src/frontend/grammar.y

   1 /*
   2  * SysDB - src/frontend/grammar.y
   3  * Copyright (C) 2013 Sebastian 'tokkee' Harl <sh@tokkee.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  18  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
  19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 %{
  29
  30 #include "frontend/connection-private.h"
  31 #include "frontend/parser.h"
  32 #include "frontend/grammar.h"
  33
  34 #include "core/store.h"
  35 #include "core/store-private.h"
  36
  37 #include "utils/error.h"
  38 #include "utils/llist.h"
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42
  43 int
  44 sdb_fe_yylex(YYSTYPE *yylval, YYLTYPE *yylloc, sdb_fe_yyscan_t yyscanner);
  45
  46 sdb_fe_yyextra_t *
  47 sdb_fe_yyget_extra(sdb_fe_yyscan_t scanner);
  48
  49 void
  50 sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg);
  51
  52 /* quick access to the current parse tree */
  53 #define pt sdb_fe_yyget_extra(scanner)->parsetree
  54
  55 /* quick access to the parser mode */
  56 #define parser_mode sdb_fe_yyget_extra(scanner)->mode
  57
  58 %}
  59
  60 %pure-parser
  61 %lex-param {sdb_fe_yyscan_t scanner}
  62 %parse-param {sdb_fe_yyscan_t scanner}
  63 %locations
  64 %error-verbose
  65 %expect 0
  66 %name-prefix="sdb_fe_yy"
  67
  68 %union {
  69         char *str;
  70
  71         sdb_llist_t     *list;
  72         sdb_conn_node_t *node;
  73
  74         sdb_store_matcher_t *m;
  75 }
  76
  77 %start statements
  78
  79 %token SCANNER_ERROR
  80
  81 %token AND OR WHERE
  82
  83 %token CMP_EQUAL CMP_REGEX
  84
  85 %token <str> IDENTIFIER STRING
  86 %token <node> FETCH LIST LOOKUP
  87
  88 /* Precedence (lowest first): */
  89 %left OR
  90 %left AND
  91 %left CMP_EQUAL
  92 %left CMP_REGEX
  93
  94 %type <list> statements
  95 %type <node> statement
  96         fetch_statement
  97         list_statement
  98         lookup_statement
  99         expression
 100
 101 %type <m> matcher
 102         compare_matcher
 103
 104 %%
 105
 106 statements:
 107         statements ';' statement
 108                 {
 109                         /* only accept this in default parse mode */
 110                         if (parser_mode != SDB_PARSE_DEFAULT) {
 111                                 sdb_fe_yyerror(&yylloc, scanner,
 112                                                 YY_("syntax error, unexpected statement, "
 113                                                         "expecting expression"));
 114                                 YYABORT;
 115                         }
 116
 117                         if ($3) {
 118                                 sdb_llist_append(pt, SDB_OBJ($3));
 119                                 sdb_object_deref(SDB_OBJ($3));
 120                         }
 121                 }
 122         |
 123         statement
 124                 {
 125                         /* only accept this in default parse mode */
 126                         if (parser_mode != SDB_PARSE_DEFAULT) {
 127                                 sdb_fe_yyerror(&yylloc, scanner,
 128                                                 YY_("syntax error, unexpected statement, "
 129                                                         "expecting expression"));
 130                                 YYABORT;
 131                         }
 132
 133                         if ($1) {
 134                                 sdb_llist_append(pt, SDB_OBJ($1));
 135                                 sdb_object_deref(SDB_OBJ($1));
 136                         }
 137                 }
 138         |
 139         expression
 140                 {
 141                         /* only accept this in expression parse mode */
 142                         if (! (parser_mode & SDB_PARSE_EXPR)) {
 143                                 sdb_fe_yyerror(&yylloc, scanner,
 144                                                 YY_("syntax error, unexpected expression, "
 145                                                         "expecting statement"));
 146                                 YYABORT;
 147                         }
 148
 149                         if ($1) {
 150                                 sdb_llist_append(pt, SDB_OBJ($1));
 151                                 sdb_object_deref(SDB_OBJ($1));
 152                         }
 153                 }
 154         ;
 155
 156 statement:
 157         fetch_statement
 158         |
 159         list_statement
 160         |
 161         lookup_statement
 162         |
 163         /* empty */
 164                 {
 165                         $$ = NULL;
 166                 }
 167         ;
 168
 169 /*
 170  * FETCH <hostname>;
 171  *
 172  * Retrieve detailed information about a single host.
 173  */
 174 fetch_statement:
 175         FETCH STRING
 176                 {
 177                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 178                                                 conn_fetch_t, conn_fetch_destroy));
 179                         CONN_FETCH($$)->name = strdup($2);
 180                         $$->cmd = CONNECTION_FETCH;
 181                         free($2); $2 = NULL;
 182                 }
 183         ;
 184
 185 /*
 186  * LIST;
 187  *
 188  * Returns a list of all hosts in the store.
 189  */
 190 list_statement:
 191         LIST
 192                 {
 193                         $$ = SDB_CONN_NODE(sdb_object_create_T(/* name = */ NULL,
 194                                                 sdb_conn_node_t));
 195                         $$->cmd = CONNECTION_LIST;
 196                 }
 197         ;
 198
 199 /*
 200  * LOOKUP <type> WHERE <expression>;
 201  *
 202  * Returns detailed information about <type> matching expression.
 203  */
 204 lookup_statement:
 205         LOOKUP IDENTIFIER WHERE expression
 206                 {
 207                         /* TODO: support other types as well */
 208                         if (strcasecmp($2, "hosts")) {
 209                                 char errmsg[strlen($2) + 32];
 210                                 snprintf(errmsg, sizeof(errmsg),
 211                                                 YY_("unknown table %s"), $2);
 212                                 sdb_fe_yyerror(&yylloc, scanner, errmsg);
 213                                 YYABORT;
 214                         }
 215
 216                         $$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
 217                                                 conn_lookup_t, conn_lookup_destroy));
 218                         CONN_LOOKUP($$)->matcher = CONN_MATCHER($4);
 219                         $$->cmd = CONNECTION_LOOKUP;
 220                         free($2); $2 = NULL;
 221                 }
 222         ;
 223
 224 expression:
 225         matcher
 226                 {
 227                         sdb_store_matcher_t *m = $1;
 228                         if (! m) {
 229                                 /* TODO: improve error reporting */
 230                                 sdb_fe_yyerror(&yylloc, scanner,
 231                                                 YY_("syntax error, invalid expression"));
 232                                 YYABORT;
 233                         }
 234
 235                         $$ = SDB_CONN_NODE(sdb_object_create_T(/* name = */ NULL,
 236                                                 conn_node_matcher_t));
 237                         $$->cmd = CONNECTION_EXPR;
 238
 239                         if ((M(m)->type == MATCHER_HOST)
 240                                         || (M(m)->type == MATCHER_AND)
 241                                         || (M(m)->type == MATCHER_OR))
 242                                 CONN_MATCHER($$)->matcher = m;
 243                         else if (M(m)->type == MATCHER_SERVICE)
 244                                 CONN_MATCHER($$)->matcher = sdb_store_host_matcher(NULL,
 245                                                 /* name_re = */ NULL, /* service = */ m,
 246                                                 /* attr = */ NULL);
 247                         else if (M(m)->type == MATCHER_ATTR)
 248                                 CONN_MATCHER($$)->matcher = sdb_store_host_matcher(NULL,
 249                                                 /* name_re = */ NULL, /* service = */ NULL,
 250                                                 /* attr = */ m);
 251                         else {
 252                                 char errbuf[1024];
 253                                 snprintf(errbuf, sizeof(errbuf),
 254                                                 YY_("syntax error, unexpected matcher type %d"),
 255                                                 M(m)->type);
 256                                 sdb_fe_yyerror(&yylloc, scanner, errbuf);
 257                                 YYABORT;
 258                         }
 259                 }
 260         ;
 261
 262 matcher:
 263         matcher AND matcher
 264                 {
 265                         $$ = sdb_store_con_matcher($1, $3);
 266                 }
 267         |
 268         matcher OR matcher
 269                 {
 270                         $$ = sdb_store_dis_matcher($1, $3);
 271                 }
 272         |
 273         compare_matcher
 274                 {
 275                         $$ = $1;
 276                 }
 277         ;
 278
 279 /*
 280  * <object_type>.<object_attr> <op> <value>
 281  *
 282  * Parse matchers comparing object attributes with a value.
 283  */
 284 compare_matcher:
 285         IDENTIFIER '.' IDENTIFIER CMP_EQUAL STRING
 286                 {
 287                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=", $5);
 288                         /* TODO: simplify memory management in the parser */
 289                         free($1); $1 = NULL;
 290                         free($3); $3 = NULL;
 291                         free($5); $5 = NULL;
 292                 }
 293         |
 294         IDENTIFIER '.' IDENTIFIER CMP_REGEX STRING
 295                 {
 296                         $$ = sdb_store_matcher_parse_cmp($1, $3, "=~", $5);
 297                         free($1); $1 = NULL;
 298                         free($3); $3 = NULL;
 299                         free($5); $5 = NULL;
 300                 }
 301         ;
 302
 303 %%
 304
 305 void
 306 sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg)
 307 {
 308         sdb_log(SDB_LOG_ERR, "frontend: parse error: %s", msg);
 309 } /* sdb_fe_yyerror */
 310
 311 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 312