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1 | |
2 | /* module.c : Implementation of the module loading/unloading mechanism. |
3 | * |
4 | */ |
5 | |
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6 | #include <lttv/module.h> |
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7 | |
8 | |
9 | struct _LttvModule |
10 | { |
11 | GModule *module; |
12 | guint ref_count; |
13 | guint load_count; |
14 | GPtrArray *dependents; |
15 | }; |
16 | |
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17 | |
18 | /* Table of loaded modules and paths where to search for modules */ |
19 | |
20 | static GHashTable *modules = NULL; |
21 | |
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22 | static GPtrArray *modulesPaths = NULL; |
23 | |
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24 | static void lttv_module_unload_all(); |
25 | |
26 | |
27 | void lttv_module_init(int argc, char **argv) |
28 | { |
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29 | modules = g_hash_table_new(g_str_hash, g_str_equal); |
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30 | modulesPaths = g_ptr_array_new(); |
31 | } |
32 | |
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33 | |
34 | void lttv_module_destroy() |
35 | { |
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36 | int i; |
37 | |
38 | /* Unload all modules */ |
39 | lttv_module_unload_all(); |
40 | |
41 | /* Free the modules paths pointer array as well as the elements */ |
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42 | for(i = 0; i < modulesPaths->len ; i++) { |
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43 | g_free(modulesPaths->pdata[i]); |
44 | } |
45 | g_ptr_array_free(modulesPaths,TRUE) ; |
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46 | modulesPaths = NULL; |
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47 | |
48 | /* destroy the hash table */ |
49 | g_hash_table_destroy(modules) ; |
50 | modules = NULL; |
51 | } |
52 | |
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53 | |
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54 | /* Add a new pathname to the modules loading search path */ |
55 | |
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56 | void lttv_module_path_add(const char *name) |
57 | { |
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58 | g_ptr_array_add(modulesPaths,(char*)g_strdup(name)); |
59 | } |
60 | |
61 | |
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62 | static LttvModule * |
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63 | module_load(const char *name, int argc, char **argv) |
64 | { |
65 | GModule *gm; |
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66 | |
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67 | LttvModule *m; |
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68 | |
69 | int i; |
70 | |
71 | char *pathname; |
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72 | |
73 | const char *module_name; |
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74 | |
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75 | LttvModuleInit init_function; |
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76 | |
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77 | /* Try to find the module along all the user specified paths */ |
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78 | |
79 | for(i = 0 ; i < modulesPaths->len ; i++) { |
80 | pathname = g_module_build_path(modulesPaths->pdata[i],name); |
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81 | gm = g_module_open(pathname,0); |
82 | g_free(pathname); |
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83 | |
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84 | if(gm != NULL) break; |
85 | } |
86 | |
87 | /* Try the default system path */ |
88 | |
89 | if(gm == NULL) { |
90 | pathname = g_module_build_path(NULL,name); |
91 | gm = g_module_open(pathname,0); |
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92 | g_free(pathname); |
93 | } |
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94 | |
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95 | /* Module cannot be found */ |
96 | |
97 | if(gm == NULL) return NULL; |
98 | |
99 | /* Check if the module was already opened using the hopefully canonical name |
100 | returned by g_module_name. */ |
101 | |
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102 | module_name = g_module_name(gm); |
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103 | |
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104 | m = g_hash_table_lookup(modules, module_name); |
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105 | |
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106 | if(m == NULL) { |
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107 | |
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108 | /* Module loaded for the first time. Insert it in the table and call the |
109 | init function if any. */ |
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110 | |
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111 | m = g_new(LttvModule, 1); |
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112 | m->module = gm; |
113 | m->ref_count = 0; |
114 | m->load_count = 0; |
115 | m->dependents = g_ptr_array_new(); |
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116 | g_hash_table_insert(modules, (gpointer)module_name, m); |
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117 | |
118 | if(!g_module_symbol(gm, "init", (gpointer)&init_function)) { |
119 | g_warning("module %s (%s) has no init function", name, pathname); |
120 | } |
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121 | else init_function(m, argc, argv); |
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122 | } |
123 | else { |
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124 | |
125 | /* Module was already opened, check that it really is the same and |
126 | undo the extra g_module_open */ |
127 | |
128 | if(m->module != gm) g_error("Two gmodules with the same pathname"); |
129 | g_module_close(gm); |
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130 | } |
131 | |
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132 | m->ref_count++; |
133 | return m; |
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134 | } |
135 | |
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136 | |
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137 | LttvModule * |
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138 | lttv_module_load(const char *name, int argc, char **argv) |
139 | { |
140 | LttvModule *m = module_load(name, argc, argv); |
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141 | |
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142 | if(m != NULL) m->load_count++; |
143 | return m; |
144 | } |
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145 | |
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146 | |
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147 | LttvModule * |
148 | lttv_module_require(LttvModule *m, const char *name, int argc, char **argv) |
149 | { |
150 | LttvModule *module; |
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151 | |
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152 | module = module_load(name, argc, argv); |
153 | if(module != NULL) g_ptr_array_add(m->dependents, module); |
154 | return module; |
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155 | } |
156 | |
157 | |
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158 | static void module_unload(LttvModule *m) |
159 | { |
160 | LttvModuleDestroy destroy_function; |
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161 | |
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162 | char *pathname; |
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163 | |
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164 | guint i, len; |
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165 | |
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166 | /* Decrement the reference count */ |
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167 | |
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168 | m->ref_count--; |
169 | if(m->ref_count > 0) return; |
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170 | |
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171 | /* We really have to unload the module, first unload its dependents */ |
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172 | |
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173 | len = m->dependents->len; |
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174 | |
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175 | for(i = 0 ; i < len ; i++) { |
176 | module_unload(m->dependents->pdata[i]); |
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177 | } |
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178 | |
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179 | if(len != m->dependents->len) g_error("dependents list modified"); |
180 | |
181 | /* Unload the module itself */ |
182 | |
183 | if(!g_module_symbol(m->module, "destroy", (gpointer)&destroy_function)) { |
184 | g_warning("module (%s) has no destroy function", pathname); |
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185 | } |
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186 | else destroy_function(); |
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187 | |
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188 | g_hash_table_remove(modules, g_module_name(m->module)); |
189 | g_ptr_array_free(m->dependents, TRUE); |
190 | g_module_close(m->module); |
191 | g_free(m); |
192 | } |
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193 | |
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194 | |
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195 | void lttv_module_unload(LttvModule *m) |
196 | { |
197 | if(m->load_count <= 0) { |
198 | g_error("more unload than load (%s)", g_module_name(m->module)); |
199 | return; |
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200 | } |
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201 | m->load_count--; |
202 | module_unload(m); |
203 | } |
204 | |
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205 | |
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206 | static void |
207 | list_modules(gpointer key, gpointer value, gpointer user_data) |
208 | { |
209 | g_ptr_array_add((GPtrArray *)user_data, value); |
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210 | } |
211 | |
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212 | |
213 | LttvModule ** |
214 | lttv_module_list(guint *nb) |
215 | { |
216 | GPtrArray *list = g_ptr_array_new(); |
217 | |
218 | LttvModule **array; |
219 | |
220 | g_hash_table_foreach(modules, list_modules, list); |
221 | *nb = list->len; |
222 | array = (LttvModule **)list->pdata; |
223 | g_ptr_array_free(list, FALSE); |
224 | return array; |
225 | } |
226 | |
227 | |
228 | LttvModule ** |
229 | lttv_module_info(LttvModule *m, const char **name, |
230 | guint *ref_count, guint *load_count, guint *nb_dependents) |
231 | { |
232 | guint i, len = m->dependents->len; |
233 | |
234 | LttvModule **array = g_new(LttvModule *, len); |
235 | |
236 | *name = g_module_name(m->module); |
237 | *ref_count = m->ref_count; |
238 | *load_count = m->load_count; |
239 | *nb_dependents = len; |
240 | for(i = 0 ; i < len ; i++) array[i] = m->dependents->pdata[i]; |
241 | return array; |
242 | } |
243 | |
244 | |
245 | static void |
246 | list_independent(gpointer key, gpointer value, gpointer user_data) |
247 | { |
248 | LttvModule *m = (LttvModule *)value; |
249 | |
250 | if(m->load_count > 0) g_ptr_array_add((GPtrArray *)user_data, m); |
251 | } |
252 | |
253 | |
254 | void |
255 | lttv_module_unload_all() |
256 | { |
257 | guint i; |
258 | |
259 | LttvModule *m; |
260 | |
261 | GPtrArray *independent_modules = g_ptr_array_new(); |
262 | |
263 | g_hash_table_foreach(modules, list_independent, independent_modules); |
264 | |
265 | for(i = 0 ; i < independent_modules->len ; i++) { |
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266 | m = (LttvModule *)independent_modules->pdata[i]; |
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267 | while(m->load_count > 0) lttv_module_unload(m); |
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268 | } |
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269 | |
270 | g_ptr_array_free(independent_modules, TRUE); |
271 | if(g_hash_table_size(modules) != 0) g_warning("cannot unload all modules"); |
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272 | } |