fn read_pid_stat_from_path>()

in below/procfs/src/lib.rs [501:552]

• 46 lines of code
• 5 McCabe index (conditional complexity)

    fn read_pid_stat_from_path<P: AsRef<Path>>(&self, path: P) -> Result<PidStat> {
        let path = path.as_ref().join("stat");
        let file = File::open(&path).map_err(|e| Error::IoError(path.clone(), e))?;
        let mut buf_reader = BufReader::new(file);
        let mut pidstat: PidStat = Default::default();

        let mut line = String::new();
        buf_reader
            .read_line(&mut line)
            .map_err(|e| Error::IoError(path.clone(), e))?;

        {
            let b_opt = line.find('(');
            let e_opt = line.rfind(')');
            if let (Some(b), Some(e)) = (b_opt, e_opt) {
                pidstat.comm = Some(line[b + 1..e].to_string());
                line.replace_range(b..e + 1, "");
            }
        }

        let items: Vec<_> = line.split_whitespace().collect();
        pidstat.pid = parse_item!(path, items.get(0), i32, line)?;
        if let Some(c) = parse_item!(path, items.get(1), char, line)? {
            if let Some(state) = PidState::from_char(c) {
                pidstat.state = Some(state);
            } else {
                return Err(Error::InvalidPidState(path, c));
            }
        }
        pidstat.ppid = parse_item!(path, items.get(2), i32, line)?;
        pidstat.pgrp = parse_item!(path, items.get(3), i32, line)?;
        pidstat.session = parse_item!(path, items.get(4), i32, line)?;
        pidstat.minflt = parse_item!(path, items.get(8), u64, line)?;
        pidstat.majflt = parse_item!(path, items.get(10), u64, line)?;
        pidstat.user_usecs = parse_usec!(path, items.get(12), line)?;
        pidstat.system_usecs = parse_usec!(path, items.get(13), line)?;
        pidstat.num_threads = parse_item!(path, items.get(18), u64, line)?;

        let uptime = self.read_uptime_secs()?;
        pidstat.running_secs = parse_sec!(path, items.get(20), line)?
            .map(|running_secs_since_boot| (uptime - running_secs_since_boot) as u64);

        pidstat.rss_bytes =
            parse_item!(path, items.get(22), u64, line)?.map(|pages| pages * *PAGE_SIZE);
        pidstat.processor = parse_item!(path, items.get(37), i32, line)?;

        if pidstat == Default::default() {
            Err(Error::InvalidFileFormat(path))
        } else {
            Ok(pidstat)
        }
    }