lib/command_py.c

   1 /*
   2  * clippy (CLI preparator in python) wrapper for FRR command_graph
   3  * Copyright (C) 2016-2017  David Lamparter for NetDEF, Inc.
   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
  20 /* note: this wrapper is intended to be used as build-time helper.  while
  21  * it should be generally correct and proper, there may be the occasional
  22  * memory leak or SEGV for things that haven't been well-tested.
  23  */
  24
  25 /* This file is "exempt" from having
  26 #include "config.h"
  27  * as the first include statement because Python.h also does environment
  28  * setup & these trample over each other.
  29  */
  30
  31 #include <Python.h>
  32 #include "structmember.h"
  33 #include <string.h>
  34 #include <stdlib.h>
  35
  36 #include "command_graph.h"
  37 #include "clippy.h"
  38
  39 struct wrap_graph;
  40 static PyObject *graph_to_pyobj(struct wrap_graph *graph,
  41                                 struct graph_node *gn);
  42
  43 /*
  44  * nodes are wrapped as follows:
  45  *  - instances can only be acquired from a graph
  46  *  - the same node will return the same wrapper object (they're buffered
  47  *    through "idx")
  48  *  - a reference is held onto the graph
  49  *  - fields are copied for easy access with PyMemberDef
  50  */
  51 struct wrap_graph_node {
  52         PyObject_HEAD
  53
  54                 bool allowrepeat;
  55         const char *type;
  56
  57         bool deprecated;
  58         bool hidden;
  59         const char *text;
  60         const char *desc;
  61         const char *varname;
  62         long long min, max;
  63
  64         struct graph_node *node;
  65         struct wrap_graph *wgraph;
  66         size_t idx;
  67 };
  68
  69 /*
  70  * graphs are wrapped as follows:
  71  *  - they can only be created by parsing a definition string
  72  *  - there's a table here for the wrapped nodes (nodewrappers), indexed
  73  *    by "idx" (corresponds to node's position in graph's table of nodes)
  74  *  - graphs do NOT hold references to nodes (would be circular)
  75  */
  76 struct wrap_graph {
  77         PyObject_HEAD
  78
  79                 char *definition;
  80         struct graph *graph;
  81         struct wrap_graph_node **nodewrappers;
  82 };
  83
  84 static PyObject *refuse_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
  85 {
  86         PyErr_SetString(PyExc_ValueError,
  87                         "cannot create instances of this type");
  88         return NULL;
  89 }
  90
  91 #define member(name, type)                                                     \
  92         {                                                                      \
  93                 (char *)#name, type, offsetof(struct wrap_graph_node, name),   \
  94                         READONLY, (char *)#name " (" #type ")"                 \
  95         }
  96 static PyMemberDef members_graph_node[] = {
  97         member(allowrepeat, T_BOOL), member(type, T_STRING),
  98         member(deprecated, T_BOOL),  member(hidden, T_BOOL),
  99         member(text, T_STRING),      member(desc, T_STRING),
 100         member(min, T_LONGLONG),     member(max, T_LONGLONG),
 101         member(varname, T_STRING),   {},
 102 };
 103 #undef member
 104
 105 /*
 106  * node.next() -- returns list of all "next" nodes.
 107  * this will include circles if the graph has them.
 108  */
 109 static PyObject *graph_node_next(PyObject *self, PyObject *args)
 110 {
 111         struct wrap_graph_node *wrap = (struct wrap_graph_node *)self;
 112         PyObject *pylist;
 113
 114         if (wrap->node->data
 115             && ((struct cmd_token *)wrap->node->data)->type == END_TKN)
 116                 return PyList_New(0);
 117         pylist = PyList_New(vector_active(wrap->node->to));
 118         for (size_t i = 0; i < vector_active(wrap->node->to); i++) {
 119                 struct graph_node *gn = vector_slot(wrap->node->to, i);
 120                 PyList_SetItem(pylist, i, graph_to_pyobj(wrap->wgraph, gn));
 121         }
 122         return pylist;
 123 };
 124
 125 /*
 126  * node.join() -- return FORK's JOIN node or None
 127  */
 128 static PyObject *graph_node_join(PyObject *self, PyObject *args)
 129 {
 130         struct wrap_graph_node *wrap = (struct wrap_graph_node *)self;
 131
 132         if (!wrap->node->data
 133             || ((struct cmd_token *)wrap->node->data)->type == END_TKN)
 134                 Py_RETURN_NONE;
 135
 136         struct cmd_token *tok = wrap->node->data;
 137         if (tok->type != FORK_TKN)
 138                 Py_RETURN_NONE;
 139
 140         return graph_to_pyobj(wrap->wgraph, tok->forkjoin);
 141 };
 142
 143 static PyMethodDef methods_graph_node[] = {
 144         {"next", graph_node_next, METH_NOARGS, "outbound graph edge list"},
 145         {"join", graph_node_join, METH_NOARGS, "outbound join node"},
 146         {}};
 147
 148 static void graph_node_wrap_free(void *arg)
 149 {
 150         struct wrap_graph_node *wrap = arg;
 151         wrap->wgraph->nodewrappers[wrap->idx] = NULL;
 152         Py_DECREF(wrap->wgraph);
 153 }
 154
 155 static PyTypeObject typeobj_graph_node = {
 156         PyVarObject_HEAD_INIT(NULL, 0).tp_name = "_clippy.GraphNode",
 157         .tp_basicsize = sizeof(struct wrap_graph_node),
 158         .tp_flags = Py_TPFLAGS_DEFAULT,
 159         .tp_doc = "struct graph_node *",
 160         .tp_new = refuse_new,
 161         .tp_free = graph_node_wrap_free,
 162         .tp_members = members_graph_node,
 163         .tp_methods = methods_graph_node,
 164 };
 165
 166 static PyObject *graph_to_pyobj(struct wrap_graph *wgraph,
 167                                 struct graph_node *gn)
 168 {
 169         struct wrap_graph_node *wrap;
 170         size_t i;
 171
 172         for (i = 0; i < vector_active(wgraph->graph->nodes); i++)
 173                 if (vector_slot(wgraph->graph->nodes, i) == gn)
 174                         break;
 175         if (i == vector_active(wgraph->graph->nodes)) {
 176                 PyErr_SetString(PyExc_ValueError, "cannot find node in graph");
 177                 return NULL;
 178         }
 179         if (wgraph->nodewrappers[i]) {
 180                 PyObject *obj = (PyObject *)wgraph->nodewrappers[i];
 181                 Py_INCREF(obj);
 182                 return obj;
 183         }
 184
 185         wrap = (struct wrap_graph_node *)typeobj_graph_node.tp_alloc(
 186                 &typeobj_graph_node, 0);
 187         if (!wrap)
 188                 return NULL;
 189         wgraph->nodewrappers[i] = wrap;
 190         Py_INCREF(wgraph);
 191
 192         wrap->idx = i;
 193         wrap->wgraph = wgraph;
 194         wrap->node = gn;
 195         wrap->type = "NULL";
 196         wrap->allowrepeat = false;
 197         if (gn->data) {
 198                 struct cmd_token *tok = gn->data;
 199                 switch (tok->type) {
 200 #define item(x) case x: wrap->type = #x; break;
 201                         item(WORD_TKN)                // words
 202                                 item(VARIABLE_TKN)    // almost anything
 203                                 item(RANGE_TKN)       // integer range
 204                                 item(IPV4_TKN)  // IPV4 addresses
 205                                 item(IPV4_PREFIX_TKN) // IPV4 network prefixes
 206                                 item(IPV6_TKN)  // IPV6 prefixes
 207                                 item(IPV6_PREFIX_TKN) // IPV6 network prefixes
 208                                 item(MAC_TKN)    // MAC address
 209                                 item(MAC_PREFIX_TKN)  // MAC address with mask
 210
 211                                 /* plumbing types */
 212                                 item(FORK_TKN) item(JOIN_TKN) item(START_TKN)
 213                                         item(END_TKN) default
 214                                 : wrap->type = "???";
 215                 }
 216
 217                 wrap->deprecated = (tok->attr == CMD_ATTR_DEPRECATED);
 218                 wrap->hidden = (tok->attr == CMD_ATTR_HIDDEN);
 219                 wrap->text = tok->text;
 220                 wrap->desc = tok->desc;
 221                 wrap->varname = tok->varname;
 222                 wrap->min = tok->min;
 223                 wrap->max = tok->max;
 224                 wrap->allowrepeat = tok->allowrepeat;
 225         }
 226
 227         return (PyObject *)wrap;
 228 }
 229
 230 #define member(name, type)                                                     \
 231         {                                                                      \
 232                 (char *)#name, type, offsetof(struct wrap_graph, name),        \
 233                         READONLY, (char *)#name " (" #type ")"                 \
 234         }
 235 static PyMemberDef members_graph[] = {
 236         member(definition, T_STRING),
 237         {},
 238 };
 239 #undef member
 240
 241 /* graph.first() - root node */
 242 static PyObject *graph_first(PyObject *self, PyObject *args)
 243 {
 244         struct wrap_graph *gwrap = (struct wrap_graph *)self;
 245         struct graph_node *gn = vector_slot(gwrap->graph->nodes, 0);
 246         return graph_to_pyobj(gwrap, gn);
 247 };
 248
 249 static PyMethodDef methods_graph[] = {
 250         {"first", graph_first, METH_NOARGS, "first graph node"},
 251         {}};
 252
 253 static PyObject *graph_parse(PyTypeObject *type, PyObject *args,
 254                              PyObject *kwds);
 255
 256 static void graph_wrap_free(void *arg)
 257 {
 258         struct wrap_graph *wgraph = arg;
 259
 260         graph_delete_graph(wgraph->graph);
 261         free(wgraph->nodewrappers);
 262         free(wgraph->definition);
 263 }
 264
 265 static PyTypeObject typeobj_graph = {
 266         PyVarObject_HEAD_INIT(NULL, 0).tp_name = "_clippy.Graph",
 267         .tp_basicsize = sizeof(struct wrap_graph),
 268         .tp_flags = Py_TPFLAGS_DEFAULT,
 269         .tp_doc = "struct graph *",
 270         .tp_new = graph_parse,
 271         .tp_free = graph_wrap_free,
 272         .tp_members = members_graph,
 273         .tp_methods = methods_graph,
 274 };
 275
 276 /* top call / entrypoint for python code */
 277 static PyObject *graph_parse(PyTypeObject *type, PyObject *args, PyObject *kwds)
 278 {
 279         const char *def, *doc = NULL;
 280         struct wrap_graph *gwrap;
 281         static const char *kwnames[] = {"cmddef", "doc", NULL};
 282
 283         gwrap = (struct wrap_graph *)typeobj_graph.tp_alloc(&typeobj_graph, 0);
 284         if (!gwrap)
 285                 return NULL;
 286
 287         if (!PyArg_ParseTupleAndKeywords(args, kwds, "s|s", (char **)kwnames,
 288                                          &def, &doc))
 289                 return NULL;
 290
 291         struct graph *graph = graph_new();
 292         struct cmd_token *token = cmd_token_new(START_TKN, 0, NULL, NULL);
 293         graph_new_node(graph, token, (void (*)(void *)) & cmd_token_del);
 294
 295         struct cmd_element cmd = {.string = def, .doc = doc};
 296         cmd_graph_parse(graph, &cmd);
 297         cmd_graph_names(graph);
 298
 299         gwrap->graph = graph;
 300         gwrap->definition = strdup(def);
 301         gwrap->nodewrappers = calloc(vector_active(graph->nodes),
 302                                      sizeof(gwrap->nodewrappers[0]));
 303         return (PyObject *)gwrap;
 304 }
 305
 306 static PyMethodDef clippy_methods[] = {
 307         {"parse", clippy_parse, METH_VARARGS, "Parse a C file"},
 308         {NULL, NULL, 0, NULL}};
 309
 310 #if PY_MAJOR_VERSION >= 3
 311 static struct PyModuleDef pymoddef_clippy = {
 312         PyModuleDef_HEAD_INIT,
 313         "_clippy",
 314         NULL, /* docstring */
 315         -1,
 316         clippy_methods,
 317 };
 318 #define modcreate() PyModule_Create(&pymoddef_clippy)
 319 #define initret(val) return val;
 320 #else
 321 #define modcreate() Py_InitModule("_clippy", clippy_methods)
 322 #define initret(val)                                                           \
 323         do {                                                                   \
 324                 if (!val)                                                      \
 325                         Py_FatalError("initialization failure");               \
 326                 return;                                                        \
 327         } while (0)
 328 #endif
 329
 330 #pragma GCC diagnostic ignored "-Wstrict-aliasing"
 331 PyMODINIT_FUNC command_py_init(void)
 332 {
 333         PyObject *pymod;
 334
 335         if (PyType_Ready(&typeobj_graph_node) < 0)
 336                 initret(NULL);
 337         if (PyType_Ready(&typeobj_graph) < 0)
 338                 initret(NULL);
 339
 340         pymod = modcreate();
 341         if (!pymod)
 342                 initret(NULL);
 343
 344         Py_INCREF(&typeobj_graph_node);
 345         PyModule_AddObject(pymod, "GraphNode", (PyObject *)&typeobj_graph_node);
 346         Py_INCREF(&typeobj_graph);
 347         PyModule_AddObject(pymod, "Graph", (PyObject *)&typeobj_graph);
 348         initret(pymod);
 349 }