list_readers.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */
 
/**
 * @file list_readers.c
 * @brief Implements the OP_PCSC_LIST_READERS opcode (conditional build).
 *
 * Lists available PC/SC reader names for a given context. On success returns
 * an array of strings. When PCSC support is disabled at build time, returns an
 * empty array after consuming its argument to keep the stack balanced.
 * 
 * OP_PCSC_LIST_READERS: (ctx_id:int) -> array<string>
 *
 * - Pops: ctx_id.
 * - Pushes: array of reader names on success; empty array on error/disabled.
 */
 
/* PCSC list_readers */
case OP_PCSC_LIST_READERS: {
#ifdef FUN_WITH_PCSC
  /* Pop context id; return [] if anything goes wrong */
  Value vid = pop_value(vm);
  int id = (int)vid.i;
  free_value(vid);
 
  pcsc_ctx_entry *e = pcsc_get_ctx(id);
  if (!e) {
    push_value(vm, make_array_from_values(NULL, 0));
    break;
  }
 
  DWORD sz = 0;
  LONG rv = SCardListReaders(e->ctx, NULL, NULL, &sz);
  if (rv != SCARD_S_SUCCESS || sz == 0) {
    push_value(vm, make_array_from_values(NULL, 0));
    break;
  }
 
  char *msz = (char *)malloc(sz);
  if (!msz) {
    push_value(vm, make_array_from_values(NULL, 0));
    break;
  }
 
  rv = SCardListReaders(e->ctx, NULL, msz, &sz);
  if (rv != SCARD_S_SUCCESS) {
    free(msz);
    push_value(vm, make_array_from_values(NULL, 0));
    break;
  }
 
  Value vals[64];
  int count = 0;
  char *p = msz;
  while (*p && count < (int)(sizeof(vals) / sizeof(vals[0]))) {
    size_t n = strlen(p);
    vals[count++] = make_string(p);
    p += n + 1;
  }
  Value arr = make_array_from_values(vals, count);
  for (int i = 0; i < count; ++i)
    free_value(vals[i]);
  free(msz);
 
  if (arr.type != VAL_ARRAY) {
    push_value(vm, make_array_from_values(NULL, 0));
  } else {
    push_value(vm, arr);
  }
#else
  /* Fallback (no PCSC): consume ctx id and return [] to keep the stack consistent */
  Value vid = pop_value(vm);
  free_value(vid);
  push_value(vm, make_array_from_values(NULL, 0));
#endif
  break;
}