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