libxml2: fallback to internal entropy

[gnattu]

Changes

This adds a patch to fallback to use the internal entropy in libxml2 instead of just abort when the system's own getentropy call failed. The patch should work for both Windows and Linux, on macOS we are using the macOS native libxml implementation which should be not affected by this.

The ubuntu focal build and msys2 Windows Clang build also uses an old version that does not use system entropy generator which is also not affected.

Issues

Fixes #530

[nyanmisaka]

I think it might be cleaner to patch it this way?
for v2.13.5: 0001-dict-Fallback-to-internal-entropy.patch
for master: 0001-dict-Fallback-to-internal-entropy-master.patch

This is a fairly trivial fix and we should submit it upstream.

[nyanmisaka]

This is a fairly trivial fix and we should submit it upstream.

Somehow I cannot fork on their selfhosted gitlab instance...

[gnattu]

This is a fairly trivial fix and we should submit it upstream.

Somehow I cannot fork on their selfhosted gitlab instance...

It seems like upstream has no interest in such use case:
https://gitlab.gnome.org/GNOME/libxml2/-/issues/854#note_2337204

[nyanmisaka]

It seems like upstream has no interest in such use case: https://gitlab.gnome.org/GNOME/libxml2/-/issues/854#note_2337204

You didn't link to the error log, and that maintainer doesn't seem to understand what you're talking about. Better tell him that libxml2 and its caller will simply crash when the Linux kernel doesn't have PRNG support.

Anyway, when Debian upgrades theirs to 2.13+, they may receive more bug reports.

[gnattu]

After debating with upstream they added a workaround strictly for Linux returning ENOSYS case: https://gitlab.gnome.org/GNOME/libxml2/-/commit/cd491ac07de361c46450bd98f57c8a5c267fa41a

This is enough for our current use case where all reports are from Linux users using a kernel does not implement the getrandom() call. We can drop the patches once the upstream released a new version.

[nyanmisaka]

After debating with upstream they added a workaround strictly for Linux returning ENOSYS case: https://gitlab.gnome.org/GNOME/libxml2/-/commit/cd491ac07de361c46450bd98f57c8a5c267fa41a

This is enough for our current use case where all reports are from Linux users using a kernel does not implement the getrandom() call. We can drop the patches once the upstream released a new version.

It looks like they really want to get rid of their internal PRNG.