sysconf.go

// Copyright 2018 Tobias Klauser. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sysconf implements the sysconf(3) function and provides the
// associated SC_* constants to query system configuration values.
package sysconf

import (
	"errors"
	"os"
)

//go:generate go run mksysconf.go

var errInvalid = errors.New("invalid parameter value")

// Sysconf returns the value of a sysconf(3) runtime system parameter.
// The name parameter should be a SC_* constant define in this package. The
// implementation is GOOS-specific and certain SC_* constants might not be
// defined for all GOOSes.
func Sysconf(name int) (int64, error) {
	// OS-specific sysconf
	if sc, err := sysconf(name); err == nil {
		return sc, nil
	}

	// POSIX default values
	if sc, err := sysconfPOSIX(name); err == nil {
		return sc, nil
	}

	switch name {
	case SC_BC_BASE_MAX:
		return _BC_BASE_MAX, nil
	case SC_BC_DIM_MAX:
		return _BC_DIM_MAX, nil
	case SC_BC_SCALE_MAX:
		return _BC_SCALE_MAX, nil
	case SC_BC_STRING_MAX:
		return _BC_STRING_MAX, nil
	case SC_COLL_WEIGHTS_MAX:
		return _COLL_WEIGHTS_MAX, nil
	case SC_EXPR_NEST_MAX:
		return _EXPR_NEST_MAX, nil
	case SC_HOST_NAME_MAX:
		return _HOST_NAME_MAX, nil
	case SC_LINE_MAX:
		return _LINE_MAX, nil
	case SC_LOGIN_NAME_MAX:
		return _LOGIN_NAME_MAX, nil
	case SC_PAGESIZE: // same as SC_PAGE_SIZE
		return int64(os.Getpagesize()), nil
	case SC_RE_DUP_MAX:
		return _RE_DUP_MAX, nil
	case SC_SYMLOOP_MAX:
		return _SYMLOOP_MAX, nil
	}

	return -1, errInvalid
}