Rewrite readc to work with ash

Also tested with dash --- does not work with bash

1 files changed, 28 insertions, 13 deletions

@@ -1,7 +1,7 @@
 #!/bin/sh
 
-# https://unix.stackexchange.com/a/464963
 readc() { # arg: <variable-name>
+        # adapted from https://unix.stackexchange.com/a/464963
         if [ -t 0 ]; then
                 # if stdin is a tty device, put it out of icanon, set min and
                 # time to sane value, but don't otherwise touch other input or
@@ -10,21 +10,36 @@ readc() { # arg: <variable-name>
                 saved_tty_settings=$(stty -g)
                 stty -icanon min 1 time 0
         fi
-        eval "$1="
-        while
-                # read one byte, using a work around for the fact that command
-                # substitution strips the last character.
-                c=$(dd bs=1 count=1 2> /dev/null; echo .)
+
+        # Sanitize any variable that's passed in
+        case "$1" in
+                c) var=_c ;;
+                var) var=_var ;;
+                '') var=REPLY ;;
+                *) var="$1" ;;
+        esac
+
+        # Zero-out the variable
+        eval "$var="
+
+        # Read one full *character*, not *byte*
+        while :; do
+                c=$(dd bs=1 count=1 2>/dev/null; echo .)
                 c=${c%.}
 
-                # break out of the loop on empty input (eof) or if a full character
-                # has been accumulated in the output variable (using "wc -m" to count
-                # the number of characters).
-                [ -n "$c" ] &&
-                        eval "$1=\${$1}"'$c
-          [ "$(($(printf %s "${'"$1"'}" | wc -m)))" -eq 0 ]'; do
-                continue
+                # Break on EOF
+                test -n "$c" || break
+
+                eval "$var=\${$var}$c"
+
+                # Break when we have a full character (wc -m)
+                test "$(eval printf %s "\$$var" | wc -m)" -eq 0 || break
         done
+
+        # Round-trip sanitized variables
+        test "x$var" = x_c && eval c="\$$var"
+        test "x$var" = x_var && eval var="\$$var"
+
         if [ -t 0 ]; then
                 # restore settings saved earlier if stdin is a tty device.
                 stty "$saved_tty_settings"