ioctl.go

package main

// #cgo pkg-config: libzfs_core
// #cgo CFLAGS: -fms-extensions -Wno-microsoft
//
// #include <sys/types.h>
// #include <stdio.h>
// #include <string.h>
// #include <stdint.h>
// #include <limits.h>
//
// #define ZFS_IOC_LIBZFS_CORE (('Z' << 8) + 0x100 + 1)
// struct zfs_cmd_new {
// 	char		zc_name[PATH_MAX]; 	/* name of pool or dataset */
// 	uint64_t	zc_nvlist_src;		/* really (char *) */
// 	uint64_t	zc_nvlist_src_size;
// 	uint64_t	zc_nvlist_dst;		/* really (char *) */
// 	uint64_t	zc_nvlist_dst_size;
// 	boolean_t	zc_nvlist_dst_filled;	/* put an nvlist in dst? */
// };
//
// typedef struct zfs_cmd {
// 	struct zfs_cmd_new;
// 	char _legacy_zfs_cmd_fields[(14 * 1024) - sizeof(struct zfs_cmd_new)];
// } zfs_cmd_t;
//
// int do_ioctl(int fd, char *name, int len, void *innvl, int insize, void *outnvl, int outsize) {
// 	zfs_cmd_t cmd;
//	memset(&cmd, 0, sizeof(cmd));
// 	memcpy(cmd.zc_name, name, len);
//	cmd.zc_nvlist_src = (uint64_t)innvl;
//	cmd.zc_nvlist_src_size = insize;
//	cmd.zc_nvlist_dst = (uint64_t)outnvl;
//	cmd.zc_nvlist_dst_size = outsize;
//	cmd.zc_nvlist_dst_filled = outnvl != NULL;
//	return ioctl(fd, ZFS_IOC_LIBZFS_CORE, (unsigned long)&cmd);
// }
import "C"
import (
	"errors"
	"fmt"
	"os"
	"unsafe"
)

func ioctl(f *os.File, name string, input, output []byte) error {
	if len(input) == 0 {
		return errors.New("input nvl required")
	}
	in := unsafe.Pointer(&input[0])

	var out unsafe.Pointer
	if len(output) != 0 {
		out = unsafe.Pointer(&output[0])
	}

	_, err := C.do_ioctl(C.int(f.Fd()),
		C.CString(name), C.int(len(name)),
		unsafe.Pointer(in), C.int(len(input)),
		unsafe.Pointer(out), C.int(len(output)))
	fmt.Fprintln(os.Stderr, err)
	return err
}