| 1 | /* extensions.c - registering and loading extensions. |
| 2 | * |
| 3 | * Copyright (C) 2001 Free Software Foundation, Inc. |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2, or (at your option) |
| 8 | * any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this software; see the file COPYING. If not, write to |
| 17 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
| 18 | * Boston, MA 02111-1307 USA |
| 19 | * |
| 20 | * As a special exception, the Free Software Foundation gives permission |
| 21 | * for additional uses of the text contained in its release of GUILE. |
| 22 | * |
| 23 | * The exception is that, if you link the GUILE library with other files |
| 24 | * to produce an executable, this does not by itself cause the |
| 25 | * resulting executable to be covered by the GNU General Public License. |
| 26 | * Your use of that executable is in no way restricted on account of |
| 27 | * linking the GUILE library code into it. |
| 28 | * |
| 29 | * This exception does not however invalidate any other reasons why |
| 30 | * the executable file might be covered by the GNU General Public License. |
| 31 | * |
| 32 | * This exception applies only to the code released by the |
| 33 | * Free Software Foundation under the name GUILE. If you copy |
| 34 | * code from other Free Software Foundation releases into a copy of |
| 35 | * GUILE, as the General Public License permits, the exception does |
| 36 | * not apply to the code that you add in this way. To avoid misleading |
| 37 | * anyone as to the status of such modified files, you must delete |
| 38 | * this exception notice from them. |
| 39 | * |
| 40 | * If you write modifications of your own for GUILE, it is your choice |
| 41 | * whether to permit this exception to apply to your modifications. |
| 42 | * If you do not wish that, delete this exception notice. */ |
| 43 | |
| 44 | #include <string.h> |
| 45 | |
| 46 | #include "libguile/_scm.h" |
| 47 | #include "libguile/strings.h" |
| 48 | #include "libguile/gc.h" |
| 49 | #include "libguile/dynl.h" |
| 50 | |
| 51 | #include "libguile/extensions.h" |
| 52 | |
| 53 | typedef struct extension_t |
| 54 | { |
| 55 | struct extension_t *next; |
| 56 | const char *lib; |
| 57 | const char *init; |
| 58 | void (*func)(void *); |
| 59 | void *data; |
| 60 | } extension_t; |
| 61 | |
| 62 | static extension_t *registered_extensions; |
| 63 | |
| 64 | /* Register a LIB/INIT pair for use by `scm_load_extension'. LIB is |
| 65 | allowed to be NULL and then only INIT is used to identify the |
| 66 | registered entry. This is useful when you don't know the library |
| 67 | name (which isn't really relevant anyway in a completely linked |
| 68 | program) and you are sure that INIT is unique (which it must be for |
| 69 | static linking). Hmm, given this reasoning, what use is LIB |
| 70 | anyway? |
| 71 | */ |
| 72 | |
| 73 | void |
| 74 | scm_c_register_extension (const char *lib, const char *init, |
| 75 | void (*func) (void *), void *data) |
| 76 | { |
| 77 | extension_t *ext = scm_malloc (sizeof(extension_t)); |
| 78 | if (lib) |
| 79 | ext->lib = scm_strdup (lib); |
| 80 | else |
| 81 | ext->lib = NULL; |
| 82 | ext->init = scm_strdup (init); |
| 83 | ext->func = func; |
| 84 | ext->data = data; |
| 85 | |
| 86 | ext->next = registered_extensions; |
| 87 | registered_extensions = ext; |
| 88 | } |
| 89 | |
| 90 | static void |
| 91 | load_extension (SCM lib, SCM init) |
| 92 | { |
| 93 | /* Search the registry. */ |
| 94 | { |
| 95 | extension_t *ext; |
| 96 | |
| 97 | for (ext = registered_extensions; ext; ext = ext->next) |
| 98 | if ((ext->lib == NULL || !strcmp (ext->lib, SCM_STRING_CHARS (lib))) |
| 99 | && !strcmp (ext->init, SCM_STRING_CHARS (init))) |
| 100 | { |
| 101 | ext->func (ext->data); |
| 102 | return; |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | #if defined (DYNAMIC_LINKING) |
| 107 | /* Dynamically link the library. */ |
| 108 | |
| 109 | scm_dynamic_call (init, scm_dynamic_link (lib)); |
| 110 | #endif |
| 111 | } |
| 112 | |
| 113 | void |
| 114 | scm_c_load_extension (const char *lib, const char *init) |
| 115 | { |
| 116 | load_extension (scm_makfrom0str (lib), scm_makfrom0str (init)); |
| 117 | } |
| 118 | |
| 119 | SCM_DEFINE (scm_load_extension, "load-extension", 2, 0, 0, |
| 120 | (SCM lib, SCM init), |
| 121 | "Load and initialize the extension designated by LIB and INIT.\n" |
| 122 | "When there is no pre-registered function for LIB/INIT, this is\n" |
| 123 | "equivalent to\n" |
| 124 | "\n" |
| 125 | "@lisp\n" |
| 126 | "(dynamic-call INIT (dynamic-link LIB))\n" |
| 127 | "@end lisp\n" |
| 128 | "\n" |
| 129 | "When there is a pre-registered function, that function is called\n" |
| 130 | "instead.\n" |
| 131 | "\n" |
| 132 | "Normally, there is no pre-registered function. This option exists\n" |
| 133 | "only for situations where dynamic linking is unavailable or unwanted.\n" |
| 134 | "In that case, you would statically link your program with the desired\n" |
| 135 | "library, and register its init function right after Guile has been\n" |
| 136 | "initialized.\n" |
| 137 | "\n" |
| 138 | "LIB should be a string denoting a shared library without any file type\n" |
| 139 | "suffix such as \".so\". The suffix is provided automatically. It\n" |
| 140 | "should also not contain any directory components. Libraries that\n" |
| 141 | "implement Guile Extensions should be put into the normal locations for\n" |
| 142 | "shared libraries. We recommend to use the naming convention\n" |
| 143 | "libguile-bla-blum for a extension related to a module `(bla blum)'.\n" |
| 144 | "\n" |
| 145 | "The normal way for a extension to be used is to write a small Scheme\n" |
| 146 | "file that defines a module, and to load the extension into this\n" |
| 147 | "module. When the module is auto-loaded, the extension is loaded as\n" |
| 148 | "well. For example,\n" |
| 149 | "\n" |
| 150 | "@lisp\n" |
| 151 | "(define-module (bla blum))\n" |
| 152 | "\n" |
| 153 | "(load-extension \"libguile-bla-blum\" \"bla_init_blum\")\n" |
| 154 | "@end lisp") |
| 155 | #define FUNC_NAME s_scm_load_extension |
| 156 | { |
| 157 | SCM_VALIDATE_STRING (1, lib); |
| 158 | SCM_VALIDATE_STRING (2, init); |
| 159 | load_extension (lib, init); |
| 160 | return SCM_UNSPECIFIED; |
| 161 | } |
| 162 | #undef FUNC_NAME |
| 163 | |
| 164 | void |
| 165 | scm_init_extensions () |
| 166 | { |
| 167 | registered_extensions = NULL; |
| 168 | #include "libguile/extensions.x" |
| 169 | } |
| 170 | |
| 171 | /* |
| 172 | Local Variables: |
| 173 | c-file-style: "gnu" |
| 174 | End: |
| 175 | */ |