fix(tvix/nix-compat): use `buf.filled()` to track read bytes r/8369

We were wrongly using `buf.initialized()` which contains more than the
filled portion to compute the number of bytes read during a poll call.

This made us go into the trailer reading state too early and finally
failing due to invalid trailer data.

Fixes b/405.

Co-authored-by: Florian Klink <flokli@flokli.de>
Change-Id: I66ba6e2116389e6b97305f85c4e0922195000e45
Signed-off-by: Ryan Lahfa <tvl@lahfa.xyz>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11978
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Reviewed-by: edef <edef@edef.eu>

0 files changed, 0 insertions, 0 deletions