util/module.c

   1 /*
   2  * QEMU Module Infrastructure
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu/osdep.h"
  17 #ifdef CONFIG_MODULES
  18 #include <gmodule.h>
  19 #endif
  20 #include "qemu/queue.h"
  21 #include "qemu/module.h"
  22
  23 typedef struct ModuleEntry
  24 {
  25     void (*init)(void);
  26     QTAILQ_ENTRY(ModuleEntry) node;
  27     module_init_type type;
  28 } ModuleEntry;
  29
  30 typedef QTAILQ_HEAD(, ModuleEntry) ModuleTypeList;
  31
  32 static ModuleTypeList init_type_list[MODULE_INIT_MAX];
  33
  34 static ModuleTypeList dso_init_list;
  35
  36 static void init_lists(void)
  37 {
  38     static int inited;
  39     int i;
  40
  41     if (inited) {
  42         return;
  43     }
  44
  45     for (i = 0; i < MODULE_INIT_MAX; i++) {
  46         QTAILQ_INIT(&init_type_list[i]);
  47     }
  48
  49     QTAILQ_INIT(&dso_init_list);
  50
  51     inited = 1;
  52 }
  53
  54
  55 static ModuleTypeList *find_type(module_init_type type)
  56 {
  57     init_lists();
  58
  59     return &init_type_list[type];
  60 }
  61
  62 void register_module_init(void (*fn)(void), module_init_type type)
  63 {
  64     ModuleEntry *e;
  65     ModuleTypeList *l;
  66
  67     e = g_malloc0(sizeof(*e));
  68     e->init = fn;
  69     e->type = type;
  70
  71     l = find_type(type);
  72
  73     QTAILQ_INSERT_TAIL(l, e, node);
  74 }
  75
  76 void register_dso_module_init(void (*fn)(void), module_init_type type)
  77 {
  78     ModuleEntry *e;
  79
  80     init_lists();
  81
  82     e = g_malloc0(sizeof(*e));
  83     e->init = fn;
  84     e->type = type;
  85
  86     QTAILQ_INSERT_TAIL(&dso_init_list, e, node);
  87 }
  88
  89 void module_call_init(module_init_type type)
  90 {
  91     ModuleTypeList *l;
  92     ModuleEntry *e;
  93
  94     l = find_type(type);
  95
  96     QTAILQ_FOREACH(e, l, node) {
  97         e->init();
  98     }
  99 }
 100
 101 #ifdef CONFIG_MODULES
 102 static int module_load_file(const char *fname)
 103 {
 104     GModule *g_module;
 105     void (*sym)(void);
 106     const char *dsosuf = HOST_DSOSUF;
 107     int len = strlen(fname);
 108     int suf_len = strlen(dsosuf);
 109     ModuleEntry *e, *next;
 110     int ret;
 111
 112     if (len <= suf_len || strcmp(&fname[len - suf_len], dsosuf)) {
 113         /* wrong suffix */
 114         ret = -EINVAL;
 115         goto out;
 116     }
 117     if (access(fname, F_OK)) {
 118         ret = -ENOENT;
 119         goto out;
 120     }
 121
 122     assert(QTAILQ_EMPTY(&dso_init_list));
 123
 124     g_module = g_module_open(fname, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
 125     if (!g_module) {
 126         fprintf(stderr, "Failed to open module: %s\n",
 127                 g_module_error());
 128         ret = -EINVAL;
 129         goto out;
 130     }
 131     if (!g_module_symbol(g_module, DSO_STAMP_FUN_STR, (gpointer *)&sym)) {
 132         fprintf(stderr, "Failed to initialize module: %s\n",
 133                 fname);
 134         /* Print some info if this is a QEMU module (but from different build),
 135          * this will make debugging user problems easier. */
 136         if (g_module_symbol(g_module, "qemu_module_dummy", (gpointer *)&sym)) {
 137             fprintf(stderr,
 138                     "Note: only modules from the same build can be loaded.\n");
 139         }
 140         g_module_close(g_module);
 141         ret = -EINVAL;
 142     } else {
 143         QTAILQ_FOREACH(e, &dso_init_list, node) {
 144             e->init();
 145             register_module_init(e->init, e->type);
 146         }
 147         ret = 0;
 148     }
 149
 150     QTAILQ_FOREACH_SAFE(e, &dso_init_list, node, next) {
 151         QTAILQ_REMOVE(&dso_init_list, e, node);
 152         g_free(e);
 153     }
 154 out:
 155     return ret;
 156 }
 157 #endif
 158
 159 bool module_load_one(const char *prefix, const char *lib_name)
 160 {
 161     bool success = false;
 162
 163 #ifdef CONFIG_MODULES
 164     char *fname = NULL;
 165     char *exec_dir;
 166     const char *search_dir;
 167     char *dirs[4];
 168     char *module_name;
 169     int i = 0, n_dirs = 0;
 170     int ret;
 171     static GHashTable *loaded_modules;
 172
 173     if (!g_module_supported()) {
 174         fprintf(stderr, "Module is not supported by system.\n");
 175         return false;
 176     }
 177
 178     if (!loaded_modules) {
 179         loaded_modules = g_hash_table_new(g_str_hash, g_str_equal);
 180     }
 181
 182     module_name = g_strdup_printf("%s%s", prefix, lib_name);
 183
 184     if (!g_hash_table_add(loaded_modules, module_name)) {
 185         g_free(module_name);
 186         return true;
 187     }
 188
 189     exec_dir = qemu_get_exec_dir();
 190     search_dir = getenv("QEMU_MODULE_DIR");
 191     if (search_dir != NULL) {
 192         dirs[n_dirs++] = g_strdup_printf("%s", search_dir);
 193     }
 194     dirs[n_dirs++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR);
 195     dirs[n_dirs++] = g_strdup_printf("%s/..", exec_dir ? : "");
 196     dirs[n_dirs++] = g_strdup_printf("%s", exec_dir ? : "");
 197     assert(n_dirs <= ARRAY_SIZE(dirs));
 198
 199     g_free(exec_dir);
 200     exec_dir = NULL;
 201
 202     for (i = 0; i < n_dirs; i++) {
 203         fname = g_strdup_printf("%s/%s%s",
 204                 dirs[i], module_name, HOST_DSOSUF);
 205         ret = module_load_file(fname);
 206         g_free(fname);
 207         fname = NULL;
 208         /* Try loading until loaded a module file */
 209         if (!ret) {
 210             success = true;
 211             break;
 212         }
 213     }
 214
 215     if (!success) {
 216         g_hash_table_remove(loaded_modules, module_name);
 217     }
 218
 219     for (i = 0; i < n_dirs; i++) {
 220         g_free(dirs[i]);
 221     }
 222
 223 #endif
 224     return success;
 225 }