go - golang, call GetVolumeInformation winapi function -

tries call getvolumeinformation function golang. want volume name.

use spec's of api:

bool winapi getvolumeinformation(   _in_opt_  lpctstr lprootpathname,   _out_opt_ lptstr  lpvolumenamebuffer,   _in_      dword   nvolumenamesize,   _out_opt_ lpdword lpvolumeserialnumber,   _out_opt_ lpdword lpmaximumcomponentlength,   _out_opt_ lpdword lpfilesystemflags,   _out_opt_ lptstr  lpfilesystemnamebuffer,   _in_      dword   nfilesystemnamesize ); 

use code:

// test package main  import (     "fmt"     "syscall"     "unsafe" )  func main() {     var lprootpathname = "c:\\"     var lpvolumenamebuffer string     var nvolumenamesize uint64     var lpvolumeserialnumber uint64     var lpmaximumcomponentlength uint64     var lpfilesystemflags uint64     var lpfilesystemnamebuffer string     var nfilesystemnamesize uint32      kernel32, _ := syscall.loadlibrary("kernel32.dll")     getvolume, _ := syscall.getprocaddress(kernel32, "getvolumeinformationw")      var nargs uintptr = 8     ret, _, callerr := syscall.syscall9(uintptr(getvolume),         nargs,         uintptr(unsafe.pointer(syscall.stringtoutf16ptr(lprootpathname))),         uintptr(unsafe.pointer(&lpvolumenamebuffer)),         uintptr(unsafe.pointer(&nvolumenamesize)),         uintptr(unsafe.pointer(&lpvolumeserialnumber)),         uintptr(unsafe.pointer(&lpmaximumcomponentlength)),         uintptr(unsafe.pointer(&lpfilesystemflags)),         uintptr(unsafe.pointer(&lpfilesystemnamebuffer)),         uintptr(unsafe.pointer(&nfilesystemnamesize)),         0)     fmt.println(ret, callerr, lpvolumenamebuffer) } 

... , have error :(

unexpected fault address 0xffffffffffffffff fatal error: fault [signal 0xc0000005 code=0x0 addr=0xffffffffffffffff pc=0x456b11] 

don't understand , google cant'd calling winapi functions , returng string result.

thank's.

package unsafe

package unsafe contains operations step around type safety of go programs.

type pointer

type pointer *arbitrarytype 

pointer represents pointer arbitrary type. there 4 special operations available type pointer not available other types.

1) pointer value of type can converted pointer.

2) pointer can converted pointer value of type.

3) uintptr can converted pointer.

4) pointer can converted uintptr.

pointer therefore allows program defeat type system , read , write arbitrary memory. should used extreme care.

you failed heed warning unsafe.pointer "should used extreme care."

try this:

package main  import (     "fmt"     "syscall"     "unsafe" )  func main() {     var rootpathname = `c:\`     var volumenamebuffer = make([]uint16, syscall.max_path+1)     var nvolumenamesize = uint32(len(volumenamebuffer))     var volumeserialnumber uint32     var maximumcomponentlength uint32     var filesystemflags uint32     var filesystemnamebuffer = make([]uint16, 255)     var nfilesystemnamesize uint32 = syscall.max_path + 1      kernel32, _ := syscall.loadlibrary("kernel32.dll")     getvolume, _ := syscall.getprocaddress(kernel32, "getvolumeinformationw")      var nargs uintptr = 8     ret, _, callerr := syscall.syscall9(uintptr(getvolume),         nargs,         uintptr(unsafe.pointer(syscall.stringtoutf16ptr(rootpathname))),         uintptr(unsafe.pointer(&volumenamebuffer[0])),         uintptr(nvolumenamesize),         uintptr(unsafe.pointer(&volumeserialnumber)),         uintptr(unsafe.pointer(&maximumcomponentlength)),         uintptr(unsafe.pointer(&filesystemflags)),         uintptr(unsafe.pointer(&filesystemnamebuffer[0])),         uintptr(nfilesystemnamesize),         0)     fmt.println(ret, callerr, syscall.utf16tostring(volumenamebuffer)) }