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 #include "qemu-common.h"
  18 #ifdef CONFIG_MODULES
  19 #include <gmodule.h>
  20 #endif
  21 #include "qemu/queue.h"
  22 #include "qemu/module.h"
  23
  24 typedef struct ModuleEntry
  25 {
  26     void (*init)(void);
  27     QTAILQ_ENTRY(ModuleEntry) node;
  28     module_init_type type;
  29 } ModuleEntry;
  30
  31 typedef QTAILQ_HEAD(, ModuleEntry) ModuleTypeList;
  32
  33 static ModuleTypeList init_type_list[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     l = find_type(type);
  96
  97     QTAILQ_FOREACH(e, l, node) {
  98         e->init();
  99     }
 100 }
 101
 102 #ifdef CONFIG_MODULES
 103 static int module_load_file(const char *fname)
 104 {
 105     GModule *g_module;
 106     void (*sym)(void);
 107     const char *dsosuf = HOST_DSOSUF;
 108     int len = strlen(fname);
 109     int suf_len = strlen(dsosuf);
 110     ModuleEntry *e, *next;
 111     int ret;
 112
 113     if (len <= suf_len || strcmp(&fname[len - suf_len], dsosuf)) {
 114         /* wrong suffix */
 115         ret = -EINVAL;
 116         goto out;
 117     }
 118     if (access(fname, F_OK)) {
 119         ret = -ENOENT;
 120         goto out;
 121     }
 122
 123     assert(QTAILQ_EMPTY(&dso_init_list));
 124
 125     g_module = g_module_open(fname, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
 126     if (!g_module) {
 127         fprintf(stderr, "Failed to open module: %s\n",
 128                 g_module_error());
 129         ret = -EINVAL;
 130         goto out;
 131     }
 132     if (!g_module_symbol(g_module, DSO_STAMP_FUN_STR, (gpointer *)&sym)) {
 133         fprintf(stderr, "Failed to initialize module: %s\n",
 134                 fname);
 135         /* Print some info if this is a QEMU module (but from different build),
 136          * this will make debugging user problems easier. */
 137         if (g_module_symbol(g_module, "qemu_module_dummy", (gpointer *)&sym)) {
 138             fprintf(stderr,
 139                     "Note: only modules from the same build can be loaded.\n");
 140         }
 141         g_module_close(g_module);
 142         ret = -EINVAL;
 143     } else {
 144         QTAILQ_FOREACH(e, &dso_init_list, node) {
 145             e->init();
 146             register_module_init(e->init, e->type);
 147         }
 148         ret = 0;
 149     }
 150
 151     QTAILQ_FOREACH_SAFE(e, &dso_init_list, node, next) {
 152         QTAILQ_REMOVE(&dso_init_list, e, node);
 153         g_free(e);
 154     }
 155 out:
 156     return ret;
 157 }
 158 #endif
 159
 160 void module_load_one(const char *prefix, const char *lib_name)
 161 {
 162 #ifdef CONFIG_MODULES
 163     char *fname = NULL;
 164     char *exec_dir;
 165     const char *search_dir;
 166     char *dirs[4];
 167     char *module_name;
 168     int i = 0, n_dirs = 0;
 169     int ret;
 170     static GHashTable *loaded_modules;
 171
 172     if (!g_module_supported()) {
 173         fprintf(stderr, "Module is not supported by system.\n");
 174         return;
 175     }
 176
 177     if (!loaded_modules) {
 178         loaded_modules = g_hash_table_new(g_str_hash, g_str_equal);
 179     }
 180
 181     module_name = g_strdup_printf("%s%s", prefix, lib_name);
 182
 183     if (g_hash_table_lookup(loaded_modules, module_name)) {
 184         g_free(module_name);
 185         return;
 186     }
 187     g_hash_table_insert(loaded_modules, module_name, module_name);
 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             break;
 211         }
 212     }
 213
 214     for (i = 0; i < n_dirs; i++) {
 215         g_free(dirs[i]);
 216     }
 217
 218 #endif
 219 }