// 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_dup       = SYS_DUP2
	_SYS_setgroups = SYS_SETGROUPS
)

//sys	Dup2(oldfd int, newfd 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	Getrlimit(resource int, rlim *Rlimit) (err error) = SYS_GETRLIMIT
//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	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	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)
//sysnb	Setregid(rgid int, egid int) (err error)
//sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
//sysnb	Setresuid(ruid int, euid int, suid int) (err error)
//sysnb	Setrlimit(resource int, rlim *Rlimit) (err error)
//sysnb	Setreuid(ruid int, euid 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)
//sysnb	getgroups(n int, list *_Gid_t) (nn int, err error)
//sysnb	setgroups(n int, list *_Gid_t) (err error)

//sysnb	Gettimeofday(tv *Timeval) (err error)
//sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, 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
}

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

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

func Pipe(p []int) (err error) {
	if len(p) != 2 {
		return EINVAL
	}
	var pp [2]_C_int
	err = pipe2(&pp, 0)
	p[0] = int(pp[0])
	p[1] = int(pp[1])
	return
}

//sysnb pipe2(p *[2]_C_int, flags int) (err error)

func Pipe2(p []int, flags int) (err error) {
	if len(p) != 2 {
		return EINVAL
	}
	var pp [2]_C_int
	err = pipe2(&pp, flags)
	p[0] = int(pp[0])
	p[1] = int(pp[1])
	return
}

// 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
)

func socketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err Errno)
func rawsocketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err Errno)

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

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)
}

func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)
