Added way to set Firefox preferences via environment variables.

rootfs/etc/cont-init.d/firefox-set-prefs-from-env.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/with-contenv sh
+
+set -e
+
+log() {
+    echo "[cont-init.d] $(basename $0): $*"
+}
+
+PREF_FILE="${1:-/config/profile/prefs.js}"
+
+if [ -z "$PREF_FILE" ]; then
+    log "ERROR: Preference file not set."
+    exit 1
+fi
+
+mkdir -p "$(dirname "$PREF_FILE")"
+[ -f "$PREF_FILE" ] || touch "$PREF_FILE"
+
+env | grep "^FF_PREF_" | while read ENV
+do
+    ENAME="$(echo "$ENV" | cut -d '=' -f1)"
+    EVAL="$(echo "$ENV" | cut -d '=' -f2-)"
+
+    if [ -z "$EVAL" ]; then
+        log "Skipping environment variable '$ENAME': no value set."
+        continue
+    fi
+
+    if echo "$EVAL" | grep -q "="; then
+        PNAME="$(echo "$EVAL" | cut -d '=' -f1)"
+        PVAL="$(echo "$EVAL" | cut -d '=' -f2-)"
+        [ -n "$PVAL" ] || PVAL='""'
+    else
+        PNAME="$EVAL"
+        PVAL='""'
+    fi 
+
+    if [ "$PVAL" = "UNSET" ]; then
+        log "Removing preference '$PNAME'..."
+        sed -i "/user_pref(\"$PNAME\",.*);/d" "$PREF_FILE"
+    elif grep -q "user_pref(\"$PNAME\"," "$PREF_FILE"; then
+        log "Setting preference '$PNAME'..."
+        sed -i "s/user_pref(\"$PNAME\",.*);/user_pref(\"$PNAME\", $PVAL);/" "$PREF_FILE"
+    else
+        log "Setting new preference '$PNAME'..."
+        echo "user_pref(\"$PNAME\", $PVAL);" >> "$PREF_FILE"
+    fi
+done