1 files changed, 304 insertions, 0 deletions

diff --git a/usr/dash/arith_yacc.c b/usr/dash/arith_yacc.c
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+/*-
+ * Copyright (c) 1993
+ *	The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 2007
+ *	Herbert Xu <herbert@gondor.apana.org.au>.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Kenneth Almquist.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <inttypes.h>
+#include <stdlib.h>
+#include "arith_yacc.h"
+#include "expand.h"
+#include "shell.h"
+#include "error.h"
+#include "output.h"
+#include "var.h"
+
+#if ARITH_BOR + 11 != ARITH_BORASS || ARITH_ASS + 11 != ARITH_EQ
+#error Arithmetic tokens are out of order.
+#endif
+
+static const char *arith_startbuf;
+
+const char *arith_buf;
+union yystype yylval;
+
+static int last_token;
+
+#define ARITH_PRECEDENCE(op, prec) [op - ARITH_BINOP_MIN] = prec
+
+static const char prec[ARITH_BINOP_MAX - ARITH_BINOP_MIN] = {
+	ARITH_PRECEDENCE(ARITH_MUL, 0),
+	ARITH_PRECEDENCE(ARITH_DIV, 0),
+	ARITH_PRECEDENCE(ARITH_REM, 0),
+	ARITH_PRECEDENCE(ARITH_ADD, 1),
+	ARITH_PRECEDENCE(ARITH_SUB, 1),
+	ARITH_PRECEDENCE(ARITH_LSHIFT, 2),
+	ARITH_PRECEDENCE(ARITH_RSHIFT, 2),
+	ARITH_PRECEDENCE(ARITH_LT, 3),
+	ARITH_PRECEDENCE(ARITH_LE, 3),
+	ARITH_PRECEDENCE(ARITH_GT, 3),
+	ARITH_PRECEDENCE(ARITH_GE, 3),
+	ARITH_PRECEDENCE(ARITH_EQ, 4),
+	ARITH_PRECEDENCE(ARITH_NE, 4),
+	ARITH_PRECEDENCE(ARITH_BAND, 5),
+	ARITH_PRECEDENCE(ARITH_BXOR, 6),
+	ARITH_PRECEDENCE(ARITH_BOR, 7),
+};
+
+#define ARITH_MAX_PREC 8
+
+static void yyerror(const char *s) __attribute__ ((noreturn));
+static void yyerror(const char *s)
+{
+	sh_error("arithmetic expression: %s: \"%s\"", s, arith_startbuf);
+	/* NOTREACHED */
+}
+
+static inline int arith_prec(int op)
+{
+	return prec[op - ARITH_BINOP_MIN];
+}
+
+static inline int higher_prec(int op1, int op2)
+{
+	return arith_prec(op1) < arith_prec(op2);
+}
+
+static intmax_t do_binop(int op, intmax_t a, intmax_t b)
+{
+	switch (op) {
+	default:
+	case ARITH_REM:
+	case ARITH_DIV:
+		if (!b)
+			yyerror("division by zero");
+		return op == ARITH_REM ? a % b : a / b;
+	case ARITH_MUL:
+		return a * b;
+	case ARITH_ADD:
+		return a + b;
+	case ARITH_SUB:
+		return a - b;
+	case ARITH_LSHIFT:
+		return a << b;
+	case ARITH_RSHIFT:
+		return a >> b;
+	case ARITH_LT:
+		return a < b;
+	case ARITH_LE:
+		return a <= b;
+	case ARITH_GT:
+		return a > b;
+	case ARITH_GE:
+		return a >= b;
+	case ARITH_EQ:
+		return a == b;
+	case ARITH_NE:
+		return a != b;
+	case ARITH_BAND:
+		return a & b;
+	case ARITH_BXOR:
+		return a ^ b;
+	case ARITH_BOR:
+		return a | b;
+	}
+}
+
+static intmax_t assignment(int var, int noeval);
+
+static intmax_t primary(int token, union yystype *val, int op, int noeval)
+{
+	intmax_t result;
+
+again:
+	switch (token) {
+	case ARITH_LPAREN:
+		result = assignment(op, noeval);
+		if (last_token != ARITH_RPAREN)
+			yyerror("expecting ')'");
+		last_token = yylex();
+		return result;
+	case ARITH_NUM:
+		last_token = op;
+		return val->val;
+	case ARITH_VAR:
+		last_token = op;
+		return noeval ? val->val : lookupvarint(val->name);
+	case ARITH_ADD:
+		token = op;
+		*val = yylval;
+		op = yylex();
+		goto again;
+	case ARITH_SUB:
+		*val = yylval;
+		return -primary(op, val, yylex(), noeval);
+	case ARITH_NOT:
+		*val = yylval;
+		return !primary(op, val, yylex(), noeval);
+	case ARITH_BNOT:
+		*val = yylval;
+		return ~primary(op, val, yylex(), noeval);
+	default:
+		yyerror("expecting primary");
+	}
+}
+
+static intmax_t binop2(intmax_t a, int op, int prec, int noeval)
+{
+	for (;;) {
+		union yystype val;
+		intmax_t b;
+		int op2;
+		int token;
+
+		token = yylex();
+		val = yylval;
+
+		b = primary(token, &val, yylex(), noeval);
+
+		op2 = last_token;
+		if (op2 >= ARITH_BINOP_MIN && op2 < ARITH_BINOP_MAX &&
+		    higher_prec(op2, op)) {
+			b = binop2(b, op2, arith_prec(op), noeval);
+			op2 = last_token;
+		}
+
+		a = noeval ? b : do_binop(op, a, b);
+
+		if (op2 < ARITH_BINOP_MIN || op2 >= ARITH_BINOP_MAX ||
+		    arith_prec(op2) >= prec)
+			return a;
+
+		op = op2;
+	}
+}
+
+static intmax_t binop(int token, union yystype *val, int op, int noeval)
+{
+	intmax_t a = primary(token, val, op, noeval);
+
+	op = last_token;
+	if (op < ARITH_BINOP_MIN || op >= ARITH_BINOP_MAX)
+		return a;
+
+	return binop2(a, op, ARITH_MAX_PREC, noeval);
+}
+
+static intmax_t and(int token, union yystype *val, int op, int noeval)
+{
+	intmax_t a = binop(token, val, op, noeval);
+	intmax_t b;
+
+	op = last_token;
+	if (op != ARITH_AND)
+		return a;
+
+	token = yylex();
+	*val = yylval;
+
+	b = and(token, val, yylex(), noeval | !a);
+
+	return a && b;
+}
+
+static intmax_t or(int token, union yystype *val, int op, int noeval)
+{
+	intmax_t a = and(token, val, op, noeval);
+	intmax_t b;
+
+	op = last_token;
+	if (op != ARITH_OR)
+		return a;
+
+	token = yylex();
+	*val = yylval;
+
+	b = or(token, val, yylex(), noeval | !!a);
+
+	return a || b;
+}
+
+static intmax_t cond(int token, union yystype *val, int op, int noeval)
+{
+	intmax_t a = or(token, val, op, noeval);
+	intmax_t b;
+	intmax_t c;
+
+	if (last_token != ARITH_QMARK)
+		return a;
+
+	b = assignment(yylex(), noeval | !a);
+
+	if (last_token != ARITH_COLON)
+		yyerror("expecting ':'");
+
+	token = yylex();
+	*val = yylval;
+
+	c = cond(token, val, yylex(), noeval | !!a);
+
+	return a ? b : c;
+}
+
+static intmax_t assignment(int var, int noeval)
+{
+	union yystype val = yylval;
+	int op = yylex();
+	intmax_t result;
+
+	if (var != ARITH_VAR)
+		return cond(var, &val, op, noeval);
+
+	if (op != ARITH_ASS && (op < ARITH_ASS_MIN || op >= ARITH_ASS_MAX))
+		return cond(var, &val, op, noeval);
+
+	result = assignment(yylex(), noeval);
+	if (noeval)
+		return result;
+
+	return setvarint(val.name,
+			 op == ARITH_ASS ? result :
+			 do_binop(op - 11, lookupvarint(val.name), result), 0);
+}
+
+intmax_t arith(const char *s)
+{
+	intmax_t result;
+
+	arith_buf = arith_startbuf = s;
+
+	result = assignment(yylex(), 0);
+
+	if (last_token)
+		yyerror("expecting EOF");
+
+	return result;
+}