lib/module.c

   1 /*
   2  * Copyright (c) 2015-16  David Lamparter, for NetDEF, Inc.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #include "config.h"
  18
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <limits.h>
  24 #include <dlfcn.h>
  25
  26 #include "module.h"
  27 #include "memory.h"
  28 #include "version.h"
  29
  30 DEFINE_MTYPE_STATIC(LIB, MODULE_LOADNAME, "Module loading name")
  31 DEFINE_MTYPE_STATIC(LIB, MODULE_LOADARGS, "Module loading arguments")
  32
  33 static struct frrmod_info frrmod_default_info = {
  34         .name = "libfrr",
  35         .version = FRR_VERSION,
  36         .description = "libfrr core module",
  37 };
  38 union _frrmod_runtime_u frrmod_default = {
  39         .r =
  40                 {
  41                         .info = &frrmod_default_info,
  42                         .finished_loading = 1,
  43                 },
  44 };
  45
  46 // if defined(HAVE_SYS_WEAK_ALIAS_ATTRIBUTE)
  47 // union _frrmod_runtime_u _frrmod_this_module
  48 //      __attribute__((weak, alias("frrmod_default")));
  49 // elif defined(HAVE_SYS_WEAK_ALIAS_PRAGMA)
  50 #pragma weak _frrmod_this_module = frrmod_default
  51 // else
  52 // error need weak symbol support
  53 // endif
  54
  55 struct frrmod_runtime *frrmod_list = &frrmod_default.r;
  56 static struct frrmod_runtime **frrmod_last = &frrmod_default.r.next;
  57 static const char *execname = NULL;
  58
  59 void frrmod_init(struct frrmod_runtime *modinfo)
  60 {
  61         modinfo->finished_loading = 1;
  62         *frrmod_last = modinfo;
  63         frrmod_last = &modinfo->next;
  64
  65         execname = modinfo->info->name;
  66 }
  67
  68 struct frrmod_runtime *frrmod_load(const char *spec, const char *dir, char *err,
  69                                    size_t err_len)
  70 {
  71         void *handle = NULL;
  72         char name[PATH_MAX], fullpath[PATH_MAX * 2], *args;
  73         struct frrmod_runtime *rtinfo, **rtinfop;
  74         const struct frrmod_info *info;
  75
  76         snprintf(name, sizeof(name), "%s", spec);
  77         args = strchr(name, ':');
  78         if (args)
  79                 *args++ = '\0';
  80
  81         if (!strchr(name, '/')) {
  82                 if (execname) {
  83                         snprintf(fullpath, sizeof(fullpath), "%s/%s_%s.so", dir,
  84                                  execname, name);
  85                         handle = dlopen(fullpath, RTLD_NOW | RTLD_GLOBAL);
  86                 }
  87                 if (!handle) {
  88                         snprintf(fullpath, sizeof(fullpath), "%s/%s.so", dir,
  89                                  name);
  90                         handle = dlopen(fullpath, RTLD_NOW | RTLD_GLOBAL);
  91                 }
  92         }
  93         if (!handle) {
  94                 snprintf(fullpath, sizeof(fullpath), "%s", name);
  95                 handle = dlopen(fullpath, RTLD_NOW | RTLD_GLOBAL);
  96         }
  97         if (!handle) {
  98                 if (err)
  99                         snprintf(err, err_len,
 100                                  "loading module \"%s\" failed: %s", name,
 101                                  dlerror());
 102                 return NULL;
 103         }
 104
 105         rtinfop = dlsym(handle, "frr_module");
 106         if (!rtinfop) {
 107                 dlclose(handle);
 108                 if (err)
 109                         snprintf(err, err_len,
 110                                  "\"%s\" is not an FRR module: %s", name,
 111                                  dlerror());
 112                 return NULL;
 113         }
 114         rtinfo = *rtinfop;
 115         rtinfo->load_name = XSTRDUP(MTYPE_MODULE_LOADNAME, name);
 116         rtinfo->dl_handle = handle;
 117         if (args)
 118                 rtinfo->load_args = XSTRDUP(MTYPE_MODULE_LOADARGS, args);
 119         info = rtinfo->info;
 120
 121         if (rtinfo->finished_loading) {
 122                 dlclose(handle);
 123                 if (err)
 124                         snprintf(err, err_len, "module \"%s\" already loaded",
 125                                  name);
 126                 goto out_fail;
 127         }
 128
 129         if (info->init && info->init()) {
 130                 dlclose(handle);
 131                 if (err)
 132                         snprintf(err, err_len,
 133                                  "module \"%s\" initialisation failed", name);
 134                 goto out_fail;
 135         }
 136
 137         rtinfo->finished_loading = 1;
 138
 139         *frrmod_last = rtinfo;
 140         frrmod_last = &rtinfo->next;
 141         return rtinfo;
 142
 143 out_fail:
 144         if (rtinfo->load_args)
 145                 XFREE(MTYPE_MODULE_LOADARGS, rtinfo->load_args);
 146         XFREE(MTYPE_MODULE_LOADNAME, rtinfo->load_name);
 147         return NULL;
 148 }
 149
 150 #if 0
 151 void frrmod_unload(struct frrmod_runtime *module)
 152 {
 153 }
 154 #endif