Function type for callback when a passwords is required.
Should copy the password into the supplied buffer, and return the
actual length of the password.
@param userdata The user data for the callback.
@param buf The buffer to copy the password into.
@param len The length of the buffer.
@return The length of the password as copied into the buffer.
Function type for callback when a passwords is required.
Should copy the password into the supplied buffer, and return the actual length of the password.
@param userdata The user data for the callback. @param buf The buffer to copy the password into. @param len The length of the buffer. @return The length of the password as copied into the buffer.