How to Safely Copy Go Strings to C char* Pointers using CGO?

Copying Go Strings to C char* Pointers using CGO

In the realm of Go, you may encounter situations where you need to seamlessly exchange data between your Go code and C libraries or applications. One such scenario is the transfer of Go strings into C character pointers (char *) using the power of CGO.

Challenge:

The desire arises to copy a Go string into a char * via CGO's magical capabilities. The question lingers: can this be achieved using the following approach?

func copy_string(cstr *C.char) {
    str := "foo"
    C.GoString(cstr) = str
}

Solution:

While the intention is noble, the approach presented in the code snippet falls short. According to the official CGO documentation, the correct method to convert a Go string into a C string involves utilizing the C.CString function:

cstr = C.CString(str)

It's important to keep in mind that C.CString obligingly allocates memory for you. However, it doesn't automatically release this memory, leaving it up to your diligent efforts. To rectify this situation, you must manually liberate the allocated memory by making an explicit call to C.free:

C.free(unsafe.Pointer(cstr))

By embracing this approach, you ensure the proper disposal of allocated memory and avoid memory leaks that would otherwise haunt your code.

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