vpd_decode.c

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/* SPDX-License-Identifier: BSD-3-Clause */
 
/*
 * This is a copy from upstream:
 * https://chromium.googlesource.com/chromiumos/platform/vpd/+/master/lib/vpd_decode.c
 */
#include "vpd_decode.h"
 
static int vpd_decode_len(
                const u32 max_len, const u8 *in, u32 *length, u32 *decoded_len)
{
        u8 more;
        int i = 0;
 
        if (!length || !decoded_len)
                return VPD_DECODE_FAIL;
 
        *length = 0;
        do {
                if (i >= max_len)
                        return VPD_DECODE_FAIL;
 
                more = in[i] & 0x80;
                *length <<= 7;
                *length |= in[i] & 0x7f;
                ++i;
        } while (more);
 
        *decoded_len = i;
        return VPD_DECODE_OK;
}
 
static int vpd_decode_entry(
                const u32 max_len, const u8 *input_buf, u32 *consumed,
                const u8 **entry, u32 *entry_len)
{
        u32 decoded_len;
 
        if (vpd_decode_len(max_len - *consumed, &input_buf[*consumed],
                           entry_len, &decoded_len) != VPD_DECODE_OK)
                return VPD_DECODE_FAIL;
        if (max_len - *consumed < decoded_len)
                return VPD_DECODE_FAIL;
 
        *consumed += decoded_len;
        *entry = input_buf + *consumed;
 
        /* entry_len is untrusted data and must be checked again. */
        if (max_len - *consumed < *entry_len)
                return VPD_DECODE_FAIL;
 
        *consumed += *entry_len;
        return VPD_DECODE_OK;
}
 
int vpd_decode_string(
                const u32 max_len, const u8 *input_buf, u32 *consumed,
                vpd_decode_callback callback, void *callback_arg)
{
        int type;
        u32 key_len;
        u32 value_len;
        const u8 *key;
        const u8 *value;
 
        /* type */
        if (*consumed >= max_len)
                return VPD_DECODE_FAIL;
 
        type = input_buf[*consumed];
 
        switch (type) {
        case VPD_TYPE_INFO:
        case VPD_TYPE_STRING:
                (*consumed)++;
 
                if (vpd_decode_entry(max_len, input_buf, consumed, &key,
                                     &key_len) != VPD_DECODE_OK)
                        return VPD_DECODE_FAIL;
 
                if (vpd_decode_entry(max_len, input_buf, consumed, &value,
                                     &value_len) != VPD_DECODE_OK)
                        return VPD_DECODE_FAIL;
 
                if (type == VPD_TYPE_STRING)
                        return callback(key, key_len, value, value_len,
                                        callback_arg);
                break;
 
        default:
                return VPD_DECODE_FAIL;
        }
 
        return VPD_DECODE_OK;
}