109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
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/*
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* vpd_decode.c
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*
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* Google VPD decoding routines.
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*
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* Copyright 2017 Google Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License v2.0 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/export.h>
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#include "vpd_decode.h"
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static int vpd_decode_len(const u32 max_len, const u8 *in,
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u32 *length, u32 *decoded_len)
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{
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u8 more;
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int i = 0;
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if (!length || !decoded_len)
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return VPD_FAIL;
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*length = 0;
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do {
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if (i >= max_len)
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return VPD_FAIL;
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more = in[i] & 0x80;
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*length <<= 7;
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*length |= in[i] & 0x7f;
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++i;
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} while (more);
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*decoded_len = i;
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return VPD_OK;
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}
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static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
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u32 *_consumed, const u8 **entry, u32 *entry_len)
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{
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u32 decoded_len;
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u32 consumed = *_consumed;
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if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
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entry_len, &decoded_len) != VPD_OK)
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return VPD_FAIL;
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if (max_len - consumed < decoded_len)
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return VPD_FAIL;
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consumed += decoded_len;
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*entry = input_buf + consumed;
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/* entry_len is untrusted data and must be checked again. */
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if (max_len - consumed < *entry_len)
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return VPD_FAIL;
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consumed += *entry_len;
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*_consumed = consumed;
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return VPD_OK;
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}
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int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
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vpd_decode_callback callback, void *callback_arg)
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{
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int type;
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u32 key_len;
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u32 value_len;
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const u8 *key;
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const u8 *value;
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/* type */
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if (*consumed >= max_len)
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return VPD_FAIL;
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type = input_buf[*consumed];
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switch (type) {
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case VPD_TYPE_INFO:
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case VPD_TYPE_STRING:
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(*consumed)++;
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if (vpd_decode_entry(max_len, input_buf, consumed, &key,
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&key_len) != VPD_OK)
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return VPD_FAIL;
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if (vpd_decode_entry(max_len, input_buf, consumed, &value,
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&value_len) != VPD_OK)
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return VPD_FAIL;
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if (type == VPD_TYPE_STRING)
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return callback(key, key_len, value, value_len,
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callback_arg);
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break;
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default:
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return VPD_FAIL;
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}
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return VPD_OK;
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}
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