// 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

import "unsafe"

const (
	_SYS_dup       = SYS_DUP2
	_SYS_setgroups = SYS_SETGROUPS32
)

func setTimespec(sec, nsec int64) Timespec {
	return Timespec{Sec: int32(sec), Nsec: int32(nsec)}
}

func setTimeval(sec, usec int64) Timeval {
	return Timeval{Sec: int32(sec), Usec: int32(usec)}
}

//sysnb pipe(p *[2]_C_int) (err error)

func Pipe(p []int) (err error) {
	if len(p) != 2 {
		return EINVAL
	}
	var pp [2]_C_int
	// Try pipe2 first for Android O, then try pipe for kernel 2.6.23.
	err = pipe2(&pp, 0)
	if err == ENOSYS {
		err = pipe(&pp)
	}
	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
}

// Underlying system call writes to newoffset via pointer.
// Implemented in assembly to avoid allocation.
func seek(fd int, offset int64, whence int) (newoffset int64, err Errno)

func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
	newoffset, errno := seek(fd, offset, whence)
	if errno != 0 {
		return 0, errno
	}
	return newoffset, nil
}

//sys	accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error)
//sys	accept4(s int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (fd int, err error)
//sys	bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
//sys	connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
//sysnb	getgroups(n int, list *_Gid_t) (nn int, err error) = SYS_GETGROUPS32
//sysnb	setgroups(n int, list *_Gid_t) (err error) = SYS_SETGROUPS32
//sys	getsockopt(s int, level int, name int, val unsafe.Pointer, vallen *_Socklen) (err error)
//sys	setsockopt(s int, level int, name int, val unsafe.Pointer, vallen uintptr) (err error)
//sysnb	socket(domain int, typ int, proto int) (fd int, err error)
//sysnb	getpeername(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
//sysnb	getsockname(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
//sys	recvfrom(fd int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error)
//sys	sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error)
//sysnb	socketpair(domain int, typ int, flags int, fd *[2]int32) (err error)
//sys	recvmsg(s int, msg *Msghdr, flags int) (n int, err error)
//sys	sendmsg(s int, msg *Msghdr, flags int) (n int, err error)

// 64-bit file system and 32-bit uid calls
// (16-bit uid calls are not always supported in newer kernels)
//sys	Dup2(oldfd int, newfd int) (err error)
//sys	Fchown(fd int, uid int, gid int) (err error) = SYS_FCHOWN32
//sys	Fstat(fd int, stat *Stat_t) (err error) = SYS_FSTAT64
//sys	fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) = SYS_FSTATAT64
//sysnb	Getegid() (egid int) = SYS_GETEGID32
//sysnb	Geteuid() (euid int) = SYS_GETEUID32
//sysnb	Getgid() (gid int) = SYS_GETGID32
//sysnb	Getuid() (uid int) = SYS_GETUID32
//sysnb	InotifyInit() (fd int, err error)
//sys	Listen(s int, n int) (err error)
//sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
//sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
//sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
//sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
//sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
//sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
//sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32
//sysnb	Setreuid(ruid int, euid int) (err error) = SYS_SETREUID32
//sys	Shutdown(fd int, how int) (err error)
//sys	Splice(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)

// Vsyscalls on amd64.
//sysnb	Gettimeofday(tv *Timeval) (err error)
//sysnb	Time(t *Time_t) (tt Time_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	Truncate(path string, length int64) (err error) = SYS_TRUNCATE64
//sys	Ftruncate(fd int, length int64) (err error) = SYS_FTRUNCATE64

//sys	mmap2(addr uintptr, length uintptr, prot int, flags int, fd int, pageOffset uintptr) (xaddr uintptr, err error)
//sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error)

func Stat(path string, stat *Stat_t) (err error) {
	return fstatat(_AT_FDCWD, path, stat, 0)
}

func Lchown(path string, uid int, gid int) (err error) {
	return Fchownat(_AT_FDCWD, path, uid, gid, _AT_SYMLINK_NOFOLLOW)
}

func Lstat(path string, stat *Stat_t) (err error) {
	return fstatat(_AT_FDCWD, path, stat, _AT_SYMLINK_NOFOLLOW)
}

func Fstatfs(fd int, buf *Statfs_t) (err error) {
	_, _, e := Syscall(SYS_FSTATFS64, uintptr(fd), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
	if e != 0 {
		err = e
	}
	return
}

func Statfs(path string, buf *Statfs_t) (err error) {
	pathp, err := BytePtrFromString(path)
	if err != nil {
		return err
	}
	_, _, e := Syscall(SYS_STATFS64, uintptr(unsafe.Pointer(pathp)), unsafe.Sizeof(*buf), uintptr(unsafe.Pointer(buf)))
	if e != 0 {
		err = e
	}
	return
}

func mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error) {
	page := uintptr(offset / 4096)
	if offset != int64(page)*4096 {
		return 0, EINVAL
	}
	return mmap2(addr, length, prot, flags, fd, page)
}

type rlimit32 struct {
	Cur uint32
	Max uint32
}

//sysnb getrlimit(resource int, rlim *rlimit32) (err error) = SYS_GETRLIMIT

const rlimInf32 = ^uint32(0)
const rlimInf64 = ^uint64(0)

func Getrlimit(resource int, rlim *Rlimit) (err error) {
	err = prlimit(0, resource, nil, rlim)
	if err != ENOSYS {
		return err
	}

	rl := rlimit32{}
	err = getrlimit(resource, &rl)
	if err != nil {
		return
	}

	if rl.Cur == rlimInf32 {
		rlim.Cur = rlimInf64
	} else {
		rlim.Cur = uint64(rl.Cur)
	}

	if rl.Max == rlimInf32 {
		rlim.Max = rlimInf64
	} else {
		rlim.Max = uint64(rl.Max)
	}
	return
}

//sysnb setrlimit(resource int, rlim *rlimit32) (err error) = SYS_SETRLIMIT

func Setrlimit(resource int, rlim *Rlimit) (err error) {
	err = prlimit(0, resource, rlim, nil)
	if err != ENOSYS {
		return err
	}

	rl := rlimit32{}
	if rlim.Cur == rlimInf64 {
		rl.Cur = rlimInf32
	} else if rlim.Cur < uint64(rlimInf32) {
		rl.Cur = uint32(rlim.Cur)
	} else {
		return EINVAL
	}
	if rlim.Max == rlimInf64 {
		rl.Max = rlimInf32
	} else if rlim.Max < uint64(rlimInf32) {
		rl.Max = uint32(rlim.Max)
	} else {
		return EINVAL
	}

	return setrlimit(resource, &rl)
}

func (r *PtraceRegs) PC() uint64 { return uint64(r.Uregs[15]) }

func (r *PtraceRegs) SetPC(pc uint64) { r.Uregs[15] = uint32(pc) }

func (iov *Iovec) SetLen(length int) {
	iov.Len = uint32(length)
}

func (msghdr *Msghdr) SetControllen(length int) {
	msghdr.Controllen = uint32(length)
}

func (cmsg *Cmsghdr) SetLen(length int) {
	cmsg.Len = uint32(length)
}

func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno) {
	panic("not implemented")
}