//go:cgo_import_dynamic libc_rename rename "libc.so"
//go:cgo_import_dynamic libc_renameat renameat "libc.so"
//go:cgo_import_dynamic libc_rmdir rmdir "libc.so"
//go:cgo_import_dynamic libc_lseek lseek "libc.so"
//go:cgo_import_dynamic libc_select select "libc.so"
//go:cgo_import_dynamic libc_setegid setegid "libc.so"
//go:cgo_import_dynamic libc_seteuid seteuid "libc.so"
//go:cgo_import_dynamic libc_setgid setgid "libc.so"

func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
	r0, _, e1 := syscall_syscall(libc_lseek_trampoline_addr, uintptr(fd), uintptr(offset), uintptr(whence))
	newoffset = int64(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

var libc_lseek_trampoline_addr uintptr

//go:cgo_import_dynamic libc_lseek lseek "/usr/lib/libSystem.B.dylib"

func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
	r0, _, e1 := syscall_syscall(libc_lseek_trampoline_addr, uintptr(fd), uintptr(offset), uintptr(whence))
	newoffset = int64(r0)
	if e1 != 0 {
		err = errnoErr(e1)
	}
	return
}

var libc_lseek_trampoline_addr uintptr

//go:cgo_import_dynamic libc_lseek lseek "/usr/lib/libSystem.B.dylib"

	// 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)

//

#define SYS__LLSEEK 140  /* from zsysnum_linux_arm.go */
// func seek(fd int, offset int64, whence int) (newoffset int64, errno int)
// Implemented in assembly to avoid allocation when
// taking the address of the return value newoffset.
// Underlying system call is
//	llseek(int fd, int offhi, int offlo, int64 *result, int whence)
TEXT ·seek(SB),NOSPLIT,$0-28
	BL	runtime·entersyscall(SB)
	MOVW	$SYS__LLSEEK, R7	// syscall entry

	RET

TEXT runtime·pwrite(SB),NOSPLIT,$0
	MOVQ	$51, BP
	SYSCALL
	MOVL	AX, ret+32(FP)
	RET

// int32 _seek(int64*, int32, int64, int32)
TEXT _seek<>(SB),NOSPLIT,$0
	MOVQ	$39, BP
	SYSCALL
	RET

// int64 seek(int32, int64, int32)
// Convenience wrapper around _seek, the actual system call.
TEXT runtime·seek(SB),NOSPLIT,$32
	LEAQ	ret+24(FP), AX
	MOVL	fd+0(FP), BX
	MOVQ	offset+8(FP), CX

	RET

#define SYS__LLSEEK 140	/* from zsysnum_linux_386.go */
// func Seek(fd int, offset int64, whence int) (newoffset int64, err int)
// Implemented in assembly to avoid allocation when
// taking the address of the return value newoffset.
// Underlying system call is
//	llseek(int fd, int offhi, int offlo, int64 *result, int whence)
TEXT ·seek(SB),NOSPLIT,$0-28
	CALL	runtime·entersyscall(SB)
	MOVL	$SYS__LLSEEK, AX	// syscall entry

	}
	_, err = ws.Seek(int64(len(ws.BytesWritten())+1), io.SeekStart)
	if err == nil {
		t.Fatalf("expected error on invalid %d seek", len(ws.BytesWritten()))
	}

	ws.Seek(0, io.SeekStart)
	_, err = ws.Seek(-1, io.SeekCurrent)
	if err == nil {
		t.Fatalf("expected error on invalid -1 seek")
	}
	_, err = ws.Seek(int64(len(ws.BytesWritten())+1), io.SeekCurrent)
	if err == nil {

	}
	copy(towrite, p)
	sws.off += int64(amt)
	return amt, nil
}

// Seek repositions the read/write position of the WriteSeeker within
// its internally maintained slice. Note that it is not possible to
// expand the size of the slice using SEEK_SET; trying to seek outside
// the slice will result in an error.
func (sws *WriteSeeker) Seek(offset int64, whence int) (int64, error) {
	switch whence {
	case io.SeekStart:

	o := &fd.wop
	o.handle = src

	// TODO(brainman): skip calling syscall.Seek if OS allows it
	curpos, err := syscall.Seek(o.handle, 0, io.SeekCurrent)
	if err != nil {
		return 0, err
	}

	if n <= 0 { // We don't know the size of the file so infer it.
		// Find the number of bytes offset from curpos until the end of the file.
		n, err = syscall.Seek(o.handle, -curpos, io.SeekEnd)
		if err != nil {
			return
		}