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 <stdlib.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     ModuleTypeList *l;
  59
  60     init_lists();
  61
  62     l = &init_type_list[type];
  63
  64     return l;
  65 }
  66
  67 void register_module_init(void (*fn)(void), module_init_type type)
  68 {
  69     ModuleEntry *e;
  70     ModuleTypeList *l;
  71
  72     e = g_malloc0(sizeof(*e));
  73     e->init = fn;
  74     e->type = type;
  75
  76     l = find_type(type);
  77
  78     QTAILQ_INSERT_TAIL(l, e, node);
  79 }
  80
  81 void register_dso_module_init(void (*fn)(void), module_init_type type)
  82 {
  83     ModuleEntry *e;
  84
  85     init_lists();
  86
  87     e = g_malloc0(sizeof(*e));
  88     e->init = fn;
  89     e->type = type;
  90
  91     QTAILQ_INSERT_TAIL(&dso_init_list, e, node);
  92 }
  93
  94 static void module_load(module_init_type type);
  95
  96 void module_call_init(module_init_type type)
  97 {
  98     ModuleTypeList *l;
  99     ModuleEntry *e;
 100
 101     module_load(type);
 102     l = find_type(type);
 103
 104     QTAILQ_FOREACH(e, l, node) {
 105         e->init();
 106     }
 107 }
 108
 109 #ifdef CONFIG_MODULES
 110 static int module_load_file(const char *fname)
 111 {
 112     GModule *g_module;
 113     void (*sym)(void);
 114     const char *dsosuf = HOST_DSOSUF;
 115     int len = strlen(fname);
 116     int suf_len = strlen(dsosuf);
 117     ModuleEntry *e, *next;
 118     int ret;
 119
 120     if (len <= suf_len || strcmp(&fname[len - suf_len], dsosuf)) {
 121         /* wrong suffix */
 122         ret = -EINVAL;
 123         goto out;
 124     }
 125     if (access(fname, F_OK)) {
 126         ret = -ENOENT;
 127         goto out;
 128     }
 129
 130     assert(QTAILQ_EMPTY(&dso_init_list));
 131
 132     g_module = g_module_open(fname, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
 133     if (!g_module) {
 134         fprintf(stderr, "Failed to open module: %s\n",
 135                 g_module_error());
 136         ret = -EINVAL;
 137         goto out;
 138     }
 139     if (!g_module_symbol(g_module, DSO_STAMP_FUN_STR, (gpointer *)&sym)) {
 140         fprintf(stderr, "Failed to initialize module: %s\n",
 141                 fname);
 142         /* Print some info if this is a QEMU module (but from different build),
 143          * this will make debugging user problems easier. */
 144         if (g_module_symbol(g_module, "qemu_module_dummy", (gpointer *)&sym)) {
 145             fprintf(stderr,
 146                     "Note: only modules from the same build can be loaded.\n");
 147         }
 148         g_module_close(g_module);
 149         ret = -EINVAL;
 150     } else {
 151         QTAILQ_FOREACH(e, &dso_init_list, node) {
 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 static void module_load(module_init_type type)
 167 {
 168 #ifdef CONFIG_MODULES
 169     char *fname = NULL;
 170     const char **mp;
 171     static const char *block_modules[] = {
 172         CONFIG_BLOCK_MODULES
 173     };
 174     char *exec_dir;
 175     char *dirs[3];
 176     int i = 0;
 177     int ret;
 178
 179     if (!g_module_supported()) {
 180         fprintf(stderr, "Module is not supported by system.\n");
 181         return;
 182     }
 183
 184     switch (type) {
 185     case MODULE_INIT_BLOCK:
 186         mp = block_modules;
 187         break;
 188     default:
 189         /* no other types have dynamic modules for now*/
 190         return;
 191     }
 192
 193     exec_dir = qemu_get_exec_dir();
 194     dirs[i++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR);
 195     dirs[i++] = g_strdup_printf("%s/..", exec_dir ? : "");
 196     dirs[i++] = g_strdup_printf("%s", exec_dir ? : "");
 197     assert(i == ARRAY_SIZE(dirs));
 198     g_free(exec_dir);
 199     exec_dir = NULL;
 200
 201     for ( ; *mp; mp++) {
 202         for (i = 0; i < ARRAY_SIZE(dirs); i++) {
 203             fname = g_strdup_printf("%s/%s%s", dirs[i], *mp, HOST_DSOSUF);
 204             ret = module_load_file(fname);
 205             g_free(fname);
 206             fname = NULL;
 207             /* Try loading until loaded a module file */
 208             if (!ret) {
 209                 break;
 210             }
 211         }
 212     }
 213
 214     for (i = 0; i < ARRAY_SIZE(dirs); i++) {
 215         g_free(dirs[i]);
 216     }
 217
 218 #endif
 219 }