#!/bin/bash
CONFFILE=/etc/sysfs.conf
CONFDIR=/etc/sysfs.d

load_conffile() {
  local FILE="$1"

  ( cat "$FILE"; echo ) |
    sed  's/#.*$//; /^[[:space:]]*$/d;
          s/^[[:space:]]*\([^=[:space:]]*\)[[:space:]]*\([^=[:space:]]*\)[[:space:]]*=[[:space:]]*\(.*\)/\1 \2 \3/' |
    while read -r f1 f2 f3; do
      if [ "$f1" = "mode" ] && [ -n "$f2" ] && [ -n "$f3" ]; then
        if [ -f "/sys/$f2" ] || [ -d "/sys/$f2" ]; then
          chmod "$f3" "/sys/$f2"
        else
          echo "unknown attribute $f2"
        fi
      elif [ "$f1" = "owner" ] && [ -n "$f2" ] && [ -n "$f3" ]; then
        if [ -f "/sys/$f2" ]; then
          chown "$f3" "/sys/$f2"
        else
          echo "unknown attribute $f2"
        fi
      elif [ "$f1" ] && [ -n "$f2" ] && [ -z "$f3" ]; then
        for path in /sys/$f1; do
          if [ -f "$path" ]; then
            # Some fields need a terminating newline, others need the
            # terminating newline to be absent. :-(
            printf "%s" "$f2" >"$path" 2>/dev/null ||
              echo "$f2" >"$path" 2>/dev/null ||
                echo "cannot write value for attribute $f1"
          else
            echo "unknown attribute $f1"
          fi
        done
      else
        echo "syntax error in $FILE: '$f1' '$f2' '$f3'"
        exit 1
      fi
    done
}

for file in $CONFFILE "$CONFDIR"/*.conf; do
  [ -r "$file" ] || continue
  load_conffile "$file"
done