Nicolas Pitre [off-list ref] writes:
It is not buffered as it writes to stderr. And some C libs do separate
calls to write() for every string format specifier. So "%s%s%c" may end
up calling write() 3 times depending on the implementation. The example
I gave in commit ed1902ef5c is real and I even observed it with strace
back then.
I think you meant 9ac13ec9 (atomic write for sideband remote
messages, 2006-10-11).
IIRC, back then we did't use to make as much use of strbuf API as we
do today; if we were doing that commit today, we would be doing
strbuf, I would suspect.