Go语言调用Windows DLL教程：解决Smart Card API参数错误

LONG WINAPI SCardEstablishContext(
    _In_   DWORD dwScope,
    _In_   LPCVOID pvReserved1,
    _In_   LPCVOID pvReserved2,
    _Out_  LPSCARDCONTEXT phContext
);

LONG WINAPI SCardListReaders(
    _In_   SCARDCONTEXT hContext,
    _In_   LPCWSTR mszGroups,
    _Out_  LPWSTR mszReaders,
    _Inout_ LPDWORD pcchReaders
);

package main

import (
    "fmt"
    "syscall"
    "unicode/utf16"
    "unsafe"
)

var (
    WinSCard, _                  = syscall.LoadLibrary(`C:\windows\system32\WinSCard.dll`)
    procSCardEstablishContext, _ = syscall.GetProcAddress(WinSCard, "SCardEstablishContext")
    procSCardReleaseContext, _   = syscall.GetProcAddress(WinSCard, "SCardReleaseContext")
    procSCardListReaders, _      = syscall.GetProcAddress(WinSCard, "SCardListReadersW") // 注意这里是 SCardListReadersW
)

const (
    SCARD_SCOPE_USER   = 0
    SCARD_SCOPE_SYSTEM = 2

    SCARD_ALL_READERS     = "SCard$AllReaders"
    // SCARD_DEFAULT_READERS = "SCard$DefaultReaders" // 示例中未使用
)

func SCardEstablishContext(dwScope uint32, pvReserved1 uintptr, pvReserved2 uintptr, phContext *syscall.Handle) (retval error) {
    r0, _, _ := syscall.Syscall6(
        uintptr(procSCardEstablishContext),
        4, // 参数数量
        uintptr(dwScope),
        pvReserved1, // 0 for reserved
        pvReserved2, // 0 for reserved
        uintptr(unsafe.Pointer(phContext)), // phContext是指针
        0,
        0,
    )
    if r0 != 0 {
        retval = syscall.Errno(r0)
    }
    return
}

func SCardReleaseContext(hContext syscall.Handle) (retval error) {
    r0, _, _ := syscall.Syscall(
        uintptr(procSCardReleaseContext),
        1, // 参数数量
        uintptr(hContext),
        0,
        0,
    )
    if r0 != 0 {
        retval = syscall.Errno(r0)
    }
    return
}

func SCardListReaders(hContext syscall.Handle, mszGroups *uint16, mszReaders *uint16, pcchReaders *uint32) (retval error) {
    r0, _, _ := syscall.Syscall6(
        uintptr(procSCardListReaders),
        4, // 参数数量
        uintptr(hContext),
        uintptr(unsafe.Pointer(mszGroups)),   // UTF-16编码的组名指针
        uintptr(unsafe.Pointer(mszReaders)),  // UTF-16编码的读者列表缓冲区指针
        uintptr(unsafe.Pointer(pcchReaders)), // 缓冲区大小指针
        0,
        0,
    )
    if r0 != 0 {
        retval = syscall.Errno(r0)
    }
    return
}

// ReturnValue 将 syscall.Errno 转换为 uint32 错误码
func ReturnValue(err error) uint32 {
    rv, ok := err.(syscall.Errno)
    if !ok {
        rv = 0 // 非 syscall.Errno 错误，视为成功或未知
    }
    return uint32(rv)
}

// UTF16ToStrings 将 UTF-16 编码的多字符串（以双空字符结束）解码为 Go 字符串切片
func UTF16ToStrings(ls []uint16) []string {
    var ss []string
    if len(ls) == 0 {
        return ss
    }
    // 确保以双空字符结束
    if ls[len(ls)-1] != 0 {
        ls = append(ls, 0)
    }
    i := 0
    for j, cu := range ls {
        if cu == 0 {
            // 遇到空字符，检查是否是双空字符结束符
            if j >= 1 && ls[j-1] == 0 {
                break // 双空字符，结束
            }
            // 提取当前字符串
            if j-i > 0 {
                ss = append(ss, string(utf16.Decode(ls[i:j])))
            }
            i = j + 1 // 移动到下一个字符串的起始位置
            continue
        }
    }
    return ss
}

func main() {
    var (
        context  syscall.Handle // 用于存储Smart Card上下文句柄
        scope    uint32         // 上下文范围
        groups   *uint16        // 读者组名（UTF-16指针）
        cReaders uint32         // 读者列表缓冲区大小
    )

    // 1. 尝试列出读者（在上下文建立前也可调用，但可能不完整）
    // 注意：SCardListReadersW可以不依赖于已建立的上下文来获取所有读者
    context = 0 // 初始时上下文句柄为0
    groups, err := syscall.UTF16PtrFromString(SCARD_ALL_READERS) // 将Go字符串转换为UTF-16指针
    if err != nil {
        fmt.Println("Reader Group conversion error: ", err)
        return
    }

    // 第一次调用 SCardListReadersW 获取所需缓冲区大小
    err = SCardListReaders(context, groups, nil, &cReaders) // mszReaders 传递 nil
    if err != nil {
        fmt.Printf("SCardListReaders (first pass) failed: 0x%X %s\n", ReturnValue(err), err)
        return
    }

    // 根据获取的大小分配缓冲区
    r := make([]uint16, cReaders)
    // 第二次调用 SCardListReadersW 填充缓冲区
    err = SCardListReaders(context, groups, &r[0], &cReaders) // mszReaders 传递缓冲区地址
    if err != nil {
        fmt.Printf("SCardListReaders (second pass) failed: 0x%X %s\n", ReturnValue(err), err)
        return
    }

    // 将 UTF-16 编码的读者列表转换为 Go 字符串切片
    readers := UTF16ToStrings(r[:cReaders])
    fmt.Println("Readers:", len(readers), readers)

    // 2. 建立Smart Card上下文
    scope = SCARD_SCOPE_SYSTEM // 设置上下文范围为系统级别
    err = SCardEstablishContext(scope, 0, 0, &context)
    if err != nil {
        fmt.Printf("SCardEstablishContext failed: 0x%X %s\n", ReturnValue(err), err)
        // 常见错误：0x8010001D - Smart card resource manager is not running.
        return
    }
    // 确保在函数退出时释放上下文资源
    defer SCardReleaseContext(context)
    fmt.Printf("Context established: %X\n", context)

    // 3. 释放DLL库（可选，因为程序退出时会自动释放）
    defer syscall.FreeLibrary(WinSCard)
}

Readers: 1 [O2 O2Micro CCID SC Reader 0]
Context established: CD00000100000000

Readers: 0 []
SCardEstablishContext failed: 0x8010001D The Smart card resource manager is not running.