arith_yacc.c revision 218466 
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: head/bin/sh/arith_yacc.c 218466 2011-02-08 23:18:06Z jilles $");
37
38#include <sys/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
57static const char *arith_startbuf;
58
59const char *arith_buf;
60union yystype yylval;
61
62static int last_token;
63
64#define ARITH_PRECEDENCE(op, prec) [op - ARITH_BINOP_MIN] = prec
65
66static 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
87static __dead2 void yyerror(const char *s)
88{
89	error("arithmetic expression: %s: \"%s\"", s, arith_startbuf);
90	/* NOTREACHED */
91}
92
93static arith_t arith_lookupvarint(char *varname)
94{
95	const char *str;
96	char *p;
97	arith_t result;
98
99	str = lookupvar(varname);
100	if (str == NULL || *str == '\0')
101		str = "0";
102	errno = 0;
103	result = strtoarith_t(str, &p, 0);
104	if (errno != 0 || *p != '\0')
105		yyerror("variable conversion error");
106	return result;
107}
108
109static inline int arith_prec(int op)
110{
111	return prec[op - ARITH_BINOP_MIN];
112}
113
114static inline int higher_prec(int op1, int op2)
115{
116	return arith_prec(op1) < arith_prec(op2);
117}
118
119static arith_t do_binop(int op, arith_t a, arith_t b)
120{
121
122	switch (op) {
123	default:
124	case ARITH_REM:
125	case ARITH_DIV:
126		if (!b)
127			yyerror("division by zero");
128		return op == ARITH_REM ? a % b : a / b;
129	case ARITH_MUL:
130		return a * b;
131	case ARITH_ADD:
132		return a + b;
133	case ARITH_SUB:
134		return a - b;
135	case ARITH_LSHIFT:
136		return a << b;
137	case ARITH_RSHIFT:
138		return a >> b;
139	case ARITH_LT:
140		return a < b;
141	case ARITH_LE:
142		return a <= b;
143	case ARITH_GT:
144		return a > b;
145	case ARITH_GE:
146		return a >= b;
147	case ARITH_EQ:
148		return a == b;
149	case ARITH_NE:
150		return a != b;
151	case ARITH_BAND:
152		return a & b;
153	case ARITH_BXOR:
154		return a ^ b;
155	case ARITH_BOR:
156		return a | b;
157	}
158}
159
160static arith_t assignment(int var, int noeval);
161
162static arith_t primary(int token, union yystype *val, int op, int noeval)
163{
164	arith_t result;
165
166again:
167	switch (token) {
168	case ARITH_LPAREN:
169		result = assignment(op, noeval);
170		if (last_token != ARITH_RPAREN)
171			yyerror("expecting ')'");
172		last_token = yylex();
173		return result;
174	case ARITH_NUM:
175		last_token = op;
176		return val->val;
177	case ARITH_VAR:
178		last_token = op;
179		return noeval ? val->val : arith_lookupvarint(val->name);
180	case ARITH_ADD:
181		token = op;
182		*val = yylval;
183		op = yylex();
184		goto again;
185	case ARITH_SUB:
186		*val = yylval;
187		return -primary(op, val, yylex(), noeval);
188	case ARITH_NOT:
189		*val = yylval;
190		return !primary(op, val, yylex(), noeval);
191	case ARITH_BNOT:
192		*val = yylval;
193		return ~primary(op, val, yylex(), noeval);
194	default:
195		yyerror("expecting primary");
196	}
197}
198
199static arith_t binop2(arith_t a, int op, int prec, int noeval)
200{
201	for (;;) {
202		union yystype val;
203		arith_t b;
204		int op2;
205		int token;
206
207		token = yylex();
208		val = yylval;
209
210		b = primary(token, &val, yylex(), noeval);
211
212		op2 = last_token;
213		if (op2 >= ARITH_BINOP_MIN && op2 < ARITH_BINOP_MAX &&
214		    higher_prec(op2, op)) {
215			b = binop2(b, op2, arith_prec(op), noeval);
216			op2 = last_token;
217		}
218
219		a = noeval ? b : do_binop(op, a, b);
220
221		if (op2 < ARITH_BINOP_MIN || op2 >= ARITH_BINOP_MAX ||
222		    arith_prec(op2) >= prec)
223			return a;
224
225		op = op2;
226	}
227}
228
229static arith_t binop(int token, union yystype *val, int op, int noeval)
230{
231	arith_t a = primary(token, val, op, noeval);
232
233	op = last_token;
234	if (op < ARITH_BINOP_MIN || op >= ARITH_BINOP_MAX)
235		return a;
236
237	return binop2(a, op, ARITH_MAX_PREC, noeval);
238}
239
240static arith_t and(int token, union yystype *val, int op, int noeval)
241{
242	arith_t a = binop(token, val, op, noeval);
243	arith_t b;
244
245	op = last_token;
246	if (op != ARITH_AND)
247		return a;
248
249	token = yylex();
250	*val = yylval;
251
252	b = and(token, val, yylex(), noeval | !a);
253
254	return a && b;
255}
256
257static arith_t or(int token, union yystype *val, int op, int noeval)
258{
259	arith_t a = and(token, val, op, noeval);
260	arith_t b;
261
262	op = last_token;
263	if (op != ARITH_OR)
264		return a;
265
266	token = yylex();
267	*val = yylval;
268
269	b = or(token, val, yylex(), noeval | !!a);
270
271	return a || b;
272}
273
274static arith_t cond(int token, union yystype *val, int op, int noeval)
275{
276	arith_t a = or(token, val, op, noeval);
277	arith_t b;
278	arith_t c;
279
280	if (last_token != ARITH_QMARK)
281		return a;
282
283	b = assignment(yylex(), noeval | !a);
284
285	if (last_token != ARITH_COLON)
286		yyerror("expecting ':'");
287
288	token = yylex();
289	*val = yylval;
290
291	c = cond(token, val, yylex(), noeval | !!a);
292
293	return a ? b : c;
294}
295
296static arith_t assignment(int var, int noeval)
297{
298	union yystype val = yylval;
299	int op = yylex();
300	arith_t result;
301	char sresult[DIGITS(result) + 1];
302
303	if (var != ARITH_VAR)
304		return cond(var, &val, op, noeval);
305
306	if (op != ARITH_ASS && (op < ARITH_ASS_MIN || op >= ARITH_ASS_MAX))
307		return cond(var, &val, op, noeval);
308
309	result = assignment(yylex(), noeval);
310	if (noeval)
311		return result;
312
313	if (op != ARITH_ASS)
314		result = do_binop(op - 11, arith_lookupvarint(val.name), result);
315	snprintf(sresult, sizeof(sresult), ARITH_FORMAT_STR, result);
316	setvar(val.name, sresult, 0);
317	return result;
318}
319
320arith_t arith(const char *s)
321{
322	struct stackmark smark;
323	arith_t result;
324
325	setstackmark(&smark);
326
327	arith_buf = arith_startbuf = s;
328
329	result = assignment(yylex(), 0);
330
331	if (last_token)
332		yyerror("expecting EOF");
333
334	popstackmark(&smark);
335
336	return result;
337}
338
339/*
340 *  The exp(1) builtin.
341 */
342int
343expcmd(int argc, char **argv)
344{
345	const char *p;
346	char *concat;
347	char **ap;
348	arith_t i;
349
350	if (argc > 1) {
351		p = argv[1];
352		if (argc > 2) {
353			/*
354			 * Concatenate arguments.
355			 */
356			STARTSTACKSTR(concat);
357			ap = argv + 2;
358			for (;;) {
359				while (*p)
360					STPUTC(*p++, concat);
361				if ((p = *ap++) == NULL)
362					break;
363				STPUTC(' ', concat);
364			}
365			STPUTC('\0', concat);
366			p = grabstackstr(concat);
367		}
368	} else
369		p = "";
370
371	i = arith(p);
372
373	out1fmt(ARITH_FORMAT_STR "\n", i);
374	return !i;
375}
376
377