cgo **char to slice string

Question

I have developed a pam module using the cgo. can not be converted to []string a ** char

func pam_sm_authenticate(pamh *C.pam_handle_t, flags C.int, argc C.int, argv **C.char) int { fmt.Println(C.GoString(*argv[0])) return 0 }

error is

invalid operation: argv[0] (type **C.char does not support indexing)

Please let me know if you know.

Answer 1

Cobbled together from the cgo wiki: https://github.com/golang/go/wiki/cgo#Turning_C_arrays_into_Go_slices.

import "C"
import "unsafe"

func GoStrings(argc C.int, argv **C.char) []string {

    length := int(argc)
    tmpslice := (*[1 << 30]*C.char)(unsafe.Pointer(argv))[:length:length]
    gostrings := make([]string, length)
    for i, s := range tmpslice {
        gostrings[i] = C.GoString(s)
    }
    return gostrings
}