1// SPDX-License-Identifier: Zlib
2
3#include "../zlib_inflate/inflate.h"
4#include "dfltcc_util.h"
5#include "dfltcc_inflate.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 hardware */
26    return is_bit_set(dfltcc_state->af.fns, DFLTCC_XPND) &&
27               is_bit_set(dfltcc_state->af.fmts, DFLTCC_FMT0);
28}
29EXPORT_SYMBOL(dfltcc_can_inflate);
30
31void dfltcc_reset_inflate_state(z_streamp strm) {
32    struct inflate_state *state = (struct inflate_state *)strm->state;
33    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
34
35    dfltcc_reset_state(dfltcc_state);
36}
37EXPORT_SYMBOL(dfltcc_reset_inflate_state);
38
39static int dfltcc_was_inflate_used(
40    z_streamp strm
41)
42{
43    struct inflate_state *state = (struct inflate_state *)strm->state;
44    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;
45
46    return !param->nt;
47}
48
49static int dfltcc_inflate_disable(
50    z_streamp strm
51)
52{
53    struct inflate_state *state = (struct inflate_state *)strm->state;
54    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
55
56    if (!dfltcc_can_inflate(strm))
57        return 0;
58    if (dfltcc_was_inflate_used(strm))
59        /* DFLTCC has already decompressed some data. Since there is not
60         * enough information to resume decompression in software, the call
61         * must fail.
62         */
63        return 1;
64    /* DFLTCC was not used yet - decompress in software */
65    memset(&dfltcc_state->af, 0, sizeof(dfltcc_state->af));
66    return 0;
67}
68
69static dfltcc_cc dfltcc_xpnd(
70    z_streamp strm
71)
72{
73    struct inflate_state *state = (struct inflate_state *)strm->state;
74    struct dfltcc_param_v0 *param = &GET_DFLTCC_STATE(state)->param;
75    size_t avail_in = strm->avail_in;
76    size_t avail_out = strm->avail_out;
77    dfltcc_cc cc;
78
79    cc = dfltcc(DFLTCC_XPND | HBT_CIRCULAR,
80                param, &strm->next_out, &avail_out,
81                &strm->next_in, &avail_in, state->window);
82    strm->avail_in = avail_in;
83    strm->avail_out = avail_out;
84    return cc;
85}
86
87dfltcc_inflate_action dfltcc_inflate(
88    z_streamp strm,
89    int flush,
90    int *ret
91)
92{
93    struct inflate_state *state = (struct inflate_state *)strm->state;
94    struct dfltcc_state *dfltcc_state = GET_DFLTCC_STATE(state);
95    struct dfltcc_param_v0 *param = &dfltcc_state->param;
96    dfltcc_cc cc;
97
98    if (flush == Z_BLOCK || flush == Z_PACKET_FLUSH) {
99        /* DFLTCC does not support stopping on block boundaries (Z_BLOCK flush option)
100         * as well as the use of Z_PACKET_FLUSH option (used exclusively by PPP driver)
101         */
102        if (dfltcc_inflate_disable(strm)) {
103            *ret = Z_STREAM_ERROR;
104            return DFLTCC_INFLATE_BREAK;
105        } else
106            return DFLTCC_INFLATE_SOFTWARE;
107    }
108
109    if (state->last) {
110        if (state->bits != 0) {
111            strm->next_in++;
112            strm->avail_in--;
113            state->bits = 0;
114        }
115        state->mode = CHECK;
116        return DFLTCC_INFLATE_CONTINUE;
117    }
118
119    if (strm->avail_in == 0 && !param->cf)
120        return DFLTCC_INFLATE_BREAK;
121
122    if (!state->window || state->wsize == 0) {
123        state->mode = MEM;
124        return DFLTCC_INFLATE_CONTINUE;
125    }
126
127    /* Translate stream to parameter block */
128    param->cvt = CVT_ADLER32;
129    param->sbb = state->bits;
130    if (param->hl)
131        param->nt = 0; /* Honor history for the first block */
132    param->cv = state->check;
133
134    /* Inflate */
135    do {
136        cc = dfltcc_xpnd(strm);
137    } while (cc == DFLTCC_CC_AGAIN);
138
139    /* Translate parameter block to stream */
140    strm->msg = oesc_msg(dfltcc_state->msg, param->oesc);
141    state->last = cc == DFLTCC_CC_OK;
142    state->bits = param->sbb;
143    state->check = param->cv;
144    if (cc == DFLTCC_CC_OP2_CORRUPT && param->oesc != 0) {
145        /* Report an error if stream is corrupted */
146        state->mode = BAD;
147        return DFLTCC_INFLATE_CONTINUE;
148    }
149    state->mode = TYPEDO;
150    /* Break if operands are exhausted, otherwise continue looping */
151    return (cc == DFLTCC_CC_OP1_TOO_SHORT || cc == DFLTCC_CC_OP2_TOO_SHORT) ?
152        DFLTCC_INFLATE_BREAK : DFLTCC_INFLATE_CONTINUE;
153}
154EXPORT_SYMBOL(dfltcc_inflate);
155