summaryrefslogtreecommitdiffstats
path: root/lib/zlib_dfltcc/dfltcc_inflate.c
blob: db107016d29b32952efa5def52873176292ec720 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
// SPDX-License-Identifier: Zlib

#include "../zlib_inflate/inflate.h"
#include "dfltcc_util.h"
#include "dfltcc.h"
#include <asm/setup.h>
#include <linux/export.h>
#include <linux/zutil.h>

/*
 * Expand.
 */
int dfltcc_can_inflate(
    z_streamp strm
)
{
    struct inflate_state *state = (struct inflate_state *)strm->state;
    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);

    /* Check for kernel dfltcc command line parameter */
    if (zlib_dfltcc_support == ZLIB_DFLTCC_DISABLED ||
            zlib_dfltcc_support == ZLIB_DFLTCC_DEFLATE_ONLY)
        return 0;

    /* Unsupported compression settings */
    if (state->wbits != HB_BITS)
        return 0;

    /* Unsupported hardware */
    return is_bit_set(dfltcc_state->af.fns, DFLTCC_XPND) &&
               is_bit_set(dfltcc_state->af.fmts, DFLTCC_FMT0);
}
EXPORT_SYMBOL(dfltcc_can_inflate);

static int dfltcc_was_inflate_used(
    z_streamp strm
)
{
    struct inflate_state *state = (struct inflate_state *)strm->state;
    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;

    return !param->nt;
}

static int dfltcc_inflate_disable(
    z_streamp strm
)
{
    struct inflate_state *state = (struct inflate_state *)strm->state;
    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);

    if (!dfltcc_can_inflate(strm))
        return 0;
    if (dfltcc_was_inflate_used(strm))
        /* DFLTCC has already decompressed some data. Since there is not
         * enough information to resume decompression in software, the call
         * must fail.
         */
        return 1;
    /* DFLTCC was not used yet - decompress in software */
    memset(&dfltcc_state->af, 0, sizeof(dfltcc_state->af));
    return 0;
}

static dfltcc_cc dfltcc_xpnd(
    z_streamp strm
)
{
    struct inflate_state *state = (struct inflate_state *)strm->state;
    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;
    size_t avail_in = strm->avail_in;
    size_t avail_out = strm->avail_out;
    dfltcc_cc cc;

    cc = dfltcc(DFLTCC_XPND | HBT_CIRCULAR,
                param, &strm->next_out, &avail_out,
                &strm->next_in, &avail_in, state->window);
    strm->avail_in = avail_in;
    strm->avail_out = avail_out;
    return cc;
}

dfltcc_inflate_action dfltcc_inflate(
    z_streamp strm,
    int flush,
    int *ret
)
{
    struct inflate_state *state = (struct inflate_state *)strm->state;
    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
    struct dfltcc_param_v0 *param = &dfltcc_state->param;
    dfltcc_cc cc;

    if (flush == Z_BLOCK) {
        /* DFLTCC does not support stopping on block boundaries */
        if (dfltcc_inflate_disable(strm)) {
            *ret = Z_STREAM_ERROR;
            return DFLTCC_INFLATE_BREAK;
        } else
            return DFLTCC_INFLATE_SOFTWARE;
    }

    if (state->last) {
        if (state->bits != 0) {
            strm->next_in++;
            strm->avail_in--;
            state->bits = 0;
        }
        state->mode = CHECK;
        return DFLTCC_INFLATE_CONTINUE;
    }

    if (strm->avail_in == 0 && !param->cf)
        return DFLTCC_INFLATE_BREAK;

    if (!state->window || state->wsize == 0) {
        state->mode = MEM;
        return DFLTCC_INFLATE_CONTINUE;
    }

    /* Translate stream to parameter block */
    param->cvt = CVT_ADLER32;
    param->sbb = state->bits;
    param->hl = state->whave; /* Software and hardware history formats match */
    param->ho = (state->write - state->whave) & ((1 << HB_BITS) - 1);
    if (param->hl)
        param->nt = 0; /* Honor history for the first block */
    param->cv = state->flags ? REVERSE(state->check) : state->check;

    /* Inflate */
    do {
        cc = dfltcc_xpnd(strm);
    } while (cc == DFLTCC_CC_AGAIN);

    /* Translate parameter block to stream */
    strm->msg = oesc_msg(dfltcc_state->msg, param->oesc);
    state->last = cc == DFLTCC_CC_OK;
    state->bits = param->sbb;
    state->whave = param->hl;
    state->write = (param->ho + param->hl) & ((1 << HB_BITS) - 1);
    state->check = state->flags ? REVERSE(param->cv) : param->cv;
    if (cc == DFLTCC_CC_OP2_CORRUPT && param->oesc != 0) {
        /* Report an error if stream is corrupted */
        state->mode = BAD;
        return DFLTCC_INFLATE_CONTINUE;
    }
    state->mode = TYPEDO;
    /* Break if operands are exhausted, otherwise continue looping */
    return (cc == DFLTCC_CC_OP1_TOO_SHORT || cc == DFLTCC_CC_OP2_TOO_SHORT) ?
        DFLTCC_INFLATE_BREAK : DFLTCC_INFLATE_CONTINUE;
}
EXPORT_SYMBOL(dfltcc_inflate);