| Wei-Ning Huang | ad2ac9d | 2017-04-12 18:56:18 +0200 | [diff] [blame] | 1 | /* |
| 2 | * vpd_decode.c |
| 3 | * |
| 4 | * Google VPD decoding routines. |
| 5 | * |
| 6 | * Copyright 2017 Google Inc. |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License v2.0 as published by |
| 10 | * the Free Software Foundation. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | */ |
| 17 | |
| 18 | #include <linux/export.h> |
| 19 | |
| 20 | #include "vpd_decode.h" |
| 21 | |
| 22 | static int vpd_decode_len(const s32 max_len, const u8 *in, |
| 23 | s32 *length, s32 *decoded_len) |
| 24 | { |
| 25 | u8 more; |
| 26 | int i = 0; |
| 27 | |
| 28 | if (!length || !decoded_len) |
| 29 | return VPD_FAIL; |
| 30 | |
| 31 | *length = 0; |
| 32 | do { |
| 33 | if (i >= max_len) |
| 34 | return VPD_FAIL; |
| 35 | |
| 36 | more = in[i] & 0x80; |
| 37 | *length <<= 7; |
| 38 | *length |= in[i] & 0x7f; |
| 39 | ++i; |
| 40 | } while (more); |
| 41 | |
| 42 | *decoded_len = i; |
| 43 | |
| 44 | return VPD_OK; |
| 45 | } |
| 46 | |
| 47 | int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed, |
| 48 | vpd_decode_callback callback, void *callback_arg) |
| 49 | { |
| 50 | int type; |
| 51 | int res; |
| 52 | s32 key_len; |
| 53 | s32 value_len; |
| 54 | s32 decoded_len; |
| 55 | const u8 *key; |
| 56 | const u8 *value; |
| 57 | |
| 58 | /* type */ |
| 59 | if (*consumed >= max_len) |
| 60 | return VPD_FAIL; |
| 61 | |
| 62 | type = input_buf[*consumed]; |
| 63 | |
| 64 | switch (type) { |
| 65 | case VPD_TYPE_INFO: |
| 66 | case VPD_TYPE_STRING: |
| 67 | (*consumed)++; |
| 68 | |
| 69 | /* key */ |
| 70 | res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], |
| 71 | &key_len, &decoded_len); |
| 72 | if (res != VPD_OK || *consumed + decoded_len >= max_len) |
| 73 | return VPD_FAIL; |
| 74 | |
| 75 | *consumed += decoded_len; |
| 76 | key = &input_buf[*consumed]; |
| 77 | *consumed += key_len; |
| 78 | |
| 79 | /* value */ |
| 80 | res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], |
| 81 | &value_len, &decoded_len); |
| 82 | if (res != VPD_OK || *consumed + decoded_len > max_len) |
| 83 | return VPD_FAIL; |
| 84 | |
| 85 | *consumed += decoded_len; |
| 86 | value = &input_buf[*consumed]; |
| 87 | *consumed += value_len; |
| 88 | |
| 89 | if (type == VPD_TYPE_STRING) |
| 90 | return callback(key, key_len, value, value_len, |
| 91 | callback_arg); |
| 92 | break; |
| 93 | |
| 94 | default: |
| 95 | return VPD_FAIL; |
| 96 | } |
| 97 | |
| 98 | return VPD_OK; |
| 99 | } |