Execute program and read output using Kotlin/Native

PosixExec.kt

fun exec(command: String): String {
    val returnBuffer = StringBuilder()
    val file = popen(command, "r")
    try {
        memScoped {
            val readBufferLength = 128
            val buffer = allocArray<ByteVar>(readBufferLength)
            var line = fgets(buffer, readBufferLength, file)?.toKString()
            while (line != null) {
                returnBuffer.append(line)
                line = fgets(buffer, readBufferLength, file)?.toKString()
            }
        }
    } finally {
        pclose(file)
    }
    return returnBuffer.toString()
}