The color resolution is expected in bits 4-6 of the packed fields byte
of the logical screen descriptor (byte 10 of the GIF data stream),
according to the specification[1], section 18.
[1] <https://www.w3.org/Graphics/GIF/spec-gif89a.txt>
Apparently, this has not been tested for a long time, and might be a
refactoring relict. Anyhow, we have to pass the context to
`GIFNextPixel` as well.
The fix for PHP bug 43828[1] changed the algorithm from drawing filled
pies from drawing multiple triangles to drawing a single polygon. Due
to quirks of the filled polygon drawing algorithm, we had to filter out
extraneous vertices. This lead, however, to a bug regarding displaced
starting and ending points near 90° and 270° degrees, which we fix by
reinserting these vertices if they had been removed.
This fix is a port of libgd/libgd@1406b1a.
[1] <https://bugs.php.net/bug.php?id=43828>
`_gdScaleHoriz()` and `_gdScaleVert()` may fail, but don't signal
failure since they are void functions. We change that according to
upstream libgd.
We also remove the unused `Scale()` function, which doesn't exist in
upstream libgd either, right away.
* PHP-7.2:
Fix#77369 - memcpy with negative length via crafted DNS response
Fix more issues with encodilng length
Fix#77270: imagecolormatch Out Of Bounds Write on Heap
Fix bug #77380 (Global out of bounds read in xmlrpc base64 code)
Fix bug #77371 (heap buffer overflow in mb regex functions - compile_string_node)
Fix bug #77370 - check that we do not read past buffer end when parsing multibytes
Fix#77269: Potential unsigned underflow in gdImageScale
Fix bug #77247 (heap buffer overflow in phar_detect_phar_fname_ext)
Fix bug #77242 (heap out of bounds read in xmlrpc_decode())
Regenerate certs for openssl tests
* PHP-7.1:
Fix#77369 - memcpy with negative length via crafted DNS response
Fix more issues with encodilng length
Fix#77270: imagecolormatch Out Of Bounds Write on Heap
Fix bug #77380 (Global out of bounds read in xmlrpc base64 code)
Fix bug #77371 (heap buffer overflow in mb regex functions - compile_string_node)
Fix bug #77370 - check that we do not read past buffer end when parsing multibytes
Fix#77269: Potential unsigned underflow in gdImageScale
Fix bug #77247 (heap buffer overflow in phar_detect_phar_fname_ext)
Fix bug #77242 (heap out of bounds read in xmlrpc_decode())
Regenerate certs for openssl tests
At least some of the image reading functions may return images which
use color indexes greater than or equal to im->colorsTotal. We cater
to this by always using a buffer size which is sufficient for
`gdMaxColors` in `gdImageColorMatch()`.
The broken JPEG image triggers a notice, two warnings and outputs a
message to stderr directly. The additional notice is pretty useless,
and the direct output to stderr is bad. Therefore, we port the
relevant differences from upstream to our bundled libgd. This leaves
us with two warnings; the first one is triggered by libjpeg and shows
the actual problem, the second one is triggered by our libgd wrapper
whenever an image can't be read, what may not have necessarily
triggered a warning before.
We must not draw anti-aliased lines on palette images, because that is
not supported by `gdImageSetAAPixelColor()` and it wouldn't make much
sense to support it, due to the limitation to at most 256 colors.
Besides that we still hope to sync the complete bundled libgd sometime,
the upstream implementation of `gdImageCrop()` is much simpler than the
current one, and thus better readable and less error prone.
* 'master' of git.php.net:/php-src:
Update NEWS
Fixed bug #75571: Potential infinite loop in gdImageCreateFromGifCtx
Fix bug #74782: remove file name from output to avoid XSS
* 'PHP-7.2' of git.php.net:/php-src:
Update NEWS
Fixed bug #75571: Potential infinite loop in gdImageCreateFromGifCtx
Fix bug #74782: remove file name from output to avoid XSS
* 'PHP-7.1' of git.php.net:/php-src:
Update NEWS
Fixed bug #75571: Potential infinite loop in gdImageCreateFromGifCtx
Fix bug #74782: remove file name from output to avoid XSS
Christoph M. Becker