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avcodec/sanm: FOBJ left/top are signed values

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The left/top parameters of a FOBJ are signed values.  Adjust
codec1 code accordingly to not draw outside the buffer area.
Rebel Assault 1 makes heavy use of this.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
This commit is contained in:
Manuel Lauss
2025-03-11 13:20:05 +01:00
parent a48dd03fd9
commit f6c6ba95fd
1 changed files with 18 additions and 15 deletions
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33
libavcodec/sanm.c
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@ -558,18 +558,18 @@ static int rle_decode(SANMVideoContext *ctx, uint8_t *dst, const int out_size)
static int old_codec1(SANMVideoContext *ctx, int top,
int left, int width, int height)
{
uint8_t *dst = ((uint8_t *)ctx->frm0) + left + top * ctx->pitch;
int i, j, len, flag, code, val, pos, end;
int i, j, len, flag, code, val, end, pxoff;
const int maxpxo = ctx->height * ctx->pitch;
uint8_t *dst = (uint8_t *)ctx->frm0;
for (i = 0; i < height; i++) {
pos = 0;
if (bytestream2_get_bytes_left(&ctx->gb) < 2)
return AVERROR_INVALIDDATA;
len = bytestream2_get_le16u(&ctx->gb);
end = bytestream2_tell(&ctx->gb) + len;
pxoff = left + ((top + i) * ctx->pitch);
while (bytestream2_tell(&ctx->gb) < end) {
if (bytestream2_get_bytes_left(&ctx->gb) < 2)
return AVERROR_INVALIDDATA;
@ -577,25 +577,28 @@ static int old_codec1(SANMVideoContext *ctx, int top,
code = bytestream2_get_byteu(&ctx->gb);
flag = code & 1;
code = (code >> 1) + 1;
if (pos + code > width)
return AVERROR_INVALIDDATA;
if (flag) {
val = bytestream2_get_byteu(&ctx->gb);
if (val)
memset(dst + pos, val, code);
pos += code;
if (val) {
for (j = 0; j < code; j++) {
if (pxoff >= 0 && pxoff < maxpxo)
*(dst + pxoff) = val;
pxoff++;
}
} else {
pxoff += code;
}
} else {
if (bytestream2_get_bytes_left(&ctx->gb) < code)
return AVERROR_INVALIDDATA;
for (j = 0; j < code; j++) {
val = bytestream2_get_byteu(&ctx->gb);
if (val)
dst[pos] = val;
pos++;
if ((pxoff >= 0) && (pxoff < maxpxo) && val)
*(dst + pxoff) = val;
pxoff++;
}
}
}
dst += ctx->pitch;
}
ctx->rotate_code = 0;
@ -1236,8 +1239,8 @@ static int old_codec48(SANMVideoContext *ctx, int width, int height)
static int process_frame_obj(SANMVideoContext *ctx)
{
uint16_t codec = bytestream2_get_le16u(&ctx->gb);
uint16_t left = bytestream2_get_le16u(&ctx->gb);
uint16_t top = bytestream2_get_le16u(&ctx->gb);
int16_t left = bytestream2_get_le16u(&ctx->gb);
int16_t top = bytestream2_get_le16u(&ctx->gb);
uint16_t w = bytestream2_get_le16u(&ctx->gb);
uint16_t h = bytestream2_get_le16u(&ctx->gb);