gmodule/gmodule.c

   1 /* GMODULE - GLIB wrapper code for dynamic module loading
   2  * Copyright (C) 1998 Tim Janik
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  20  * file for a list of people on the GLib Team.  See the ChangeLog
  21  * files for a list of changes.  These files are distributed with
  22  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  23  */
  24
  25 /*
  26  * MT safe
  27  */
  28
  29 #include "config.h"
  30
  31 #include "glib.h"
  32 #include "gmodule.h"
  33
  34 #include <errno.h>
  35 #include <string.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <fcntl.h>
  39 #ifdef G_OS_UNIX
  40 #include <unistd.h>
  41 #endif
  42 #ifdef G_OS_WIN32
  43 #include <io.h>         /* For open() and close() prototypes. */
  44 #endif
  45
  46 #include "gmoduleconf.h"
  47 #include "gstdio.h"
  48
  49 /**
  50  * SECTION:modules
  51  * @title: Dynamic Loading of Modules
  52  * @short_description: portable method for dynamically loading 'plug-ins'
  53  *
  54  * These functions provide a portable way to dynamically load object files
  55  * (commonly known as 'plug-ins'). The current implementation supports all
  56  * systems that provide an implementation of dlopen() (e.g. Linux/Sun), as
  57  * well as Windows platforms via DLLs.
  58  *
  59  * A program which wants to use these functions must be linked to the
  60  * libraries output by the command `pkg-config --libs gmodule-2.0`.
  61  *
  62  * To use them you must first determine whether dynamic loading
  63  * is supported on the platform by calling g_module_supported().
  64  * If it is, you can open a module with g_module_open(),
  65  * find the module's symbols (e.g. function names) with g_module_symbol(),
  66  * and later close the module with g_module_close().
  67  * g_module_name() will return the file name of a currently opened module.
  68  *
  69  * If any of the above functions fail, the error status can be found with
  70  * g_module_error().
  71  *
  72  * The #GModule implementation features reference counting for opened modules,
  73  * and supports hook functions within a module which are called when the
  74  * module is loaded and unloaded (see #GModuleCheckInit and #GModuleUnload).
  75  *
  76  * If your module introduces static data to common subsystems in the running
  77  * program, e.g. through calling
  78  * `g_quark_from_static_string ("my-module-stuff")`,
  79  * it must ensure that it is never unloaded, by calling g_module_make_resident().
  80  *
  81  * Example: Calling a function defined in a GModule
  82  * |[<!-- language="C" -->
  83  * // the function signature for 'say_hello'
  84  * typedef void (* SayHelloFunc) (const char *message);
  85  *
  86  * gboolean
  87  * just_say_hello (const char *filename, GError **error)
  88  * {
  89  *   SayHelloFunc  say_hello;
  90  *   GModule      *module;
  91  *
  92  *   module = g_module_open (filename, G_MODULE_BIND_LAZY);
  93  *   if (!module)
  94  *     {
  95  *       g_set_error (error, FOO_ERROR, FOO_ERROR_BLAH,
  96  *                    "%s", g_module_error ());
  97  *       return FALSE;
  98  *     }
  99  *
 100  *   if (!g_module_symbol (module, "say_hello", (gpointer *)&say_hello))
 101  *     {
 102  *       g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
 103  *                    "%s: %s", filename, g_module_error ());
 104  *       if (!g_module_close (module))
 105  *         g_warning ("%s: %s", filename, g_module_error ());
 106  *       return FALSE;
 107  *     }
 108  *
 109  *   if (say_hello == NULL)
 110  *     {
 111  *       g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
 112  *                    "symbol say_hello is NULL");
 113  *       if (!g_module_close (module))
 114  *         g_warning ("%s: %s", filename, g_module_error ());
 115  *       return FALSE;
 116  *     }
 117  *
 118  *   // call our function in the module
 119  *   say_hello ("Hello world!");
 120  *
 121  *   if (!g_module_close (module))
 122  *     g_warning ("%s: %s", filename, g_module_error ());
 123  *   return TRUE;
 124  *  }
 125  * ]|
 126  */
 127
 128 /**
 129  * GModule:
 130  *
 131  * The #GModule struct is an opaque data structure to represent a
 132  * [dynamically-loaded module][glib-Dynamic-Loading-of-Modules].
 133  * It should only be accessed via the following functions.
 134  */
 135
 136 /**
 137  * GModuleCheckInit:
 138  * @module: the #GModule corresponding to the module which has just been loaded
 139  *
 140  * Specifies the type of the module initialization function.
 141  * If a module contains a function named g_module_check_init() it is called
 142  * automatically when the module is loaded. It is passed the #GModule structure
 143  * and should return %NULL on success or a string describing the initialization
 144  * error.
 145  *
 146  * Returns: %NULL on success, or a string describing the initialization error
 147  */
 148
 149 /**
 150  * GModuleUnload:
 151  * @module: the #GModule about to be unloaded
 152  *
 153  * Specifies the type of the module function called when it is unloaded.
 154  * If a module contains a function named g_module_unload() it is called
 155  * automatically when the module is unloaded.
 156  * It is passed the #GModule structure.
 157  */
 158
 159 /**
 160  * G_MODULE_SUFFIX:
 161  *
 162  * Expands to the proper shared library suffix for the current platform
 163  * without the leading dot. For most Unices and Linux this is "so", and
 164  * for Windows this is "dll".
 165  */
 166
 167 /**
 168  * G_MODULE_EXPORT:
 169  *
 170  * Used to declare functions exported by modules. This is a no-op on Linux
 171  * and Unices, but when compiling for Windows, it marks a symbol to be
 172  * exported from the library or executable being built.
 173  */
 174
 175 /**
 176  * G_MODULE_IMPORT:
 177  *
 178  * Used to declare functions imported from modules.
 179  */
 180
 181 /* We maintain a list of modules, so we can reference count them.
 182  * That's needed because some platforms don't support references counts on
 183  * modules. Also, the module for the program itself is kept seperately for
 184  * faster access and because it has special semantics.
 185  */
 186
 187
 188 /* --- structures --- */
 189 struct _GModule
 190 {
 191   gchar *file_name;
 192 #if defined (G_OS_WIN32) && !defined(_WIN64)
 193   gchar *cp_file_name;
 194 #endif
 195   gpointer handle;
 196   guint ref_count : 31;
 197   guint is_resident : 1;
 198   GModuleUnload unload;
 199   GModule *next;
 200 };
 201
 202
 203 /* --- prototypes --- */
 204 static gpointer         _g_module_open          (const gchar    *file_name,
 205                                                  gboolean        bind_lazy,
 206                                                  gboolean        bind_local);
 207 static void             _g_module_close         (gpointer        handle,
 208                                                  gboolean        is_unref);
 209 static gpointer         _g_module_self          (void);
 210 static gpointer         _g_module_symbol        (gpointer        handle,
 211                                                  const gchar    *symbol_name);
 212 static gchar*           _g_module_build_path    (const gchar    *directory,
 213                                                  const gchar    *module_name);
 214 static inline void      g_module_set_error      (const gchar    *error);
 215 static inline GModule*  g_module_find_by_handle (gpointer        handle);
 216 static inline GModule*  g_module_find_by_name   (const gchar    *name);
 217
 218
 219 /* --- variables --- */
 220 static GModule       *modules = NULL;
 221 static GModule       *main_module = NULL;
 222 static GPrivate       module_error_private = G_PRIVATE_INIT (g_free);
 223 static gboolean       module_debug_initialized = FALSE;
 224 static guint          module_debug_flags = 0;
 225
 226
 227 /* --- inline functions --- */
 228 static inline GModule*
 229 g_module_find_by_handle (gpointer handle)
 230 {
 231   GModule *module;
 232   GModule *retval = NULL;
 233
 234   if (main_module && main_module->handle == handle)
 235     retval = main_module;
 236   else
 237     for (module = modules; module; module = module->next)
 238       if (handle == module->handle)
 239         {
 240           retval = module;
 241           break;
 242         }
 243
 244   return retval;
 245 }
 246
 247 static inline GModule*
 248 g_module_find_by_name (const gchar *name)
 249 {
 250   GModule *module;
 251   GModule *retval = NULL;
 252
 253   for (module = modules; module; module = module->next)
 254     if (strcmp (name, module->file_name) == 0)
 255         {
 256           retval = module;
 257           break;
 258         }
 259
 260   return retval;
 261 }
 262
 263 static inline void
 264 g_module_set_error_unduped (gchar *error)
 265 {
 266   g_private_replace (&module_error_private, error);
 267   errno = 0;
 268 }
 269
 270 static inline void
 271 g_module_set_error (const gchar *error)
 272 {
 273   g_module_set_error_unduped (g_strdup (error));
 274 }
 275
 276
 277 /* --- include platform specifc code --- */
 278 #define SUPPORT_OR_RETURN(rv)   { g_module_set_error (NULL); }
 279 #if     (G_MODULE_IMPL == G_MODULE_IMPL_DL)
 280 #include "gmodule-dl.c"
 281 #elif   (G_MODULE_IMPL == G_MODULE_IMPL_WIN32)
 282 #include "gmodule-win32.c"
 283 #elif   (G_MODULE_IMPL == G_MODULE_IMPL_DYLD)
 284 #include "gmodule-dyld.c"
 285 #elif   (G_MODULE_IMPL == G_MODULE_IMPL_AR)
 286 #include "gmodule-ar.c"
 287 #else
 288 #undef  SUPPORT_OR_RETURN
 289 #define SUPPORT_OR_RETURN(rv)   { g_module_set_error ("dynamic modules are " \
 290                                               "not supported by this system"); return rv; }
 291 static gpointer
 292 _g_module_open (const gchar     *file_name,
 293                 gboolean         bind_lazy,
 294                 gboolean         bind_local)
 295 {
 296   return NULL;
 297 }
 298 static void
 299 _g_module_close (gpointer        handle,
 300                  gboolean        is_unref)
 301 {
 302 }
 303 static gpointer
 304 _g_module_self (void)
 305 {
 306   return NULL;
 307 }
 308 static gpointer
 309 _g_module_symbol (gpointer       handle,
 310                   const gchar   *symbol_name)
 311 {
 312   return NULL;
 313 }
 314 static gchar*
 315 _g_module_build_path (const gchar *directory,
 316                       const gchar *module_name)
 317 {
 318   return NULL;
 319 }
 320 #endif  /* no implementation */
 321
 322 /* --- functions --- */
 323
 324 /**
 325  * g_module_supported:
 326  *
 327  * Checks if modules are supported on the current platform.
 328  *
 329  * Returns: %TRUE if modules are supported
 330  */
 331 gboolean
 332 g_module_supported (void)
 333 {
 334   SUPPORT_OR_RETURN (FALSE);
 335
 336   return TRUE;
 337 }
 338
 339 static gchar*
 340 parse_libtool_archive (const gchar* libtool_name)
 341 {
 342   const guint TOKEN_DLNAME = G_TOKEN_LAST + 1;
 343   const guint TOKEN_INSTALLED = G_TOKEN_LAST + 2;
 344   const guint TOKEN_LIBDIR = G_TOKEN_LAST + 3;
 345   gchar *lt_dlname = NULL;
 346   gboolean lt_installed = TRUE;
 347   gchar *lt_libdir = NULL;
 348   gchar *name;
 349   GTokenType token;
 350   GScanner *scanner;
 351
 352   int fd = g_open (libtool_name, O_RDONLY, 0);
 353   if (fd < 0)
 354     {
 355       gchar *display_libtool_name = g_filename_display_name (libtool_name);
 356       g_module_set_error_unduped (g_strdup_printf ("failed to open libtool archive \"%s\"", display_libtool_name));
 357       g_free (display_libtool_name);
 358       return NULL;
 359     }
 360   /* search libtool's dlname specification  */
 361   scanner = g_scanner_new (NULL);
 362   g_scanner_input_file (scanner, fd);
 363   scanner->config->symbol_2_token = TRUE;
 364   g_scanner_scope_add_symbol (scanner, 0, "dlname",
 365                               GUINT_TO_POINTER (TOKEN_DLNAME));
 366   g_scanner_scope_add_symbol (scanner, 0, "installed",
 367                               GUINT_TO_POINTER (TOKEN_INSTALLED));
 368   g_scanner_scope_add_symbol (scanner, 0, "libdir",
 369                               GUINT_TO_POINTER (TOKEN_LIBDIR));
 370   while (!g_scanner_eof (scanner))
 371     {
 372       token = g_scanner_get_next_token (scanner);
 373       if (token == TOKEN_DLNAME || token == TOKEN_INSTALLED ||
 374           token == TOKEN_LIBDIR)
 375         {
 376           if (g_scanner_get_next_token (scanner) != '=' ||
 377               g_scanner_get_next_token (scanner) !=
 378               (token == TOKEN_INSTALLED ?
 379                G_TOKEN_IDENTIFIER : G_TOKEN_STRING))
 380             {
 381               gchar *display_libtool_name = g_filename_display_name (libtool_name);
 382               g_module_set_error_unduped (g_strdup_printf ("unable to parse libtool archive \"%s\"", display_libtool_name));
 383               g_free (display_libtool_name);
 384
 385               g_free (lt_dlname);
 386               g_free (lt_libdir);
 387               g_scanner_destroy (scanner);
 388               close (fd);
 389
 390               return NULL;
 391             }
 392           else
 393             {
 394               if (token == TOKEN_DLNAME)
 395                 {
 396                   g_free (lt_dlname);
 397                   lt_dlname = g_strdup (scanner->value.v_string);
 398                 }
 399               else if (token == TOKEN_INSTALLED)
 400                 lt_installed =
 401                   strcmp (scanner->value.v_identifier, "yes") == 0;
 402               else /* token == TOKEN_LIBDIR */
 403                 {
 404                   g_free (lt_libdir);
 405                   lt_libdir = g_strdup (scanner->value.v_string);
 406                 }
 407             }
 408         }
 409     }
 410
 411   if (!lt_installed)
 412     {
 413       gchar *dir = g_path_get_dirname (libtool_name);
 414       g_free (lt_libdir);
 415       lt_libdir = g_strconcat (dir, G_DIR_SEPARATOR_S ".libs", NULL);
 416       g_free (dir);
 417     }
 418
 419   name = g_strconcat (lt_libdir, G_DIR_SEPARATOR_S, lt_dlname, NULL);
 420
 421   g_free (lt_dlname);
 422   g_free (lt_libdir);
 423   g_scanner_destroy (scanner);
 424   close (fd);
 425
 426   return name;
 427 }
 428
 429 static inline gboolean
 430 str_check_suffix (const gchar* string,
 431                   const gchar* suffix)
 432 {
 433   gsize string_len = strlen (string);
 434   gsize suffix_len = strlen (suffix);
 435
 436   return string_len >= suffix_len &&
 437     strcmp (string + string_len - suffix_len, suffix) == 0;
 438 }
 439
 440 enum
 441 {
 442   G_MODULE_DEBUG_RESIDENT_MODULES = 1 << 0,
 443   G_MODULE_DEBUG_BIND_NOW_MODULES = 1 << 1
 444 };
 445
 446 static void
 447 _g_module_debug_init (void)
 448 {
 449   const GDebugKey keys[] = {
 450     { "resident-modules", G_MODULE_DEBUG_RESIDENT_MODULES },
 451     { "bind-now-modules", G_MODULE_DEBUG_BIND_NOW_MODULES }
 452   };
 453   const gchar *env;
 454
 455   env = g_getenv ("G_DEBUG");
 456
 457   module_debug_flags =
 458     !env ? 0 : g_parse_debug_string (env, keys, G_N_ELEMENTS (keys));
 459
 460   module_debug_initialized = TRUE;
 461 }
 462
 463 static GRecMutex g_module_global_lock;
 464
 465 GModule*
 466 g_module_open (const gchar    *file_name,
 467                GModuleFlags    flags)
 468 {
 469   GModule *module;
 470   gpointer handle = NULL;
 471   gchar *name = NULL;
 472
 473   SUPPORT_OR_RETURN (NULL);
 474
 475   g_rec_mutex_lock (&g_module_global_lock);
 476
 477   if (G_UNLIKELY (!module_debug_initialized))
 478     _g_module_debug_init ();
 479
 480   if (module_debug_flags & G_MODULE_DEBUG_BIND_NOW_MODULES)
 481     flags &= ~G_MODULE_BIND_LAZY;
 482
 483   if (!file_name)
 484     {
 485       if (!main_module)
 486         {
 487           handle = _g_module_self ();
 488           if (handle)
 489             {
 490               main_module = g_new (GModule, 1);
 491               main_module->file_name = NULL;
 492 #if defined (G_OS_WIN32) && !defined(_WIN64)
 493               main_module->cp_file_name = NULL;
 494 #endif
 495               main_module->handle = handle;
 496               main_module->ref_count = 1;
 497               main_module->is_resident = TRUE;
 498               main_module->unload = NULL;
 499               main_module->next = NULL;
 500             }
 501         }
 502       else
 503         main_module->ref_count++;
 504
 505       g_rec_mutex_unlock (&g_module_global_lock);
 506       return main_module;
 507     }
 508
 509   /* we first search the module list by name */
 510   module = g_module_find_by_name (file_name);
 511   if (module)
 512     {
 513       module->ref_count++;
 514
 515       g_rec_mutex_unlock (&g_module_global_lock);
 516       return module;
 517     }
 518
 519   /* check whether we have a readable file right away */
 520   if (g_file_test (file_name, G_FILE_TEST_IS_REGULAR))
 521     name = g_strdup (file_name);
 522   /* try completing file name with standard library suffix */
 523   if (!name)
 524     {
 525       name = g_strconcat (file_name, "." G_MODULE_SUFFIX, NULL);
 526       if (!g_file_test (name, G_FILE_TEST_IS_REGULAR))
 527         {
 528           g_free (name);
 529           name = NULL;
 530         }
 531     }
 532   /* try completing by appending libtool suffix */
 533   if (!name)
 534     {
 535       name = g_strconcat (file_name, ".la", NULL);
 536       if (!g_file_test (name, G_FILE_TEST_IS_REGULAR))
 537         {
 538           g_free (name);
 539           name = NULL;
 540         }
 541     }
 542   /* we can't access() the file, lets hope the platform backends finds
 543    * it via library paths
 544    */
 545   if (!name)
 546     {
 547       gchar *dot = strrchr (file_name, '.');
 548       gchar *slash = strrchr (file_name, G_DIR_SEPARATOR);
 549
 550       /* make sure the name has a suffix */
 551       if (!dot || dot < slash)
 552         name = g_strconcat (file_name, "." G_MODULE_SUFFIX, NULL);
 553       else
 554         name = g_strdup (file_name);
 555     }
 556
 557   /* ok, try loading the module */
 558   if (name)
 559     {
 560       /* if it's a libtool archive, figure library file to load */
 561       if (str_check_suffix (name, ".la")) /* libtool archive? */
 562         {
 563           gchar *real_name = parse_libtool_archive (name);
 564
 565           /* real_name might be NULL, but then module error is already set */
 566           if (real_name)
 567             {
 568               g_free (name);
 569               name = real_name;
 570             }
 571         }
 572       if (name)
 573         handle = _g_module_open (name, (flags & G_MODULE_BIND_LAZY) != 0,
 574                         (flags & G_MODULE_BIND_LOCAL) != 0);
 575     }
 576   else
 577     {
 578       gchar *display_file_name = g_filename_display_name (file_name);
 579       g_module_set_error_unduped (g_strdup_printf ("unable to access file \"%s\"", display_file_name));
 580       g_free (display_file_name);
 581     }
 582   g_free (name);
 583
 584   if (handle)
 585     {
 586       gchar *saved_error;
 587       GModuleCheckInit check_init;
 588       const gchar *check_failed = NULL;
 589
 590       /* search the module list by handle, since file names are not unique */
 591       module = g_module_find_by_handle (handle);
 592       if (module)
 593         {
 594           _g_module_close (module->handle, TRUE);
 595           module->ref_count++;
 596           g_module_set_error (NULL);
 597
 598           g_rec_mutex_unlock (&g_module_global_lock);
 599           return module;
 600         }
 601
 602       saved_error = g_strdup (g_module_error ());
 603       g_module_set_error (NULL);
 604
 605       module = g_new (GModule, 1);
 606       module->file_name = g_strdup (file_name);
 607 #if defined (G_OS_WIN32) && !defined(_WIN64)
 608       module->cp_file_name = g_locale_from_utf8 (file_name, -1,
 609                                                  NULL, NULL, NULL);
 610 #endif
 611       module->handle = handle;
 612       module->ref_count = 1;
 613       module->is_resident = FALSE;
 614       module->unload = NULL;
 615       module->next = modules;
 616       modules = module;
 617
 618       /* check initialization */
 619       if (g_module_symbol (module, "g_module_check_init", (gpointer) &check_init) && check_init != NULL)
 620         check_failed = check_init (module);
 621
 622       /* we don't call unload() if the initialization check failed. */
 623       if (!check_failed)
 624         g_module_symbol (module, "g_module_unload", (gpointer) &module->unload);
 625
 626       if (check_failed)
 627         {
 628           gchar *error;
 629
 630           error = g_strconcat ("GModule (", file_name, ") ",
 631                                "initialization check failed: ",
 632                                check_failed, NULL);
 633           g_module_close (module);
 634           module = NULL;
 635           g_module_set_error (error);
 636           g_free (error);
 637         }
 638       else
 639         g_module_set_error (saved_error);
 640
 641       g_free (saved_error);
 642     }
 643
 644   if (module != NULL &&
 645       (module_debug_flags & G_MODULE_DEBUG_RESIDENT_MODULES))
 646     g_module_make_resident (module);
 647
 648   g_rec_mutex_unlock (&g_module_global_lock);
 649   return module;
 650 }
 651
 652 #if defined (G_OS_WIN32) && !defined(_WIN64)
 653
 654 #undef g_module_open
 655
 656 /**
 657  * GModuleFlags:
 658  * @G_MODULE_BIND_LAZY: specifies that symbols are only resolved when
 659  *     needed. The default action is to bind all symbols when the module
 660  *     is loaded.
 661  * @G_MODULE_BIND_LOCAL: specifies that symbols in the module should
 662  *     not be added to the global name space. The default action on most
 663  *     platforms is to place symbols in the module in the global name space,
 664  *     which may cause conflicts with existing symbols.
 665  * @G_MODULE_BIND_MASK: mask for all flags.
 666  *
 667  * Flags passed to g_module_open().
 668  * Note that these flags are not supported on all platforms.
 669  */
 670
 671 /**
 672  * g_module_open:
 673  * @file_name: (allow-none): the name of the file containing the module, or %NULL
 674  *     to obtain a #GModule representing the main program itself
 675  * @flags: the flags used for opening the module. This can be the
 676  *     logical OR of any of the #GModuleFlags
 677  *
 678  * Opens a module. If the module has already been opened,
 679  * its reference count is incremented.
 680  *
 681  * First of all g_module_open() tries to open @file_name as a module.
 682  * If that fails and @file_name has the ".la"-suffix (and is a libtool
 683  * archive) it tries to open the corresponding module. If that fails
 684  * and it doesn't have the proper module suffix for the platform
 685  * (#G_MODULE_SUFFIX), this suffix will be appended and the corresponding
 686  * module will be opended. If that fails and @file_name doesn't have the
 687  * ".la"-suffix, this suffix is appended and g_module_open() tries to open
 688  * the corresponding module. If eventually that fails as well, %NULL is
 689  * returned.
 690  *
 691  * Returns: a #GModule on success, or %NULL on failure
 692  */
 693 GModule *
 694 g_module_open (const gchar  *file_name,
 695                GModuleFlags  flags)
 696 {
 697   gchar *utf8_file_name = g_locale_to_utf8 (file_name, -1, NULL, NULL, NULL);
 698   GModule *retval = g_module_open_utf8 (utf8_file_name, flags);
 699
 700   g_free (utf8_file_name);
 701
 702   return retval;
 703 }
 704
 705 #endif
 706
 707 /**
 708  * g_module_close:
 709  * @module: a #GModule to close
 710  *
 711  * Closes a module.
 712  *
 713  * Returns: %TRUE on success
 714  */
 715 gboolean
 716 g_module_close (GModule *module)
 717 {
 718   SUPPORT_OR_RETURN (FALSE);
 719
 720   g_return_val_if_fail (module != NULL, FALSE);
 721   g_return_val_if_fail (module->ref_count > 0, FALSE);
 722
 723   g_rec_mutex_lock (&g_module_global_lock);
 724
 725   module->ref_count--;
 726
 727   if (!module->ref_count && !module->is_resident && module->unload)
 728     {
 729       GModuleUnload unload;
 730
 731       unload = module->unload;
 732       module->unload = NULL;
 733       unload (module);
 734     }
 735
 736   if (!module->ref_count && !module->is_resident)
 737     {
 738       GModule *last;
 739       GModule *node;
 740
 741       last = NULL;
 742
 743       node = modules;
 744       while (node)
 745         {
 746           if (node == module)
 747             {
 748               if (last)
 749                 last->next = node->next;
 750               else
 751                 modules = node->next;
 752               break;
 753             }
 754           last = node;
 755           node = last->next;
 756         }
 757       module->next = NULL;
 758
 759       _g_module_close (module->handle, FALSE);
 760       g_free (module->file_name);
 761 #if defined (G_OS_WIN32) && !defined(_WIN64)
 762       g_free (module->cp_file_name);
 763 #endif
 764       g_free (module);
 765     }
 766
 767   g_rec_mutex_unlock (&g_module_global_lock);
 768   return g_module_error() == NULL;
 769 }
 770
 771 /**
 772  * g_module_make_resident:
 773  * @module: a #GModule to make permanently resident
 774  *
 775  * Ensures that a module will never be unloaded.
 776  * Any future g_module_close() calls on the module will be ignored.
 777  */
 778 void
 779 g_module_make_resident (GModule *module)
 780 {
 781   g_return_if_fail (module != NULL);
 782
 783   module->is_resident = TRUE;
 784 }
 785
 786 /**
 787  * g_module_error:
 788  *
 789  * Gets a string describing the last module error.
 790  *
 791  * Returns: a string describing the last module error
 792  */
 793 const gchar *
 794 g_module_error (void)
 795 {
 796   return g_private_get (&module_error_private);
 797 }
 798
 799 /**
 800  * g_module_symbol:
 801  * @module: a #GModule
 802  * @symbol_name: the name of the symbol to find
 803  * @symbol: (out): returns the pointer to the symbol value
 804  *
 805  * Gets a symbol pointer from a module, such as one exported
 806  * by #G_MODULE_EXPORT. Note that a valid symbol can be %NULL.
 807  *
 808  * Returns: %TRUE on success
 809  */
 810 gboolean
 811 g_module_symbol (GModule     *module,
 812                  const gchar *symbol_name,
 813                  gpointer    *symbol)
 814 {
 815   const gchar *module_error;
 816
 817   if (symbol)
 818     *symbol = NULL;
 819   SUPPORT_OR_RETURN (FALSE);
 820
 821   g_return_val_if_fail (module != NULL, FALSE);
 822   g_return_val_if_fail (symbol_name != NULL, FALSE);
 823   g_return_val_if_fail (symbol != NULL, FALSE);
 824
 825   g_rec_mutex_lock (&g_module_global_lock);
 826
 827 #ifdef  G_MODULE_NEED_USCORE
 828   {
 829     gchar *name;
 830
 831     name = g_strconcat ("_", symbol_name, NULL);
 832     *symbol = _g_module_symbol (module->handle, name);
 833     g_free (name);
 834   }
 835 #else   /* !G_MODULE_NEED_USCORE */
 836   *symbol = _g_module_symbol (module->handle, symbol_name);
 837 #endif  /* !G_MODULE_NEED_USCORE */
 838
 839   module_error = g_module_error ();
 840   if (module_error)
 841     {
 842       gchar *error;
 843
 844       error = g_strconcat ("'", symbol_name, "': ", module_error, NULL);
 845       g_module_set_error (error);
 846       g_free (error);
 847       *symbol = NULL;
 848     }
 849
 850   g_rec_mutex_unlock (&g_module_global_lock);
 851   return !module_error;
 852 }
 853
 854 /**
 855  * g_module_name:
 856  * @module: a #GModule
 857  *
 858  * Returns the filename that the module was opened with.
 859  *
 860  * If @module refers to the application itself, "main" is returned.
 861  *
 862  * Returns: (transfer none): the filename of the module
 863  */
 864 const gchar *
 865 g_module_name (GModule *module)
 866 {
 867   g_return_val_if_fail (module != NULL, NULL);
 868
 869   if (module == main_module)
 870     return "main";
 871
 872   return module->file_name;
 873 }
 874
 875 #if defined (G_OS_WIN32) && !defined(_WIN64)
 876
 877 #undef g_module_name
 878
 879 const gchar *
 880 g_module_name (GModule *module)
 881 {
 882   g_return_val_if_fail (module != NULL, NULL);
 883
 884   if (module == main_module)
 885     return "main";
 886
 887   return module->cp_file_name;
 888 }
 889
 890 #endif
 891
 892 /**
 893  * g_module_build_path:
 894  * @directory: (allow-none): the directory where the module is. This can be
 895  *     %NULL or the empty string to indicate that the standard platform-specific
 896  *     directories will be used, though that is not recommended
 897  * @module_name: the name of the module
 898  *
 899  * A portable way to build the filename of a module. The platform-specific
 900  * prefix and suffix are added to the filename, if needed, and the result
 901  * is added to the directory, using the correct separator character.
 902  *
 903  * The directory should specify the directory where the module can be found.
 904  * It can be %NULL or an empty string to indicate that the module is in a
 905  * standard platform-specific directory, though this is not recommended
 906  * since the wrong module may be found.
 907  *
 908  * For example, calling g_module_build_path() on a Linux system with a
 909  * @directory of `/lib` and a @module_name of "mylibrary" will return
 910  * `/lib/libmylibrary.so`. On a Windows system, using `\Windows` as the
 911  * directory it will return `\Windows\mylibrary.dll`.
 912  *
 913  * Returns: the complete path of the module, including the standard library
 914  *     prefix and suffix. This should be freed when no longer needed
 915  */
 916 gchar *
 917 g_module_build_path (const gchar *directory,
 918                      const gchar *module_name)
 919 {
 920   g_return_val_if_fail (module_name != NULL, NULL);
 921
 922   return _g_module_build_path (directory, module_name);
 923 }