// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// +build linux

package fdtrack

import (
	"io"
	"os"
	"syscall"
)

func fdlimit() int {
	var nofile syscall.Rlimit
	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &nofile); err != nil {
		return 0
	}
	return int(nofile.Cur)
}

func fdusage() (int, error) {
	f, err := os.Open("/proc/self/fd")
	if err != nil {
		return 0, err
	}
	defer f.Close()
	const batchSize = 100
	n := 0
	for {
		list, err := f.Readdirnames(batchSize)
		n += len(list)
		if err == io.EOF {
			break
		} else if err != nil {
			return 0, err
		}
	}
	return n, nil
}