lib/frrscript.h

   1 /* Scripting foo
   2  * Copyright (C) 2020  NVIDIA Corporation
   3  * Quentin Young
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; either version 2 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19 #ifndef __FRRSCRIPT_H__
  20 #define __FRRSCRIPT_H__
  21
  22 #include <zebra.h>
  23
  24 #ifdef HAVE_SCRIPTING
  25
  26 #include <lua.h>
  27 #include "frrlua.h"
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 typedef void (*encoder_func)(lua_State *, const void *);
  34 typedef void *(*decoder_func)(lua_State *, int);
  35
  36 struct frrscript_codec {
  37         const char *typename;
  38         encoder_func encoder;
  39         decoder_func decoder;
  40 };
  41
  42 struct frrscript {
  43         /* Script name */
  44         char *name;
  45
  46         /* Lua state */
  47         struct lua_State *L;
  48 };
  49
  50 struct frrscript_env {
  51         /* Value type */
  52         const char *typename;
  53
  54         /* Binding name */
  55         const char *name;
  56
  57         /* Value */
  58         const void *val;
  59 };
  60
  61 /*
  62  * Create new FRR script.
  63  */
  64 struct frrscript *frrscript_load(const char *name,
  65                                  int (*load_cb)(struct frrscript *));
  66
  67 /*
  68  * Destroy FRR script.
  69  */
  70 void frrscript_unload(struct frrscript *fs);
  71
  72 /*
  73  * Register a Lua codec for a type.
  74  *
  75  * tname
  76  *    Name of type; e.g., "peer", "ospf_interface", etc. Chosen at will.
  77  *
  78  * codec(s)
  79  *    Function pointer to codec struct. Encoder function should push a Lua
  80  *    table representing the passed argument - which will have the C type
  81  *    associated with the chosen 'tname' to the provided stack. The decoder
  82  *    function should pop a value from the top of the stack and return a heap
  83  *    chunk containing that value. Allocations should be made with MTYPE_TMP.
  84  *
  85  *    If using the plural function variant, pass a NULL-terminated array.
  86  *
  87  */
  88 void frrscript_register_type_codec(struct frrscript_codec *codec);
  89 void frrscript_register_type_codecs(struct frrscript_codec *codecs);
  90
  91 /*
  92  * Initialize scripting subsystem. Call this before anything else.
  93  *
  94  * scriptdir
  95  *    Directory in which to look for scripts
  96  */
  97 void frrscript_init(const char *scriptdir);
  98
  99 #define ENCODE_ARGS(name, value)                                               \
 100         do {                                                                   \
 101                 ENCODE_ARGS_WITH_STATE(L, value);                              \
 102                 lua_setglobal(L, name);                                        \
 103         } while (0)
 104
 105 #define DECODE_ARGS(name, value)                                               \
 106         do {                                                                   \
 107                 lua_getglobal(L, name);                                        \
 108                 DECODE_ARGS_WITH_STATE(L, value)                               \
 109         } while (0)
 110
 111 #define ENCODE_ARGS_WITH_STATE(L, value)                                       \
 112         _Generic((value), \
 113 long long * : lua_pushintegerp,                                 \
 114 struct prefix * : lua_pushprefix,                               \
 115 struct interface * : lua_pushinterface,                         \
 116 struct in_addr * : lua_pushinaddr,                              \
 117 struct in6_addr * : lua_pushin6addr,                            \
 118 union sockunion * : lua_pushsockunion,                          \
 119 time_t * : lua_pushtimet,                                       \
 120 char * : lua_pushstring_wrapper                                 \
 121 )(L, value)
 122
 123 #define DECODE_ARGS_WITH_STATE(L, value) _Generic((value), )(L, value);
 124
 125 /*
 126  * Call script.
 127  *
 128  * fs
 129  *    The script to call; this is obtained from frrscript_load().
 130  *
 131  * env
 132  *    The script's environment. Specify this as an array of frrscript_env.
 133  *
 134  * Returns:
 135  *    0 if the script ran successfully, nonzero otherwise.
 136  */
 137 int _frrscript_call(struct frrscript *fs);
 138
 139 #define frrscript_call(fs, ...)                                                \
 140         ({                                                                     \
 141                 lua_State *L = fs->L;                                          \
 142                 MAP_LISTS(ENCODE_ARGS, ##__VA_ARGS__);                         \
 143                 int ret = _frrscript_call(fs);                                 \
 144                 if (ret == 0) {                                                \
 145                         MAP_LISTS(DECODE_ARGS, ##__VA_ARGS__);                 \
 146                 }                                                              \
 147                 ret;                                                           \
 148         })
 149
 150 /*
 151  * Get result from finished script.
 152  *
 153  * fs
 154  *    The script. This script must have been run already.
 155  *
 156  * result
 157  *    The result to extract from the script.
 158  *    This reuses the frrscript_env type, but only the typename and name fields
 159  *    need to be set. The value is returned directly.
 160  *
 161  * Returns:
 162  *    The script result of the specified name and type, or NULL.
 163  */
 164 void *frrscript_get_result(struct frrscript *fs,
 165                            const struct frrscript_env *result);
 166
 167 #ifdef __cplusplus
 168 }
 169 #endif /* __cplusplus */
 170
 171 #endif /* HAVE_SCRIPTING */
 172
 173 #endif /* __FRRSCRIPT_H__ */