Merge branch 'release/v2.0.0'v2.0.0

* release/v2.0.0:
  Add a basic install recipe
  Use tabs for indentation
  Pare down Makefile for tests
  Relicense to GPLv3+
  Adjust wording in README.md
  Update clone URL in README.md
  Apply shebang for doomsh with make recipe
  Make paths to ignored files absolute

1 files changed, 146 insertions, 0 deletions

diff --git a/doomsh.bash b/doomsh.bash
new file mode 100644
index 0000000..13d0dc9
--- /dev/null
+++ b/doomsh.bash
@@ -0,0 +1,146 @@
+#!bash
+#
+# Copyright (C) 2016, 2018, 2021 Tom Ryder <tom@sanctum.geek.nz>
+#
+# This file is part of doomsh.
+#
+# doomsh is free software: you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option) any later
+# version.
+#
+# doomsh is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# doomsh.  If not, see <https://www.gnu.org/licenses/>.
+
+# doomsh: Play with low ulimits in Bash
+self=doomsh
+
+# Don't try to play doomsh if already playing doomsh
+if [[ $DOOMSH ]] ; then
+	printf '%s: Already playing doomsh!\n' \
+		"$self" >&2
+	exit 2
+fi
+
+# Show the coloured logo; thanks to Frans P. de Vries for the classic ASCII art
+# <http://www.gamers.org/~fpv/doombann.html>
+printf >&2 %s "$( {
+	tput AF 3 || tput setaf 3
+	tput md || tput bold
+} 2>/dev/null )"
+while IFS= read -r line ; do
+	printf >&2 '%s\n' "$line"
+done <<EOF
+______ _____ _____ __   ___
+| __  \  _  |  _  |  \ /  |
+| | \ | | | | | | | . V . |
+| | / | \_/ | \_/ | |\ /| |
+| |/ / \   / \   /| | V | |
+| ' /   \_/   \_/ \_|   | |
+|__/					\_|
+EOF
+printf >&2 %s "$( {
+	tput me || tput sgr0
+} 2>/dev/null )"
+
+# Need to figure out a skill level
+declare -i skill
+
+# If we have an argument, that must be the skill level
+if (($#)) ; then
+	skill=$1
+	shift
+
+# Otherwise, we'll give the user a menu to choose from
+else
+	while IFS= read -r line ; do
+		printf >&2 '%s\n' "$line"
+	done <<EOF
+
+1. I'm too young to die
+2. Hey, not too rough
+3. Hurt me plenty
+4. Ultra-Violence
+5. Nightmare!
+
+EOF
+	read -er -p '[1-5]: ' skill
+
+	# If the user chose "Nightmare!" mode, get them to confirm, in the true
+	# spirit of things; otherwise, quit
+	if ((skill == 5)) ; then
+		while IFS= read -r line ; do
+			printf '%s\n' "$line" >&2
+		done <<EOF
+
+Are you sure? This skill level isn't even remotely fair.
+EOF
+		read -er -p '[y/N]: ' confirm
+		[[ $confirm == [Yy]* ]] || exit 1
+	fi
+fi
+
+# Don't accept any other skill level settings
+case $skill in
+	1|2|3|4|5)
+		;;
+	*)
+		printf '%s: Unknown skill level\n' \
+			"$self" >&2
+		exit 2
+esac
+
+# Form a red prompt (hopefully) using terminal escapes
+ps1=$(printf '%sdoomsh[%u]\$%s ' \
+	"$( {
+		tput AF 1 || tput setaf 1
+	} 2>/dev/null )" \
+	"$skill" \
+	"$( {
+		tput me || tput sgr0
+	} 2>/dev/null )"
+)
+
+# Set the limits based on the skill level
+declare -i filesize files stack memory
+filesize=$((1 << (8 - skill)))
+files=$((11 - skill))
+stack=$((1 << (11 - skill)))
+memory=$((1 << (19 - skill)))
+
+# Display the limits
+printf >&2 '\n'
+printf >&2 'File size writing limit: %u blocks\n' \
+	"$filesize"
+printf >&2 'Open files limit: %u\n' \
+	"$files"
+printf >&2 'Stack size: %u kbytes\n' \
+	"$stack"
+printf >&2 'Memory size: %u kbytes\n' \
+	"$memory"
+printf >&2 '\n'
+
+# Record the current seconds since shell start, so we can tell how long the
+# user lasts before giving up or segfaulting
+declare -i start
+start=$SECONDS
+
+# Open a subshell so that the ulimit settings don't persist after the fork
+(
+	# We only proceed if the ulimit call succeeds
+	ulimit \
+		-f "$filesize" \
+		-n "$files" \
+		-s "$stack" \
+		-v "$memory" \
+		|| exit 2
+	DOOMSH=$skill PS1=$ps1 bash --norc
+)
+
+# Give the user some statistics about their performance
+printf >&2 '%s: You lasted %u seconds at skill level %u!\n' \
+	"$self" "$((SECONDS - start))" "$skill"