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 static bool modules_init_done[MODULE_INIT_MAX];
  34
  35 static ModuleTypeList dso_init_list;
  36
  37 static void init_lists(void)
  38 {
  39     static int inited;
  40     int i;
  41
  42     if (inited) {
  43         return;
  44     }
  45
  46     for (i = 0; i < MODULE_INIT_MAX; i++) {
  47         QTAILQ_INIT(&init_type_list[i]);
  48     }
  49
  50     QTAILQ_INIT(&dso_init_list);
  51
  52     inited = 1;
  53 }
  54
  55
  56 static ModuleTypeList *find_type(module_init_type type)
  57 {
  58     init_lists();
  59
  60     return &init_type_list[type];
  61 }
  62
  63 void register_module_init(void (*fn)(void), module_init_type type)
  64 {
  65     ModuleEntry *e;
  66     ModuleTypeList *l;
  67
  68     e = g_malloc0(sizeof(*e));
  69     e->init = fn;
  70     e->type = type;
  71
  72     l = find_type(type);
  73
  74     QTAILQ_INSERT_TAIL(l, e, node);
  75 }
  76
  77 void register_dso_module_init(void (*fn)(void), module_init_type type)
  78 {
  79     ModuleEntry *e;
  80
  81     init_lists();
  82
  83     e = g_malloc0(sizeof(*e));
  84     e->init = fn;
  85     e->type = type;
  86
  87     QTAILQ_INSERT_TAIL(&dso_init_list, e, node);
  88 }
  89
  90 void module_call_init(module_init_type type)
  91 {
  92     ModuleTypeList *l;
  93     ModuleEntry *e;
  94
  95     if (modules_init_done[type]) {
  96         return;
  97     }
  98
  99     l = find_type(type);
 100
 101     QTAILQ_FOREACH(e, l, node) {
 102         e->init();
 103     }
 104
 105     modules_init_done[type] = true;
 106 }
 107
 108 #ifdef CONFIG_MODULES
 109 static int module_load_file(const char *fname)
 110 {
 111     GModule *g_module;
 112     void (*sym)(void);
 113     const char *dsosuf = HOST_DSOSUF;
 114     int len = strlen(fname);
 115     int suf_len = strlen(dsosuf);
 116     ModuleEntry *e, *next;
 117     int ret;
 118
 119     if (len <= suf_len || strcmp(&fname[len - suf_len], dsosuf)) {
 120         /* wrong suffix */
 121         ret = -EINVAL;
 122         goto out;
 123     }
 124     if (access(fname, F_OK)) {
 125         ret = -ENOENT;
 126         goto out;
 127     }
 128
 129     assert(QTAILQ_EMPTY(&dso_init_list));
 130
 131     g_module = g_module_open(fname, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
 132     if (!g_module) {
 133         fprintf(stderr, "Failed to open module: %s\n",
 134                 g_module_error());
 135         ret = -EINVAL;
 136         goto out;
 137     }
 138     if (!g_module_symbol(g_module, DSO_STAMP_FUN_STR, (gpointer *)&sym)) {
 139         fprintf(stderr, "Failed to initialize module: %s\n",
 140                 fname);
 141         /* Print some info if this is a QEMU module (but from different build),
 142          * this will make debugging user problems easier. */
 143         if (g_module_symbol(g_module, "qemu_module_dummy", (gpointer *)&sym)) {
 144             fprintf(stderr,
 145                     "Note: only modules from the same build can be loaded.\n");
 146         }
 147         g_module_close(g_module);
 148         ret = -EINVAL;
 149     } else {
 150         QTAILQ_FOREACH(e, &dso_init_list, node) {
 151             e->init();
 152             register_module_init(e->init, e->type);
 153         }
 154         ret = 0;
 155     }
 156
 157     QTAILQ_FOREACH_SAFE(e, &dso_init_list, node, next) {
 158         QTAILQ_REMOVE(&dso_init_list, e, node);
 159         g_free(e);
 160     }
 161 out:
 162     return ret;
 163 }
 164 #endif
 165
 166 bool module_load_one(const char *prefix, const char *lib_name)
 167 {
 168     bool success = false;
 169
 170 #ifdef CONFIG_MODULES
 171     char *fname = NULL;
 172     char *exec_dir;
 173     const char *search_dir;
 174     char *dirs[4];
 175     char *module_name;
 176     int i = 0, n_dirs = 0;
 177     int ret;
 178     static GHashTable *loaded_modules;
 179
 180     if (!g_module_supported()) {
 181         fprintf(stderr, "Module is not supported by system.\n");
 182         return false;
 183     }
 184
 185     if (!loaded_modules) {
 186         loaded_modules = g_hash_table_new(g_str_hash, g_str_equal);
 187     }
 188
 189     module_name = g_strdup_printf("%s%s", prefix, lib_name);
 190
 191     if (!g_hash_table_add(loaded_modules, module_name)) {
 192         g_free(module_name);
 193         return true;
 194     }
 195
 196     exec_dir = qemu_get_exec_dir();
 197     search_dir = getenv("QEMU_MODULE_DIR");
 198     if (search_dir != NULL) {
 199         dirs[n_dirs++] = g_strdup_printf("%s", search_dir);
 200     }
 201     dirs[n_dirs++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR);
 202     dirs[n_dirs++] = g_strdup_printf("%s/..", exec_dir ? : "");
 203     dirs[n_dirs++] = g_strdup_printf("%s", exec_dir ? : "");
 204     assert(n_dirs <= ARRAY_SIZE(dirs));
 205
 206     g_free(exec_dir);
 207     exec_dir = NULL;
 208
 209     for (i = 0; i < n_dirs; i++) {
 210         fname = g_strdup_printf("%s/%s%s",
 211                 dirs[i], module_name, HOST_DSOSUF);
 212         ret = module_load_file(fname);
 213         g_free(fname);
 214         fname = NULL;
 215         /* Try loading until loaded a module file */
 216         if (!ret) {
 217             success = true;
 218             break;
 219         }
 220     }
 221
 222     if (!success) {
 223         g_hash_table_remove(loaded_modules, module_name);
 224         g_free(module_name);
 225     }
 226
 227     for (i = 0; i < n_dirs; i++) {
 228         g_free(dirs[i]);
 229     }
 230
 231 #endif
 232     return success;
 233 }