pngdec: Stop trying to decode once inflate returns Z_STREAM_END

If the input buffer contains more data after the deflate stream,
the loop previously left running infinitely, with inflate returning
Z_STREAM_END.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit a81cad8f86d1feb7e4bfae29e43f3e994935a5c7)
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit a63e83cd4b43c3dcef38f7fefe41c002a263af0f)
pcx: Consume the whole packet if giving up due to missing palette

Previously, we returned 0, meaning successful decoding but 0
bytes consumed, leading to an infinite loop.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 9fb0de86b49e9fb0709a8ad1e1875e35da841887)
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 812955a12b190012c134be33a93f27308953eb2f)
xan: Use bytestream2 to limit reading to within the buffer

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 30db94dc399f6e4ef8905049d9b740556f0fce47)
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 145de32896b37a508f11bcf11dfcc94487301716)
xan: Only read within the data that actually was initialized

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit fc739b3eefa0b58d64e7661621da94a94dbc8a82)
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 09ace619d6ccb2c0a45b5fdead29f926409fa129)