pash-posix: Add comments and simplify yn()

pash-posix

@@ -6,9 +6,7 @@ pw_add() {
     pass_name=$1
     set -- -c
 
-    yn "Generate a password?"
-
-    if glob "$REPLY" '[yY]'; then
+    if yn "Generate a password?"; then
         pass=$("$gpg" --gen-random --armor "${PASH_LENGTH:-50}" |\
                cut -c -"${PASH_LENGTH:-50}")
 
@@ -30,9 +28,7 @@ pw_add() {
 }
 
 pw_del() {
-    yn "Delete pass file '$1'?"
-
-    glob "$REPLY" '[yY]' && {
+    yn "Delete pass file '$1'?" && {
         rm -f "$1.gpg"
         rmdir -p "${1%/*}" 2>/dev/null
     }
@@ -64,10 +60,27 @@ pw_list() {
 
 yn() {
     printf '%s [y/n]: ' "$1"
+
+    # Enable raw input to allow for a single
+    # byte to be read from stdin without needing
+    # to wait for the user to press Return.
     stty -icanon
+
+    # Read a single byte from stdin using 'dd'.
+    # POSIX 'read' has no support for single or
+    # 'N' character based input from the user.
     REPLY=$(dd ibs=1 count=1 2>/dev/null)
+
+    # Disable raw input, leaving the terminal
+    # how we *should* have found it.
     stty icanon
+
     printf '\n'
+
+    # Handle the answer here directly enabling
+    # this function's return status to be used
+    # in place of repeating this code throughout.
+    glob "$REPLY" '[yY]' || return 1 && return 0
 }
 
 die() {