pcsc.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 pcsc.c
 * @brief PC/SC smartcard helper registries and lookup utilities.
 *
 * Provides small fixed-size registries for PC/SC contexts and card handles,
 * plus allocation and lookup helpers used by VM opcodes when FUN_WITH_PCSC
 * is enabled.
 */
 
#ifdef FUN_WITH_PCSC
#if defined(__has_include)
#if __has_include(<PCSC/winscard.h>)
#include <PCSC/winscard.h>
#include <PCSC/wintypes.h>
#elif __has_include(<winscard.h>)
#include <winscard.h>
#else
#error "FUN_WITH_PCSC is enabled but PCSC headers were not found"
#endif
#else
#include <PCSC/winscard.h>
#include <PCSC/wintypes.h>
#endif
#include <string.h>
 
typedef struct {
  SCARDCONTEXT ctx;
  int in_use;
} pcsc_ctx_entry;
 
typedef struct {
  SCARDHANDLE h;
  DWORD proto;
  int in_use;
} pcsc_card_entry;
 
static pcsc_ctx_entry g_pcsc_ctx[8];
static pcsc_card_entry g_pcsc_card[32];
 
/**
 * @brief Allocate a free context slot in the PC/SC registry.
 *
 * @return A 1-based slot id on success, or 0 if no free slot is available.
 */
static int pcsc_alloc_ctx_slot(void) {
  for (int i = 0; i < (int)(sizeof(g_pcsc_ctx) / sizeof(g_pcsc_ctx[0])); ++i) {
    if (!g_pcsc_ctx[i].in_use) {
      g_pcsc_ctx[i].in_use = 1;
      g_pcsc_ctx[i].ctx = 0;
      return i + 1;
    }
  }
  return 0;
}
 
/**
 * @brief Allocate a free card slot in the PC/SC registry.
 *
 * @return A 1-based slot id on success, or 0 if no free slot is available.
 */
static int pcsc_alloc_card_slot(void) {
  for (int i = 0; i < (int)(sizeof(g_pcsc_card) / sizeof(g_pcsc_card[0])); ++i) {
    if (!g_pcsc_card[i].in_use) {
      g_pcsc_card[i].in_use = 1;
      g_pcsc_card[i].h = 0;
      g_pcsc_card[i].proto = 0;
      return i + 1;
    }
  }
  return 0;
}
 
/**
 * @brief Lookup a context slot by id.
 *
 * @param id 1-based context id previously returned by pcsc_alloc_ctx_slot().
 * @return Pointer to the registry entry if valid and in use; NULL otherwise.
 */
static pcsc_ctx_entry *pcsc_get_ctx(int id) {
  if (id <= 0) return NULL;
  int idx = id - 1;
  if (idx < 0 || idx >= (int)(sizeof(g_pcsc_ctx) / sizeof(g_pcsc_ctx[0]))) return NULL;
  if (!g_pcsc_ctx[idx].in_use) return NULL;
  return &g_pcsc_ctx[idx];
}
 
/**
 * @brief Lookup a card slot by id.
 *
 * @param id 1-based card id previously returned by pcsc_alloc_card_slot().
 * @return Pointer to the registry entry if valid and in use; NULL otherwise.
 */
static pcsc_card_entry *pcsc_get_card(int id) {
  if (id <= 0) return NULL;
  int idx = id - 1;
  if (idx < 0 || idx >= (int)(sizeof(g_pcsc_card) / sizeof(g_pcsc_card[0]))) return NULL;
  if (!g_pcsc_card[idx].in_use) return NULL;
  return &g_pcsc_card[idx];
}
#endif