libalpine: add various functions from openbsd installer

isin - is element in list
rmel - remove element from list
ask - Ask a question and read response
ask_until - repeat a question til a non-blank response
ask_which - repeat a question til a listed option is entered

1 files changed, 119 insertions, 7 deletions

diff --git a/libalpine.sh.in b/libalpine.sh.in
index 8661643..4ea5201 100755..100644
--- a/libalpine.sh.in
+++ b/libalpine.sh.in
@@ -71,6 +71,16 @@ cfg_add() {
 	[ -z "$NOCOMMIT" ] && lbu_add "$@"
 }
 
+# Detect if we are running Xen
+is_xen() {
+	test -d /proc/xen
+}
+
+# Detect if we are running Xen Dom0
+is_xen_dom0() {
+	is_xen && \
+	grep -q "control_d" /proc/xen/capabilities
+}
 # from OpenBSD installer
 
 # Ask for a password, saving the input in $resp.
@@ -106,13 +116,115 @@ askpassword() {
 	IFS=$_oifs
 }
 
-# Detect if we are running Xen
-is_xen() {
-	test -d /proc/xen
+# test the first argument against the remaining ones, return success on a match
+isin() {
+	local _a=$1 _b
+	shift
+	for _b; do
+		[ "$_a" = "$_b" ] && return 0
+	done
+	return 1
 }
 
-# Detect if we are running Xen Dom0
-is_xen_dom0() {
-	is_xen && \
-	grep -q "control_d" /proc/xen/capabilities
+# remove all occurrences of first argument from list formed by
+# the remaining arguments
+rmel() {
+	local   _a=$1 _b
+
+	shift
+	for _b; do
+		[ "$_a" != "$_b" ] && echo -n "$_b "
+	done
+}
+
+# Issue a read into the global variable $resp. 
+_ask() {
+	local _redo=0
+
+	read resp
+	case "$resp" in
+	!)      echo "Type 'exit' to return to setup."
+		sh
+		_redo=1
+		;;
+	!*)     eval "${resp#?}"
+		_redo=1
+		;;
+	esac
+	return $_redo
+}
+
+# Ask for user input.
+#
+#    $1    = the question to ask the user
+#    $2    = the default answer
+#
+# Save the user input (or the default) in $resp.
+#
+# Allow the user to escape to shells ('!') or execute commands
+# ('!foo') before entering the input.
+ask() {
+	local _question=$1 _default=$2
+
+	while :; do
+		echo -n "$_question "
+		[ -z "$_default" ] || echo -n "[$_default] "
+		_ask && : ${resp:=$_default} && break
+	done
 }
+
+# Ask for user input until a non-empty reply is entered.
+#
+#    $1    = the question to ask the user
+#    $2    = the default answer
+#
+# Save the user input (or the default) in $resp.
+ask_until() {
+	resp=
+	while [ -z "$resp" ] ; do
+		ask "$1" "$2"
+	done
+}
+
+# Ask for the user to select one value from a list, or 'done'.
+#
+# $1 = name of the list items (disk, cd, etc.)
+# $2 = question to ask
+# $3 = list of valid choices
+# $4 = default choice, if it is not specified use the first item in $3
+#
+# N.B.! $3 and $4 will be "expanded" using eval, so be sure to escape them
+#       if they contain spooky stuff
+#
+# At exit $resp holds selected item, or 'done'
+ask_which() {
+	local _name=$1 _query=$2 _list=$3 _def=$4 _dynlist _dyndef
+
+	while :; do
+		# Put both lines in ask prompt, rather than use a
+		# separate 'echo' to ensure the entire question is
+		# re-ask'ed after a '!' or '!foo' shell escape.
+		eval "_dynlist=\"$_list\""
+		eval "_dyndef=\"$_def\""
+
+		# Clean away whitespace and determine the default
+		set -o noglob
+		set -- $_dyndef; _dyndef="$1"
+		set -- $_dynlist; _dynlist="$*"
+		set +o noglob
+		[ $# -lt 1 ] && resp=done && return
+
+		: ${_dyndef:=$1}
+		echo "Available ${_name}s are: $_dynlist."
+		echo -n "Which one $_query? (or 'done') "
+		[ -n "$_dyndef" ] && echo -n "[$_dyndef] "
+		_ask || continue
+		[ -z "$resp" ] && resp="$_dyndef"
+
+		# Quote $resp to prevent user from confusing isin() by
+		# entering something like 'a a'.
+		isin "$resp" $_dynlist done && break
+		echo "'$resp' is not a valid choice."
+	done
+}
+