FIX: cleaninput() for sed-replacement needs more escaping and unique separator.

Commit 8e4364f5e1 removed the deletion of the "|" character from cleaninput. That was okay for the cleaninput() use in _addto(), but not in those cases that used $input for replacement via sed.

Added corresponding tests for replace, append and prepend actions similar to what was added for the add action in the above commit.

To really fix the problem (and not just remove all "|" characters from the text), a separator character must be found that is not part of $input, and this must be used in the sed expression. As cleaninput() already modifies the global $input variable, another $inputSep global variable is used to pass back this information.

In addition, backslashes must be escaped in $input, or replacements like \1 wreak havoc.

todo.sh

@@ -272,8 +272,16 @@ cleaninput()
     input=$(echo $input | tr -d '\r\n')
 
     if [ "$1" = "for sed" ]; then
-        # This action uses sed and & as the matched string so escape it
-        input=`echo $input | sed 's/\&/\\\&/g'`
+        # This action uses sed and & as the matched string so escape it.
+        # Backslashes must be escaped, too.
+        input=`echo $input | sed -e 's+\\\+\\\\\\\\+g' -e 's/\&/\\\&/g'`
+
+        # Find a separator that doesn't occur in $input, sed cannot handle it, and escaping doesn't help.
+        # In the worst case (no separator found), the replacement text after the "|" is lost.
+        for inputSep in '%' '#' '@' ':' '!' '|'
+        do
+            [[ "$input" = *${inputSep}* ]] || break
+        done
     fi
 }
 
@@ -319,6 +327,7 @@ replaceOrPrepend()
     input=$*
   fi
   cleaninput "for sed"
+  sep=${inputSep:-|}
 
   # Retrieve existing priority and prepended date
   priority=$(sed -e "$item!d" -e $item's/^\(([A-Z]) \)\{0,1\}\([0-9]\{2,4\}-[0-9]\{2\}-[0-9]\{2\} \)\{0,1\}.*/\1/' "$TODO_FILE")
@@ -333,7 +342,7 @@ replaceOrPrepend()
   # Temporarily remove any existing priority and prepended date, perform the
   # change (replace/prepend) and re-insert the existing priority and prepended
   # date again.
-  sed -i.bak -e "$item s/^${priority}${prepdate}//" -e "$item s|^.*|${priority}${prepdate}${input}${backref}|" "$TODO_FILE"
+  sed -i.bak -e "$item s/^${priority}${prepdate}//" -e "$item s${sep}^.*${sep}${priority}${prepdate}${input}${backref}${sep}" "$TODO_FILE"
   if [ $TODOTXT_VERBOSE -gt 0 ]; then
     newtodo=$(sed "$item!d" "$TODO_FILE")
     case "$action" in
@@ -840,8 +849,9 @@ case $action in
       *)                        appendspace=" ";;
     esac
     cleaninput "for sed"
+    sep=${inputSep:-|}
 
-    if sed -i.bak $item" s|^.*|&${appendspace}${input}|" "$TODO_FILE"; then
+    if sed -i.bak $item" s${sep}^.*${sep}&${appendspace}${input}${sep}" "$TODO_FILE"; then
         if [ $TODOTXT_VERBOSE -gt 0 ]; then
             newtodo=$(sed "$item!d" "$TODO_FILE")
             echo "$item $newtodo"