1// SPDX-License-Identifier: Zlib
2
3#include "../zlib_inflate/inflate.h"
4#include "dfltcc_util.h"
5#include "dfltcc.h"
6#include <asm/setup.h>
7#include <linux/export.h>
8#include <linux/zutil.h>
9
10/*
11 * Expand.
12 */
13int dfltcc_can_inflate(
14    z_streamp strm
15)
16{
17    struct inflate_state *state = (struct inflate_state *)strm->state;
18    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
19
20    /* Check for kernel dfltcc command line parameter */
21    if (zlib_dfltcc_support == ZLIB_DFLTCC_DISABLED ||
22            zlib_dfltcc_support == ZLIB_DFLTCC_DEFLATE_ONLY)
23        return 0;
24
25    /* Unsupported compression settings */
26    if (state->wbits != HB_BITS)
27        return 0;
28
29    /* Unsupported hardware */
30    return is_bit_set(dfltcc_state->af.fns, DFLTCC_XPND) &&
31               is_bit_set(dfltcc_state->af.fmts, DFLTCC_FMT0);
32}
33EXPORT_SYMBOL(dfltcc_can_inflate);
34
35static int dfltcc_was_inflate_used(
36    z_streamp strm
37)
38{
39    struct inflate_state *state = (struct inflate_state *)strm->state;
40    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;
41
42    return !param->nt;
43}
44
45static int dfltcc_inflate_disable(
46    z_streamp strm
47)
48{
49    struct inflate_state *state = (struct inflate_state *)strm->state;
50    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
51
52    if (!dfltcc_can_inflate(strm))
53        return 0;
54    if (dfltcc_was_inflate_used(strm))
55        /* DFLTCC has already decompressed some data. Since there is not
56         * enough information to resume decompression in software, the call
57         * must fail.
58         */
59        return 1;
60    /* DFLTCC was not used yet - decompress in software */
61    memset(&dfltcc_state->af, 0, sizeof(dfltcc_state->af));
62    return 0;
63}
64
65static dfltcc_cc dfltcc_xpnd(
66    z_streamp strm
67)
68{
69    struct inflate_state *state = (struct inflate_state *)strm->state;
70    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;
71    size_t avail_in = strm->avail_in;
72    size_t avail_out = strm->avail_out;
73    dfltcc_cc cc;
74
75    cc = dfltcc(DFLTCC_XPND | HBT_CIRCULAR,
76                param, &strm->next_out, &avail_out,
77                &strm->next_in, &avail_in, state->window);
78    strm->avail_in = avail_in;
79    strm->avail_out = avail_out;
80    return cc;
81}
82
83dfltcc_inflate_action dfltcc_inflate(
84    z_streamp strm,
85    int flush,
86    int *ret
87)
88{
89    struct inflate_state *state = (struct inflate_state *)strm->state;
90    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
91    struct dfltcc_param_v0 *param = &dfltcc_state->param;
92    dfltcc_cc cc;
93
94    if (flush == Z_BLOCK) {
95        /* DFLTCC does not support stopping on block boundaries */
96        if (dfltcc_inflate_disable(strm)) {
97            *ret = Z_STREAM_ERROR;
98            return DFLTCC_INFLATE_BREAK;
99        } else
100            return DFLTCC_INFLATE_SOFTWARE;
101    }
102
103    if (state->last) {
104        if (state->bits != 0) {
105            strm->next_in++;
106            strm->avail_in--;
107            state->bits = 0;
108        }
109        state->mode = CHECK;
110        return DFLTCC_INFLATE_CONTINUE;
111    }
112
113    if (strm->avail_in == 0 && !param->cf)
114        return DFLTCC_INFLATE_BREAK;
115
116    if (!state->window || state->wsize == 0) {
117        state->mode = MEM;
118        return DFLTCC_INFLATE_CONTINUE;
119    }
120
121    /* Translate stream to parameter block */
122    param->cvt = CVT_ADLER32;
123    param->sbb = state->bits;
124    param->hl = state->whave; /* Software and hardware history formats match */
125    param->ho = (state->write - state->whave) & ((1 << HB_BITS) - 1);
126    if (param->hl)
127        param->nt = 0; /* Honor history for the first block */
128    param->cv = state->check;
129
130    /* Inflate */
131    do {
132        cc = dfltcc_xpnd(strm);
133    } while (cc == DFLTCC_CC_AGAIN);
134
135    /* Translate parameter block to stream */
136    strm->msg = oesc_msg(dfltcc_state->msg, param->oesc);
137    state->last = cc == DFLTCC_CC_OK;
138    state->bits = param->sbb;
139    state->whave = param->hl;
140    state->write = (param->ho + param->hl) & ((1 << HB_BITS) - 1);
141    state->check = param->cv;
142    if (cc == DFLTCC_CC_OP2_CORRUPT && param->oesc != 0) {
143        /* Report an error if stream is corrupted */
144        state->mode = BAD;
145        return DFLTCC_INFLATE_CONTINUE;
146    }
147    state->mode = TYPEDO;
148    /* Break if operands are exhausted, otherwise continue looping */
149    return (cc == DFLTCC_CC_OP1_TOO_SHORT || cc == DFLTCC_CC_OP2_TOO_SHORT) ?
150        DFLTCC_INFLATE_BREAK : DFLTCC_INFLATE_CONTINUE;
151}
152EXPORT_SYMBOL(dfltcc_inflate);
153