Here is a patch which invokes kill_myself_with_sig(SIGPIPE) if fwrite fails
with errno=EPIPE.
Quitting with a signal rather than a diagnostic output emulates GNU tee
which is in line with the apparent reason for busybox tee in ignoring
SIGPIPE in the first place.
I have tested it with and
I also note that busybox tee treats a filename single hyphen as stdout,
contrary to POSIX.
I mention it only because it might save a few bytes to remove this special
case, and treat it as a regular file.
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/tee.html
OPERANDS
The following
