// Copyright 2020 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.

//go:build zos && s390x

// Many of the following syscalls are not available on all versions of z/OS.
// Some missing calls have legacy implementations/simulations but others
// will be missing completely. To achieve consistent failing behaviour on
// legacy systems, we first test the function pointer via a safeloading
// mechanism to see if the function exists on a given system. Then execution
// is branched to either continue the function call, or return an error.

package unix

import (
    "bytes"
    "fmt"
    "os"
    "reflect"
    "regexp"
    "runtime"
    "sort"
    "strings"
    "sync"
    "syscall"
    "unsafe"
)

//go:noescape
func initZosLibVec()

//go:noescape
func GetZosLibVec() uintptr

func init() {
    initZosLibVec()
    r0, _, _ := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS_____GETENV_A<<4, uintptr(unsafe.Pointer(&([]byte("__ZOS_XSYSTRACE\x00"))[0])))
    if r0 != 0 {
        n, _, _ := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___ATOI_A<<4, r0)
        ZosTraceLevel = int(n)
        r0, _, _ := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS_____GETENV_A<<4, uintptr(unsafe.Pointer(&([]byte("__ZOS_XSYSTRACEFD\x00"))[0])))
        if r0 != 0 {
            fd, _, _ := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___ATOI_A<<4, r0)
            f := os.NewFile(fd, "zostracefile")
            if f != nil {
                ZosTracefile = f
            }
        }

    }
}

//go:noescape
func CallLeFuncWithErr(funcdesc uintptr, parms ...uintptr) (ret, errno2 uintptr, err Errno)

//go:noescape
func CallLeFuncWithPtrReturn(funcdesc uintptr, parms ...uintptr) (ret, errno2 uintptr, err Errno)

// -------------------------------
// pointer validity test
// good pointer returns 0
// bad pointer returns 1
//
//go:nosplit
func ptrtest(uintptr) uint64

// Load memory at ptr location with error handling if the location is invalid
//
//go:noescape
func safeload(ptr uintptr) (value uintptr, error uintptr)

const (
    entrypointLocationOffset = 8 // From function descriptor

    xplinkEyecatcher   = 0x00c300c500c500f1 // ".C.E.E.1"
    eyecatcherOffset   = 16                 // From function entrypoint (negative)
    ppa1LocationOffset = 8                  // From function entrypoint (negative)

    nameLenOffset = 0x14 // From PPA1 start
    nameOffset    = 0x16 // From PPA1 start
)

func getPpaOffset(funcptr uintptr) int64 {
    entrypoint, err := safeload(funcptr + entrypointLocationOffset)
    if err != 0 {
        return -1
    }

    // XPLink functions have ".C.E.E.1" as the first 8 bytes (EBCDIC)
    val, err := safeload(entrypoint - eyecatcherOffset)
    if err != 0 {
        return -1
    }
    if val != xplinkEyecatcher {
        return -1
    }

    ppaoff, err := safeload(entrypoint - ppa1LocationOffset)
    if err != 0 {
        return -1
    }

    ppaoff >>= 32
    return int64(ppaoff)
}

//-------------------------------
// function descriptor pointer validity test
// good pointer returns 0
// bad pointer returns 1

// TODO: currently mksyscall_zos_s390x.go generate empty string for funcName
// have correct funcName pass to the funcptrtest function
func funcptrtest(funcptr uintptr, funcName string) uint64 {
    entrypoint, err := safeload(funcptr + entrypointLocationOffset)
    if err != 0 {
        return 1
    }

    ppaoff := getPpaOffset(funcptr)
    if ppaoff == -1 {
        return 1
    }

    // PPA1 offset value is from the start of the entire function block, not the entrypoint
    ppa1 := (entrypoint - eyecatcherOffset) + uintptr(ppaoff)

    nameLen, err := safeload(ppa1 + nameLenOffset)
    if err != 0 {
        return 1
    }

    nameLen >>= 48
    if nameLen > 128 {
        return 1
    }

    // no function name input to argument end here
    if funcName == "" {
        return 0
    }

    var funcname [128]byte
    for i := 0; i < int(nameLen); i += 8 {
        v, err := safeload(ppa1 + nameOffset + uintptr(i))
        if err != 0 {
            return 1
        }
        funcname[i] = byte(v >> 56)
        funcname[i+1] = byte(v >> 48)
        funcname[i+2] = byte(v >> 40)
        funcname[i+3] = byte(v >> 32)
        funcname[i+4] = byte(v >> 24)
        funcname[i+5] = byte(v >> 16)
        funcname[i+6] = byte(v >> 8)
        funcname[i+7] = byte(v)
    }

    runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___E2A_L<<4, // __e2a_l
        []uintptr{uintptr(unsafe.Pointer(&funcname[0])), nameLen})

    name := string(funcname[:nameLen])
    if name != funcName {
        return 1
    }

    return 0
}

// For detection of capabilities on a system.
// Is function descriptor f a valid function?
func isValidLeFunc(f uintptr) error {
    ret := funcptrtest(f, "")
    if ret != 0 {
        return fmt.Errorf("Bad pointer, not an LE function ")
    }
    return nil
}

// Retrieve function name from descriptor
func getLeFuncName(f uintptr) (string, error) {
    // assume it has been checked, only check ppa1 validity here
    entry := ((*[2]uintptr)(unsafe.Pointer(f)))[1]
    preamp := ((*[4]uint32)(unsafe.Pointer(entry - eyecatcherOffset)))

    offsetPpa1 := preamp[2]
    if offsetPpa1 > 0x0ffff {
        return "", fmt.Errorf("PPA1 offset seems too big 0x%x\n", offsetPpa1)
    }

    ppa1 := uintptr(unsafe.Pointer(preamp)) + uintptr(offsetPpa1)
    res := ptrtest(ppa1)
    if res != 0 {
        return "", fmt.Errorf("PPA1 address not valid")
    }

    size := *(*uint16)(unsafe.Pointer(ppa1 + nameLenOffset))
    if size > 128 {
        return "", fmt.Errorf("Function name seems too long, length=%d\n", size)
    }

    var name [128]byte
    funcname := (*[128]byte)(unsafe.Pointer(ppa1 + nameOffset))
    copy(name[0:size], funcname[0:size])

    runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___E2A_L<<4, // __e2a_l
        []uintptr{uintptr(unsafe.Pointer(&name[0])), uintptr(size)})

    return string(name[:size]), nil
}

// Check z/OS version
func zosLeVersion() (version, release uint32) {
    p1 := (*(*uintptr)(unsafe.Pointer(uintptr(1208)))) >> 32
    p1 = *(*uintptr)(unsafe.Pointer(uintptr(p1 + 88)))
    p1 = *(*uintptr)(unsafe.Pointer(uintptr(p1 + 8)))
    p1 = *(*uintptr)(unsafe.Pointer(uintptr(p1 + 984)))
    vrm := *(*uint32)(unsafe.Pointer(p1 + 80))
    version = (vrm & 0x00ff0000) >> 16
    release = (vrm & 0x0000ff00) >> 8
    return
}

// returns a zos C FILE * for stdio fd 0, 1, 2
func ZosStdioFilep(fd int32) uintptr {
    return uintptr(*(*uint64)(unsafe.Pointer(uintptr(*(*uint64)(unsafe.Pointer(uintptr(*(*uint64)(unsafe.Pointer(uintptr(uint64(*(*uint32)(unsafe.Pointer(uintptr(1208)))) + 80))) + uint64((fd+2)<<3))))))))
}

func copyStat(stat *Stat_t, statLE *Stat_LE_t) {
    stat.Dev = uint64(statLE.Dev)
    stat.Ino = uint64(statLE.Ino)
    stat.Nlink = uint64(statLE.Nlink)
    stat.Mode = uint32(statLE.Mode)
    stat.Uid = uint32(statLE.Uid)
    stat.Gid = uint32(statLE.Gid)
    stat.Rdev = uint64(statLE.Rdev)
    stat.Size = statLE.Size
    stat.Atim.Sec = int64(statLE.Atim)
    stat.Atim.Nsec = 0 //zos doesn't return nanoseconds
    stat.Mtim.Sec = int64(statLE.Mtim)
    stat.Mtim.Nsec = 0 //zos doesn't return nanoseconds
    stat.Ctim.Sec = int64(statLE.Ctim)
    stat.Ctim.Nsec = 0 //zos doesn't return nanoseconds
    stat.Blksize = int64(statLE.Blksize)
    stat.Blocks = statLE.Blocks
}

func svcCall(fnptr unsafe.Pointer, argv *unsafe.Pointer, dsa *uint64)
func svcLoad(name *byte) unsafe.Pointer
func svcUnload(name *byte, fnptr unsafe.Pointer) int64

func (d *Dirent) NameString() string {
    if d == nil {
        return ""
    }
    s := string(d.Name[:])
    idx := strings.IndexByte(s, 0)
    if idx == -1 {
        return s
    } else {
        return s[:idx]
    }
}

func DecodeData(dest []byte, sz int, val uint64) {
    for i := 0; i < sz; i++ {
        dest[sz-1-i] = byte((val >> (uint64(i * 8))) & 0xff)
    }
}

func EncodeData(data []byte) uint64 {
    var value uint64
    sz := len(data)
    for i := 0; i < sz; i++ {
        value |= uint64(data[i]) << uint64(((sz - i - 1) * 8))
    }
    return value
}

func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
    if sa.Port < 0 || sa.Port > 0xFFFF {
        return nil, 0, EINVAL
    }
    sa.raw.Len = SizeofSockaddrInet4
    sa.raw.Family = AF_INET
    p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
    p[0] = byte(sa.Port >> 8)
    p[1] = byte(sa.Port)
    for i := 0; i < len(sa.Addr); i++ {
        sa.raw.Addr[i] = sa.Addr[i]
    }
    return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
}

func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
    if sa.Port < 0 || sa.Port > 0xFFFF {
        return nil, 0, EINVAL
    }
    sa.raw.Len = SizeofSockaddrInet6
    sa.raw.Family = AF_INET6
    p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
    p[0] = byte(sa.Port >> 8)
    p[1] = byte(sa.Port)
    sa.raw.Scope_id = sa.ZoneId
    for i := 0; i < len(sa.Addr); i++ {
        sa.raw.Addr[i] = sa.Addr[i]
    }
    return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
}

func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
    name := sa.Name
    n := len(name)
    if n >= len(sa.raw.Path) || n == 0 {
        return nil, 0, EINVAL
    }
    sa.raw.Len = byte(3 + n) // 2 for Family, Len; 1 for NUL
    sa.raw.Family = AF_UNIX
    for i := 0; i < n; i++ {
        sa.raw.Path[i] = int8(name[i])
    }
    return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
}

func anyToSockaddr(_ int, rsa *RawSockaddrAny) (Sockaddr, error) {
    // TODO(neeilan): Implement use of first param (fd)
    switch rsa.Addr.Family {
    case AF_UNIX:
        pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
        sa := new(SockaddrUnix)
        // For z/OS, only replace NUL with @ when the
        // length is not zero.
        if pp.Len != 0 && pp.Path[0] == 0 {
            // "Abstract" Unix domain socket.
            // Rewrite leading NUL as @ for textual display.
            // (This is the standard convention.)
            // Not friendly to overwrite in place,
            // but the callers below don't care.
            pp.Path[0] = '@'
        }

        // Assume path ends at NUL.
        //
        // For z/OS, the length of the name is a field
        // in the structure. To be on the safe side, we
        // will still scan the name for a NUL but only
        // to the length provided in the structure.
        //
        // This is not technically the Linux semantics for
        // abstract Unix domain sockets--they are supposed
        // to be uninterpreted fixed-size binary blobs--but
        // everyone uses this convention.
        n := 0
        for n < int(pp.Len) && pp.Path[n] != 0 {
            n++
        }
        sa.Name = string(unsafe.Slice((*byte)(unsafe.Pointer(&pp.Path[0])), n))
        return sa, nil

    case AF_INET:
        pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
        sa := new(SockaddrInet4)
        p := (*[2]byte)(unsafe.Pointer(&pp.Port))
        sa.Port = int(p[0])<<8 + int(p[1])
        for i := 0; i < len(sa.Addr); i++ {
            sa.Addr[i] = pp.Addr[i]
        }
        return sa, nil

    case AF_INET6:
        pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
        sa := new(SockaddrInet6)
        p := (*[2]byte)(unsafe.Pointer(&pp.Port))
        sa.Port = int(p[0])<<8 + int(p[1])
        sa.ZoneId = pp.Scope_id
        for i := 0; i < len(sa.Addr); i++ {
            sa.Addr[i] = pp.Addr[i]
        }
        return sa, nil
    }
    return nil, EAFNOSUPPORT
}

func Accept(fd int) (nfd int, sa Sockaddr, err error) {
    var rsa RawSockaddrAny
    var len _Socklen = SizeofSockaddrAny
    nfd, err = accept(fd, &rsa, &len)
    if err != nil {
        return
    }
    // TODO(neeilan): Remove 0 in call
    sa, err = anyToSockaddr(0, &rsa)
    if err != nil {
        Close(nfd)
        nfd = 0
    }
    return
}

func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
    var rsa RawSockaddrAny
    var len _Socklen = SizeofSockaddrAny
    nfd, err = accept4(fd, &rsa, &len, flags)
    if err != nil {
        return
    }
    if len > SizeofSockaddrAny {
        panic("RawSockaddrAny too small")
    }
    // TODO(neeilan): Remove 0 in call
    sa, err = anyToSockaddr(0, &rsa)
    if err != nil {
        Close(nfd)
        nfd = 0
    }
    return
}

func Ctermid() (tty string, err error) {
    var termdev [1025]byte
    runtime.EnterSyscall()
    r0, err2, err1 := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___CTERMID_A<<4, uintptr(unsafe.Pointer(&termdev[0])))
    runtime.ExitSyscall()
    if r0 == 0 {
        return "", fmt.Errorf("%s (errno2=0x%x)\n", err1.Error(), err2)
    }
    s := string(termdev[:])
    idx := strings.Index(s, string(rune(0)))
    if idx == -1 {
        tty = s
    } else {
        tty = s[:idx]
    }
    return
}

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

func (msghdr *Msghdr) SetControllen(length int) {
    msghdr.Controllen = int32(length)
}

func (cmsg *Cmsghdr) SetLen(length int) {
    cmsg.Len = int32(length)
}

//sys   fcntl(fd int, cmd int, arg int) (val int, err error)
//sys   Flistxattr(fd int, dest []byte) (sz int, err error) = SYS___FLISTXATTR_A
//sys   Fremovexattr(fd int, attr string) (err error) = SYS___FREMOVEXATTR_A
//sys    read(fd int, p []byte) (n int, err error)
//sys    write(fd int, p []byte) (n int, err error)

//sys   Fgetxattr(fd int, attr string, dest []byte) (sz int, err error) = SYS___FGETXATTR_A
//sys   Fsetxattr(fd int, attr string, data []byte, flag int) (err error) = SYS___FSETXATTR_A

//sys    accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error) = SYS___ACCEPT_A
//sys    accept4(s int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (fd int, err error) = SYS___ACCEPT4_A
//sys    bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error) = SYS___BIND_A
//sys    connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error) = SYS___CONNECT_A
//sysnb    getgroups(n int, list *_Gid_t) (nn int, err error)
//sysnb    setgroups(n int, list *_Gid_t) (err error)
//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    socketpair(domain int, typ int, proto int, fd *[2]int32) (err error)
//sysnb    getpeername(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error) = SYS___GETPEERNAME_A
//sysnb    getsockname(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error) = SYS___GETSOCKNAME_A
//sys   Removexattr(path string, attr string) (err error) = SYS___REMOVEXATTR_A
//sys    recvfrom(fd int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error) = SYS___RECVFROM_A
//sys    sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error) = SYS___SENDTO_A
//sys    recvmsg(s int, msg *Msghdr, flags int) (n int, err error) = SYS___RECVMSG_A
//sys    sendmsg(s int, msg *Msghdr, flags int) (n int, err error) = SYS___SENDMSG_A
//sys   mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error) = SYS_MMAP
//sys   munmap(addr uintptr, length uintptr) (err error) = SYS_MUNMAP
//sys   ioctl(fd int, req int, arg uintptr) (err error) = SYS_IOCTL
//sys   ioctlPtr(fd int, req int, arg unsafe.Pointer) (err error) = SYS_IOCTL
//sys    shmat(id int, addr uintptr, flag int) (ret uintptr, err error) = SYS_SHMAT
//sys    shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error) = SYS_SHMCTL64
//sys    shmdt(addr uintptr) (err error) = SYS_SHMDT
//sys    shmget(key int, size int, flag int) (id int, err error) = SYS_SHMGET

//sys   Access(path string, mode uint32) (err error) = SYS___ACCESS_A
//sys   Chdir(path string) (err error) = SYS___CHDIR_A
//sys    Chown(path string, uid int, gid int) (err error) = SYS___CHOWN_A
//sys    Chmod(path string, mode uint32) (err error) = SYS___CHMOD_A
//sys   Creat(path string, mode uint32) (fd int, err error) = SYS___CREAT_A
//sys    Dup(oldfd int) (fd int, err error)
//sys    Dup2(oldfd int, newfd int) (err error)
//sys    Dup3(oldfd int, newfd int, flags int) (err error) = SYS_DUP3
//sys    Dirfd(dirp uintptr) (fd int, err error) = SYS_DIRFD
//sys    EpollCreate(size int) (fd int, err error) = SYS_EPOLL_CREATE
//sys    EpollCreate1(flags int) (fd int, err error) = SYS_EPOLL_CREATE1
//sys    EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error) = SYS_EPOLL_CTL
//sys    EpollPwait(epfd int, events []EpollEvent, msec int, sigmask *int) (n int, err error) = SYS_EPOLL_PWAIT
//sys    EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error) = SYS_EPOLL_WAIT
//sys    Errno2() (er2 int) = SYS___ERRNO2
//sys    Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD
//sys    Exit(code int)
//sys    Faccessat(dirfd int, path string, mode uint32, flags int) (err error) = SYS___FACCESSAT_A

func Faccessat2(dirfd int, path string, mode uint32, flags int) (err error) {
    return Faccessat(dirfd, path, mode, flags)
}

//sys    Fchdir(fd int) (err error)
//sys    Fchmod(fd int, mode uint32) (err error)
//sys    Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) = SYS___FCHMODAT_A
//sys    Fchown(fd int, uid int, gid int) (err error)
//sys    Fchownat(fd int, path string, uid int, gid int, flags int) (err error) = SYS___FCHOWNAT_A
//sys    FcntlInt(fd uintptr, cmd int, arg int) (retval int, err error) = SYS_FCNTL
//sys    Fdatasync(fd int) (err error) = SYS_FDATASYNC
//sys    fstat(fd int, stat *Stat_LE_t) (err error)
//sys    fstatat(dirfd int, path string, stat *Stat_LE_t, flags int) (err error) = SYS___FSTATAT_A

func Fstat(fd int, stat *Stat_t) (err error) {
    var statLE Stat_LE_t
    err = fstat(fd, &statLE)
    copyStat(stat, &statLE)
    return
}

func Fstatat(dirfd int, path string, stat *Stat_t, flags int) (err error) {
    var statLE Stat_LE_t
    err = fstatat(dirfd, path, &statLE, flags)
    copyStat(stat, &statLE)
    return
}

func impl_Getxattr(path string, attr string, dest []byte) (sz int, err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(path)
    if err != nil {
        return
    }
    var _p1 *byte
    _p1, err = BytePtrFromString(attr)
    if err != nil {
        return
    }
    var _p2 unsafe.Pointer
    if len(dest) > 0 {
        _p2 = unsafe.Pointer(&dest[0])
    } else {
        _p2 = unsafe.Pointer(&_zero)
    }
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___GETXATTR_A<<4, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(dest)))
    sz = int(r0)
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_GetxattrAddr() *(func(path string, attr string, dest []byte) (sz int, err error))

var Getxattr = enter_Getxattr

func enter_Getxattr(path string, attr string, dest []byte) (sz int, err error) {
    funcref := get_GetxattrAddr()
    if validGetxattr() {
        *funcref = impl_Getxattr
    } else {
        *funcref = error_Getxattr
    }
    return (*funcref)(path, attr, dest)
}

func error_Getxattr(path string, attr string, dest []byte) (sz int, err error) {
    return -1, ENOSYS
}

func validGetxattr() bool {
    if funcptrtest(GetZosLibVec()+SYS___GETXATTR_A<<4, "") == 0 {
        if name, err := getLeFuncName(GetZosLibVec() + SYS___GETXATTR_A<<4); err == nil {
            return name == "__getxattr_a"
        }
    }
    return false
}

//sys   Lgetxattr(link string, attr string, dest []byte) (sz int, err error) = SYS___LGETXATTR_A
//sys   Lsetxattr(path string, attr string, data []byte, flags int) (err error) = SYS___LSETXATTR_A

func impl_Setxattr(path string, attr string, data []byte, flags int) (err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(path)
    if err != nil {
        return
    }
    var _p1 *byte
    _p1, err = BytePtrFromString(attr)
    if err != nil {
        return
    }
    var _p2 unsafe.Pointer
    if len(data) > 0 {
        _p2 = unsafe.Pointer(&data[0])
    } else {
        _p2 = unsafe.Pointer(&_zero)
    }
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___SETXATTR_A<<4, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(_p2), uintptr(len(data)), uintptr(flags))
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_SetxattrAddr() *(func(path string, attr string, data []byte, flags int) (err error))

var Setxattr = enter_Setxattr

func enter_Setxattr(path string, attr string, data []byte, flags int) (err error) {
    funcref := get_SetxattrAddr()
    if validSetxattr() {
        *funcref = impl_Setxattr
    } else {
        *funcref = error_Setxattr
    }
    return (*funcref)(path, attr, data, flags)
}

func error_Setxattr(path string, attr string, data []byte, flags int) (err error) {
    return ENOSYS
}

func validSetxattr() bool {
    if funcptrtest(GetZosLibVec()+SYS___SETXATTR_A<<4, "") == 0 {
        if name, err := getLeFuncName(GetZosLibVec() + SYS___SETXATTR_A<<4); err == nil {
            return name == "__setxattr_a"
        }
    }
    return false
}

//sys    Fstatfs(fd int, buf *Statfs_t) (err error) = SYS_FSTATFS
//sys    Fstatvfs(fd int, stat *Statvfs_t) (err error) = SYS_FSTATVFS
//sys    Fsync(fd int) (err error)
//sys    Futimes(fd int, tv []Timeval) (err error) = SYS_FUTIMES
//sys    Futimesat(dirfd int, path string, tv []Timeval) (err error) = SYS___FUTIMESAT_A
//sys    Ftruncate(fd int, length int64) (err error)
//sys    Getrandom(buf []byte, flags int) (n int, err error) = SYS_GETRANDOM
//sys    InotifyInit() (fd int, err error) = SYS_INOTIFY_INIT
//sys    InotifyInit1(flags int) (fd int, err error) = SYS_INOTIFY_INIT1
//sys    InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error) = SYS___INOTIFY_ADD_WATCH_A
//sys    InotifyRmWatch(fd int, watchdesc uint32) (success int, err error) = SYS_INOTIFY_RM_WATCH
//sys   Listxattr(path string, dest []byte) (sz int, err error) = SYS___LISTXATTR_A
//sys   Llistxattr(path string, dest []byte) (sz int, err error) = SYS___LLISTXATTR_A
//sys   Lremovexattr(path string, attr string) (err error) = SYS___LREMOVEXATTR_A
//sys    Lutimes(path string, tv []Timeval) (err error) = SYS___LUTIMES_A
//sys   Mprotect(b []byte, prot int) (err error) = SYS_MPROTECT
//sys   Msync(b []byte, flags int) (err error) = SYS_MSYNC
//sys   Console2(cmsg *ConsMsg2, modstr *byte, concmd *uint32) (err error) = SYS___CONSOLE2

// Pipe2 begin

//go:nosplit
func getPipe2Addr() *(func([]int, int) error)

var Pipe2 = pipe2Enter

func pipe2Enter(p []int, flags int) (err error) {
    if funcptrtest(GetZosLibVec()+SYS_PIPE2<<4, "") == 0 {
        *getPipe2Addr() = pipe2Impl
    } else {
        *getPipe2Addr() = pipe2Error
    }
    return (*getPipe2Addr())(p, flags)
}

func pipe2Impl(p []int, flags int) (err error) {
    var pp [2]_C_int
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_PIPE2<<4, uintptr(unsafe.Pointer(&pp[0])), uintptr(flags))
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    } else {
        p[0] = int(pp[0])
        p[1] = int(pp[1])
    }
    return
}
func pipe2Error(p []int, flags int) (err error) {
    return fmt.Errorf("Pipe2 is not available on this system")
}

// Pipe2 end

//sys   Poll(fds []PollFd, timeout int) (n int, err error) = SYS_POLL

func Readdir(dir uintptr) (dirent *Dirent, err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___READDIR_A<<4, uintptr(dir))
    runtime.ExitSyscall()
    dirent = (*Dirent)(unsafe.Pointer(r0))
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//sys    Readdir_r(dirp uintptr, entry *direntLE, result **direntLE) (err error) = SYS___READDIR_R_A
//sys    Statfs(path string, buf *Statfs_t) (err error) = SYS___STATFS_A
//sys    Syncfs(fd int) (err error) = SYS_SYNCFS
//sys   Times(tms *Tms) (ticks uintptr, err error) = SYS_TIMES
//sys   W_Getmntent(buff *byte, size int) (lastsys int, err error) = SYS_W_GETMNTENT
//sys   W_Getmntent_A(buff *byte, size int) (lastsys int, err error) = SYS___W_GETMNTENT_A

//sys   mount_LE(path string, filesystem string, fstype string, mtm uint32, parmlen int32, parm string) (err error) = SYS___MOUNT_A
//sys   unmount_LE(filesystem string, mtm int) (err error) = SYS___UMOUNT_A
//sys   Chroot(path string) (err error) = SYS___CHROOT_A
//sys   Select(nmsgsfds int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (ret int, err error) = SYS_SELECT
//sysnb Uname(buf *Utsname) (err error) = SYS_____OSNAME_A
//sys   Unshare(flags int) (err error) = SYS_UNSHARE

func Ptsname(fd int) (name string, err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___PTSNAME_A<<4, uintptr(fd))
    runtime.ExitSyscall()
    if r0 == 0 {
        err = errnoErr2(e1, e2)
    } else {
        name = u2s(unsafe.Pointer(r0))
    }
    return
}

func u2s(cstr unsafe.Pointer) string {
    str := (*[1024]uint8)(cstr)
    i := 0
    for str[i] != 0 {
        i++
    }
    return string(str[:i])
}

func Close(fd int) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_CLOSE<<4, uintptr(fd))
    runtime.ExitSyscall()
    for i := 0; e1 == EAGAIN && i < 10; i++ {
        runtime.EnterSyscall()
        CallLeFuncWithErr(GetZosLibVec()+SYS_USLEEP<<4, uintptr(10))
        runtime.ExitSyscall()
        runtime.EnterSyscall()
        r0, e2, e1 = CallLeFuncWithErr(GetZosLibVec()+SYS_CLOSE<<4, uintptr(fd))
        runtime.ExitSyscall()
    }
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

// Dummy function: there are no semantics for Madvise on z/OS
func Madvise(b []byte, advice int) (err error) {
    return
}

func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
    return mapper.Mmap(fd, offset, length, prot, flags)
}

func Munmap(b []byte) (err error) {
    return mapper.Munmap(b)
}

func MmapPtr(fd int, offset int64, addr unsafe.Pointer, length uintptr, prot int, flags int) (ret unsafe.Pointer, err error) {
    xaddr, err := mapper.mmap(uintptr(addr), length, prot, flags, fd, offset)
    return unsafe.Pointer(xaddr), err
}

func MunmapPtr(addr unsafe.Pointer, length uintptr) (err error) {
    return mapper.munmap(uintptr(addr), length)
}

//sys   Gethostname(buf []byte) (err error) = SYS___GETHOSTNAME_A
//sysnb    Getgid() (gid int)
//sysnb    Getpid() (pid int)
//sysnb    Getpgid(pid int) (pgid int, err error) = SYS_GETPGID

func Getpgrp() (pid int) {
    pid, _ = Getpgid(0)
    return
}

//sysnb    Getppid() (pid int)
//sys    Getpriority(which int, who int) (prio int, err error)
//sysnb    Getrlimit(resource int, rlim *Rlimit) (err error) = SYS_GETRLIMIT

//sysnb getrusage(who int, rusage *rusage_zos) (err error) = SYS_GETRUSAGE

func Getrusage(who int, rusage *Rusage) (err error) {
    var ruz rusage_zos
    err = getrusage(who, &ruz)
    //Only the first two fields of Rusage are set
    rusage.Utime.Sec = ruz.Utime.Sec
    rusage.Utime.Usec = int64(ruz.Utime.Usec)
    rusage.Stime.Sec = ruz.Stime.Sec
    rusage.Stime.Usec = int64(ruz.Stime.Usec)
    return
}

//sys    Getegid() (egid int) = SYS_GETEGID
//sys    Geteuid() (euid int) = SYS_GETEUID
//sysnb Getsid(pid int) (sid int, err error) = SYS_GETSID
//sysnb    Getuid() (uid int)
//sysnb    Kill(pid int, sig Signal) (err error)
//sys    Lchown(path string, uid int, gid int) (err error) = SYS___LCHOWN_A
//sys    Link(path string, link string) (err error) = SYS___LINK_A
//sys    Linkat(oldDirFd int, oldPath string, newDirFd int, newPath string, flags int) (err error) = SYS___LINKAT_A
//sys    Listen(s int, n int) (err error)
//sys    lstat(path string, stat *Stat_LE_t) (err error) = SYS___LSTAT_A

func Lstat(path string, stat *Stat_t) (err error) {
    var statLE Stat_LE_t
    err = lstat(path, &statLE)
    copyStat(stat, &statLE)
    return
}

// for checking symlinks begins with $VERSION/ $SYSNAME/ $SYSSYMR/ $SYSSYMA/
func isSpecialPath(path []byte) (v bool) {
    var special = [4][8]byte{
        {'V', 'E', 'R', 'S', 'I', 'O', 'N', '/'},
        {'S', 'Y', 'S', 'N', 'A', 'M', 'E', '/'},
        {'S', 'Y', 'S', 'S', 'Y', 'M', 'R', '/'},
        {'S', 'Y', 'S', 'S', 'Y', 'M', 'A', '/'}}

    var i, j int
    for i = 0; i < len(special); i++ {
        for j = 0; j < len(special[i]); j++ {
            if path[j] != special[i][j] {
                break
            }
        }
        if j == len(special[i]) {
            return true
        }
    }
    return false
}

func realpath(srcpath string, abspath []byte) (pathlen int, errno int) {
    var source [1024]byte
    copy(source[:], srcpath)
    source[len(srcpath)] = 0
    ret := runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___REALPATH_A<<4, //__realpath_a()
        []uintptr{uintptr(unsafe.Pointer(&source[0])),
            uintptr(unsafe.Pointer(&abspath[0]))})
    if ret != 0 {
        index := bytes.IndexByte(abspath[:], byte(0))
        if index != -1 {
            return index, 0
        }
    } else {
        errptr := (*int)(unsafe.Pointer(runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___ERRNO<<4, []uintptr{}))) //__errno()
        return 0, *errptr
    }
    return 0, 245 // EBADDATA   245
}

func Readlink(path string, buf []byte) (n int, err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(path)
    if err != nil {
        return
    }
    var _p1 unsafe.Pointer
    if len(buf) > 0 {
        _p1 = unsafe.Pointer(&buf[0])
    } else {
        _p1 = unsafe.Pointer(&_zero)
    }
    n = int(runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___READLINK_A<<4,
        []uintptr{uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(buf))}))
    runtime.KeepAlive(unsafe.Pointer(_p0))
    if n == -1 {
        value := *(*int32)(unsafe.Pointer(runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___ERRNO<<4, []uintptr{})))
        err = errnoErr(Errno(value))
    } else {
        if buf[0] == '$' {
            if isSpecialPath(buf[1:9]) {
                cnt, err1 := realpath(path, buf)
                if err1 == 0 {
                    n = cnt
                }
            }
        }
    }
    return
}

func impl_Readlinkat(dirfd int, path string, buf []byte) (n int, err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(path)
    if err != nil {
        return
    }
    var _p1 unsafe.Pointer
    if len(buf) > 0 {
        _p1 = unsafe.Pointer(&buf[0])
    } else {
        _p1 = unsafe.Pointer(&_zero)
    }
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___READLINKAT_A<<4, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(_p1), uintptr(len(buf)))
    runtime.ExitSyscall()
    n = int(r0)
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
        return n, err
    } else {
        if buf[0] == '$' {
            if isSpecialPath(buf[1:9]) {
                cnt, err1 := realpath(path, buf)
                if err1 == 0 {
                    n = cnt
                }
            }
        }
    }
    return
}

//go:nosplit
func get_ReadlinkatAddr() *(func(dirfd int, path string, buf []byte) (n int, err error))

var Readlinkat = enter_Readlinkat

func enter_Readlinkat(dirfd int, path string, buf []byte) (n int, err error) {
    funcref := get_ReadlinkatAddr()
    if funcptrtest(GetZosLibVec()+SYS___READLINKAT_A<<4, "") == 0 {
        *funcref = impl_Readlinkat
    } else {
        *funcref = error_Readlinkat
    }
    return (*funcref)(dirfd, path, buf)
}

func error_Readlinkat(dirfd int, path string, buf []byte) (n int, err error) {
    n = -1
    err = ENOSYS
    return
}

//sys    Mkdir(path string, mode uint32) (err error) = SYS___MKDIR_A
//sys    Mkdirat(dirfd int, path string, mode uint32) (err error) = SYS___MKDIRAT_A
//sys   Mkfifo(path string, mode uint32) (err error) = SYS___MKFIFO_A
//sys    Mknod(path string, mode uint32, dev int) (err error) = SYS___MKNOD_A
//sys    Mknodat(dirfd int, path string, mode uint32, dev int) (err error) = SYS___MKNODAT_A
//sys    PivotRoot(newroot string, oldroot string) (err error) = SYS___PIVOT_ROOT_A
//sys    Pread(fd int, p []byte, offset int64) (n int, err error)
//sys    Pwrite(fd int, p []byte, offset int64) (n int, err error)
//sys    Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error) = SYS___PRCTL_A
//sysnb    Prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT
//sys    Rename(from string, to string) (err error) = SYS___RENAME_A
//sys    Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error) = SYS___RENAMEAT_A
//sys    Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error) = SYS___RENAMEAT2_A
//sys    Rmdir(path string) (err error) = SYS___RMDIR_A
//sys   Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
//sys    Setegid(egid int) (err error) = SYS_SETEGID
//sys    Seteuid(euid int) (err error) = SYS_SETEUID
//sys    Sethostname(p []byte) (err error) = SYS___SETHOSTNAME_A
//sys   Setns(fd int, nstype int) (err error) = SYS_SETNS
//sys    Setpriority(which int, who int, prio int) (err error)
//sysnb    Setpgid(pid int, pgid int) (err error) = SYS_SETPGID
//sysnb    Setrlimit(resource int, lim *Rlimit) (err error)
//sysnb    Setregid(rgid int, egid int) (err error) = SYS_SETREGID
//sysnb    Setreuid(ruid int, euid int) (err error) = SYS_SETREUID
//sysnb    Setsid() (pid int, err error) = SYS_SETSID
//sys    Setuid(uid int) (err error) = SYS_SETUID
//sys    Setgid(uid int) (err error) = SYS_SETGID
//sys    Shutdown(fd int, how int) (err error)
//sys    stat(path string, statLE *Stat_LE_t) (err error) = SYS___STAT_A

func Stat(path string, sta *Stat_t) (err error) {
    var statLE Stat_LE_t
    err = stat(path, &statLE)
    copyStat(sta, &statLE)
    return
}

//sys    Symlink(path string, link string) (err error) = SYS___SYMLINK_A
//sys    Symlinkat(oldPath string, dirfd int, newPath string) (err error) = SYS___SYMLINKAT_A
//sys    Sync() = SYS_SYNC
//sys    Truncate(path string, length int64) (err error) = SYS___TRUNCATE_A
//sys    Tcgetattr(fildes int, termptr *Termios) (err error) = SYS_TCGETATTR
//sys    Tcsetattr(fildes int, when int, termptr *Termios) (err error) = SYS_TCSETATTR
//sys    Umask(mask int) (oldmask int)
//sys    Unlink(path string) (err error) = SYS___UNLINK_A
//sys    Unlinkat(dirfd int, path string, flags int) (err error) = SYS___UNLINKAT_A
//sys    Utime(path string, utim *Utimbuf) (err error) = SYS___UTIME_A

//sys    open(path string, mode int, perm uint32) (fd int, err error) = SYS___OPEN_A

func Open(path string, mode int, perm uint32) (fd int, err error) {
    if mode&O_ACCMODE == 0 {
        mode |= O_RDONLY
    }
    return open(path, mode, perm)
}

//sys    openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) = SYS___OPENAT_A

func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
    if flags&O_ACCMODE == 0 {
        flags |= O_RDONLY
    }
    return openat(dirfd, path, flags, mode)
}

//sys    openat2(dirfd int, path string, open_how *OpenHow, size int) (fd int, err error) = SYS___OPENAT2_A

func Openat2(dirfd int, path string, how *OpenHow) (fd int, err error) {
    if how.Flags&O_ACCMODE == 0 {
        how.Flags |= O_RDONLY
    }
    return openat2(dirfd, path, how, SizeofOpenHow)
}

func ZosFdToPath(dirfd int) (path string, err error) {
    var buffer [1024]byte
    runtime.EnterSyscall()
    ret, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_W_IOCTL<<4, uintptr(dirfd), 17, 1024, uintptr(unsafe.Pointer(&buffer[0])))
    runtime.ExitSyscall()
    if ret == 0 {
        zb := bytes.IndexByte(buffer[:], 0)
        if zb == -1 {
            zb = len(buffer)
        }
        CallLeFuncWithErr(GetZosLibVec()+SYS___E2A_L<<4, uintptr(unsafe.Pointer(&buffer[0])), uintptr(zb))
        return string(buffer[:zb]), nil
    }
    return "", errnoErr2(e1, e2)
}

//sys    remove(path string) (err error)

func Remove(path string) error {
    return remove(path)
}

const ImplementsGetwd = true

func Getcwd(buf []byte) (n int, err error) {
    var p unsafe.Pointer
    if len(buf) > 0 {
        p = unsafe.Pointer(&buf[0])
    } else {
        p = unsafe.Pointer(&_zero)
    }
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___GETCWD_A<<4, uintptr(p), uintptr(len(buf)))
    runtime.ExitSyscall()
    n = clen(buf) + 1
    if r0 == 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Getwd() (wd string, err error) {
    var buf [PathMax]byte
    n, err := Getcwd(buf[0:])
    if err != nil {
        return "", err
    }
    // Getcwd returns the number of bytes written to buf, including the NUL.
    if n < 1 || n > len(buf) || buf[n-1] != 0 {
        return "", EINVAL
    }
    return string(buf[0 : n-1]), nil
}

func Getgroups() (gids []int, err error) {
    n, err := getgroups(0, nil)
    if err != nil {
        return nil, err
    }
    if n == 0 {
        return nil, nil
    }

    // Sanity check group count.  Max is 1<<16 on Linux.
    if n < 0 || n > 1<<20 {
        return nil, EINVAL
    }

    a := make([]_Gid_t, n)
    n, err = getgroups(n, &a[0])
    if err != nil {
        return nil, err
    }
    gids = make([]int, n)
    for i, v := range a[0:n] {
        gids[i] = int(v)
    }
    return
}

func Setgroups(gids []int) (err error) {
    if len(gids) == 0 {
        return setgroups(0, nil)
    }

    a := make([]_Gid_t, len(gids))
    for i, v := range gids {
        a[i] = _Gid_t(v)
    }
    return setgroups(len(a), &a[0])
}

func gettid() uint64

func Gettid() (tid int) {
    return int(gettid())
}

type WaitStatus uint32

// Wait status is 7 bits at bottom, either 0 (exited),
// 0x7F (stopped), or a signal number that caused an exit.
// The 0x80 bit is whether there was a core dump.
// An extra number (exit code, signal causing a stop)
// is in the high bits.  At least that's the idea.
// There are various irregularities.  For example, the
// "continued" status is 0xFFFF, distinguishing itself
// from stopped via the core dump bit.

const (
    mask    = 0x7F
    core    = 0x80
    exited  = 0x00
    stopped = 0x7F
    shift   = 8
)

func (w WaitStatus) Exited() bool { return w&mask == exited }

func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }

func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }

func (w WaitStatus) Continued() bool { return w == 0xFFFF }

func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }

func (w WaitStatus) ExitStatus() int {
    if !w.Exited() {
        return -1
    }
    return int(w>>shift) & 0xFF
}

func (w WaitStatus) Signal() Signal {
    if !w.Signaled() {
        return -1
    }
    return Signal(w & mask)
}

func (w WaitStatus) StopSignal() Signal {
    if !w.Stopped() {
        return -1
    }
    return Signal(w>>shift) & 0xFF
}

func (w WaitStatus) TrapCause() int { return -1 }

//sys    waitid(idType int, id int, info *Siginfo, options int) (err error)

func Waitid(idType int, id int, info *Siginfo, options int, rusage *Rusage) (err error) {
    return waitid(idType, id, info, options)
}

//sys    waitpid(pid int, wstatus *_C_int, options int) (wpid int, err error)

func impl_Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_WAIT4<<4, uintptr(pid), uintptr(unsafe.Pointer(wstatus)), uintptr(options), uintptr(unsafe.Pointer(rusage)))
    runtime.ExitSyscall()
    wpid = int(r0)
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_Wait4Addr() *(func(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error))

var Wait4 = enter_Wait4

func enter_Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
    funcref := get_Wait4Addr()
    if funcptrtest(GetZosLibVec()+SYS_WAIT4<<4, "") == 0 {
        *funcref = impl_Wait4
    } else {
        *funcref = legacyWait4
    }
    return (*funcref)(pid, wstatus, options, rusage)
}

func legacyWait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
    // TODO(mundaym): z/OS doesn't have wait4. I don't think getrusage does what we want.
    // At the moment rusage will not be touched.
    var status _C_int
    wpid, err = waitpid(pid, &status, options)
    if wstatus != nil {
        *wstatus = WaitStatus(status)
    }
    return
}

//sysnb    gettimeofday(tv *timeval_zos) (err error)

func Gettimeofday(tv *Timeval) (err error) {
    var tvz timeval_zos
    err = gettimeofday(&tvz)
    tv.Sec = tvz.Sec
    tv.Usec = int64(tvz.Usec)
    return
}

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 { //fix
    return Timeval{Sec: sec, Usec: 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
    err = pipe(&pp)
    p[0] = int(pp[0])
    p[1] = int(pp[1])
    return
}

//sys    utimes(path string, timeval *[2]Timeval) (err error) = SYS___UTIMES_A

func Utimes(path string, tv []Timeval) (err error) {
    if tv == nil {
        return utimes(path, nil)
    }
    if len(tv) != 2 {
        return EINVAL
    }
    return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

//sys    utimensat(dirfd int, path string, ts *[2]Timespec, flags int) (err error) = SYS___UTIMENSAT_A

func validUtimensat() bool {
    if funcptrtest(GetZosLibVec()+SYS___UTIMENSAT_A<<4, "") == 0 {
        if name, err := getLeFuncName(GetZosLibVec() + SYS___UTIMENSAT_A<<4); err == nil {
            return name == "__utimensat_a"
        }
    }
    return false
}

// Begin UtimesNano

//go:nosplit
func get_UtimesNanoAddr() *(func(path string, ts []Timespec) (err error))

var UtimesNano = enter_UtimesNano

func enter_UtimesNano(path string, ts []Timespec) (err error) {
    funcref := get_UtimesNanoAddr()
    if validUtimensat() {
        *funcref = utimesNanoImpl
    } else {
        *funcref = legacyUtimesNano
    }
    return (*funcref)(path, ts)
}

func utimesNanoImpl(path string, ts []Timespec) (err error) {
    if ts == nil {
        return utimensat(AT_FDCWD, path, nil, 0)
    }
    if len(ts) != 2 {
        return EINVAL
    }
    return utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
}

func legacyUtimesNano(path string, ts []Timespec) (err error) {
    if len(ts) != 2 {
        return EINVAL
    }
    // Not as efficient as it could be because Timespec and
    // Timeval have different types in the different OSes
    tv := [2]Timeval{
        NsecToTimeval(TimespecToNsec(ts[0])),
        NsecToTimeval(TimespecToNsec(ts[1])),
    }
    return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

// End UtimesNano

// Begin UtimesNanoAt

//go:nosplit
func get_UtimesNanoAtAddr() *(func(dirfd int, path string, ts []Timespec, flags int) (err error))

var UtimesNanoAt = enter_UtimesNanoAt

func enter_UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) (err error) {
    funcref := get_UtimesNanoAtAddr()
    if validUtimensat() {
        *funcref = utimesNanoAtImpl
    } else {
        *funcref = legacyUtimesNanoAt
    }
    return (*funcref)(dirfd, path, ts, flags)
}

func utimesNanoAtImpl(dirfd int, path string, ts []Timespec, flags int) (err error) {
    if ts == nil {
        return utimensat(dirfd, path, nil, flags)
    }
    if len(ts) != 2 {
        return EINVAL
    }
    return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
}

func legacyUtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) (err error) {
    if path[0] != '/' {
        dirPath, err := ZosFdToPath(dirfd)
        if err != nil {
            return err
        }
        path = dirPath + "/" + path
    }
    if flags == AT_SYMLINK_NOFOLLOW {
        if len(ts) != 2 {
            return EINVAL
        }

        if ts[0].Nsec >= 5e8 {
            ts[0].Sec++
        }
        ts[0].Nsec = 0
        if ts[1].Nsec >= 5e8 {
            ts[1].Sec++
        }
        ts[1].Nsec = 0

        // Not as efficient as it could be because Timespec and
        // Timeval have different types in the different OSes
        tv := []Timeval{
            NsecToTimeval(TimespecToNsec(ts[0])),
            NsecToTimeval(TimespecToNsec(ts[1])),
        }
        return Lutimes(path, tv)
    }
    return UtimesNano(path, ts)
}

// End UtimesNanoAt

func Getsockname(fd int) (sa Sockaddr, err error) {
    var rsa RawSockaddrAny
    var len _Socklen = SizeofSockaddrAny
    if err = getsockname(fd, &rsa, &len); err != nil {
        return
    }
    // TODO(neeilan) : Remove this 0 ( added to get sys/unix compiling on z/OS )
    return anyToSockaddr(0, &rsa)
}

const (
    // identifier constants
    nwmHeaderIdentifier    = 0xd5e6d4c8
    nwmFilterIdentifier    = 0xd5e6d4c6
    nwmTCPConnIdentifier   = 0xd5e6d4c3
    nwmRecHeaderIdentifier = 0xd5e6d4d9
    nwmIPStatsIdentifier   = 0xd5e6d4c9d7e2e340
    nwmIPGStatsIdentifier  = 0xd5e6d4c9d7c7e2e3
    nwmTCPStatsIdentifier  = 0xd5e6d4e3c3d7e2e3
    nwmUDPStatsIdentifier  = 0xd5e6d4e4c4d7e2e3
    nwmICMPGStatsEntry     = 0xd5e6d4c9c3d4d7c7
    nwmICMPTStatsEntry     = 0xd5e6d4c9c3d4d7e3

    // nwmHeader constants
    nwmVersion1   = 1
    nwmVersion2   = 2
    nwmCurrentVer = 2

    nwmTCPConnType     = 1
    nwmGlobalStatsType = 14

    // nwmFilter constants
    nwmFilterLclAddrMask = 0x20000000 // Local address
    nwmFilterSrcAddrMask = 0x20000000 // Source address
    nwmFilterLclPortMask = 0x10000000 // Local port
    nwmFilterSrcPortMask = 0x10000000 // Source port

    // nwmConnEntry constants
    nwmTCPStateClosed   = 1
    nwmTCPStateListen   = 2
    nwmTCPStateSynSent  = 3
    nwmTCPStateSynRcvd  = 4
    nwmTCPStateEstab    = 5
    nwmTCPStateFinWait1 = 6
    nwmTCPStateFinWait2 = 7
    nwmTCPStateClosWait = 8
    nwmTCPStateLastAck  = 9
    nwmTCPStateClosing  = 10
    nwmTCPStateTimeWait = 11
    nwmTCPStateDeletTCB = 12

    // Existing constants on linux
    BPF_TCP_CLOSE        = 1
    BPF_TCP_LISTEN       = 2
    BPF_TCP_SYN_SENT     = 3
    BPF_TCP_SYN_RECV     = 4
    BPF_TCP_ESTABLISHED  = 5
    BPF_TCP_FIN_WAIT1    = 6
    BPF_TCP_FIN_WAIT2    = 7
    BPF_TCP_CLOSE_WAIT   = 8
    BPF_TCP_LAST_ACK     = 9
    BPF_TCP_CLOSING      = 10
    BPF_TCP_TIME_WAIT    = 11
    BPF_TCP_NEW_SYN_RECV = -1
    BPF_TCP_MAX_STATES   = -2
)

type nwmTriplet struct {
    offset uint32
    length uint32
    number uint32
}

type nwmQuadruplet struct {
    offset uint32
    length uint32
    number uint32
    match  uint32
}

type nwmHeader struct {
    ident       uint32
    length      uint32
    version     uint16
    nwmType     uint16
    bytesNeeded uint32
    options     uint32
    _           [16]byte
    inputDesc   nwmTriplet
    outputDesc  nwmQuadruplet
}

type nwmFilter struct {
    ident         uint32
    flags         uint32
    resourceName  [8]byte
    resourceId    uint32
    listenerId    uint32
    local         [28]byte // union of sockaddr4 and sockaddr6
    remote        [28]byte // union of sockaddr4 and sockaddr6
    _             uint16
    _             uint16
    asid          uint16
    _             [2]byte
    tnLuName      [8]byte
    tnMonGrp      uint32
    tnAppl        [8]byte
    applData      [40]byte
    nInterface    [16]byte
    dVipa         [16]byte
    dVipaPfx      uint16
    dVipaPort     uint16
    dVipaFamily   byte
    _             [3]byte
    destXCF       [16]byte
    destXCFPfx    uint16
    destXCFFamily byte
    _             [1]byte
    targIP        [16]byte
    targIPPfx     uint16
    targIPFamily  byte
    _             [1]byte
    _             [20]byte
}

type nwmRecHeader struct {
    ident  uint32
    length uint32
    number byte
    _      [3]byte
}

type nwmTCPStatsEntry struct {
    ident             uint64
    currEstab         uint32
    activeOpened      uint32
    passiveOpened     uint32
    connClosed        uint32
    estabResets       uint32
    attemptFails      uint32
    passiveDrops      uint32
    timeWaitReused    uint32
    inSegs            uint64
    predictAck        uint32
    predictData       uint32
    inDupAck          uint32
    inBadSum          uint32
    inBadLen          uint32
    inShort           uint32
    inDiscOldTime     uint32
    inAllBeforeWin    uint32
    inSomeBeforeWin   uint32
    inAllAfterWin     uint32
    inSomeAfterWin    uint32
    inOutOfOrder      uint32
    inAfterClose      uint32
    inWinProbes       uint32
    inWinUpdates      uint32
    outWinUpdates     uint32
    outSegs           uint64
    outDelayAcks      uint32
    outRsts           uint32
    retransSegs       uint32
    retransTimeouts   uint32
    retransDrops      uint32
    pmtuRetrans       uint32
    pmtuErrors        uint32
    outWinProbes      uint32
    probeDrops        uint32
    keepAliveProbes   uint32
    keepAliveDrops    uint32
    finwait2Drops     uint32
    acceptCount       uint64
    inBulkQSegs       uint64
    inDiscards        uint64
    connFloods        uint32
    connStalls        uint32
    cfgEphemDef       uint16
    ephemInUse        uint16
    ephemHiWater      uint16
    flags             byte
    _                 [1]byte
    ephemExhaust      uint32
    smcRCurrEstabLnks uint32
    smcRLnkActTimeOut uint32
    smcRActLnkOpened  uint32
    smcRPasLnkOpened  uint32
    smcRLnksClosed    uint32
    smcRCurrEstab     uint32
    smcRActiveOpened  uint32
    smcRPassiveOpened uint32
    smcRConnClosed    uint32
    smcRInSegs        uint64
    smcROutSegs       uint64
    smcRInRsts        uint32
    smcROutRsts       uint32
    smcDCurrEstabLnks uint32
    smcDActLnkOpened  uint32
    smcDPasLnkOpened  uint32
    smcDLnksClosed    uint32
    smcDCurrEstab     uint32
    smcDActiveOpened  uint32
    smcDPassiveOpened uint32
    smcDConnClosed    uint32
    smcDInSegs        uint64
    smcDOutSegs       uint64
    smcDInRsts        uint32
    smcDOutRsts       uint32
}

type nwmConnEntry struct {
    ident             uint32
    local             [28]byte // union of sockaddr4 and sockaddr6
    remote            [28]byte // union of sockaddr4 and sockaddr6
    startTime         [8]byte  // uint64, changed to prevent padding from being inserted
    lastActivity      [8]byte  // uint64
    bytesIn           [8]byte  // uint64
    bytesOut          [8]byte  // uint64
    inSegs            [8]byte  // uint64
    outSegs           [8]byte  // uint64
    state             uint16
    activeOpen        byte
    flag01            byte
    outBuffered       uint32
    inBuffered        uint32
    maxSndWnd         uint32
    reXmtCount        uint32
    congestionWnd     uint32
    ssThresh          uint32
    roundTripTime     uint32
    roundTripVar      uint32
    sendMSS           uint32
    sndWnd            uint32
    rcvBufSize        uint32
    sndBufSize        uint32
    outOfOrderCount   uint32
    lcl0WindowCount   uint32
    rmt0WindowCount   uint32
    dupacks           uint32
    flag02            byte
    sockOpt6Cont      byte
    asid              uint16
    resourceName      [8]byte
    resourceId        uint32
    subtask           uint32
    sockOpt           byte
    sockOpt6          byte
    clusterConnFlag   byte
    proto             byte
    targetAppl        [8]byte
    luName            [8]byte
    clientUserId      [8]byte
    logMode           [8]byte
    timeStamp         uint32
    timeStampAge      uint32
    serverResourceId  uint32
    intfName          [16]byte
    ttlsStatPol       byte
    ttlsStatConn      byte
    ttlsSSLProt       uint16
    ttlsNegCiph       [2]byte
    ttlsSecType       byte
    ttlsFIPS140Mode   byte
    ttlsUserID        [8]byte
    applData          [40]byte
    inOldestTime      [8]byte // uint64
    outOldestTime     [8]byte // uint64
    tcpTrustedPartner byte
    _                 [3]byte
    bulkDataIntfName  [16]byte
    ttlsNegCiph4      [4]byte
    smcReason         uint32
    lclSMCLinkId      uint32
    rmtSMCLinkId      uint32
    smcStatus         byte
    smcFlags          byte
    _                 [2]byte
    rcvWnd            uint32
    lclSMCBufSz       uint32
    rmtSMCBufSz       uint32
    ttlsSessID        [32]byte
    ttlsSessIDLen     int16
    _                 [1]byte
    smcDStatus        byte
    smcDReason        uint32
}

var svcNameTable [][]byte = [][]byte{
    []byte("\xc5\xe9\xc2\xd5\xd4\xc9\xc6\xf4"), // svc_EZBNMIF4
}

const (
    svc_EZBNMIF4 = 0
)

func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
    jobname := []byte("\x5c\x40\x40\x40\x40\x40\x40\x40") // "*"
    responseBuffer := [4096]byte{0}
    var bufferAlet, reasonCode uint32 = 0, 0
    var bufferLen, returnValue, returnCode int32 = 4096, 0, 0

    dsa := [18]uint64{0}
    var argv [7]unsafe.Pointer
    argv[0] = unsafe.Pointer(&jobname[0])
    argv[1] = unsafe.Pointer(&responseBuffer[0])
    argv[2] = unsafe.Pointer(&bufferAlet)
    argv[3] = unsafe.Pointer(&bufferLen)
    argv[4] = unsafe.Pointer(&returnValue)
    argv[5] = unsafe.Pointer(&returnCode)
    argv[6] = unsafe.Pointer(&reasonCode)

    request := (*struct {
        header nwmHeader
        filter nwmFilter
    })(unsafe.Pointer(&responseBuffer[0]))

    EZBNMIF4 := svcLoad(&svcNameTable[svc_EZBNMIF4][0])
    if EZBNMIF4 == nil {
        return nil, errnoErr(EINVAL)
    }

    // GetGlobalStats EZBNMIF4 call
    request.header.ident = nwmHeaderIdentifier
    request.header.length = uint32(unsafe.Sizeof(request.header))
    request.header.version = nwmCurrentVer
    request.header.nwmType = nwmGlobalStatsType
    request.header.options = 0x80000000

    svcCall(EZBNMIF4, &argv[0], &dsa[0])

    // outputDesc field is filled by EZBNMIF4 on success
    if returnCode != 0 || request.header.outputDesc.offset == 0 {
        return nil, errnoErr(EINVAL)
    }

    // Check that EZBNMIF4 returned a nwmRecHeader
    recHeader := (*nwmRecHeader)(unsafe.Pointer(&responseBuffer[request.header.outputDesc.offset]))
    if recHeader.ident != nwmRecHeaderIdentifier {
        return nil, errnoErr(EINVAL)
    }

    // Parse nwmTriplets to get offsets of returned entries
    var sections []*uint64
    var sectionDesc *nwmTriplet = (*nwmTriplet)(unsafe.Pointer(&responseBuffer[0]))
    for i := uint32(0); i < uint32(recHeader.number); i++ {
        offset := request.header.outputDesc.offset + uint32(unsafe.Sizeof(*recHeader)) + i*uint32(unsafe.Sizeof(*sectionDesc))
        sectionDesc = (*nwmTriplet)(unsafe.Pointer(&responseBuffer[offset]))
        for j := uint32(0); j < sectionDesc.number; j++ {
            offset = request.header.outputDesc.offset + sectionDesc.offset + j*sectionDesc.length
            sections = append(sections, (*uint64)(unsafe.Pointer(&responseBuffer[offset])))
        }
    }

    // Find nwmTCPStatsEntry in returned entries
    var tcpStats *nwmTCPStatsEntry = nil
    for _, ptr := range sections {
        switch *ptr {
        case nwmTCPStatsIdentifier:
            if tcpStats != nil {
                return nil, errnoErr(EINVAL)
            }
            tcpStats = (*nwmTCPStatsEntry)(unsafe.Pointer(ptr))
        case nwmIPStatsIdentifier:
        case nwmIPGStatsIdentifier:
        case nwmUDPStatsIdentifier:
        case nwmICMPGStatsEntry:
        case nwmICMPTStatsEntry:
        default:
            return nil, errnoErr(EINVAL)
        }
    }
    if tcpStats == nil {
        return nil, errnoErr(EINVAL)
    }

    // GetConnectionDetail EZBNMIF4 call
    responseBuffer = [4096]byte{0}
    dsa = [18]uint64{0}
    bufferAlet, reasonCode = 0, 0
    bufferLen, returnValue, returnCode = 4096, 0, 0
    nameptr := (*uint32)(unsafe.Pointer(uintptr(0x21c))) // Get jobname of current process
    nameptr = (*uint32)(unsafe.Pointer(uintptr(*nameptr + 12)))
    argv[0] = unsafe.Pointer(uintptr(*nameptr))

    request.header.ident = nwmHeaderIdentifier
    request.header.length = uint32(unsafe.Sizeof(request.header))
    request.header.version = nwmCurrentVer
    request.header.nwmType = nwmTCPConnType
    request.header.options = 0x80000000

    request.filter.ident = nwmFilterIdentifier

    var localSockaddr RawSockaddrAny
    socklen := _Socklen(SizeofSockaddrAny)
    err := getsockname(fd, &localSockaddr, &socklen)
    if err != nil {
        return nil, errnoErr(EINVAL)
    }
    if localSockaddr.Addr.Family == AF_INET {
        localSockaddr := (*RawSockaddrInet4)(unsafe.Pointer(&localSockaddr.Addr))
        localSockFilter := (*RawSockaddrInet4)(unsafe.Pointer(&request.filter.local[0]))
        localSockFilter.Family = AF_INET
        var i int
        for i = 0; i < 4; i++ {
            if localSockaddr.Addr[i] != 0 {
                break
            }
        }
        if i != 4 {
            request.filter.flags |= nwmFilterLclAddrMask
            for i = 0; i < 4; i++ {
                localSockFilter.Addr[i] = localSockaddr.Addr[i]
            }
        }
        if localSockaddr.Port != 0 {
            request.filter.flags |= nwmFilterLclPortMask
            localSockFilter.Port = localSockaddr.Port
        }
    } else if localSockaddr.Addr.Family == AF_INET6 {
        localSockaddr := (*RawSockaddrInet6)(unsafe.Pointer(&localSockaddr.Addr))
        localSockFilter := (*RawSockaddrInet6)(unsafe.Pointer(&request.filter.local[0]))
        localSockFilter.Family = AF_INET6
        var i int
        for i = 0; i < 16; i++ {
            if localSockaddr.Addr[i] != 0 {
                break
            }
        }
        if i != 16 {
            request.filter.flags |= nwmFilterLclAddrMask
            for i = 0; i < 16; i++ {
                localSockFilter.Addr[i] = localSockaddr.Addr[i]
            }
        }
        if localSockaddr.Port != 0 {
            request.filter.flags |= nwmFilterLclPortMask
            localSockFilter.Port = localSockaddr.Port
        }
    }

    svcCall(EZBNMIF4, &argv[0], &dsa[0])

    // outputDesc field is filled by EZBNMIF4 on success
    if returnCode != 0 || request.header.outputDesc.offset == 0 {
        return nil, errnoErr(EINVAL)
    }

    // Check that EZBNMIF4 returned a nwmConnEntry
    conn := (*nwmConnEntry)(unsafe.Pointer(&responseBuffer[request.header.outputDesc.offset]))
    if conn.ident != nwmTCPConnIdentifier {
        return nil, errnoErr(EINVAL)
    }

    // Copy data from the returned data structures into tcpInfo
    // Stats from nwmConnEntry are specific to that connection.
    // Stats from nwmTCPStatsEntry are global (to the interface?)
    // Fields may not be an exact match. Some fields have no equivalent.
    var tcpinfo TCPInfo
    tcpinfo.State = uint8(conn.state)
    tcpinfo.Ca_state = 0 // dummy
    tcpinfo.Retransmits = uint8(tcpStats.retransSegs)
    tcpinfo.Probes = uint8(tcpStats.outWinProbes)
    tcpinfo.Backoff = 0 // dummy
    tcpinfo.Options = 0 // dummy
    tcpinfo.Rto = tcpStats.retransTimeouts
    tcpinfo.Ato = tcpStats.outDelayAcks
    tcpinfo.Snd_mss = conn.sendMSS
    tcpinfo.Rcv_mss = conn.sendMSS // dummy
    tcpinfo.Unacked = 0            // dummy
    tcpinfo.Sacked = 0             // dummy
    tcpinfo.Lost = 0               // dummy
    tcpinfo.Retrans = conn.reXmtCount
    tcpinfo.Fackets = 0 // dummy
    tcpinfo.Last_data_sent = uint32(*(*uint64)(unsafe.Pointer(&conn.lastActivity[0])))
    tcpinfo.Last_ack_sent = uint32(*(*uint64)(unsafe.Pointer(&conn.outOldestTime[0])))
    tcpinfo.Last_data_recv = uint32(*(*uint64)(unsafe.Pointer(&conn.inOldestTime[0])))
    tcpinfo.Last_ack_recv = uint32(*(*uint64)(unsafe.Pointer(&conn.inOldestTime[0])))
    tcpinfo.Pmtu = conn.sendMSS // dummy, NWMIfRouteMtu is a candidate
    tcpinfo.Rcv_ssthresh = conn.ssThresh
    tcpinfo.Rtt = conn.roundTripTime
    tcpinfo.Rttvar = conn.roundTripVar
    tcpinfo.Snd_ssthresh = conn.ssThresh // dummy
    tcpinfo.Snd_cwnd = conn.congestionWnd
    tcpinfo.Advmss = conn.sendMSS        // dummy
    tcpinfo.Reordering = 0               // dummy
    tcpinfo.Rcv_rtt = conn.roundTripTime // dummy
    tcpinfo.Rcv_space = conn.sendMSS     // dummy
    tcpinfo.Total_retrans = conn.reXmtCount

    svcUnload(&svcNameTable[svc_EZBNMIF4][0], EZBNMIF4)

    return &tcpinfo, nil
}

// GetsockoptString returns the string value of the socket option opt for the
// socket associated with fd at the given socket level.
func GetsockoptString(fd, level, opt int) (string, error) {
    buf := make([]byte, 256)
    vallen := _Socklen(len(buf))
    err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
    if err != nil {
        return "", err
    }

    return ByteSliceToString(buf[:vallen]), nil
}

func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
    var msg Msghdr
    var rsa RawSockaddrAny
    msg.Name = (*byte)(unsafe.Pointer(&rsa))
    msg.Namelen = SizeofSockaddrAny
    var iov Iovec
    if len(p) > 0 {
        iov.Base = (*byte)(unsafe.Pointer(&p[0]))
        iov.SetLen(len(p))
    }
    var dummy byte
    if len(oob) > 0 {
        // receive at least one normal byte
        if len(p) == 0 {
            iov.Base = &dummy
            iov.SetLen(1)
        }
        msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
        msg.SetControllen(len(oob))
    }
    msg.Iov = &iov
    msg.Iovlen = 1
    if n, err = recvmsg(fd, &msg, flags); err != nil {
        return
    }
    oobn = int(msg.Controllen)
    recvflags = int(msg.Flags)
    // source address is only specified if the socket is unconnected
    if rsa.Addr.Family != AF_UNSPEC {
        // TODO(neeilan): Remove 0 arg added to get this compiling on z/OS
        from, err = anyToSockaddr(0, &rsa)
    }
    return
}

func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
    _, err = SendmsgN(fd, p, oob, to, flags)
    return
}

func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
    var ptr unsafe.Pointer
    var salen _Socklen
    if to != nil {
        var err error
        ptr, salen, err = to.sockaddr()
        if err != nil {
            return 0, err
        }
    }
    var msg Msghdr
    msg.Name = (*byte)(unsafe.Pointer(ptr))
    msg.Namelen = int32(salen)
    var iov Iovec
    if len(p) > 0 {
        iov.Base = (*byte)(unsafe.Pointer(&p[0]))
        iov.SetLen(len(p))
    }
    var dummy byte
    if len(oob) > 0 {
        // send at least one normal byte
        if len(p) == 0 {
            iov.Base = &dummy
            iov.SetLen(1)
        }
        msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
        msg.SetControllen(len(oob))
    }
    msg.Iov = &iov
    msg.Iovlen = 1
    if n, err = sendmsg(fd, &msg, flags); err != nil {
        return 0, err
    }
    if len(oob) > 0 && len(p) == 0 {
        n = 0
    }
    return n, nil
}

func Opendir(name string) (uintptr, error) {
    p, err := BytePtrFromString(name)
    if err != nil {
        return 0, err
    }
    err = nil
    runtime.EnterSyscall()
    dir, e2, e1 := CallLeFuncWithPtrReturn(GetZosLibVec()+SYS___OPENDIR_A<<4, uintptr(unsafe.Pointer(p)))
    runtime.ExitSyscall()
    runtime.KeepAlive(unsafe.Pointer(p))
    if dir == 0 {
        err = errnoErr2(e1, e2)
    }
    return dir, err
}

// clearsyscall.Errno resets the errno value to 0.
func clearErrno()

func Closedir(dir uintptr) error {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_CLOSEDIR<<4, dir)
    runtime.ExitSyscall()
    if r0 != 0 {
        return errnoErr2(e1, e2)
    }
    return nil
}

func Seekdir(dir uintptr, pos int) {
    runtime.EnterSyscall()
    CallLeFuncWithErr(GetZosLibVec()+SYS_SEEKDIR<<4, dir, uintptr(pos))
    runtime.ExitSyscall()
}

func Telldir(dir uintptr) (int, error) {
    p, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_TELLDIR<<4, dir)
    pos := int(p)
    if int64(p) == -1 {
        return pos, errnoErr2(e1, e2)
    }
    return pos, nil
}

// FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
    // struct flock is packed on z/OS. We can't emulate that in Go so
    // instead we pack it here.
    var flock [24]byte
    *(*int16)(unsafe.Pointer(&flock[0])) = lk.Type
    *(*int16)(unsafe.Pointer(&flock[2])) = lk.Whence
    *(*int64)(unsafe.Pointer(&flock[4])) = lk.Start
    *(*int64)(unsafe.Pointer(&flock[12])) = lk.Len
    *(*int32)(unsafe.Pointer(&flock[20])) = lk.Pid
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_FCNTL<<4, fd, uintptr(cmd), uintptr(unsafe.Pointer(&flock)))
    runtime.ExitSyscall()
    lk.Type = *(*int16)(unsafe.Pointer(&flock[0]))
    lk.Whence = *(*int16)(unsafe.Pointer(&flock[2]))
    lk.Start = *(*int64)(unsafe.Pointer(&flock[4]))
    lk.Len = *(*int64)(unsafe.Pointer(&flock[12]))
    lk.Pid = *(*int32)(unsafe.Pointer(&flock[20]))
    if r0 == 0 {
        return nil
    }
    return errnoErr2(e1, e2)
}

func impl_Flock(fd int, how int) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_FLOCK<<4, uintptr(fd), uintptr(how))
    runtime.ExitSyscall()
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_FlockAddr() *(func(fd int, how int) (err error))

var Flock = enter_Flock

func validFlock(fp uintptr) bool {
    if funcptrtest(GetZosLibVec()+SYS_FLOCK<<4, "") == 0 {
        if name, err := getLeFuncName(GetZosLibVec() + SYS_FLOCK<<4); err == nil {
            return name == "flock"
        }
    }
    return false
}

func enter_Flock(fd int, how int) (err error) {
    funcref := get_FlockAddr()
    if validFlock(GetZosLibVec() + SYS_FLOCK<<4) {
        *funcref = impl_Flock
    } else {
        *funcref = legacyFlock
    }
    return (*funcref)(fd, how)
}

func legacyFlock(fd int, how int) error {

    var flock_type int16
    var fcntl_cmd int

    switch how {
    case LOCK_SH | LOCK_NB:
        flock_type = F_RDLCK
        fcntl_cmd = F_SETLK
    case LOCK_EX | LOCK_NB:
        flock_type = F_WRLCK
        fcntl_cmd = F_SETLK
    case LOCK_EX:
        flock_type = F_WRLCK
        fcntl_cmd = F_SETLKW
    case LOCK_UN:
        flock_type = F_UNLCK
        fcntl_cmd = F_SETLKW
    default:
    }

    flock := Flock_t{
        Type:   int16(flock_type),
        Whence: int16(0),
        Start:  int64(0),
        Len:    int64(0),
        Pid:    int32(Getppid()),
    }

    err := FcntlFlock(uintptr(fd), fcntl_cmd, &flock)
    return err
}

func Mlock(b []byte) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MLOCKALL<<4, _BPX_NONSWAP)
    runtime.ExitSyscall()
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Mlock2(b []byte, flags int) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MLOCKALL<<4, _BPX_NONSWAP)
    runtime.ExitSyscall()
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Mlockall(flags int) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MLOCKALL<<4, _BPX_NONSWAP)
    runtime.ExitSyscall()
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Munlock(b []byte) (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MLOCKALL<<4, _BPX_SWAP)
    runtime.ExitSyscall()
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Munlockall() (err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MLOCKALL<<4, _BPX_SWAP)
    runtime.ExitSyscall()
    if r0 != 0 {
        err = errnoErr2(e1, e2)
    }
    return
}

func ClockGettime(clockid int32, ts *Timespec) error {

    var ticks_per_sec uint32 = 100 //TODO(kenan): value is currently hardcoded; need sysconf() call otherwise
    var nsec_per_sec int64 = 1000000000

    if ts == nil {
        return EFAULT
    }
    if clockid == CLOCK_REALTIME || clockid == CLOCK_MONOTONIC {
        var nanotime int64 = runtime.Nanotime1()
        ts.Sec = nanotime / nsec_per_sec
        ts.Nsec = nanotime % nsec_per_sec
    } else if clockid == CLOCK_PROCESS_CPUTIME_ID || clockid == CLOCK_THREAD_CPUTIME_ID {
        var tm Tms
        _, err := Times(&tm)
        if err != nil {
            return EFAULT
        }
        ts.Sec = int64(tm.Utime / ticks_per_sec)
        ts.Nsec = int64(tm.Utime) * nsec_per_sec / int64(ticks_per_sec)
    } else {
        return EINVAL
    }
    return nil
}

// Chtag

//go:nosplit
func get_ChtagAddr() *(func(path string, ccsid uint64, textbit uint64) error)

var Chtag = enter_Chtag

func enter_Chtag(path string, ccsid uint64, textbit uint64) error {
    funcref := get_ChtagAddr()
    if validSetxattr() {
        *funcref = impl_Chtag
    } else {
        *funcref = legacy_Chtag
    }
    return (*funcref)(path, ccsid, textbit)
}

func legacy_Chtag(path string, ccsid uint64, textbit uint64) error {
    tag := ccsid<<16 | textbit<<15
    var tag_buff [8]byte
    DecodeData(tag_buff[:], 8, tag)
    return Setxattr(path, "filetag", tag_buff[:], XATTR_REPLACE)
}

func impl_Chtag(path string, ccsid uint64, textbit uint64) error {
    tag := ccsid<<16 | textbit<<15
    var tag_buff [4]byte
    DecodeData(tag_buff[:], 4, tag)
    return Setxattr(path, "system.filetag", tag_buff[:], XATTR_REPLACE)
}

// End of Chtag

// Nanosleep

//go:nosplit
func get_NanosleepAddr() *(func(time *Timespec, leftover *Timespec) error)

var Nanosleep = enter_Nanosleep

func enter_Nanosleep(time *Timespec, leftover *Timespec) error {
    funcref := get_NanosleepAddr()
    if funcptrtest(GetZosLibVec()+SYS_NANOSLEEP<<4, "") == 0 {
        *funcref = impl_Nanosleep
    } else {
        *funcref = legacyNanosleep
    }
    return (*funcref)(time, leftover)
}

func impl_Nanosleep(time *Timespec, leftover *Timespec) error {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_NANOSLEEP<<4, uintptr(unsafe.Pointer(time)), uintptr(unsafe.Pointer(leftover)))
    runtime.ExitSyscall()
    if int64(r0) == -1 {
        return errnoErr2(e1, e2)
    }
    return nil
}

func legacyNanosleep(time *Timespec, leftover *Timespec) error {
    t0 := runtime.Nanotime1()
    var secrem uint32
    var nsecrem uint32
    total := time.Sec*1000000000 + time.Nsec
    elapsed := runtime.Nanotime1() - t0
    var rv int32
    var rc int32
    var err error
    // repeatedly sleep for 1 second until less than 1 second left
    for total-elapsed > 1000000000 {
        rv, rc, _ = BpxCondTimedWait(uint32(1), uint32(0), uint32(CW_CONDVAR), &secrem, &nsecrem)
        if rv != 0 && rc != 112 { // 112 is EAGAIN
            if leftover != nil && rc == 120 { // 120 is EINTR
                leftover.Sec = int64(secrem)
                leftover.Nsec = int64(nsecrem)
            }
            err = Errno(rc)
            return err
        }
        elapsed = runtime.Nanotime1() - t0
    }
    // sleep the remainder
    if total > elapsed {
        rv, rc, _ = BpxCondTimedWait(uint32(0), uint32(total-elapsed), uint32(CW_CONDVAR), &secrem, &nsecrem)
    }
    if leftover != nil && rc == 120 {
        leftover.Sec = int64(secrem)
        leftover.Nsec = int64(nsecrem)
    }
    if rv != 0 && rc != 112 {
        err = Errno(rc)
    }
    return err
}

// End of Nanosleep

var (
    Stdin  = 0
    Stdout = 1
    Stderr = 2
)

// Do the interface allocations only once for common
// Errno values.
var (
    errEAGAIN error = syscall.EAGAIN
    errEINVAL error = syscall.EINVAL
    errENOENT error = syscall.ENOENT
)

var ZosTraceLevel int
var ZosTracefile *os.File

var (
    signalNameMapOnce sync.Once
    signalNameMap     map[string]syscall.Signal
)

// errnoErr returns common boxed Errno values, to prevent
// allocations at runtime.
func errnoErr(e Errno) error {
    switch e {
    case 0:
        return nil
    case EAGAIN:
        return errEAGAIN
    case EINVAL:
        return errEINVAL
    case ENOENT:
        return errENOENT
    }
    return e
}

var reg *regexp.Regexp

// enhanced with zos specific errno2
func errnoErr2(e Errno, e2 uintptr) error {
    switch e {
    case 0:
        return nil
    case EAGAIN:
        return errEAGAIN
        /*
            Allow the retrieval of errno2 for EINVAL and ENOENT on zos
                case EINVAL:
                    return errEINVAL
                case ENOENT:
                    return errENOENT
        */
    }
    if ZosTraceLevel > 0 {
        var name string
        if reg == nil {
            reg = regexp.MustCompile("(^unix\\.[^/]+$|.*\\/unix\\.[^/]+$)")
        }
        i := 1
        pc, file, line, ok := runtime.Caller(i)
        if ok {
            name = runtime.FuncForPC(pc).Name()
        }
        for ok && reg.MatchString(runtime.FuncForPC(pc).Name()) {
            i += 1
            pc, file, line, ok = runtime.Caller(i)
        }
        if ok {
            if ZosTracefile == nil {
                ZosConsolePrintf("From %s:%d\n", file, line)
                ZosConsolePrintf("%s: %s (errno2=0x%x)\n", name, e.Error(), e2)
            } else {
                fmt.Fprintf(ZosTracefile, "From %s:%d\n", file, line)
                fmt.Fprintf(ZosTracefile, "%s: %s (errno2=0x%x)\n", name, e.Error(), e2)
            }
        } else {
            if ZosTracefile == nil {
                ZosConsolePrintf("%s (errno2=0x%x)\n", e.Error(), e2)
            } else {
                fmt.Fprintf(ZosTracefile, "%s (errno2=0x%x)\n", e.Error(), e2)
            }
        }
    }
    return e
}

// ErrnoName returns the error name for error number e.
func ErrnoName(e Errno) string {
    i := sort.Search(len(errorList), func(i int) bool {
        return errorList[i].num >= e
    })
    if i < len(errorList) && errorList[i].num == e {
        return errorList[i].name
    }
    return ""
}

// SignalName returns the signal name for signal number s.
func SignalName(s syscall.Signal) string {
    i := sort.Search(len(signalList), func(i int) bool {
        return signalList[i].num >= s
    })
    if i < len(signalList) && signalList[i].num == s {
        return signalList[i].name
    }
    return ""
}

// SignalNum returns the syscall.Signal for signal named s,
// or 0 if a signal with such name is not found.
// The signal name should start with "SIG".
func SignalNum(s string) syscall.Signal {
    signalNameMapOnce.Do(func() {
        signalNameMap = make(map[string]syscall.Signal, len(signalList))
        for _, signal := range signalList {
            signalNameMap[signal.name] = signal.num
        }
    })
    return signalNameMap[s]
}

// clen returns the index of the first NULL byte in n or len(n) if n contains no NULL byte.
func clen(n []byte) int {
    i := bytes.IndexByte(n, 0)
    if i == -1 {
        i = len(n)
    }
    return i
}

// Mmap manager, for use by operating system-specific implementations.

type mmapper struct {
    sync.Mutex
    active map[*byte][]byte // active mappings; key is last byte in mapping
    mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, error)
    munmap func(addr uintptr, length uintptr) error
}

func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
    if length <= 0 {
        return nil, EINVAL
    }

    // Set __MAP_64 by default
    flags |= __MAP_64

    // Map the requested memory.
    addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
    if errno != nil {
        return nil, errno
    }

    // Slice memory layout
    var sl = struct {
        addr uintptr
        len  int
        cap  int
    }{addr, length, length}

    // Use unsafe to turn sl into a []byte.
    b := *(*[]byte)(unsafe.Pointer(&sl))

    // Register mapping in m and return it.
    p := &b[cap(b)-1]
    m.Lock()
    defer m.Unlock()
    m.active[p] = b
    return b, nil
}

func (m *mmapper) Munmap(data []byte) (err error) {
    if len(data) == 0 || len(data) != cap(data) {
        return EINVAL
    }

    // Find the base of the mapping.
    p := &data[cap(data)-1]
    m.Lock()
    defer m.Unlock()
    b := m.active[p]
    if b == nil || &b[0] != &data[0] {
        return EINVAL
    }

    // Unmap the memory and update m.
    if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != nil {
        return errno
    }
    delete(m.active, p)
    return nil
}

func Read(fd int, p []byte) (n int, err error) {
    n, err = read(fd, p)
    if raceenabled {
        if n > 0 {
            raceWriteRange(unsafe.Pointer(&p[0]), n)
        }
        if err == nil {
            raceAcquire(unsafe.Pointer(&ioSync))
        }
    }
    return
}

func Write(fd int, p []byte) (n int, err error) {
    if raceenabled {
        raceReleaseMerge(unsafe.Pointer(&ioSync))
    }
    n, err = write(fd, p)
    if raceenabled && n > 0 {
        raceReadRange(unsafe.Pointer(&p[0]), n)
    }
    return
}

// For testing: clients can set this flag to force
// creation of IPv6 sockets to return EAFNOSUPPORT.
var SocketDisableIPv6 bool

// Sockaddr represents a socket address.
type Sockaddr interface {
    sockaddr() (ptr unsafe.Pointer, len _Socklen, err error) // lowercase; only we can define Sockaddrs
}

// SockaddrInet4 implements the Sockaddr interface for AF_INET type sockets.
type SockaddrInet4 struct {
    Port int
    Addr [4]byte
    raw  RawSockaddrInet4
}

// SockaddrInet6 implements the Sockaddr interface for AF_INET6 type sockets.
type SockaddrInet6 struct {
    Port   int
    ZoneId uint32
    Addr   [16]byte
    raw    RawSockaddrInet6
}

// SockaddrUnix implements the Sockaddr interface for AF_UNIX type sockets.
type SockaddrUnix struct {
    Name string
    raw  RawSockaddrUnix
}

func Bind(fd int, sa Sockaddr) (err error) {
    ptr, n, err := sa.sockaddr()
    if err != nil {
        return err
    }
    return bind(fd, ptr, n)
}

func Connect(fd int, sa Sockaddr) (err error) {
    ptr, n, err := sa.sockaddr()
    if err != nil {
        return err
    }
    return connect(fd, ptr, n)
}

func Getpeername(fd int) (sa Sockaddr, err error) {
    var rsa RawSockaddrAny
    var len _Socklen = SizeofSockaddrAny
    if err = getpeername(fd, &rsa, &len); err != nil {
        return
    }
    return anyToSockaddr(fd, &rsa)
}

func GetsockoptByte(fd, level, opt int) (value byte, err error) {
    var n byte
    vallen := _Socklen(1)
    err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
    return n, err
}

func GetsockoptInt(fd, level, opt int) (value int, err error) {
    var n int32
    vallen := _Socklen(4)
    err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
    return int(n), err
}

func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
    vallen := _Socklen(4)
    err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
    return value, err
}

func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
    var value IPMreq
    vallen := _Socklen(SizeofIPMreq)
    err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
    return &value, err
}

func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
    var value IPv6Mreq
    vallen := _Socklen(SizeofIPv6Mreq)
    err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
    return &value, err
}

func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
    var value IPv6MTUInfo
    vallen := _Socklen(SizeofIPv6MTUInfo)
    err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
    return &value, err
}

func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
    var value ICMPv6Filter
    vallen := _Socklen(SizeofICMPv6Filter)
    err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
    return &value, err
}

func GetsockoptLinger(fd, level, opt int) (*Linger, error) {
    var linger Linger
    vallen := _Socklen(SizeofLinger)
    err := getsockopt(fd, level, opt, unsafe.Pointer(&linger), &vallen)
    return &linger, err
}

func GetsockoptTimeval(fd, level, opt int) (*Timeval, error) {
    var tv Timeval
    vallen := _Socklen(unsafe.Sizeof(tv))
    err := getsockopt(fd, level, opt, unsafe.Pointer(&tv), &vallen)
    return &tv, err
}

func GetsockoptUint64(fd, level, opt int) (value uint64, err error) {
    var n uint64
    vallen := _Socklen(8)
    err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
    return n, err
}

func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
    var rsa RawSockaddrAny
    var len _Socklen = SizeofSockaddrAny
    if n, err = recvfrom(fd, p, flags, &rsa, &len); err != nil {
        return
    }
    if rsa.Addr.Family != AF_UNSPEC {
        from, err = anyToSockaddr(fd, &rsa)
    }
    return
}

func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
    ptr, n, err := to.sockaddr()
    if err != nil {
        return err
    }
    return sendto(fd, p, flags, ptr, n)
}

func SetsockoptByte(fd, level, opt int, value byte) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(&value), 1)
}

func SetsockoptInt(fd, level, opt int, value int) (err error) {
    var n = int32(value)
    return setsockopt(fd, level, opt, unsafe.Pointer(&n), 4)
}

func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(&value[0]), 4)
}

func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPMreq)
}

func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPv6Mreq)
}

func SetsockoptICMPv6Filter(fd, level, opt int, filter *ICMPv6Filter) error {
    return setsockopt(fd, level, opt, unsafe.Pointer(filter), SizeofICMPv6Filter)
}

func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(l), SizeofLinger)
}

func SetsockoptString(fd, level, opt int, s string) (err error) {
    var p unsafe.Pointer
    if len(s) > 0 {
        p = unsafe.Pointer(&[]byte(s)[0])
    }
    return setsockopt(fd, level, opt, p, uintptr(len(s)))
}

func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(tv), unsafe.Sizeof(*tv))
}

func SetsockoptUint64(fd, level, opt int, value uint64) (err error) {
    return setsockopt(fd, level, opt, unsafe.Pointer(&value), 8)
}

func Socket(domain, typ, proto int) (fd int, err error) {
    if domain == AF_INET6 && SocketDisableIPv6 {
        return -1, EAFNOSUPPORT
    }
    fd, err = socket(domain, typ, proto)
    return
}

func Socketpair(domain, typ, proto int) (fd [2]int, err error) {
    var fdx [2]int32
    err = socketpair(domain, typ, proto, &fdx)
    if err == nil {
        fd[0] = int(fdx[0])
        fd[1] = int(fdx[1])
    }
    return
}

var ioSync int64

func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }

func SetNonblock(fd int, nonblocking bool) (err error) {
    flag, err := fcntl(fd, F_GETFL, 0)
    if err != nil {
        return err
    }
    if nonblocking {
        flag |= O_NONBLOCK
    } else {
        flag &= ^O_NONBLOCK
    }
    _, err = fcntl(fd, F_SETFL, flag)
    return err
}

// Exec calls execve(2), which replaces the calling executable in the process
// tree. argv0 should be the full path to an executable ("/bin/ls") and the
// executable name should also be the first argument in argv (["ls", "-l"]).
// envv are the environment variables that should be passed to the new
// process (["USER=go", "PWD=/tmp"]).
func Exec(argv0 string, argv []string, envv []string) error {
    return syscall.Exec(argv0, argv, envv)
}

func Getag(path string) (ccsid uint16, flag uint16, err error) {
    var val [8]byte
    sz, err := Getxattr(path, "ccsid", val[:])
    if err != nil {
        return
    }
    ccsid = uint16(EncodeData(val[0:sz]))
    sz, err = Getxattr(path, "flags", val[:])
    if err != nil {
        return
    }
    flag = uint16(EncodeData(val[0:sz]) >> 15)
    return
}

// Mount begin
func impl_Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(source)
    if err != nil {
        return
    }
    var _p1 *byte
    _p1, err = BytePtrFromString(target)
    if err != nil {
        return
    }
    var _p2 *byte
    _p2, err = BytePtrFromString(fstype)
    if err != nil {
        return
    }
    var _p3 *byte
    _p3, err = BytePtrFromString(data)
    if err != nil {
        return
    }
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MOUNT1_A<<4, uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(_p1)), uintptr(unsafe.Pointer(_p2)), uintptr(flags), uintptr(unsafe.Pointer(_p3)))
    runtime.ExitSyscall()
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_MountAddr() *(func(source string, target string, fstype string, flags uintptr, data string) (err error))

var Mount = enter_Mount

func enter_Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
    funcref := get_MountAddr()
    if validMount() {
        *funcref = impl_Mount
    } else {
        *funcref = legacyMount
    }
    return (*funcref)(source, target, fstype, flags, data)
}

func legacyMount(source string, target string, fstype string, flags uintptr, data string) (err error) {
    if needspace := 8 - len(fstype); needspace <= 0 {
        fstype = fstype[0:8]
    } else {
        fstype += "        "[0:needspace]
    }
    return mount_LE(target, source, fstype, uint32(flags), int32(len(data)), data)
}

func validMount() bool {
    if funcptrtest(GetZosLibVec()+SYS___MOUNT1_A<<4, "") == 0 {
        if name, err := getLeFuncName(GetZosLibVec() + SYS___MOUNT1_A<<4); err == nil {
            return name == "__mount1_a"
        }
    }
    return false
}

// Mount end

// Unmount begin
func impl_Unmount(target string, flags int) (err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(target)
    if err != nil {
        return
    }
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___UMOUNT2_A<<4, uintptr(unsafe.Pointer(_p0)), uintptr(flags))
    runtime.ExitSyscall()
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_UnmountAddr() *(func(target string, flags int) (err error))

var Unmount = enter_Unmount

func enter_Unmount(target string, flags int) (err error) {
    funcref := get_UnmountAddr()
    if funcptrtest(GetZosLibVec()+SYS___UMOUNT2_A<<4, "") == 0 {
        *funcref = impl_Unmount
    } else {
        *funcref = legacyUnmount
    }
    return (*funcref)(target, flags)
}

func legacyUnmount(name string, mtm int) (err error) {
    // mountpoint is always a full path and starts with a '/'
    // check if input string is not a mountpoint but a filesystem name
    if name[0] != '/' {
        return unmount_LE(name, mtm)
    }
    // treat name as mountpoint
    b2s := func(arr []byte) string {
        var str string
        for i := 0; i < len(arr); i++ {
            if arr[i] == 0 {
                str = string(arr[:i])
                break
            }
        }
        return str
    }
    var buffer struct {
        header W_Mnth
        fsinfo [64]W_Mntent
    }
    fs_count, err := W_Getmntent_A((*byte)(unsafe.Pointer(&buffer)), int(unsafe.Sizeof(buffer)))
    if err == nil {
        err = EINVAL
        for i := 0; i < fs_count; i++ {
            if b2s(buffer.fsinfo[i].Mountpoint[:]) == name {
                err = unmount_LE(b2s(buffer.fsinfo[i].Fsname[:]), mtm)
                break
            }
        }
    } else if fs_count == 0 {
        err = EINVAL
    }
    return err
}

// Unmount end

func direntIno(buf []byte) (uint64, bool) {
    return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
}

func direntReclen(buf []byte) (uint64, bool) {
    return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
}

func direntNamlen(buf []byte) (uint64, bool) {
    reclen, ok := direntReclen(buf)
    if !ok {
        return 0, false
    }
    return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
}

func direntLeToDirentUnix(dirent *direntLE, dir uintptr, path string) (Dirent, error) {
    var d Dirent

    d.Ino = uint64(dirent.Ino)
    offset, err := Telldir(dir)
    if err != nil {
        return d, err
    }

    d.Off = int64(offset)
    s := string(bytes.Split(dirent.Name[:], []byte{0})[0])
    copy(d.Name[:], s)

    d.Reclen = uint16(24 + len(d.NameString()))
    var st Stat_t
    path = path + "/" + s
    err = Lstat(path, &st)
    if err != nil {
        return d, err
    }

    d.Type = uint8(st.Mode >> 24)
    return d, err
}

func Getdirentries(fd int, buf []byte, basep *uintptr) (n int, err error) {
    // Simulation of Getdirentries port from the Darwin implementation.
    // COMMENTS FROM DARWIN:
    // It's not the full required semantics, but should handle the case
    // of calling Getdirentries or ReadDirent repeatedly.
    // It won't handle assigning the results of lseek to *basep, or handle
    // the directory being edited underfoot.

    skip, err := Seek(fd, 0, 1 /* SEEK_CUR */)
    if err != nil {
        return 0, err
    }

    // Get path from fd to avoid unavailable call (fdopendir)
    path, err := ZosFdToPath(fd)
    if err != nil {
        return 0, err
    }
    d, err := Opendir(path)
    if err != nil {
        return 0, err
    }
    defer Closedir(d)

    var cnt int64
    for {
        var entryLE direntLE
        var entrypLE *direntLE
        e := Readdir_r(d, &entryLE, &entrypLE)
        if e != nil {
            return n, e
        }
        if entrypLE == nil {
            break
        }
        if skip > 0 {
            skip--
            cnt++
            continue
        }

        // Dirent on zos has a different structure
        entry, e := direntLeToDirentUnix(&entryLE, d, path)
        if e != nil {
            return n, e
        }

        reclen := int(entry.Reclen)
        if reclen > len(buf) {
            // Not enough room. Return for now.
            // The counter will let us know where we should start up again.
            // Note: this strategy for suspending in the middle and
            // restarting is O(n^2) in the length of the directory. Oh well.
            break
        }

        // Copy entry into return buffer.
        s := unsafe.Slice((*byte)(unsafe.Pointer(&entry)), reclen)
        copy(buf, s)

        buf = buf[reclen:]
        n += reclen
        cnt++
    }
    // Set the seek offset of the input fd to record
    // how many files we've already returned.
    _, err = Seek(fd, cnt, 0 /* SEEK_SET */)
    if err != nil {
        return n, err
    }

    return n, nil
}

func Err2ad() (eadd *int) {
    r0, _, _ := CallLeFuncWithErr(GetZosLibVec() + SYS___ERR2AD<<4)
    eadd = (*int)(unsafe.Pointer(r0))
    return
}

func ZosConsolePrintf(format string, v ...interface{}) (int, error) {
    type __cmsg struct {
        _            uint16
        _            [2]uint8
        __msg_length uint32
        __msg        uintptr
        _            [4]uint8
    }
    msg := fmt.Sprintf(format, v...)
    strptr := unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&msg)).Data)
    len := (*reflect.StringHeader)(unsafe.Pointer(&msg)).Len
    cmsg := __cmsg{__msg_length: uint32(len), __msg: uintptr(strptr)}
    cmd := uint32(0)
    runtime.EnterSyscall()
    rc, err2, err1 := CallLeFuncWithErr(GetZosLibVec()+SYS_____CONSOLE_A<<4, uintptr(unsafe.Pointer(&cmsg)), 0, uintptr(unsafe.Pointer(&cmd)))
    runtime.ExitSyscall()
    if rc != 0 {
        return 0, fmt.Errorf("%s (errno2=0x%x)\n", err1.Error(), err2)
    }
    return 0, nil
}
func ZosStringToEbcdicBytes(str string, nullterm bool) (ebcdicBytes []byte) {
    if nullterm {
        ebcdicBytes = []byte(str + "\x00")
    } else {
        ebcdicBytes = []byte(str)
    }
    A2e(ebcdicBytes)
    return
}
func ZosEbcdicBytesToString(b []byte, trimRight bool) (str string) {
    res := make([]byte, len(b))
    copy(res, b)
    E2a(res)
    if trimRight {
        str = string(bytes.TrimRight(res, " \x00"))
    } else {
        str = string(res)
    }
    return
}

func fdToPath(dirfd int) (path string, err error) {
    var buffer [1024]byte
    // w_ctrl()
    ret := runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS_W_IOCTL<<4,
        []uintptr{uintptr(dirfd), 17, 1024, uintptr(unsafe.Pointer(&buffer[0]))})
    if ret == 0 {
        zb := bytes.IndexByte(buffer[:], 0)
        if zb == -1 {
            zb = len(buffer)
        }
        // __e2a_l()
        runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___E2A_L<<4,
            []uintptr{uintptr(unsafe.Pointer(&buffer[0])), uintptr(zb)})
        return string(buffer[:zb]), nil
    }
    // __errno()
    errno := int(*(*int32)(unsafe.Pointer(runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___ERRNO<<4,
        []uintptr{}))))
    // __errno2()
    errno2 := int(runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS___ERRNO2<<4,
        []uintptr{}))
    // strerror_r()
    ret = runtime.CallLeFuncByPtr(runtime.XplinkLibvec+SYS_STRERROR_R<<4,
        []uintptr{uintptr(errno), uintptr(unsafe.Pointer(&buffer[0])), 1024})
    if ret == 0 {
        zb := bytes.IndexByte(buffer[:], 0)
        if zb == -1 {
            zb = len(buffer)
        }
        return "", fmt.Errorf("%s (errno2=0x%x)", buffer[:zb], errno2)
    } else {
        return "", fmt.Errorf("fdToPath errno %d (errno2=0x%x)", errno, errno2)
    }
}

func impl_Mkfifoat(dirfd int, path string, mode uint32) (err error) {
    var _p0 *byte
    _p0, err = BytePtrFromString(path)
    if err != nil {
        return
    }
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS___MKFIFOAT_A<<4, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode))
    runtime.ExitSyscall()
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

//go:nosplit
func get_MkfifoatAddr() *(func(dirfd int, path string, mode uint32) (err error))

var Mkfifoat = enter_Mkfifoat

func enter_Mkfifoat(dirfd int, path string, mode uint32) (err error) {
    funcref := get_MkfifoatAddr()
    if funcptrtest(GetZosLibVec()+SYS___MKFIFOAT_A<<4, "") == 0 {
        *funcref = impl_Mkfifoat
    } else {
        *funcref = legacy_Mkfifoat
    }
    return (*funcref)(dirfd, path, mode)
}

func legacy_Mkfifoat(dirfd int, path string, mode uint32) (err error) {
    dirname, err := ZosFdToPath(dirfd)
    if err != nil {
        return err
    }
    return Mkfifo(dirname+"/"+path, mode)
}

//sys    Posix_openpt(oflag int) (fd int, err error) = SYS_POSIX_OPENPT
//sys    Grantpt(fildes int) (rc int, err error) = SYS_GRANTPT
//sys    Unlockpt(fildes int) (rc int, err error) = SYS_UNLOCKPT

func fcntlAsIs(fd uintptr, cmd int, arg uintptr) (val int, err error) {
    runtime.EnterSyscall()
    r0, e2, e1 := CallLeFuncWithErr(GetZosLibVec()+SYS_FCNTL<<4, uintptr(fd), uintptr(cmd), arg)
    runtime.ExitSyscall()
    val = int(r0)
    if int64(r0) == -1 {
        err = errnoErr2(e1, e2)
    }
    return
}

func Fcntl(fd uintptr, cmd int, op interface{}) (ret int, err error) {
    switch op.(type) {
    case *Flock_t:
        err = FcntlFlock(fd, cmd, op.(*Flock_t))
        if err != nil {
            ret = -1
        }
        return
    case int:
        return FcntlInt(fd, cmd, op.(int))
    case *F_cnvrt:
        return fcntlAsIs(fd, cmd, uintptr(unsafe.Pointer(op.(*F_cnvrt))))
    case unsafe.Pointer:
        return fcntlAsIs(fd, cmd, uintptr(op.(unsafe.Pointer)))
    default:
        return -1, EINVAL
    }
    return
}

func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
    if raceenabled {
        raceReleaseMerge(unsafe.Pointer(&ioSync))
    }
    return sendfile(outfd, infd, offset, count)
}

func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
    // TODO: use LE call instead if the call is implemented
    originalOffset, err := Seek(infd, 0, SEEK_CUR)
    if err != nil {
        return -1, err
    }
    //start reading data from in_fd
    if offset != nil {
        _, err := Seek(infd, *offset, SEEK_SET)
        if err != nil {
            return -1, err
        }
    }

    buf := make([]byte, count)
    readBuf := make([]byte, 0)
    var n int = 0
    for i := 0; i < count; i += n {
        n, err := Read(infd, buf)
        if n == 0 {
            if err != nil {
                return -1, err
            } else { // EOF
                break
            }
        }
        readBuf = append(readBuf, buf...)
        buf = buf[0:0]
    }

    n2, err := Write(outfd, readBuf)
    if err != nil {
        return -1, err
    }

    //When sendfile() returns, this variable will be set to the
    // offset of the byte following the last byte that was read.
    if offset != nil {
        *offset = *offset + int64(n)
        // If offset is not NULL, then sendfile() does not modify the file
        // offset of in_fd
        _, err := Seek(infd, originalOffset, SEEK_SET)
        if err != nil {
            return -1, err
        }
    }
    return n2, nil
}
