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Code Issues Releases Activity

avcodec/sanm: codec21 improvements

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- don't draw outside the buffers
- don't wrap around when coordinates go over the edge

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
This commit is contained in:
Manuel Lauss
2025-08-25 13:33:57 +02:00
parent 67b28acba3
commit d18c25f1a9
1 changed files with 26 additions and 24 deletions
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50
libavcodec/sanm.c
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@@ -832,39 +832,41 @@ static int old_codec23(SANMVideoContext *ctx, GetByteContext *gb, int top, int l
static int old_codec21(SANMVideoContext *ctx, GetByteContext *gb, int top, int left,
int width, int height)
{
const uint32_t maxpxo = ctx->height * ctx->pitch;
const uint16_t mx = ctx->width, my = ctx->height, p = ctx->pitch;
uint8_t *dst = (uint8_t *)ctx->fbuf, c;
int i, j, k, pc, sk, pxoff;
int j, y, pc, sk, ls;
dst = (uint8_t *)ctx->fbuf;
for (i = 0; i < height; i++) {
if (bytestream2_get_bytes_left(gb) < 2)
return 0;
pxoff = left + ((top + i) * ctx->pitch);
k = bytestream2_get_le16u(gb);
if (((top + height) < 0) || (top >= my) || (left + width < 0) || (left >= mx))
return 0;
y = top;
for (; (bytestream2_get_bytes_left(gb) > 2) && (height > 0) && (y < my); height--, y++) {
ls = bytestream2_get_le16u(gb);
if (y < 0) {
if (ls >= bytestream2_get_bytes_left(gb))
return 0;
bytestream2_skip(gb, ls);
continue;
}
sk = 1;
pc = 0;
while (k > 0 && pc <= width) {
if (bytestream2_get_bytes_left(gb) < 2)
return AVERROR_INVALIDDATA;
pc = left;
while ((bytestream2_get_bytes_left(gb) > 1) && (ls > 1) && (pc <= (width + left))) {
j = bytestream2_get_le16u(gb);
k -= 2;
ls -= 2;
if (sk) {
pxoff += j;
pc += j;
if (pc < mx)
pc += j;
} else {
if (bytestream2_get_bytes_left(gb) < (j + 1))
return AVERROR_INVALIDDATA;
do {
while ((bytestream2_get_bytes_left(gb) > 0) && (ls > 0) && (j >= 0)) {
c = bytestream2_get_byteu(gb);
if (pxoff >=0 && pxoff < maxpxo) {
*(dst + pxoff) = c;
if ((pc >= 0) && (pc < mx)) {
*(dst + (y * p) + pc) = c;
}
pxoff++;
pc++;
ls--;
j--;
k--;
} while (j > -1);
if (pc < mx)
pc++;
}
}
sk ^= 1;
}