mxml/mxml-private.c

//
// Private functions for Mini-XML, a small XML file parsing library.
//
// https://www.msweet.org/mxml
//
// Copyright © 2003-2024 by Michael R Sweet.
//
// Licensed under Apache License v2.0.  See the file "LICENSE" for more
// information.
//

#include "mxml-private.h"


//
// Some crazy people think that unloading a shared object is a good or safe
// thing to do.  Unfortunately, most objects are simply *not* safe to unload
// and bad things *will* happen.
//
// The following mess of conditional code allows us to provide a destructor
// function in Mini-XML for our thread-global storage so that it can possibly
// be unloaded safely, although since there is no standard way to do so I
// can't even provide any guarantees that you can do it safely on all platforms.
//
// This code currently supports AIX, HP-UX, Linux, macOS, Solaris, and
// Windows.  It might work on the BSDs and IRIX, but I haven't tested that.
//

#if defined(__sun) || defined(_AIX)
#  pragma fini(_mxml_fini)
#  define _MXML_FINI _mxml_fini
#elif defined(__hpux)
#  pragma FINI _mxml_fini
#  define _MXML_FINI _mxml_fini
#elif defined(__GNUC__) // Linux and macOS
#  define _MXML_FINI __attribute((destructor)) _mxml_fini
#else
#  define _MXML_FINI _fini
#endif // __sun


//
// '_mxml_error()' - Display an error message.
//

void
_mxml_error(const char *format,		// I - Printf-style format string
           ...)				// I - Additional arguments as needed
{
  va_list	ap;			// Pointer to arguments
  char		s[1024];		// Message string
  _mxml_global_t *global = _mxml_global();
					// Global data


  // Range check input...
  if (!format)
    return;

  // Format the error message string...
  va_start(ap, format);
  vsnprintf(s, sizeof(s), format, ap);
  va_end(ap);

  // And then display the error message...
  if (global->error_cb)
    (*global->error_cb)(s);
  else
    fprintf(stderr, "%s\n", s);
}


#ifdef HAVE_PTHREAD_H			// POSIX threading
#  include <pthread.h>

static int		_mxml_initialized = 0;
					// Have we been initialized?
static pthread_key_t	_mxml_key;	// Thread local storage key
static pthread_once_t	_mxml_key_once = PTHREAD_ONCE_INIT;
					// One-time initialization object
static void		_mxml_init(void);
static void		_mxml_destructor(void *g);


//
// '_mxml_destructor()' - Free memory used for globals...
//

static void
_mxml_destructor(void *g)		// I - Global data
{
  free(g);
}


//
// '_mxml_fini()' - Clean up when unloaded.
//

static void
_MXML_FINI(void)
{
  if (_mxml_initialized)
    pthread_key_delete(_mxml_key);
}


//
// '_mxml_global()' - Get global data.
//

_mxml_global_t *			// O - Global data
_mxml_global(void)
{
  _mxml_global_t	*global;	// Global data


  pthread_once(&_mxml_key_once, _mxml_init);

  if ((global = (_mxml_global_t *)pthread_getspecific(_mxml_key)) == NULL)
  {
    global = (_mxml_global_t *)calloc(1, sizeof(_mxml_global_t));
    pthread_setspecific(_mxml_key, global);

    global->num_entity_cbs = 1;
    global->entity_cbs[0]  = _mxml_entity_cb;
    global->wrap           = 72;
  }

  return (global);
}


//
// '_mxml_init()' - Initialize global data...
//

static void
_mxml_init(void)
{
  _mxml_initialized = 1;
  pthread_key_create(&_mxml_key, _mxml_destructor);
}


#elif defined(_WIN32) && defined(MXML1_EXPORTS) // WIN32 threading
#  include <windows.h>

static DWORD _mxml_tls_index;		// Index for global storage


//
// 'DllMain()' - Main entry for library.
//

BOOL WINAPI				// O - Success/failure
DllMain(HINSTANCE hinst,		// I - DLL module handle
        DWORD     reason,		// I - Reason
        LPVOID    reserved)		// I - Unused
{
  _mxml_global_t	*global;	// Global data


  (void)hinst;
  (void)reserved;

  switch (reason)
  {
    case DLL_PROCESS_ATTACH :		// Called on library initialization
        if ((_mxml_tls_index = TlsAlloc()) == TLS_OUT_OF_INDEXES)
          return (FALSE);
        break;

    case DLL_THREAD_DETACH :		// Called when a thread terminates
        if ((global = (_mxml_global_t *)TlsGetValue(_mxml_tls_index)) != NULL)
          free(global);
        break;

    case DLL_PROCESS_DETACH :		// Called when library is unloaded
        if ((global = (_mxml_global_t *)TlsGetValue(_mxml_tls_index)) != NULL)
          free(global);

        TlsFree(_mxml_tls_index);
        break;

    default:
        break;
  }

  return (TRUE);
}


//
// '_mxml_global()' - Get global data.
//

_mxml_global_t *			// O - Global data
_mxml_global(void)
{
  _mxml_global_t	*global;	// Global data


  if ((global = (_mxml_global_t *)TlsGetValue(_mxml_tls_index)) == NULL)
  {
    global = (_mxml_global_t *)calloc(1, sizeof(_mxml_global_t));

    global->num_entity_cbs = 1;
    global->entity_cbs[0]  = _mxml_entity_cb;
    global->wrap           = 72;

    TlsSetValue(_mxml_tls_index, (LPVOID)global);
  }

  return (global);
}


#else					// No threading
//
// '_mxml_global()' - Get global data.
//

_mxml_global_t *			// O - Global data
_mxml_global(void)
{
  static _mxml_global_t	global =	// Global data
  {
    NULL,				// error_cb
    1,					// num_entity_cbs
    { _mxml_entity_cb },		// entity_cbs
    72,					// wrap
    NULL,				// custom_load_cb
    NULL				// custom_save_cb
  };


  return (&global);
}
#endif // HAVE_PTHREAD_H