bin/sh/arith_yacc.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2007
   5  *      Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Kenneth Almquist.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 __FBSDID("$FreeBSD$");
  37
  38 #include <limits.h>
  39 #include <errno.h>
  40 #include <inttypes.h>
  41 #include <stdlib.h>
  42 #include <stdio.h>
  43 #include "arith.h"
  44 #include "arith_yacc.h"
  45 #include "expand.h"
  46 #include "shell.h"
  47 #include "error.h"
  48 #include "memalloc.h"
  49 #include "output.h"
  50 #include "options.h"
  51 #include "var.h"
  52
  53 #if ARITH_BOR + 11 != ARITH_BORASS || ARITH_ASS + 11 != ARITH_EQ
  54 #error Arithmetic tokens are out of order.
  55 #endif
  56
  57 static const char *arith_startbuf;
  58
  59 const char *arith_buf;
  60 union yystype yylval;
  61
  62 static int last_token;
  63
  64 #define ARITH_PRECEDENCE(op, prec) [op - ARITH_BINOP_MIN] = prec
  65
  66 static const char prec[ARITH_BINOP_MAX - ARITH_BINOP_MIN] = {
  67         ARITH_PRECEDENCE(ARITH_MUL, 0),
  68         ARITH_PRECEDENCE(ARITH_DIV, 0),
  69         ARITH_PRECEDENCE(ARITH_REM, 0),
  70         ARITH_PRECEDENCE(ARITH_ADD, 1),
  71         ARITH_PRECEDENCE(ARITH_SUB, 1),
  72         ARITH_PRECEDENCE(ARITH_LSHIFT, 2),
  73         ARITH_PRECEDENCE(ARITH_RSHIFT, 2),
  74         ARITH_PRECEDENCE(ARITH_LT, 3),
  75         ARITH_PRECEDENCE(ARITH_LE, 3),
  76         ARITH_PRECEDENCE(ARITH_GT, 3),
  77         ARITH_PRECEDENCE(ARITH_GE, 3),
  78         ARITH_PRECEDENCE(ARITH_EQ, 4),
  79         ARITH_PRECEDENCE(ARITH_NE, 4),
  80         ARITH_PRECEDENCE(ARITH_BAND, 5),
  81         ARITH_PRECEDENCE(ARITH_BXOR, 6),
  82         ARITH_PRECEDENCE(ARITH_BOR, 7),
  83 };
  84
  85 #define ARITH_MAX_PREC 8
  86
  87 int letcmd(int, char **);
  88
  89 static __dead2 void yyerror(const char *s)
  90 {
  91         error("arithmetic expression: %s: \"%s\"", s, arith_startbuf);
  92         /* NOTREACHED */
  93 }
  94
  95 static arith_t arith_lookupvarint(char *varname)
  96 {
  97         const char *str;
  98         char *p;
  99         arith_t result;
 100
 101         str = lookupvar(varname);
 102         if (uflag && str == NULL)
 103                 yyerror("variable not set");
 104         if (str == NULL || *str == '\0')
 105                 str = "0";
 106         errno = 0;
 107         result = strtoarith_t(str, &p, 0);
 108         if (errno != 0 || *p != '\0')
 109                 yyerror("variable conversion error");
 110         return result;
 111 }
 112
 113 static inline int arith_prec(int op)
 114 {
 115         return prec[op - ARITH_BINOP_MIN];
 116 }
 117
 118 static inline int higher_prec(int op1, int op2)
 119 {
 120         return arith_prec(op1) < arith_prec(op2);
 121 }
 122
 123 static arith_t do_binop(int op, arith_t a, arith_t b)
 124 {
 125
 126         switch (op) {
 127         default:
 128         case ARITH_REM:
 129         case ARITH_DIV:
 130                 if (!b)
 131                         yyerror("division by zero");
 132                 if (a == ARITH_MIN && b == -1)
 133                         yyerror("divide error");
 134                 return op == ARITH_REM ? a % b : a / b;
 135         case ARITH_MUL:
 136                 return (uintmax_t)a * (uintmax_t)b;
 137         case ARITH_ADD:
 138                 return (uintmax_t)a + (uintmax_t)b;
 139         case ARITH_SUB:
 140                 return (uintmax_t)a - (uintmax_t)b;
 141         case ARITH_LSHIFT:
 142                 return (uintmax_t)a << (b & (sizeof(uintmax_t) * CHAR_BIT - 1));
 143         case ARITH_RSHIFT:
 144                 return a >> (b & (sizeof(uintmax_t) * CHAR_BIT - 1));
 145         case ARITH_LT:
 146                 return a < b;
 147         case ARITH_LE:
 148                 return a <= b;
 149         case ARITH_GT:
 150                 return a > b;
 151         case ARITH_GE:
 152                 return a >= b;
 153         case ARITH_EQ:
 154                 return a == b;
 155         case ARITH_NE:
 156                 return a != b;
 157         case ARITH_BAND:
 158                 return a & b;
 159         case ARITH_BXOR:
 160                 return a ^ b;
 161         case ARITH_BOR:
 162                 return a | b;
 163         }
 164 }
 165
 166 static arith_t assignment(int var, int noeval);
 167
 168 static arith_t primary(int token, union yystype *val, int op, int noeval)
 169 {
 170         arith_t result;
 171
 172 again:
 173         switch (token) {
 174         case ARITH_LPAREN:
 175                 result = assignment(op, noeval);
 176                 if (last_token != ARITH_RPAREN)
 177                         yyerror("expecting ')'");
 178                 last_token = yylex();
 179                 return result;
 180         case ARITH_NUM:
 181                 last_token = op;
 182                 return val->val;
 183         case ARITH_VAR:
 184                 last_token = op;
 185                 return noeval ? val->val : arith_lookupvarint(val->name);
 186         case ARITH_ADD:
 187                 token = op;
 188                 *val = yylval;
 189                 op = yylex();
 190                 goto again;
 191         case ARITH_SUB:
 192                 *val = yylval;
 193                 return -primary(op, val, yylex(), noeval);
 194         case ARITH_NOT:
 195                 *val = yylval;
 196                 return !primary(op, val, yylex(), noeval);
 197         case ARITH_BNOT:
 198                 *val = yylval;
 199                 return ~primary(op, val, yylex(), noeval);
 200         default:
 201                 yyerror("expecting primary");
 202         }
 203 }
 204
 205 static arith_t binop2(arith_t a, int op, int precedence, int noeval)
 206 {
 207         for (;;) {
 208                 union yystype val;
 209                 arith_t b;
 210                 int op2;
 211                 int token;
 212
 213                 token = yylex();
 214                 val = yylval;
 215
 216                 b = primary(token, &val, yylex(), noeval);
 217
 218                 op2 = last_token;
 219                 if (op2 >= ARITH_BINOP_MIN && op2 < ARITH_BINOP_MAX &&
 220                     higher_prec(op2, op)) {
 221                         b = binop2(b, op2, arith_prec(op), noeval);
 222                         op2 = last_token;
 223                 }
 224
 225                 a = noeval ? b : do_binop(op, a, b);
 226
 227                 if (op2 < ARITH_BINOP_MIN || op2 >= ARITH_BINOP_MAX ||
 228                     arith_prec(op2) >= precedence)
 229                         return a;
 230
 231                 op = op2;
 232         }
 233 }
 234
 235 static arith_t binop(int token, union yystype *val, int op, int noeval)
 236 {
 237         arith_t a = primary(token, val, op, noeval);
 238
 239         op = last_token;
 240         if (op < ARITH_BINOP_MIN || op >= ARITH_BINOP_MAX)
 241                 return a;
 242
 243         return binop2(a, op, ARITH_MAX_PREC, noeval);
 244 }
 245
 246 static arith_t and(int token, union yystype *val, int op, int noeval)
 247 {
 248         arith_t a = binop(token, val, op, noeval);
 249         arith_t b;
 250
 251         op = last_token;
 252         if (op != ARITH_AND)
 253                 return a;
 254
 255         token = yylex();
 256         *val = yylval;
 257
 258         b = and(token, val, yylex(), noeval | !a);
 259
 260         return a && b;
 261 }
 262
 263 static arith_t or(int token, union yystype *val, int op, int noeval)
 264 {
 265         arith_t a = and(token, val, op, noeval);
 266         arith_t b;
 267
 268         op = last_token;
 269         if (op != ARITH_OR)
 270                 return a;
 271
 272         token = yylex();
 273         *val = yylval;
 274
 275         b = or(token, val, yylex(), noeval | !!a);
 276
 277         return a || b;
 278 }
 279
 280 static arith_t cond(int token, union yystype *val, int op, int noeval)
 281 {
 282         arith_t a = or(token, val, op, noeval);
 283         arith_t b;
 284         arith_t c;
 285
 286         if (last_token != ARITH_QMARK)
 287                 return a;
 288
 289         b = assignment(yylex(), noeval | !a);
 290
 291         if (last_token != ARITH_COLON)
 292                 yyerror("expecting ':'");
 293
 294         token = yylex();
 295         *val = yylval;
 296
 297         c = cond(token, val, yylex(), noeval | !!a);
 298
 299         return a ? b : c;
 300 }
 301
 302 static arith_t assignment(int var, int noeval)
 303 {
 304         union yystype val = yylval;
 305         int op = yylex();
 306         arith_t result;
 307         char sresult[DIGITS(result) + 1];
 308
 309         if (var != ARITH_VAR)
 310                 return cond(var, &val, op, noeval);
 311
 312         if (op != ARITH_ASS && (op < ARITH_ASS_MIN || op >= ARITH_ASS_MAX))
 313                 return cond(var, &val, op, noeval);
 314
 315         result = assignment(yylex(), noeval);
 316         if (noeval)
 317                 return result;
 318
 319         if (op != ARITH_ASS)
 320                 result = do_binop(op - 11, arith_lookupvarint(val.name), result);
 321         snprintf(sresult, sizeof(sresult), ARITH_FORMAT_STR, result);
 322         setvar(val.name, sresult, 0);
 323         return result;
 324 }
 325
 326 arith_t arith(const char *s)
 327 {
 328         struct stackmark smark;
 329         arith_t result;
 330
 331         setstackmark(&smark);
 332
 333         arith_buf = arith_startbuf = s;
 334
 335         result = assignment(yylex(), 0);
 336
 337         if (last_token)
 338                 yyerror("expecting EOF");
 339
 340         popstackmark(&smark);
 341
 342         return result;
 343 }
 344
 345 /*
 346  *  The exp(1) builtin.
 347  */
 348 int
 349 letcmd(int argc, char **argv)
 350 {
 351         const char *p;
 352         char *concat;
 353         char **ap;
 354         arith_t i;
 355
 356         if (argc > 1) {
 357                 p = argv[1];
 358                 if (argc > 2) {
 359                         /*
 360                          * Concatenate arguments.
 361                          */
 362                         STARTSTACKSTR(concat);
 363                         ap = argv + 2;
 364                         for (;;) {
 365                                 while (*p)
 366                                         STPUTC(*p++, concat);
 367                                 if ((p = *ap++) == NULL)
 368                                         break;
 369                                 STPUTC(' ', concat);
 370                         }
 371                         STPUTC('\0', concat);
 372                         p = grabstackstr(concat);
 373                 }
 374         } else
 375                 p = "";
 376
 377         i = arith(p);
 378
 379         out1fmt(ARITH_FORMAT_STR "\n", i);
 380         return !i;
 381 }