// Copyright 2016 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

import "unsafe"

const (
	_SYS_setgroups  = SYS_SETGROUPS
	_SYS_clone3     = 435
	_SYS_faccessat2 = 439
	_SYS_fchmodat2  = 452
)

//sys	Dup2(oldfd int, newfd int) (err error)
//sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error)
//sys	Fchown(fd int, uid int, gid int) (err error)
//sys	Fstat(fd int, stat *Stat_t) (err error)
//sys	fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_NEWFSTATAT
//sys	Fstatfs(fd int, buf *Statfs_t) (err error)
//sys	Ftruncate(fd int, length int64) (err error)
//sysnb	Getegid() (egid int)
//sysnb	Geteuid() (euid int)
//sysnb	Getgid() (gid int)
//sysnb	Getuid() (uid int)
//sysnb	InotifyInit() (fd int, err error)
//sys	Lchown(path string, uid int, gid int) (err error)
//sys	Lstat(path string, stat *Stat_t) (err error)
//sys	Pause() (err error)
//sys	pread(fd int, p []byte, offset int64) (n int, err error) = SYS_PREAD64
//sys	pwrite(fd int, p []byte, offset int64) (n int, err error) = SYS_PWRITE64
//sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
//sys	Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
//sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)
//sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
//sys	Setfsgid(gid int) (err error)
//sys	Setfsuid(uid int) (err error)
//sys	Splice(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int64, err error)
//sys	Stat(path string, stat *Stat_t) (err error)
//sys	Statfs(path string, buf *Statfs_t) (err error)
//sys	SyncFileRange(fd int, off int64, n int64, flags int) (err error) = SYS_SYNC_FILE_RANGE
//sys	Truncate(path string, length int64) (err error)
//sys	Ustat(dev int, ubuf *Ustat_t) (err error)
//sysnb	getgroups(n int, list *_Gid_t) (nn int, err error)

//sys	futimesat(dirfd int, path string, times *[2]Timeval) (err error)
//sysnb	Gettimeofday(tv *Timeval) (err error)

func Time(t *Time_t) (tt Time_t, err error) {
	var tv Timeval
	err = Gettimeofday(&tv)
	if err != nil {
		return 0, err
	}
	if t != nil {
		*t = Time_t(tv.Sec)
	}
	return Time_t(tv.Sec), nil
}

//sys	Utime(path string, buf *Utimbuf) (err error)
//sys	utimes(path string, times *[2]Timeval) (err error)

func setTimespec(sec, nsec int64) Timespec {
	return Timespec{Sec: sec, Nsec: nsec}
}

func setTimeval(sec, usec int64) Timeval {
	return Timeval{Sec: sec, Usec: usec}
}

// Linux on s390x uses the old mmap interface, which requires arguments to be passed in a struct.
// mmap2 also requires arguments to be passed in a struct; it is currently not exposed in <asm/unistd.h>.
func mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error) {
	mmap_args := [6]uintptr{addr, length, uintptr(prot), uintptr(flags), uintptr(fd), uintptr(offset)}
	r0, _, e1 := Syscall(SYS_MMAP, uintptr(unsafe.Pointer(&mmap_args[0])), 0, 0)
	xaddr = uintptr(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

// On s390x Linux, all the socket calls go through an extra indirection.
// The arguments to the underlying system call are the number below
// and a pointer to an array of uintptr.  We hide the pointer in the
// socketcall assembly to avoid allocation on every system call.

const (
	// see linux/net.h
	_SOCKET      = 1
	_BIND        = 2
	_CONNECT     = 3
	_LISTEN      = 4
	_ACCEPT      = 5
	_GETSOCKNAME = 6
	_GETPEERNAME = 7
	_SOCKETPAIR  = 8
	_SEND        = 9
	_RECV        = 10
	_SENDTO      = 11
	_RECVFROM    = 12
	_SHUTDOWN    = 13
	_SETSOCKOPT  = 14
	_GETSOCKOPT  = 15
	_SENDMSG     = 16
	_RECVMSG     = 17
	_ACCEPT4     = 18
	_RECVMMSG    = 19
	_SENDMMSG    = 20
)

// socketcall and rawsocketcall are accessed via assembly in x/net.
//
//go:linkname socketcall
func socketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err Errno)

//go:linkname rawsocketcall
func rawsocketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err Errno)

func accept4(s int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (fd int, err error) {
	fd, e := socketcall(_ACCEPT4, uintptr(s), uintptr(unsafe.Pointer(rsa)), uintptr(unsafe.Pointer(addrlen)), uintptr(flags), 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func getsockname(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error) {
	_, e := rawsocketcall(_GETSOCKNAME, uintptr(s), uintptr(unsafe.Pointer(rsa)), uintptr(unsafe.Pointer(addrlen)), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func getpeername(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error) {
	_, e := rawsocketcall(_GETPEERNAME, uintptr(s), uintptr(unsafe.Pointer(rsa)), uintptr(unsafe.Pointer(addrlen)), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func socketpair(domain int, typ int, flags int, fd *[2]int32) (err error) {
	_, e := rawsocketcall(_SOCKETPAIR, uintptr(domain), uintptr(typ), uintptr(flags), uintptr(unsafe.Pointer(fd)), 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error) {
	_, e := socketcall(_BIND, uintptr(s), uintptr(addr), uintptr(addrlen), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error) {
	_, e := socketcall(_CONNECT, uintptr(s), uintptr(addr), uintptr(addrlen), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func socket(domain int, typ int, proto int) (fd int, err error) {
	fd, e := rawsocketcall(_SOCKET, uintptr(domain), uintptr(typ), uintptr(proto), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func getsockopt(s int, level int, name int, val unsafe.Pointer, vallen *_Socklen) (err error) {
	_, e := socketcall(_GETSOCKOPT, uintptr(s), uintptr(level), uintptr(name), uintptr(val), uintptr(unsafe.Pointer(vallen)), 0)
	if e != 0 {
		err = e
	}
	return
}

func setsockopt(s int, level int, name int, val unsafe.Pointer, vallen uintptr) (err error) {
	_, e := socketcall(_SETSOCKOPT, uintptr(s), uintptr(level), uintptr(name), uintptr(val), vallen, 0)
	if e != 0 {
		err = e
	}
	return
}

func recvfrom(s int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error) {
	var base uintptr
	if len(p) > 0 {
		base = uintptr(unsafe.Pointer(&p[0]))
	}
	n, e := socketcall(_RECVFROM, uintptr(s), base, uintptr(len(p)), uintptr(flags), uintptr(unsafe.Pointer(from)), uintptr(unsafe.Pointer(fromlen)))
	if e != 0 {
		err = e
	}
	return
}

func sendto(s int, p []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error) {
	var base uintptr
	if len(p) > 0 {
		base = uintptr(unsafe.Pointer(&p[0]))
	}
	_, e := socketcall(_SENDTO, uintptr(s), base, uintptr(len(p)), uintptr(flags), uintptr(to), uintptr(addrlen))
	if e != 0 {
		err = e
	}
	return
}

func recvmsg(s int, msg *Msghdr, flags int) (n int, err error) {
	n, e := socketcall(_RECVMSG, uintptr(s), uintptr(unsafe.Pointer(msg)), uintptr(flags), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func sendmsg(s int, msg *Msghdr, flags int) (n int, err error) {
	n, e := socketcall(_SENDMSG, uintptr(s), uintptr(unsafe.Pointer(msg)), uintptr(flags), 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func Listen(s int, n int) (err error) {
	_, e := socketcall(_LISTEN, uintptr(s), uintptr(n), 0, 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func Shutdown(s, how int) (err error) {
	_, e := socketcall(_SHUTDOWN, uintptr(s), uintptr(how), 0, 0, 0, 0)
	if e != 0 {
		err = e
	}
	return
}

func (r *PtraceRegs) PC() uint64 { return r.Psw.Addr }

func (r *PtraceRegs) SetPC(pc uint64) { r.Psw.Addr = pc }

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint64(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint64(length)
}

func (cmsg *Cmsghdr) SetLen(length int) {
	cmsg.Len = uint64(length)
}
