/* GMODULE - GLIB wrapper code for dynamic module loading
* Copyright (C) 1998 Tim Janik
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#include "config.h"
#include "glib.h"
#include "gmodule.h"
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef G_OS_UNIX
#include <unistd.h>
#endif
#ifdef G_OS_WIN32
#include <io.h> /* For open() and close() prototypes. */
#endif
#include "gmoduleconf.h"
#include "gstdio.h"
/**
* SECTION:modules
* @title: Dynamic Loading of Modules
* @short_description: portable method for dynamically loading 'plug-ins'
*
* These functions provide a portable way to dynamically load object files
* (commonly known as 'plug-ins'). The current implementation supports all
* systems that provide an implementation of dlopen() (e.g. Linux/Sun), as
* well as Windows platforms via DLLs.
*
* A program which wants to use these functions must be linked to the
* libraries output by the command `pkg-config --libs gmodule-2.0`.
*
* To use them you must first determine whether dynamic loading
* is supported on the platform by calling g_module_supported().
* If it is, you can open a module with g_module_open(),
* find the module's symbols (e.g. function names) with g_module_symbol(),
* and later close the module with g_module_close().
* g_module_name() will return the file name of a currently opened module.
*
* If any of the above functions fail, the error status can be found with
* g_module_error().
*
* The #GModule implementation features reference counting for opened modules,
* and supports hook functions within a module which are called when the
* module is loaded and unloaded (see #GModuleCheckInit and #GModuleUnload).
*
* If your module introduces static data to common subsystems in the running
* program, e.g. through calling
* `g_quark_from_static_string ("my-module-stuff")`,
* it must ensure that it is never unloaded, by calling g_module_make_resident().
*
* Example: Calling a function defined in a GModule
* |[<!-- language="C" -->
* // the function signature for 'say_hello'
* typedef void (* SayHelloFunc) (const char *message);
*
* gboolean
* just_say_hello (const char *filename, GError **error)
* {
* SayHelloFunc say_hello;
* GModule *module;
*
* module = g_module_open (filename, G_MODULE_BIND_LAZY);
* if (!module)
* {
* g_set_error (error, FOO_ERROR, FOO_ERROR_BLAH,
* "%s", g_module_error ());
* return FALSE;
* }
*
* if (!g_module_symbol (module, "say_hello", (gpointer *)&say_hello))
* {
* g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
* "%s: %s", filename, g_module_error ());
* if (!g_module_close (module))
* g_warning ("%s: %s", filename, g_module_error ());
* return FALSE;
* }
*
* if (say_hello == NULL)
* {
* g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
* "symbol say_hello is NULL");
* if (!g_module_close (module))
* g_warning ("%s: %s", filename, g_module_error ());
* return FALSE;
* }
*
* // call our function in the module
* say_hello ("Hello world!");
*
* if (!g_module_close (module))
* g_warning ("%s: %s", filename, g_module_error ());
* return TRUE;
* }
* ]|
*/
/**
* GModule:
*
* The #GModule struct is an opaque data structure to represent a
* [dynamically-loaded module][glib-Dynamic-Loading-of-Modules].
* It should only be accessed via the following functions.
*/
/**
* GModuleCheckInit:
* @module: the #GModule corresponding to the module which has just been loaded
*
* Specifies the type of the module initialization function.
* If a module contains a function named g_module_check_init() it is called
* automatically when the module is loaded. It is passed the #GModule structure
* and should return %NULL on success or a string describing the initialization
* error.
*
* Returns: %NULL on success, or a string describing the initialization error
*/
/**
* GModuleUnload:
* @module: the #GModule about to be unloaded
*
* Specifies the type of the module function called when it is unloaded.
* If a module contains a function named g_module_unload() it is called
* automatically when the module is unloaded.
* It is passed the #GModule structure.
*/
/**
* G_MODULE_SUFFIX:
*
* Expands to the proper shared library suffix for the current platform
* without the leading dot. For most Unices and Linux this is "so", and
* for Windows this is "dll".
*/
/**
* G_MODULE_EXPORT:
*
* Used to declare functions exported by libraries or modules.
*
* When compiling for Windows, it marks the symbol as `dllexport`.
*
* When compiling for Linux and Unices, it marks the symbol as having `default`
* visibility. This is no-op unless the code is being compiled with a
* non-default
* [visibility flag](https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fvisibility-1260)
* such as `hidden`.
*/
/**
* G_MODULE_IMPORT:
*
* Used to declare functions imported from modules.
*/
/* We maintain a list of modules, so we can reference count them.
* That's needed because some platforms don't support references counts on
* modules. Also, the module for the program itself is kept seperately for
* faster access and because it has special semantics.
*/
/* --- structures --- */
struct _GModule
{
gchar *file_name;
gpointer handle;
guint ref_count : 31;
guint is_resident : 1;
GModuleUnload unload;
GModule *next;
};
/* --- prototypes --- */
static gpointer _g_module_open (const gchar *file_name,
gboolean bind_lazy,
gboolean bind_local);
static void _g_module_close (gpointer handle,
gboolean is_unref);
static gpointer _g_module_self (void);
static gpointer _g_module_symbol (gpointer handle,
const gchar *symbol_name);
static gchar* _g_module_build_path (const gchar *directory,
const gchar *module_name);
static inline void g_module_set_error (const gchar *error);
static inline GModule* g_module_find_by_handle (gpointer handle);
static inline GModule* g_module_find_by_name (const gchar *name);
/* --- variables --- */
static GModule *modules = NULL;
static GModule *main_module = NULL;
static GPrivate module_error_private = G_PRIVATE_INIT (g_free);
static gboolean module_debug_initialized = FALSE;
static guint module_debug_flags = 0;
/* --- inline functions --- */
static inline GModule*
g_module_find_by_handle (gpointer handle)
{
GModule *module;
GModule *retval = NULL;
if (main_module && main_module->handle == handle)
retval = main_module;
else
for (module = modules; module; module = module->next)
if (handle == module->handle)
{
retval = module;
break;
}
return retval;
}
static inline GModule*
g_module_find_by_name (const gchar *name)
{
GModule *module;
GModule *retval = NULL;
for (module = modules; module; module = module->next)
if (strcmp (name, module->file_name) == 0)
{
retval = module;
break;
}
return retval;
}
static inline void
g_module_set_error_unduped (gchar *error)
{
g_private_replace (&module_error_private, error);
errno = 0;
}
static inline void
g_module_set_error (const gchar *error)
{
g_module_set_error_unduped (g_strdup (error));
}
/* --- include platform specifc code --- */
#define SUPPORT_OR_RETURN(rv) { g_module_set_error (NULL); }
#if (G_MODULE_IMPL == G_MODULE_IMPL_DL)
#include "gmodule-dl.c"
#elif (G_MODULE_IMPL == G_MODULE_IMPL_WIN32)
#include "gmodule-win32.c"
#elif (G_MODULE_IMPL == G_MODULE_IMPL_DYLD)
#include "gmodule-dyld.c"
#elif (G_MODULE_IMPL == G_MODULE_IMPL_AR)
#include "gmodule-ar.c"
#else
#undef SUPPORT_OR_RETURN
#define SUPPORT_OR_RETURN(rv) { g_module_set_error ("dynamic modules are " \
"not supported by this system"); return rv; }
static gpointer
_g_module_open (const gchar *file_name,
gboolean bind_lazy,
gboolean bind_local)
{
return NULL;
}
static void
_g_module_close (gpointer handle,
gboolean is_unref)
{
}
static gpointer
_g_module_self (void)
{
return NULL;
}
static gpointer
_g_module_symbol (gpointer handle,
const gchar *symbol_name)
{
return NULL;
}
static gchar*
_g_module_build_path (const gchar *directory,
const gchar *module_name)
{
return NULL;
}
#endif /* no implementation */
/* --- functions --- */
/**
* g_module_supported:
*
* Checks if modules are supported on the current platform.
*
* Returns: %TRUE if modules are supported
*/
gboolean
g_module_supported (void)
{
SUPPORT_OR_RETURN (FALSE);
return TRUE;
}
static gchar*
parse_libtool_archive (const gchar* libtool_name)
{
const guint TOKEN_DLNAME = G_TOKEN_LAST + 1;
const guint TOKEN_INSTALLED = G_TOKEN_LAST + 2;
const guint TOKEN_LIBDIR = G_TOKEN_LAST + 3;
gchar *lt_dlname = NULL;
gboolean lt_installed = TRUE;
gchar *lt_libdir = NULL;
gchar *name;
GTokenType token;
GScanner *scanner;
int fd = g_open (libtool_name, O_RDONLY, 0);
if (fd < 0)
{
gchar *display_libtool_name = g_filename_display_name (libtool_name);
g_module_set_error_unduped (g_strdup_printf ("failed to open libtool archive \"%s\"", display_libtool_name));
g_free (display_libtool_name);
return NULL;
}
/* search libtool's dlname specification */
scanner = g_scanner_new (NULL);
g_scanner_input_file (scanner, fd);
scanner->config->symbol_2_token = TRUE;
g_scanner_scope_add_symbol (scanner, 0, "dlname",
GUINT_TO_POINTER (TOKEN_DLNAME));
g_scanner_scope_add_symbol (scanner, 0, "installed",
GUINT_TO_POINTER (TOKEN_INSTALLED));
g_scanner_scope_add_symbol (scanner, 0, "libdir",
GUINT_TO_POINTER (TOKEN_LIBDIR));
while (!g_scanner_eof (scanner))
{
token = g_scanner_get_next_token (scanner);
if (token == TOKEN_DLNAME || token == TOKEN_INSTALLED ||
token == TOKEN_LIBDIR)
{
if (g_scanner_get_next_token (scanner) != '=' ||
g_scanner_get_next_token (scanner) !=
(token == TOKEN_INSTALLED ?
G_TOKEN_IDENTIFIER : G_TOKEN_STRING))
{
gchar *display_libtool_name = g_filename_display_name (libtool_name);
g_module_set_error_unduped (g_strdup_printf ("unable to parse libtool archive \"%s\"", display_libtool_name));
g_free (display_libtool_name);
g_free (lt_dlname);
g_free (lt_libdir);
g_scanner_destroy (scanner);
close (fd);
return NULL;
}
else
{
if (token == TOKEN_DLNAME)
{
g_free (lt_dlname);
lt_dlname = g_strdup (scanner->value.v_string);
}
else if (token == TOKEN_INSTALLED)
lt_installed =
strcmp (scanner->value.v_identifier, "yes") == 0;
else /* token == TOKEN_LIBDIR */
{
g_free (lt_libdir);
lt_libdir = g_strdup (scanner->value.v_string);
}
}
}
}
if (!lt_installed)
{
gchar *dir = g_path_get_dirname (libtool_name);
g_free (lt_libdir);
lt_libdir = g_strconcat (dir, G_DIR_SEPARATOR_S ".libs", NULL);
g_free (dir);
}
name = g_strconcat (lt_libdir, G_DIR_SEPARATOR_S, lt_dlname, NULL);
g_free (lt_dlname);
g_free (lt_libdir);
g_scanner_destroy (scanner);
close (fd);
return name;
}
static inline gboolean
str_check_suffix (const gchar* string,
const gchar* suffix)
{
gsize string_len = strlen (string);
gsize suffix_len = strlen (suffix);
return string_len >= suffix_len &&
strcmp (string + string_len - suffix_len, suffix) == 0;
}
enum
{
G_MODULE_DEBUG_RESIDENT_MODULES = 1 << 0,
G_MODULE_DEBUG_BIND_NOW_MODULES = 1 << 1
};
static void
_g_module_debug_init (void)
{
const GDebugKey keys[] = {
{ "resident-modules", G_MODULE_DEBUG_RESIDENT_MODULES },
{ "bind-now-modules", G_MODULE_DEBUG_BIND_NOW_MODULES }
};
const gchar *env;
env = g_getenv ("G_DEBUG");
module_debug_flags =
!env ? 0 : g_parse_debug_string (env, keys, G_N_ELEMENTS (keys));
module_debug_initialized = TRUE;
}
static GRecMutex g_module_global_lock;
/**
* g_module_open:
* @file_name: (nullable): the name of the file containing the module, or %NULL
* to obtain a #GModule representing the main program itself
* @flags: the flags used for opening the module. This can be the
* logical OR of any of the #GModuleFlags
*
* Opens a module. If the module has already been opened,
* its reference count is incremented.
*
* First of all g_module_open() tries to open @file_name as a module.
* If that fails and @file_name has the ".la"-suffix (and is a libtool
* archive) it tries to open the corresponding module. If that fails
* and it doesn't have the proper module suffix for the platform
* (#G_MODULE_SUFFIX), this suffix will be appended and the corresponding
* module will be opended. If that fails and @file_name doesn't have the
* ".la"-suffix, this suffix is appended and g_module_open() tries to open
* the corresponding module. If eventually that fails as well, %NULL is
* returned.
*
* Returns: a #GModule on success, or %NULL on failure
*/
GModule*
g_module_open (const gchar *file_name,
GModuleFlags flags)
{
GModule *module;
gpointer handle = NULL;
gchar *name = NULL;
SUPPORT_OR_RETURN (NULL);
g_rec_mutex_lock (&g_module_global_lock);
if (G_UNLIKELY (!module_debug_initialized))
_g_module_debug_init ();
if (module_debug_flags & G_MODULE_DEBUG_BIND_NOW_MODULES)
flags &= ~G_MODULE_BIND_LAZY;
if (!file_name)
{
if (!main_module)
{
handle = _g_module_self ();
/* On Android 64 bit, RTLD_DEFAULT is (void *)0x0
* so it always fails to create main_module if file_name is NULL */
#if !defined(__BIONIC__) || !defined(__LP64__)
if (handle)
#endif
{
main_module = g_new (GModule, 1);
main_module->file_name = NULL;
main_module->handle = handle;
main_module->ref_count = 1;
main_module->is_resident = TRUE;
main_module->unload = NULL;
main_module->next = NULL;
}
}
else
main_module->ref_count++;
g_rec_mutex_unlock (&g_module_global_lock);
return main_module;
}
/* we first search the module list by name */
module = g_module_find_by_name (file_name);
if (module)
{
module->ref_count++;
g_rec_mutex_unlock (&g_module_global_lock);
return module;
}
/* check whether we have a readable file right away */
if (g_file_test (file_name, G_FILE_TEST_IS_REGULAR))
name = g_strdup (file_name);
/* try completing file name with standard library suffix */
if (!name)
{
name = g_strconcat (file_name, "." G_MODULE_SUFFIX, NULL);
if (!g_file_test (name, G_FILE_TEST_IS_REGULAR))
{
g_free (name);
name = NULL;
}
}
/* try completing by appending libtool suffix */
if (!name)
{
name = g_strconcat (file_name, ".la", NULL);
if (!g_file_test (name, G_FILE_TEST_IS_REGULAR))
{
g_free (name);
name = NULL;
}
}
/* we can't access() the file, lets hope the platform backends finds
* it via library paths
*/
if (!name)
{
gchar *dot = strrchr (file_name, '.');
gchar *slash = strrchr (file_name, G_DIR_SEPARATOR);
/* make sure the name has a suffix */
if (!dot || dot < slash)
name = g_strconcat (file_name, "." G_MODULE_SUFFIX, NULL);
else
name = g_strdup (file_name);
}
/* ok, try loading the module */
if (name)
{
/* if it's a libtool archive, figure library file to load */
if (str_check_suffix (name, ".la")) /* libtool archive? */
{
gchar *real_name = parse_libtool_archive (name);
/* real_name might be NULL, but then module error is already set */
if (real_name)
{
g_free (name);
name = real_name;
}
}
if (name)
handle = _g_module_open (name, (flags & G_MODULE_BIND_LAZY) != 0,
(flags & G_MODULE_BIND_LOCAL) != 0);
}
else
{
gchar *display_file_name = g_filename_display_name (file_name);
g_module_set_error_unduped (g_strdup_printf ("unable to access file \"%s\"", display_file_name));
g_free (display_file_name);
}
g_free (name);
if (handle)
{
gchar *saved_error;
GModuleCheckInit check_init;
const gchar *check_failed = NULL;
/* search the module list by handle, since file names are not unique */
module = g_module_find_by_handle (handle);
if (module)
{
_g_module_close (module->handle, TRUE);
module->ref_count++;
g_module_set_error (NULL);
g_rec_mutex_unlock (&g_module_global_lock);
return module;
}
saved_error = g_strdup (g_module_error ());
g_module_set_error (NULL);
module = g_new (GModule, 1);
module->file_name = g_strdup (file_name);
module->handle = handle;
module->ref_count = 1;
module->is_resident = FALSE;
module->unload = NULL;
module->next = modules;
modules = module;
/* check initialization */
if (g_module_symbol (module, "g_module_check_init", (gpointer) &check_init) && check_init != NULL)
check_failed = check_init (module);
/* we don't call unload() if the initialization check failed. */
if (!check_failed)
g_module_symbol (module, "g_module_unload", (gpointer) &module->unload);
if (check_failed)
{
gchar *error;
error = g_strconcat ("GModule (", file_name, ") ",
"initialization check failed: ",
check_failed, NULL);
g_module_close (module);
module = NULL;
g_module_set_error (error);
g_free (error);
}
else
g_module_set_error (saved_error);
g_free (saved_error);
}
if (module != NULL &&
(module_debug_flags & G_MODULE_DEBUG_RESIDENT_MODULES))
g_module_make_resident (module);
g_rec_mutex_unlock (&g_module_global_lock);
return module;
}
/**
* g_module_close:
* @module: a #GModule to close
*
* Closes a module.
*
* Returns: %TRUE on success
*/
gboolean
g_module_close (GModule *module)
{
SUPPORT_OR_RETURN (FALSE);
g_return_val_if_fail (module != NULL, FALSE);
g_return_val_if_fail (module->ref_count > 0, FALSE);
g_rec_mutex_lock (&g_module_global_lock);
module->ref_count--;
if (!module->ref_count && !module->is_resident && module->unload)
{
GModuleUnload unload;
unload = module->unload;
module->unload = NULL;
unload (module);
}
if (!module->ref_count && !module->is_resident)
{
GModule *last;
GModule *node;
last = NULL;
node = modules;
while (node)
{
if (node == module)
{
if (last)
last->next = node->next;
else
modules = node->next;
break;
}
last = node;
node = last->next;
}
module->next = NULL;
_g_module_close (module->handle, FALSE);
g_free (module->file_name);
g_free (module);
}
g_rec_mutex_unlock (&g_module_global_lock);
return g_module_error() == NULL;
}
/**
* g_module_make_resident:
* @module: a #GModule to make permanently resident
*
* Ensures that a module will never be unloaded.
* Any future g_module_close() calls on the module will be ignored.
*/
void
g_module_make_resident (GModule *module)
{
g_return_if_fail (module != NULL);
module->is_resident = TRUE;
}
/**
* g_module_error:
*
* Gets a string describing the last module error.
*
* Returns: a string describing the last module error
*/
const gchar *
g_module_error (void)
{
return g_private_get (&module_error_private);
}
/**
* g_module_symbol:
* @module: a #GModule
* @symbol_name: the name of the symbol to find
* @symbol: (out): returns the pointer to the symbol value
*
* Gets a symbol pointer from a module, such as one exported
* by #G_MODULE_EXPORT. Note that a valid symbol can be %NULL.
*
* Returns: %TRUE on success
*/
gboolean
g_module_symbol (GModule *module,
const gchar *symbol_name,
gpointer *symbol)
{
const gchar *module_error;
if (symbol)
*symbol = NULL;
SUPPORT_OR_RETURN (FALSE);
g_return_val_if_fail (module != NULL, FALSE);
g_return_val_if_fail (symbol_name != NULL, FALSE);
g_return_val_if_fail (symbol != NULL, FALSE);
g_rec_mutex_lock (&g_module_global_lock);
#ifdef G_MODULE_NEED_USCORE
{
gchar *name;
name = g_strconcat ("_", symbol_name, NULL);
*symbol = _g_module_symbol (module->handle, name);
g_free (name);
}
#else /* !G_MODULE_NEED_USCORE */
*symbol = _g_module_symbol (module->handle, symbol_name);
#endif /* !G_MODULE_NEED_USCORE */
module_error = g_module_error ();
if (module_error)
{
gchar *error;
error = g_strconcat ("'", symbol_name, "': ", module_error, NULL);
g_module_set_error (error);
g_free (error);
*symbol = NULL;
}
g_rec_mutex_unlock (&g_module_global_lock);
return !module_error;
}
/**
* g_module_name:
* @module: a #GModule
*
* Returns the filename that the module was opened with.
*
* If @module refers to the application itself, "main" is returned.
*
* Returns: (transfer none): the filename of the module
*/
const gchar *
g_module_name (GModule *module)
{
g_return_val_if_fail (module != NULL, NULL);
if (module == main_module)
return "main";
return module->file_name;
}
/**
* g_module_build_path:
* @directory: (nullable): the directory where the module is. This can be
* %NULL or the empty string to indicate that the standard platform-specific
* directories will be used, though that is not recommended
* @module_name: the name of the module
*
* A portable way to build the filename of a module. The platform-specific
* prefix and suffix are added to the filename, if needed, and the result
* is added to the directory, using the correct separator character.
*
* The directory should specify the directory where the module can be found.
* It can be %NULL or an empty string to indicate that the module is in a
* standard platform-specific directory, though this is not recommended
* since the wrong module may be found.
*
* For example, calling g_module_build_path() on a Linux system with a
* @directory of `/lib` and a @module_name of "mylibrary" will return
* `/lib/libmylibrary.so`. On a Windows system, using `\Windows` as the
* directory it will return `\Windows\mylibrary.dll`.
*
* Returns: the complete path of the module, including the standard library
* prefix and suffix. This should be freed when no longer needed
*/
gchar *
g_module_build_path (const gchar *directory,
const gchar *module_name)
{
g_return_val_if_fail (module_name != NULL, NULL);
return _g_module_build_path (directory, module_name);
}
#ifdef G_OS_WIN32
/* Binary compatibility versions. Not for newly compiled code. */
_GLIB_EXTERN GModule * g_module_open_utf8 (const gchar *file_name,
GModuleFlags flags);
_GLIB_EXTERN const gchar *g_module_name_utf8 (GModule *module);
GModule*
g_module_open_utf8 (const gchar *file_name,
GModuleFlags flags)
{
return g_module_open (file_name, flags);
}
const gchar *
g_module_name_utf8 (GModule *module)
{
return g_module_name (module);
}
#endif