func getFDStats()

in metric/system/process/process_linux_common.go [445:484]
34 lines of code
9 McCabe index (conditional complexity)

func getFDStats(hostfs resolve.Resolver, pid int) (ProcFDInfo, error) {
	state := ProcFDInfo{}

	path := hostfs.Join("proc", strconv.Itoa(pid), "limits")
	data, err := os.ReadFile(path)
	if err != nil {
		return state, fmt.Errorf("error opening file %s: %w", path, err)
	}

	for _, line := range strings.Split(string(data), "\n") {
		if strings.HasPrefix(line, "Max open files") {
			fields := strings.Fields(line)
			if len(fields) == 6 {

				softLimit, err := strconv.ParseUint(fields[3], 10, 64)
				if err != nil {
					return state, fmt.Errorf("error parsing limits value %s for pid %d: %w", fields[3], pid, err)
				}
				state.Limit.Soft = opt.UintWith(softLimit)

				hardLimit, err := strconv.ParseUint(fields[4], 10, 64)
				if err != nil {
					return state, fmt.Errorf("error parsing limits value %s for pid %d: %w", fields[3], pid, err)
				}
				state.Limit.Hard = opt.UintWith(hardLimit)
			}

		}
	}

	pathFD := hostfs.Join("proc", strconv.Itoa(pid), "fd")
	fds, err := os.ReadDir(pathFD)
	if errors.Is(err, os.ErrPermission) { // ignore permission errors, passthrough other data
		return state, nil
	} else if err != nil {
		return state, fmt.Errorf("error reading FD directory for pid %d: %w", pid, err)
	}
	state.Open = opt.UintWith(uint64(len(fds)))
	return state, nil
}