#       [getPlatform] procedure.  An empty string means that the associated
  #       entity does not require a specific platform.  The varName argument
  #       is the name of a variable in the context of the immediate caller
  #       that will receive a modified platform name, if applicable.  Upon
  #       failure, a script error will be raised.  The return value is
  #       undefined.
  #
  # <internal>
  proc verifyPlatform { platform varName } {
    #
    # NOTE: The platform name must be matched exactly and case-sensitively.
    #
    switch -exact -- $platform {
      "" {
        #

        if {[info exists usePgp]} then {
          set localUsePgp $usePgp
        } else {
          set localUsePgp false
        }

        #
        # NOTE: Since not all potential callers to this procedure may login
        #       first, attempt to do that now, if necessary.
        #
        maybeResetCookieAndLoginSimple

        #
        # NOTE: Download the list of platforms associated with this package
        #       from the package repository server.  This may fail and raise
        #       a script error.
        #
        set platforms [downloadAllPlatforms \
            $language $version $localPackageName $localFileNames $localUsePgp]

    if {[string length $publicUserName] > 0 && \
        [string length $publicPassword] > 0} then {
      return [resetCookieAndLogin $publicUserName $publicPassword]
    }

    error "missing API keys and no public login credentials configured"
  }

  #
  # NOTE: This procedure attempts to login using the configured package
  #       repository server API key -OR- using the public access account,
  #       if not already logged in.  Upon success, it will set the login
  #       cookie to the one from the raw response data.  Upon failure, a
  #       script error will be raised.  There are no arguments.
  #
  # <internal>
  proc maybeResetCookieAndLoginSimple {} {
    variable loginCookie

    #
    # NOTE: Attempt to verify that we are currently logged in.  If so, do
    #       nothing; otherwise, attempt to login.
    #
    if {![info exists loginCookie] || [llength $loginCookie] != 2} then {
      resetCookieAndLoginSimple
    }
  }

  #
  # NOTE: This procedure resets the currently configured login cookie, if
  #       any, and then attempts to login using the specified user name and
  #       password.  Upon success, it will set the login cookie to the one
  #       from the raw response data.  Upon failure, a script error will be
  #       raised.  The userName argument must be the name of a package file