在Go中使用C库时，如何正确地将UTF-8编码的char数组转换为Go字符串？
问题描述：
I'm trying to use a C library in Go. The C.PrlFoundVmInfo_GetName function writes a UTF-8 encoded string into name with length nBufSize.
// PRL_CHAR sName[1024];
var sName [1024]C.PRL_CHAR
// PRL_UINT32 nBufSize = sizeof(sName);
var nBufSize C.PRL_UINT32 = C.PRL_UINT32(unsafe.Sizeof(sName))
ret = C.PrlFoundVmInfo_GetName(hFoundVmInfo, (*C.PRL_CHAR)(unsafe.Pointer(&sName)), &nBufSize)
// printf("VM name: %s
", sName);
var gName string = C.GoString((*C.char)(unsafe.Pointer(&sName)))
fmt.Printf("VM %d name: \"%s\"
", nBufSize, gName)
What is the proper way to declare name (and nBufSize) and how do i convert name to a Go string? The above code dosen't work as I expect. It prints:
VM 1024 name: ""
...
C API Documentation, extract
PrlFoundVmInfo_GetName - Parameters
PRL_RESULT PrlFoundVmInfo_GetName(
PRL_HANDLE handle,
PRL_STR sName,
PRL_UINT32_PTR pnNameBufLength
);
- handle - A handle of type PHT_FOUND_VM_INFO identifying the container.
- sName - [out] A pointer to a buffer that receives the name. Pass a null pointer to determine the required buffer size.
- pnNameBufLength - [in] The size of the buffer used to receive the output data (in bytes). [out] The required buffer size if the buffer parameter contains a null pointer or if the specified buffer size is not large enough.
The full documentation is available at C API Documentation - PrlFoundVmInfo_GetName
答
This was the solution, create a byte array and make sName point to it. When it has been used use C.GoStringN to convert the content to a Go string.
var buf = make([]byte, 1024)
var sName C.PRL_STR = (C.PRL_STR)(unsafe.Pointer(&buf))
var nBufSize C.PRL_UINT32 = 1024
ret = C.PrlFoundVmInfo_GetName(*hFoundVmInfo, sName, &nBufSize)
gName := C.GoStringN((*_Ctype_char)(unsafe.Pointer(sName)), C.int(nBufSize))
fmt.Printf("VM %d name: \"%s\"
", nBufSize, gName)
答
A few special functions convert between Go and C types by making copies of the data. In pseudo-Go definitions:
// C string, length to Go string func C.GoStringN(*C.char, C.int) string