glib/gmodule/gmodule.c
Philip Withnall 00bfb3ab44 tree: Fix various typos and outdated terminology
This was mostly machine generated with the following command:
```
codespell \
    --builtin clear,rare,usage \
    --skip './po/*' --skip './.git/*' --skip './NEWS*' \
    --write-changes .
```
using the latest git version of `codespell` as per [these
instructions](https://github.com/codespell-project/codespell#user-content-updating).

Then I manually checked each change using `git add -p`, made a few
manual fixups and dropped a load of incorrect changes.

There are still some outdated or loaded terms used in GLib, mostly to do
with git branch terminology. They will need to be changed later as part
of a wider migration of git terminology.

If I’ve missed anything, please file an issue!

Signed-off-by: Philip Withnall <withnall@endlessm.com>
2020-06-12 15:01:08 +01:00

892 lines
24 KiB
C

/* 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 separately 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);
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 specific 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_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)
{
}
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 opened. 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);
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);
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