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