z_DATA_ERROR;
            goto inf_leave;

        default:
            /* can't happen, but makes compilers happy */
            ret = Z_STREAM_ERROR;
            goto inf_leave;
        }

    /* Write leftover output and return unused input */
  inf_leave:
    if (left < state->wsize) {
        if (out(out_desc, state->window, state->wsize - left) &&
            ret == Z_STREAM_END)
            ret = Z_BUF_ERROR;
    }
    strm->next_in = next;
    strm->avail_in = have;
    return ret;
}

int ZEXPORT inflateBackEnd(z_streamp strm) {
    if (strm == Z_NULL || strm->state == Z_NULL || strm->zfree == (free_func)0)
        return Z_STREAM_ERROR;
    ZFREE(strm, strm->state);
    strm->state = Z_NULL;
    Tracev((stderr, "inflate: end\n"));
    return Z_OK;
}

Coverage Report

Created: 2026-10-12 07:13

Line	Count	Source
1		/* infback.c -- inflate using a call-back interface
2		* Copyright (C) 1995-2026 Mark Adler
3		* For conditions of distribution and use, see copyright notice in zlib.h
4		*/
5
6		/*
7		This code is largely copied from inflate.c. Normally either infback.o or
8		inflate.o would be linked into an application--not both. The interface
9		with inffast.c is retained so that optimized assembler-coded versions of
10		inflate_fast() can be used with either inflate.c or infback.c.
11		*/
12
13		#include "zutil.h"
14		#include "inftrees.h"
15		#include "inflate.h"
16		#include "inffast.h"
17
18		/*
19		strm provides memory allocation functions in zalloc and zfree, or
20		Z_NULL to use the library memory allocation functions.
21
22		windowBits is in the range 8..15, and window is a user-supplied
23		window and output buffer that is 2**windowBits bytes.
24		*/
25		int ZEXPORT inflateBackInit_(z_streamp strm, int windowBits,
26		unsigned char FAR window, const char version,
27	0	int stream_size) {
28	0	struct inflate_state FAR *state;
29
30	0	if (version == Z_NULL \|\| version[0] != ZLIB_VERSION[0] \|\|
31	0	stream_size != (int)(sizeof(z_stream)))
32	0	return Z_VERSION_ERROR;
33	0	if (strm == Z_NULL \|\| window == Z_NULL \|\|
34	0	windowBits < 8 \|\| windowBits > 15)
35	0	return Z_STREAM_ERROR;
36	0	strm->msg = Z_NULL; /* in case we return an error */
37	0	if (strm->zalloc == (alloc_func)0) {
38		#ifdef Z_SOLO
39		return Z_STREAM_ERROR;
40		#else
41	0	strm->zalloc = zcalloc;
42	0	strm->opaque = (voidpf)0;
43	0	#endif
44	0	}
45	0	if (strm->zfree == (free_func)0)
46		#ifdef Z_SOLO
47		return Z_STREAM_ERROR;
48		#else
49	0	strm->zfree = zcfree;
50	0	#endif
51	0	state = (struct inflate_state FAR *)ZALLOC(strm, 1,
52	0	sizeof(struct inflate_state));
53	0	if (state == Z_NULL) return Z_MEM_ERROR;
54	0	Tracev((stderr, "inflate: allocated\n"));
55	0	strm->state = (struct internal_state FAR *)state;
56	0	state->dmax = 32768U;
57	0	state->wbits = (uInt)windowBits;
58	0	state->wsize = 1U << windowBits;
59	0	state->window = window;
60	0	state->wnext = 0;
61	0	state->whave = 0;
62	0	state->sane = 1;
63	0	return Z_OK;
64	0	}
65
66		/* Macros for inflateBack(): */
67
68		/* Load returned state from inflate_fast() */
69		#define LOAD() \
70	0	do { \
71	0	put = strm->next_out; \
72	0	left = strm->avail_out; \
73	0	next = strm->next_in; \
74	0	have = strm->avail_in; \
75	0	hold = state->hold; \
76	0	bits = state->bits; \
77	0	} while (0)
78
79		/* Set state from registers for inflate_fast() */
80		#define RESTORE() \
81	0	do { \
82	0	strm->next_out = put; \
83	0	strm->avail_out = left; \
84	0	strm->next_in = next; \
85	0	strm->avail_in = have; \
86	0	state->hold = hold; \
87	0	state->bits = bits; \
88	0	} while (0)
89
90		/* Clear the input bit accumulator */
91		#define INITBITS() \
92	0	do { \
93	0	hold = 0; \
94	0	bits = 0; \
95	0	} while (0)
96
97		/* Assure that some input is available. If input is requested, but denied,
98		then return a Z_BUF_ERROR from inflateBack(). */
99		#define PULL() \
100	0	do { \
101	0	if (have == 0) { \
102	0	have = in(in_desc, &next); \
103	0	if (have == 0) { \
104	0	next = Z_NULL; \
105	0	ret = Z_BUF_ERROR; \
106	0	goto inf_leave; \
107	0	} \
108	0	} \
109	0	} while (0)
110
111		/* Get a byte of input into the bit accumulator, or return from inflateBack()
112		with an error if there is no input available. */
113		#define PULLBYTE() \
114	0	do { \
115	0	PULL(); \
116	0	have--; \
117	0	hold += (unsigned long)(*next++) << bits; \
118	0	bits += 8; \
119	0	} while (0)
120
121		/* Assure that there are at least n bits in the bit accumulator. If there is
122		not enough available input to do that, then return from inflateBack() with
123		an error. */
124		#define NEEDBITS(n) \
125	0	do { \
126	0	while (bits < (unsigned)(n)) \
127	0	PULLBYTE(); \
128	0	} while (0)
129
130		/* Return the low n bits of the bit accumulator (n < 16) */
131		#define BITS(n) \
132	0	((unsigned)hold & ((1U << (n)) - 1))
133
134		/* Remove n bits from the bit accumulator */
135		#define DROPBITS(n) \
136	0	do { \
137	0	hold >>= (n); \
138	0	bits -= (unsigned)(n); \
139	0	} while (0)
140
141		/* Remove zero to seven bits as needed to go to a byte boundary */
142		#define BYTEBITS() \
143	0	do { \
144	0	hold >>= bits & 7; \
145	0	bits -= bits & 7; \
146	0	} while (0)
147
148		/* Assure that some output space is available, by writing out the window
149		if it's full. If the write fails, return from inflateBack() with a
150		Z_BUF_ERROR. */
151		#define ROOM() \
152	0	do { \
153	0	if (left == 0) { \
154	0	put = state->window; \
155	0	left = state->wsize; \
156	0	state->whave = left; \
157	0	if (out(out_desc, put, left)) { \
158	0	ret = Z_BUF_ERROR; \
159	0	goto inf_leave; \
160	0	} \
161	0	} \
162	0	} while (0)
163
164		/*
165		strm provides the memory allocation functions and window buffer on input,
166		and provides information on the unused input on return. For Z_DATA_ERROR
167		returns, strm will also provide an error message.
168
169		in() and out() are the call-back input and output functions. When
170		inflateBack() needs more input, it calls in(). When inflateBack() has
171		filled the window with output, or when it completes with data in the
172		window, it calls out() to write out the data. The application must not
173		change the provided input until in() is called again or inflateBack()
174		returns. The application must not change the window/output buffer until
175		inflateBack() returns.
176
177		in() and out() are called with a descriptor parameter provided in the
178		inflateBack() call. This parameter can be a structure that provides the
179		information required to do the read or write, as well as accumulated
180		information on the input and output such as totals and check values.
181
182		in() should return zero on failure. out() should return non-zero on
183		failure. If either in() or out() fails, than inflateBack() returns a
184		Z_BUF_ERROR. strm->next_in can be checked for Z_NULL to see whether it
185		was in() or out() that caused in the error. Otherwise, inflateBack()
186		returns Z_STREAM_END on success, Z_DATA_ERROR for an deflate format
187		error, or Z_MEM_ERROR if it could not allocate memory for the state.
188		inflateBack() can also return Z_STREAM_ERROR if the input parameters
189		are not correct, i.e. strm is Z_NULL or the state was not initialized.
190		*/
191		int ZEXPORT inflateBack(z_streamp strm, in_func in, void FAR *in_desc,
192	0	out_func out, void FAR *out_desc) {
193	0	struct inflate_state FAR *state;
194	0	z_const unsigned char FAR next; / next input */
195	0	unsigned char FAR put; / next output */
196	0	unsigned have, left; /* available input and output */
197	0	unsigned long hold; /* bit buffer */
198	0	unsigned bits; /* bits in bit buffer */
199	0	unsigned copy; /* number of stored or match bytes to copy */
200	0	unsigned char FAR from; / where to copy match bytes from */
201	0	code here; /* current decoding table entry */
202	0	code last; /* parent table entry */
203	0	unsigned len; /* length to copy for repeats, bits to drop */
204	0	int ret; /* return code */
205	0	static const unsigned short order[19] = /* permutation of code lengths */
206	0	{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
207
208		/* Check that the strm exists and that the state was initialized */
209	0	if (strm == Z_NULL \|\| strm->state == Z_NULL)
210	0	return Z_STREAM_ERROR;
211	0	state = (struct inflate_state FAR *)strm->state;
212
213		/* Reset the state */
214	0	strm->msg = Z_NULL;
215	0	state->mode = TYPE;
216	0	state->last = 0;
217	0	state->whave = 0;
218	0	next = strm->next_in;
219	0	have = next != Z_NULL ? strm->avail_in : 0;
220	0	hold = 0;
221	0	bits = 0;
222	0	put = state->window;
223	0	left = state->wsize;
224
225		/* Inflate until end of block marked as last */
226	0	for (;;)
227	0	switch (state->mode) {
228	0	case TYPE:
229		/* determine and dispatch block type */
230	0	if (state->last) {
231	0	BYTEBITS();
232	0	state->mode = DONE;
233	0	break;
234	0	}
235	0	NEEDBITS(3);
236	0	state->last = BITS(1);
237	0	DROPBITS(1);
238	0	switch (BITS(2)) {
239	0	case 0: /* stored block */
240	0	Tracev((stderr, "inflate: stored block%s\n",
241	0	state->last ? " (last)" : ""));
242	0	state->mode = STORED;
243	0	break;
244	0	case 1: /* fixed block */
245	0	inflate_fixed(state);
246	0	Tracev((stderr, "inflate: fixed codes block%s\n",
247	0	state->last ? " (last)" : ""));
248	0	state->mode = LEN; /* decode codes */
249	0	break;
250	0	case 2: /* dynamic block */
251	0	Tracev((stderr, "inflate: dynamic codes block%s\n",
252	0	state->last ? " (last)" : ""));
253	0	state->mode = TABLE;
254	0	break;
255	0	default:
256	0	strm->msg = (z_const char *)"invalid block type";
257	0	state->mode = BAD;
258	0	}
259	0	DROPBITS(2);
260	0	break;
261
262	0	case STORED:
263		/* get and verify stored block length */
264	0	BYTEBITS(); /* go to byte boundary */
265	0	NEEDBITS(32);
266	0	if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
267	0	strm->msg = (z_const char *)"invalid stored block lengths";
268	0	state->mode = BAD;
269	0	break;
270	0	}
271	0	state->length = (unsigned)hold & 0xffff;
272	0	Tracev((stderr, "inflate: stored length %u\n",
273	0	state->length));
274	0	INITBITS();
275
276		/* copy stored block from input to output */
277	0	while (state->length != 0) {
278	0	copy = state->length;
279	0	PULL();
280	0	ROOM();
281	0	if (copy > have) copy = have;
282	0	if (copy > left) copy = left;
283	0	zmemcpy(put, next, copy);
284	0	have -= copy;
285	0	next += copy;
286	0	left -= copy;
287	0	put += copy;
288	0	state->length -= copy;
289	0	}
290	0	Tracev((stderr, "inflate: stored end\n"));
291	0	state->mode = TYPE;
292	0	break;
293
294	0	case TABLE:
295		/* get dynamic table entries descriptor */
296	0	NEEDBITS(14);
297	0	state->nlen = BITS(5) + 257;
298	0	DROPBITS(5);
299	0	state->ndist = BITS(5) + 1;
300	0	DROPBITS(5);
301	0	state->ncode = BITS(4) + 4;
302	0	DROPBITS(4);
303	0	#ifndef PKZIP_BUG_WORKAROUND
304	0	if (state->nlen > 286 \|\| state->ndist > 30) {
305	0	strm->msg = (z_const char *)
306	0	"too many length or distance symbols";
307	0	state->mode = BAD;
308	0	break;
309	0	}
310	0	#endif
311	0	Tracev((stderr, "inflate: table sizes ok\n"));
312
313		/* get code length code lengths (not a typo) */
314	0	state->have = 0;
315	0	while (state->have < state->ncode) {
316	0	NEEDBITS(3);
317	0	state->lens[order[state->have++]] = (unsigned short)BITS(3);
318	0	DROPBITS(3);
319	0	}
320	0	while (state->have < 19)
321	0	state->lens[order[state->have++]] = 0;
322	0	state->next = state->codes;
323	0	state->lencode = (code const FAR *)(state->next);
324	0	state->lenbits = 7;
325	0	ret = inflate_table(CODES, state->lens, 19, &(state->next),
326	0	&(state->lenbits), state->work);
327	0	if (ret) {
328	0	strm->msg = (z_const char *)"invalid code lengths set";
329	0	state->mode = BAD;
330	0	break;
331	0	}
332	0	Tracev((stderr, "inflate: code lengths ok\n"));
333
334		/* get length and distance code code lengths */
335	0	state->have = 0;
336	0	while (state->have < state->nlen + state->ndist) {
337	0	for (;;) {
338	0	here = state->lencode[BITS(state->lenbits)];
339	0	if ((unsigned)(here.bits) <= bits) break;
340	0	PULLBYTE();
341	0	}
342	0	if (here.val < 16) {
343	0	DROPBITS(here.bits);
344	0	state->lens[state->have++] = here.val;
345	0	}
346	0	else {
347	0	if (here.val == 16) {
348	0	NEEDBITS(here.bits + 2);
349	0	DROPBITS(here.bits);
350	0	if (state->have == 0) {
351	0	strm->msg = (z_const char *)
352	0	"invalid bit length repeat";
353	0	state->mode = BAD;
354	0	break;
355	0	}
356	0	len = (unsigned)(state->lens[state->have - 1]);
357	0	copy = 3 + BITS(2);
358	0	DROPBITS(2);
359	0	}
360	0	else if (here.val == 17) {
361	0	NEEDBITS(here.bits + 3);
362	0	DROPBITS(here.bits);
363	0	len = 0;
364	0	copy = 3 + BITS(3);
365	0	DROPBITS(3);
366	0	}
367	0	else {
368	0	NEEDBITS(here.bits + 7);
369	0	DROPBITS(here.bits);
370	0	len = 0;
371	0	copy = 11 + BITS(7);
372	0	DROPBITS(7);
373	0	}
374	0	if (state->have + copy > state->nlen + state->ndist) {
375	0	strm->msg = (z_const char *)
376	0	"invalid bit length repeat";
377	0	state->mode = BAD;
378	0	break;
379	0	}
380	0	while (copy--)
381	0	state->lens[state->have++] = (unsigned short)len;
382	0	}
383	0	}
384
385		/* handle error breaks in while */
386	0	if (state->mode == BAD) break;
387
388		/* check for end-of-block code (better have one) */
389	0	if (state->lens[256] == 0) {
390	0	strm->msg = (z_const char *)
391	0	"invalid code -- missing end-of-block";
392	0	state->mode = BAD;
393	0	break;
394	0	}
395
396		/* build code tables -- note: do not change the lenbits or distbits
397		values here (9 and 6) without reading the comments in inftrees.h
398		concerning the ENOUGH constants, which depend on those values */
399	0	state->next = state->codes;
400	0	state->lencode = (code const FAR *)(state->next);
401	0	state->lenbits = 9;
402	0	ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
403	0	&(state->lenbits), state->work);
404	0	if (ret) {
405	0	strm->msg = (z_const char *)"invalid literal/lengths set";
406	0	state->mode = BAD;
407	0	break;
408	0	}
409	0	state->distcode = (code const FAR *)(state->next);
410	0	state->distbits = 6;
411	0	ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
412	0	&(state->next), &(state->distbits), state->work);
413	0	if (ret) {
414	0	strm->msg = (z_const char *)"invalid distances set";
415	0	state->mode = BAD;
416	0	break;
417	0	}
418	0	Tracev((stderr, "inflate: codes ok\n"));
419	0	state->mode = LEN;
420		/* fallthrough */
421
422	0	case LEN:
423		/* use inflate_fast() if we have enough input and output */
424	0	if (have >= 6 && left >= 258) {
425	0	RESTORE();
426	0	if (state->whave < state->wsize)
427	0	state->whave = state->wsize - left;
428	0	inflate_fast(strm, state->wsize);
429	0	LOAD();
430	0	break;
431	0	}
432
433		/* get a literal, length, or end-of-block code */
434	0	for (;;) {
435	0	here = state->lencode[BITS(state->lenbits)];
436	0	if ((unsigned)(here.bits) <= bits) break;
437	0	PULLBYTE();
438	0	}
439	0	if (here.op && (here.op & 0xf0) == 0) {
440	0	last = here;
441	0	for (;;) {
442	0	here = state->lencode[last.val +
443	0	(BITS(last.bits + last.op) >> last.bits)];
444	0	if ((unsigned)(last.bits + here.bits) <= bits) break;
445	0	PULLBYTE();
446	0	}
447	0	DROPBITS(last.bits);
448	0	}
449	0	DROPBITS(here.bits);
450	0	state->length = (unsigned)here.val;
451
452		/* process literal */
453	0	if (here.op == 0) {
454	0	Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
455	0	"inflate: literal '%c'\n" :
456	0	"inflate: literal 0x%02x\n", here.val));
457	0	ROOM();
458	0	*put++ = (unsigned char)(state->length);
459	0	left--;
460	0	state->mode = LEN;
461	0	break;
462	0	}
463
464		/* process end of block */
465	0	if (here.op & 32) {
466	0	Tracevv((stderr, "inflate: end of block\n"));
467	0	state->mode = TYPE;
468	0	break;
469	0	}
470
471		/* invalid code */
472	0	if (here.op & 64) {
473	0	strm->msg = (z_const char *)"invalid literal/length code";
474	0	state->mode = BAD;
475	0	break;
476	0	}
477
478		/* length code -- get extra bits, if any */
479	0	state->extra = (unsigned)(here.op) & 15;
480	0	if (state->extra != 0) {
481	0	NEEDBITS(state->extra);
482	0	state->length += BITS(state->extra);
483	0	DROPBITS(state->extra);
484	0	}
485	0	Tracevv((stderr, "inflate: length %u\n", state->length));
486
487		/* get distance code */
488	0	for (;;) {
489	0	here = state->distcode[BITS(state->distbits)];
490	0	if ((unsigned)(here.bits) <= bits) break;
491	0	PULLBYTE();
492	0	}
493	0	if ((here.op & 0xf0) == 0) {
494	0	last = here;
495	0	for (;;) {
496	0	here = state->distcode[last.val +
497	0	(BITS(last.bits + last.op) >> last.bits)];
498	0	if ((unsigned)(last.bits + here.bits) <= bits) break;
499	0	PULLBYTE();
500	0	}
501	0	DROPBITS(last.bits);
502	0	}
503	0	DROPBITS(here.bits);
504	0	if (here.op & 64) {
505	0	strm->msg = (z_const char *)"invalid distance code";
506	0	state->mode = BAD;
507	0	break;
508	0	}
509	0	state->offset = (unsigned)here.val;
510
511		/* get distance extra bits, if any */
512	0	state->extra = (unsigned)(here.op) & 15;
513	0	if (state->extra != 0) {
514	0	NEEDBITS(state->extra);
515	0	state->offset += BITS(state->extra);
516	0	DROPBITS(state->extra);
517	0	}
518	0	if (state->offset > state->wsize - (state->whave < state->wsize ?
519	0	left : 0)) {
520	0	strm->msg = (z_const char *)"invalid distance too far back";
521	0	state->mode = BAD;
522	0	break;
523	0	}
524	0	Tracevv((stderr, "inflate: distance %u\n", state->offset));
525
526		/* copy match from window to output */
527	0	do {
528	0	ROOM();
529	0	copy = state->wsize - state->offset;
530	0	if (copy < left) {
531	0	from = put + copy;
532	0	copy = left - copy;
533	0	}
534	0	else {
535	0	from = put - state->offset;
536	0	copy = left;
537	0	}
538	0	if (copy > state->length) copy = state->length;
539	0	state->length -= copy;
540	0	left -= copy;
541	0	do {
542	0	put++ = from++;
543	0	} while (--copy);
544	0	} while (state->length != 0);
545	0	break;
546
547	0	case DONE:
548		/* inflate stream terminated properly */
549	0	ret = Z_STREAM_END;
550	0	goto inf_leave;
551
552	0	case BAD:
553	0	ret = Z_DATA_ERROR;
554	0	goto inf_leave;
555
556	0	default:
557		/* can't happen, but makes compilers happy */
558	0	ret = Z_STREAM_ERROR;
559	0	goto inf_leave;
560	0	}
561
562		/* Write leftover output and return unused input */
563	0	inf_leave:
564	0	if (left < state->wsize) {
565	0	if (out(out_desc, state->window, state->wsize - left) &&
566	0	ret == Z_STREAM_END)
567	0	ret = Z_BUF_ERROR;
568	0	}
569	0	strm->next_in = next;
570	0	strm->avail_in = have;
571	0	return ret;
572	0	}
573
574	0	int ZEXPORT inflateBackEnd(z_streamp strm) {
575	0	if (strm == Z_NULL \|\| strm->state == Z_NULL \|\| strm->zfree == (free_func)0)
576	0	return Z_STREAM_ERROR;
577	0	ZFREE(strm, strm->state);
578	0	strm->state = Z_NULL;
579	0	Tracev((stderr, "inflate: end\n"));
580	0	return Z_OK;
581	0	}