mirror of https://git.ffmpeg.org/ffmpeg.git
avcodec/ccaption_dec: do not modify packet data in case of parity error
To dissallow similar errors in future, make pointers const.
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@ -341,11 +341,13 @@ static void write_char(CCaptionSubContext *ctx, struct Screen *screen, char ch)
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* If the second byte doesn't pass parity, it returns INVALIDDATA
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* user can ignore the whole pair and pass the other pair.
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*/
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static int validate_cc_data_pair(uint8_t *cc_data_pair)
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static int validate_cc_data_pair(const uint8_t *cc_data_pair, uint8_t *hi)
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{
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uint8_t cc_valid = (*cc_data_pair & 4) >>2;
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uint8_t cc_type = *cc_data_pair & 3;
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*hi = cc_data_pair[1];
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if (!cc_valid)
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return AVERROR_INVALIDDATA;
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@ -355,7 +357,7 @@ static int validate_cc_data_pair(uint8_t *cc_data_pair)
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return AVERROR_INVALIDDATA;
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}
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if (!av_parity(cc_data_pair[1])) {
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cc_data_pair[1]=0x7F;
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*hi = 0x7F;
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}
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}
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@ -782,26 +784,24 @@ static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avp
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int64_t start_time;
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int64_t end_time;
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int bidx = ctx->buffer_index;
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uint8_t *bptr = NULL;
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const uint8_t *bptr = avpkt->data;
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int len = avpkt->size;
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int ret = 0;
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int i;
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bptr = avpkt->data;
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for (i = 0; i < len; i += 3) {
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uint8_t cc_type = bptr[i] & 1;
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uint8_t hi, cc_type = bptr[i] & 1;
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if (ctx->data_field < 0)
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ctx->data_field = cc_type;
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if (validate_cc_data_pair(bptr + i))
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if (validate_cc_data_pair(bptr + i, &hi))
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continue;
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if (cc_type != ctx->data_field)
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continue;
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ret = process_cc608(ctx, bptr[i + 1] & 0x7f, bptr[i + 2] & 0x7f);
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ret = process_cc608(ctx, hi & 0x7f, bptr[i + 2] & 0x7f);
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if (ret < 0)
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return ret;
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