lib/module.h

   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 #ifndef _FRR_MODULE_H
  18 #define _FRR_MODULE_H
  19
  20 #include <stdint.h>
  21 #include <stdbool.h>
  22
  23 #ifdef __cplusplus
  24 extern "C" {
  25 #endif
  26
  27 #if !defined(__GNUC__)
  28 #error module code needs GCC visibility extensions
  29 #elif __GNUC__ < 4
  30 #error module code needs GCC visibility extensions
  31 #else
  32 # define DSO_PUBLIC __attribute__ ((visibility ("default")))
  33 # define DSO_SELF   __attribute__ ((visibility ("protected")))
  34 # define DSO_LOCAL  __attribute__ ((visibility ("hidden")))
  35 #endif
  36
  37 struct frrmod_runtime;
  38
  39 struct frrmod_info {
  40         /* single-line few-word title */
  41         const char *name;
  42         /* human-readable version number, should not contain spaces */
  43         const char *version;
  44         /* one-paragraph description */
  45         const char *description;
  46
  47         int (*init)(void);
  48 };
  49
  50 /* primary entry point structure to be present in loadable module under
  51  * "_frrmod_this_module" dlsym() name
  52  *
  53  * note space for future extensions is reserved below, so other modules
  54  * (e.g. memory management, hooks) can add fields
  55  *
  56  * const members/info are in frrmod_info.
  57  */
  58 struct frrmod_runtime {
  59         struct frrmod_runtime *next;
  60
  61         const struct frrmod_info *info;
  62         void *dl_handle;
  63         bool finished_loading;
  64
  65         char *load_name;
  66         char *load_args;
  67 };
  68
  69 /* space-reserving foo */
  70 struct _frrmod_runtime_size {
  71         struct frrmod_runtime r;
  72         /* this will barf if frrmod_runtime exceeds 1024 bytes ... */
  73         uint8_t space[1024 - sizeof(struct frrmod_runtime)];
  74 };
  75 union _frrmod_runtime_u {
  76         struct frrmod_runtime r;
  77         struct _frrmod_runtime_size s;
  78 };
  79
  80 extern union _frrmod_runtime_u _frrmod_this_module;
  81 #define THIS_MODULE (&_frrmod_this_module.r)
  82
  83 #define FRR_COREMOD_SETUP(...)                                                 \
  84         static const struct frrmod_info _frrmod_info = {__VA_ARGS__};          \
  85         DSO_LOCAL union _frrmod_runtime_u _frrmod_this_module = {{             \
  86                 NULL,                                                          \
  87                 &_frrmod_info,                                                 \
  88         }};
  89 #define FRR_MODULE_SETUP(...)                                                  \
  90         FRR_COREMOD_SETUP(__VA_ARGS__)                                         \
  91         DSO_SELF struct frrmod_runtime *frr_module = &_frrmod_this_module.r;
  92
  93 extern struct frrmod_runtime *frrmod_list;
  94
  95 extern void frrmod_init(struct frrmod_runtime *modinfo);
  96 extern struct frrmod_runtime *frrmod_load(const char *spec, const char *dir,
  97                                           char *err, size_t err_len);
  98 #if 0
  99 /* not implemented yet */
 100 extern void frrmod_unload(struct frrmod_runtime *module);
 101 #endif
 102
 103 #ifdef __cplusplus
 104 }
 105 #endif
 106
 107 #endif /* _FRR_MODULE_H */