Disclaimer: I work on Chrome and I have contributed a (very) small number of fixes to libxml2/libxslt for some of the recent security bugs.
Speaking from personal experience, working on libxslt... not easy for many reasons beyond the complexity of XSLT itself. For instance:
- libxslt is linked against by all sorts of random apps and changes to libxslt (and libxml2) must not break ABI compatibility. This often constrains the shape of possible patches, and makes it that much harder to write systemic fixes.
- libxslt reaches into libxml and reuses fields in creative ways, e.g. libxml2's `xmlDoc` has a `compression` field that is ostensibly for storing the zlib compression level [1], but libxslt has co-opted it for a completely different purpose [2].
- There's a lot of missing institutional knowledge and no clear place to go for answers, e.g. what does a compile-time flag that guards "refactored parts of libxslt" [3] do exactly?
[1] https://gitlab.gnome.org/GNOME/libxml2/-/blob/ca10c7d7b513f3...
[2] https://gitlab.gnome.org/GNOME/libxslt/-/blob/841a1805a9a9aa...
[3] https://gitlab.gnome.org/GNOME/libxslt/-/blob/841a1805a9a9aa...
Speaking from personal experience, working on libxslt... not easy for many reasons beyond the complexity of XSLT itself. For instance:
- libxslt is linked against by all sorts of random apps and changes to libxslt (and libxml2) must not break ABI compatibility. This often constrains the shape of possible patches, and makes it that much harder to write systemic fixes.
- libxslt reaches into libxml and reuses fields in creative ways, e.g. libxml2's `xmlDoc` has a `compression` field that is ostensibly for storing the zlib compression level [1], but libxslt has co-opted it for a completely different purpose [2].
- There's a lot of missing institutional knowledge and no clear place to go for answers, e.g. what does a compile-time flag that guards "refactored parts of libxslt" [3] do exactly?
[1] https://gitlab.gnome.org/GNOME/libxml2/-/blob/ca10c7d7b513f3...
[2] https://gitlab.gnome.org/GNOME/libxslt/-/blob/841a1805a9a9aa...
[3] https://gitlab.gnome.org/GNOME/libxslt/-/blob/841a1805a9a9aa...