// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package syscall contains an interface to the low-level operating system
// primitives.  The details vary depending on the underlying system.
// Its primary use is inside other packages that provide a more portable
// interface to the system, such as "os", "time" and "net".  Use those
// packages rather than this one if you can.
// For details of the functions and data types in this package consult
// the manuals for the appropriate operating system.
// These calls return err == nil to indicate success; otherwise
// err is an operating system error describing the failure.
// On most systems, that error has type syscall.Errno.
package syscall

import "unsafe"

// StringByteSlice returns a NUL-terminated slice of bytes containing the text of s.
// If s contains a NUL byte this function panics instead of
// returning an error.
func StringByteSlice(s string) []byte {
	a, err := byteSliceFromString(s)
	if err != nil {
		panic("syscall: string with NUL passed to StringByteSlice")
	}
	return a
}

// byteSliceFromString returns a NUL-terminated slice of bytes
// containing the text of s. If s contains a NUL byte at any
// location, it returns (nil, EINVAL).
func byteSliceFromString(s string) ([]byte, error) {
	for i := 0; i < len(s); i++ {
		if s[i] == 0 {
			return nil, EINVAL
		}
	}
	a := make([]byte, len(s)+1)
	copy(a, s)
	return a, nil
}

// StringBytePtr returns a pointer to a NUL-terminated array of bytes containing the text of s.
// If s contains a NUL byte this function panics instead of
// returning an error.
func StringBytePtr(s string) *byte { return &StringByteSlice(s)[0] }

// bytePtrFromString returns a pointer to a NUL-terminated array of
// bytes containing the text of s. If s contains a NUL byte at any
// location, it returns (nil, EINVAL).
func bytePtrFromString(s string) (*byte, error) {
	a, err := byteSliceFromString(s)
	if err != nil {
		return nil, err
	}
	return &a[0], nil
}

// Single-word zero for use when we need a valid pointer to 0 bytes.
// See mksyscall.pl.
var _zero uintptr

var dummy *byte

const sizeofPtr uintptr = uintptr(unsafe.Sizeof(dummy))

func (ts *Timespec) Unix() (sec int64, nsec int64) {
	return int64(ts.Sec), int64(ts.Nsec)
}

func (tv *Timeval) Unix() (sec int64, nsec int64) {
	return int64(tv.Sec), int64(tv.Usec) * 1000
}

func (ts *Timespec) Nano() int64 {
	return int64(ts.Sec)*1e9 + int64(ts.Nsec)
}

func (tv *Timeval) Nano() int64 {
	return int64(tv.Sec)*1e9 + int64(tv.Usec)*1000
}
