Function drfront_appdata_logdir 

pub unsafe extern "C" fn drfront_appdata_logdir(
    root: *const c_char,
    subdir: *const c_char,
    use_root: *mut bool_,
    buf: *mut c_char,
    buflen: usize,
) -> drfront_status_t

If a tool is installed into a “Program Files” directory on Windows, or into “/usr/…” on Linux, it needs to store its log files elsewhere. This utility function helps to select that alternative location. First, it checks whether \p root is in a location where log files should not be created, and returns that result in \p use_root. If \p use_root is false, this function returns a suggested alternative directory for log files in \p buf. It looks in standard locations such as “$APPDATA” or “$USERPROFILE/Application Data” on Windows or in temp directories if those fail or if on Linux. It appends \p subdir to the base application data or temp directory. It is up to the caller to create the returned directory if it does not exist.

@param[in] root The location where the tool’s binaries are installed. @param[in] subdir A directory to append to the application data directory to form a result in \p buf. @param[out] use_root Returns whether \p root is suitable for storing log files. @param[out] buf If \p use_root is false, this buffer is filled with a suggested directory for storing log files. The directory ends with \p subdir. If \p use_root is true, \p buf’s contents are undefined. @param[in] buflen The maximum capacity of \p buf, in elements.