lib/module.h

   1 /*
   2  * Copyright (c) 2015-16  David Lamparter, for NetDEF, Inc.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  17  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  19  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  20  * DEALINGS IN THE SOFTWARE.
  21  */
  22
  23 #ifndef _FRR_MODULE_H
  24 #define _FRR_MODULE_H
  25
  26 #include <stdint.h>
  27 #include <stdbool.h>
  28
  29 #if !defined(__GNUC__)
  30 #error module code needs GCC visibility extensions
  31 #elif __GNUC__ < 4
  32 #error module code needs GCC visibility extensions
  33 #else
  34 # define DSO_PUBLIC __attribute__ ((visibility ("default")))
  35 # define DSO_SELF   __attribute__ ((visibility ("protected")))
  36 # define DSO_LOCAL  __attribute__ ((visibility ("hidden")))
  37 #endif
  38
  39 struct frrmod_runtime;
  40
  41 struct frrmod_info {
  42         /* single-line few-word title */
  43         const char *name;
  44         /* human-readable version number, should not contain spaces */
  45         const char *version;
  46         /* one-paragraph description */
  47         const char *description;
  48
  49         int (*init)(void);
  50 };
  51
  52 /* primary entry point structure to be present in loadable module under
  53  * "_frrmod_this_module" dlsym() name
  54  *
  55  * note space for future extensions is reserved below, so other modules
  56  * (e.g. memory management, hooks) can add fields
  57  *
  58  * const members/info are in frrmod_info.
  59  */
  60 struct frrmod_runtime {
  61         struct frrmod_runtime *next;
  62
  63         const struct frrmod_info *info;
  64         void *dl_handle;
  65         bool finished_loading;
  66
  67         char *load_name;
  68         char *load_args;
  69 };
  70
  71 /* space-reserving foo */
  72 struct _frrmod_runtime_size {
  73         struct frrmod_runtime r;
  74         /* this will barf if frrmod_runtime exceeds 1024 bytes ... */
  75         uint8_t space[1024 - sizeof(struct frrmod_runtime)];
  76 };
  77 union _frrmod_runtime_u {
  78         struct frrmod_runtime r;
  79         struct _frrmod_runtime_size s;
  80 };
  81
  82 extern union _frrmod_runtime_u _frrmod_this_module;
  83 #define THIS_MODULE (&_frrmod_this_module.r)
  84
  85 #define FRR_COREMOD_SETUP(...)                                                 \
  86         static const struct frrmod_info _frrmod_info = {__VA_ARGS__};          \
  87         DSO_LOCAL union _frrmod_runtime_u _frrmod_this_module = {              \
  88                 .r.info = &_frrmod_info,                                       \
  89         };
  90 #define FRR_MODULE_SETUP(...)                                                  \
  91         FRR_COREMOD_SETUP(__VA_ARGS__)                                         \
  92         DSO_SELF struct frrmod_runtime *frr_module = &_frrmod_this_module.r;
  93
  94 extern struct frrmod_runtime *frrmod_list;
  95
  96 extern void frrmod_init(struct frrmod_runtime *modinfo);
  97 extern struct frrmod_runtime *frrmod_load(const char *spec, const char *dir,
  98                                           char *err, size_t err_len);
  99 #if 0
 100 /* not implemented yet */
 101 extern void frrmod_unload(struct frrmod_runtime *module);
 102 #endif
 103
 104 #endif /* _FRR_MODULE_H */