# Following path conversion functions assume that cygrdives are mounted at root.
# Your fstab entry should look like this:
#
#     none / cygdrive binary,posix=0,noacl,user 0 0
#
declare -A _CYGDRIVEMAP=([C]="/c" [P]="/p")

# Convert mixed path to unix path. Mixed path is using windows drive at the beginning,
# but with forward slashes already
to_unix_path () {
  local _DRIVE
  if [ "${1#[A-Z]:/}" != "$1" ]; then
    _DRIVE="${1:0:1}"
    echo "${_CYGDRIVEMAP[$_DRIVE]}${1:2}"
    return
  fi
  echo $1
}

# Example call
echo $(to_unix_path "C:/Users/starstuck")