bonsix/tests/bonsai/dj.sh

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#!/bin/sh
# Copyright (c) 2024 DTB <trinity@trinity.moe>
# Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
# SPDX-License-Identifier: FSFAP
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice and this
# notice are preserved. This file is offered as-is, without any warranty.
! dj -h
# This test is theoretically Linux-dependent; write(2) should return -1 on
# error.
# Right now dj(1) interprets the return value of write(2) as the amount of
# bytes written. This can decrement the stored quantity of bytes written,
# which is an int, so doesn't underflow but goes negative. dj(1) tries to
# again to write(2) if an error occurs in which no bytes are written, so in
# total two write(2)s are attempted and so the written byte quantity is -2.
# This is a bug and will change, but for now is at least documented.
dj -Hi /dev/zero -o /dev/full \
| xargs -I out "$BIN/strcmp" '1+0 > 0+0; 1024 > -2' out
# Read nothing from /dev/null, write nothing to /dev/null.
dj -Hi /dev/null -o /dev/null \
| xargs -I out "$BIN/strcmp" '0+0 > 0+0; 0 > 0' out