golang，调用WinVolumeInformation winapi函数

Question

尝试从golang调用GetVolumeInformation函数。要获取卷名。

使用api的规范：

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
);

使用代码：

// 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)
}

…最后有错误:(

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

不理解，Google无法帮助调用winapi函数和returng字符串作为结果。

谢谢。

Answer 1

包裹不安全

不安全的软件包包含绕过Go程序的类型安全的操作。

类型指针

type Pointer *ArbitraryType

指针表示指向任意类型的指针。指针类型有四个特殊操作，而其他类型则不可用。

1）任何类型的指针值都可以转换为Pointer。

2）指针可以转换为任何类型的指针值。

3）可以将uintptr转换为Pointer。

4）指针可以转换为uintptr。

因此，指针允许程序击败类型系统并读写任意存储器。使用时应格外小心。

您没有注意unsafe.Pointer“应格外小心” 的警告。

试试这个：

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))
}