busybox/coreutils/expr.c

/* vi: set sw=4 ts=4: */
/*
 * Mini expr implementation for busybox
 *
 * based on GNU expr Mike Parker.
 * Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
 *
 * Busybox modifications
 * Copyright (c) 2000  Edward Betts <edward@debian.org>.
 * Copyright (C) 2003-2005  Vladimir Oleynik <dzo@simtreas.ru>
 *  - reduced 464 bytes.
 *  - 64 math support
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* This program evaluates expressions.  Each token (operator, operand,
 * parenthesis) of the expression must be a separate argument.  The
 * parser used is a reasonably general one, though any incarnation of
 * it is language-specific.  It is especially nice for expressions.
 *
 * No parse tree is needed; a new node is evaluated immediately.
 * One function can handle multiple operators all of equal precedence,
 * provided they all associate ((x op x) op x). */

/* no getopt needed */

#include "libbb.h"
#include "xregex.h"

#if ENABLE_EXPR_MATH_SUPPORT_64
typedef int64_t arith_t;

#define PF_REZ      "ll"
#define PF_REZ_TYPE (long long)
#define STRTOL(s, e, b) strtoll(s, e, b)
#else
typedef long arith_t;

#define PF_REZ      "l"
#define PF_REZ_TYPE (long)
#define STRTOL(s, e, b) strtol(s, e, b)
#endif

/* TODO: use bb_strtol[l]? It's easier to check for errors... */

/* The kinds of value we can have.  */
enum {
	INTEGER,
	STRING
};

/* A value is.... */
struct valinfo {
	smallint type;                  /* Which kind. */
	union {                         /* The value itself. */
		arith_t i;
		char *s;
	} u;
};
typedef struct valinfo VALUE;

/* The arguments given to the program, minus the program name.  */
struct globals {
	char **args;
};
#define G (*(struct globals*)&bb_common_bufsiz1)

/* forward declarations */
static VALUE *eval(void);


/* Return a VALUE for I.  */

static VALUE *int_value(arith_t i)
{
	VALUE *v;

	v = xzalloc(sizeof(VALUE));
	if (INTEGER) /* otherwise xzaaloc did it already */
		v->type = INTEGER;
	v->u.i = i;
	return v;
}

/* Return a VALUE for S.  */

static VALUE *str_value(const char *s)
{
	VALUE *v;

	v = xzalloc(sizeof(VALUE));
	if (STRING) /* otherwise xzaaloc did it already */
		v->type = STRING;
	v->u.s = xstrdup(s);
	return v;
}

/* Free VALUE V, including structure components.  */

static void freev(VALUE *v)
{
	if (v->type == STRING)
		free(v->u.s);
	free(v);
}

/* Return nonzero if V is a null-string or zero-number.  */

static int null(VALUE *v)
{
	if (v->type == INTEGER)
		return v->u.i == 0;
	/* STRING: */
	return v->u.s[0] == '\0' || LONE_CHAR(v->u.s, '0');
}

/* Coerce V to a STRING value (can't fail).  */

static void tostring(VALUE *v)
{
	if (v->type == INTEGER) {
		v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
		v->type = STRING;
	}
}

/* Coerce V to an INTEGER value.  Return 1 on success, 0 on failure.  */

static bool toarith(VALUE *v)
{
	if (v->type == STRING) {
		arith_t i;
		char *e;

		/* Don't interpret the empty string as an integer.  */
		/* Currently does not worry about overflow or int/long differences. */
		i = STRTOL(v->u.s, &e, 10);
		if ((v->u.s == e) || *e)
			return 0;
		free(v->u.s);
		v->u.i = i;
		v->type = INTEGER;
	}
	return 1;
}

/* Return str[0]+str[1] if the next token matches STR exactly.
   STR must not be NULL.  */

static int nextarg(const char *str)
{
	if (*G.args == NULL || strcmp(*G.args, str) != 0)
		return 0;
	return (unsigned char)str[0] + (unsigned char)str[1];
}

/* The comparison operator handling functions.  */

static int cmp_common(VALUE *l, VALUE *r, int op)
{
	arith_t ll, rr;

	ll = l->u.i;
	rr = r->u.i;
	if (l->type == STRING || r->type == STRING) {
		tostring(l);
		tostring(r);
		ll = strcmp(l->u.s, r->u.s);
		rr = 0;
	}
	/* calculating ll - rr and checking the result is prone to overflows.
	 * We'll do it differently: */
	if (op == '<')
		return ll < rr;
	if (op == ('<' + '='))
		return ll <= rr;
	if (op == '=' || (op == '=' + '='))
		return ll == rr;
	if (op == '!' + '=')
		return ll != rr;
	if (op == '>')
		return ll > rr;
	/* >= */
	return ll >= rr;
}

/* The arithmetic operator handling functions.  */

static arith_t arithmetic_common(VALUE *l, VALUE *r, int op)
{
	arith_t li, ri;

	if (!toarith(l) || !toarith(r))
		bb_error_msg_and_die("non-numeric argument");
	li = l->u.i;
	ri = r->u.i;
	if (op == '+')
		return li + ri;
	if (op == '-')
		return li - ri;
	if (op == '*')
		return li * ri;
	if (ri == 0)
		bb_error_msg_and_die("division by zero");
	if (op == '/')
		return li / ri;
	return li % ri;
}

/* Do the : operator.
   SV is the VALUE for the lhs (the string),
   PV is the VALUE for the rhs (the pattern).  */

static VALUE *docolon(VALUE *sv, VALUE *pv)
{
	VALUE *v;
	regex_t re_buffer;
	const int NMATCH = 2;
	regmatch_t re_regs[NMATCH];

	tostring(sv);
	tostring(pv);

	if (pv->u.s[0] == '^') {
		bb_error_msg("\
warning: unportable BRE: `%s': using `^' as the first character\n\
of a basic regular expression is not portable; it is being ignored", pv->u.s);
	}

	memset(&re_buffer, 0, sizeof(re_buffer));
	memset(re_regs, 0, sizeof(*re_regs));
	xregcomp(&re_buffer, pv->u.s, 0);

	/* expr uses an anchored pattern match, so check that there was a
	 * match and that the match starts at offset 0. */
	if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
	 && re_regs[0].rm_so == 0
	) {
		/* Were \(...\) used? */
		if (re_buffer.re_nsub > 0) {
			sv->u.s[re_regs[1].rm_eo] = '\0';
			v = str_value(sv->u.s + re_regs[1].rm_so);
		} else {
			v = int_value(re_regs[0].rm_eo);
		}
	} else {
		/* Match failed -- return the right kind of null.  */
		if (re_buffer.re_nsub > 0)
			v = str_value("");
		else
			v = int_value(0);
	}
//FIXME: sounds like here is a bit missing: regfree(&re_buffer);
	return v;
}

/* Handle bare operands and ( expr ) syntax.  */

static VALUE *eval7(void)
{
	VALUE *v;

	if (!*G.args)
		bb_error_msg_and_die("syntax error");

	if (nextarg("(")) {
		G.args++;
		v = eval();
		if (!nextarg(")"))
			bb_error_msg_and_die("syntax error");
		G.args++;
		return v;
	}

	if (nextarg(")"))
		bb_error_msg_and_die("syntax error");

	return str_value(*G.args++);
}

/* Handle match, substr, index, length, and quote keywords.  */

static VALUE *eval6(void)
{
	static const char keywords[] ALIGN1 =
		"quote\0""length\0""match\0""index\0""substr\0";

	VALUE *r, *i1, *i2;
	VALUE *l = l; /* silence gcc */
	VALUE *v = v; /* silence gcc */
	int key = *G.args ? index_in_strings(keywords, *G.args) + 1 : 0;

	if (key == 0) /* not a keyword */
		return eval7();
	G.args++; /* We have a valid token, so get the next argument.  */
	if (key == 1) { /* quote */
		if (!*G.args)
			bb_error_msg_and_die("syntax error");
		return str_value(*G.args++);
	}
	if (key == 2) { /* length */
		r = eval6();
		tostring(r);
		v = int_value(strlen(r->u.s));
		freev(r);
	} else
		l = eval6();

	if (key == 3) { /* match */
		r = eval6();
		v = docolon(l, r);
		freev(l);
		freev(r);
	}
	if (key == 4) { /* index */
		r = eval6();
		tostring(l);
		tostring(r);
		v = int_value(strcspn(l->u.s, r->u.s) + 1);
		if (v->u.i == (arith_t) strlen(l->u.s) + 1)
			v->u.i = 0;
		freev(l);
		freev(r);
	}
	if (key == 5) { /* substr */
		i1 = eval6();
		i2 = eval6();
		tostring(l);
		if (!toarith(i1) || !toarith(i2)
		 || i1->u.i > (arith_t) strlen(l->u.s)
		 || i1->u.i <= 0 || i2->u.i <= 0)
			v = str_value("");
		else {
			v = xmalloc(sizeof(VALUE));
			v->type = STRING;
			v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
		}
		freev(l);
		freev(i1);
		freev(i2);
	}
	return v;

}

/* Handle : operator (pattern matching).
   Calls docolon to do the real work.  */

static VALUE *eval5(void)
{
	VALUE *l, *r, *v;

	l = eval6();
	while (nextarg(":")) {
		G.args++;
		r = eval6();
		v = docolon(l, r);
		freev(l);
		freev(r);
		l = v;
	}
	return l;
}

/* Handle *, /, % operators.  */

static VALUE *eval4(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval5();
	while (1) {
		op = nextarg("*");
		if (!op) { op = nextarg("/");
		 if (!op) { op = nextarg("%");
		  if (!op) return l;
		}}
		G.args++;
		r = eval5();
		val = arithmetic_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle +, - operators.  */

static VALUE *eval3(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval4();
	while (1) {
		op = nextarg("+");
		if (!op) {
			op = nextarg("-");
			if (!op) return l;
		}
		G.args++;
		r = eval4();
		val = arithmetic_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle comparisons.  */

static VALUE *eval2(void)
{
	VALUE *l, *r;
	int op;
	arith_t val;

	l = eval3();
	while (1) {
		op = nextarg("<");
		if (!op) { op = nextarg("<=");
		 if (!op) { op = nextarg("=");
		  if (!op) { op = nextarg("==");
		   if (!op) { op = nextarg("!=");
		    if (!op) { op = nextarg(">=");
		     if (!op) { op = nextarg(">");
		      if (!op) return l;
		}}}}}}
		G.args++;
		r = eval3();
		toarith(l);
		toarith(r);
		val = cmp_common(l, r, op);
		freev(l);
		freev(r);
		l = int_value(val);
	}
}

/* Handle &.  */

static VALUE *eval1(void)
{
	VALUE *l, *r;

	l = eval2();
	while (nextarg("&")) {
		G.args++;
		r = eval2();
		if (null(l) || null(r)) {
			freev(l);
			freev(r);
			l = int_value(0);
		} else
			freev(r);
	}
	return l;
}

/* Handle |.  */

static VALUE *eval(void)
{
	VALUE *l, *r;

	l = eval1();
	while (nextarg("|")) {
		G.args++;
		r = eval1();
		if (null(l)) {
			freev(l);
			l = r;
		} else
			freev(r);
	}
	return l;
}

int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int expr_main(int argc, char **argv)
{
	VALUE *v;

	if (argc == 1) {
		bb_error_msg_and_die("too few arguments");
	}

	G.args = argv + 1;

	v = eval();
	if (*G.args)
		bb_error_msg_and_die("syntax error");

	if (v->type == INTEGER)
		printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
	else
		puts(v->u.s);

	fflush_stdout_and_exit(null(v));
}
1	niro	532	/* vi: set sw=4 ts=4: */
2			/*
3			* Mini expr implementation for busybox
4			*
5			* based on GNU expr Mike Parker.
6			* Copyright (C) 86, 1991-1997, 1999 Free Software Foundation, Inc.
7			*
8			* Busybox modifications
9			* Copyright (c) 2000 Edward Betts <edward@debian.org>.
10			* Copyright (C) 2003-2005 Vladimir Oleynik <dzo@simtreas.ru>
11			* - reduced 464 bytes.
12			* - 64 math support
13			*
14			* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
15			*/
16
17			/* This program evaluates expressions. Each token (operator, operand,
18			* parenthesis) of the expression must be a separate argument. The
19			* parser used is a reasonably general one, though any incarnation of
20			* it is language-specific. It is especially nice for expressions.
21			*
22			* No parse tree is needed; a new node is evaluated immediately.
23			* One function can handle multiple operators all of equal precedence,
24			* provided they all associate ((x op x) op x). */
25
26			/* no getopt needed */
27
28	niro	816	#include "libbb.h"
29	niro	532	#include "xregex.h"
30
31			#if ENABLE_EXPR_MATH_SUPPORT_64
32			typedef int64_t arith_t;
33
34			#define PF_REZ "ll"
35			#define PF_REZ_TYPE (long long)
36			#define STRTOL(s, e, b) strtoll(s, e, b)
37			#else
38			typedef long arith_t;
39
40			#define PF_REZ "l"
41			#define PF_REZ_TYPE (long)
42			#define STRTOL(s, e, b) strtol(s, e, b)
43			#endif
44
45			/* TODO: use bb_strtol[l]? It's easier to check for errors... */
46
47	niro	816	/* The kinds of value we can have. */
48			enum {
49			INTEGER,
50			STRING
51			};
52
53	niro	532	/* A value is.... */
54			struct valinfo {
55	niro	816	smallint type; /* Which kind. */
56			union { /* The value itself. */
57	niro	532	arith_t i;
58			char *s;
59			} u;
60			};
61			typedef struct valinfo VALUE;
62
63			/* The arguments given to the program, minus the program name. */
64	niro	816	struct globals {
65			char **args;
66			};
67			#define G ((struct globals)&bb_common_bufsiz1)
68	niro	532
69	niro	816	/* forward declarations */
70	niro	532	static VALUE *eval(void);
71
72
73			/* Return a VALUE for I. */
74
75			static VALUE *int_value(arith_t i)
76			{
77			VALUE *v;
78
79	niro	816	v = xzalloc(sizeof(VALUE));
80			if (INTEGER) /* otherwise xzaaloc did it already */
81			v->type = INTEGER;
82	niro	532	v->u.i = i;
83			return v;
84			}
85
86			/* Return a VALUE for S. */
87
88	niro	816	static VALUE str_value(const char s)
89	niro	532	{
90			VALUE *v;
91
92	niro	816	v = xzalloc(sizeof(VALUE));
93			if (STRING) /* otherwise xzaaloc did it already */
94			v->type = STRING;
95	niro	532	v->u.s = xstrdup(s);
96			return v;
97			}
98
99			/* Free VALUE V, including structure components. */
100
101	niro	816	static void freev(VALUE *v)
102	niro	532	{
103	niro	816	if (v->type == STRING)
104	niro	532	free(v->u.s);
105			free(v);
106			}
107
108			/* Return nonzero if V is a null-string or zero-number. */
109
110	niro	816	static int null(VALUE *v)
111	niro	532	{
112	niro	816	if (v->type == INTEGER)
113	niro	532	return v->u.i == 0;
114	niro	816	/* STRING: */
115			return v->u.s[0] == '\0' \|\| LONE_CHAR(v->u.s, '0');
116	niro	532	}
117
118	niro	816	/* Coerce V to a STRING value (can't fail). */
119	niro	532
120	niro	816	static void tostring(VALUE *v)
121	niro	532	{
122	niro	816	if (v->type == INTEGER) {
123	niro	532	v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
124	niro	816	v->type = STRING;
125	niro	532	}
126			}
127
128	niro	816	/* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
129	niro	532
130	niro	816	static bool toarith(VALUE *v)
131	niro	532	{
132	niro	816	if (v->type == STRING) {
133	niro	532	arith_t i;
134			char *e;
135
136			/* Don't interpret the empty string as an integer. */
137			/* Currently does not worry about overflow or int/long differences. */
138			i = STRTOL(v->u.s, &e, 10);
139			if ((v->u.s == e) \|\| *e)
140			return 0;
141			free(v->u.s);
142			v->u.i = i;
143	niro	816	v->type = INTEGER;
144	niro	532	}
145			return 1;
146			}
147
148	niro	816	/* Return str[0]+str[1] if the next token matches STR exactly.
149	niro	532	STR must not be NULL. */
150
151	niro	816	static int nextarg(const char *str)
152	niro	532	{
153	niro	816	if (G.args == NULL \|\| strcmp(G.args, str) != 0)
154	niro	532	return 0;
155	niro	816	return (unsigned char)str[0] + (unsigned char)str[1];
156	niro	532	}
157
158			/* The comparison operator handling functions. */
159
160	niro	816	static int cmp_common(VALUE l, VALUE r, int op)
161	niro	532	{
162	niro	816	arith_t ll, rr;
163	niro	532
164	niro	816	ll = l->u.i;
165			rr = r->u.i;
166			if (l->type == STRING \|\| r->type == STRING) {
167	niro	532	tostring(l);
168			tostring(r);
169	niro	816	ll = strcmp(l->u.s, r->u.s);
170			rr = 0;
171			}
172			/* calculating ll - rr and checking the result is prone to overflows.
173			* We'll do it differently: */
174	niro	532	if (op == '<')
175	niro	816	return ll < rr;
176			if (op == ('<' + '='))
177			return ll <= rr;
178			if (op == '=' \|\| (op == '=' + '='))
179			return ll == rr;
180			if (op == '!' + '=')
181			return ll != rr;
182			if (op == '>')
183			return ll > rr;
184			/* >= */
185			return ll >= rr;
186	niro	532	}
187
188			/* The arithmetic operator handling functions. */
189
190	niro	816	static arith_t arithmetic_common(VALUE l, VALUE r, int op)
191	niro	532	{
192			arith_t li, ri;
193
194			if (!toarith(l) \|\| !toarith(r))
195			bb_error_msg_and_die("non-numeric argument");
196			li = l->u.i;
197			ri = r->u.i;
198			if (op == '+')
199			return li + ri;
200	niro	816	if (op == '-')
201	niro	532	return li - ri;
202	niro	816	if (op == '*')
203	niro	532	return li * ri;
204	niro	816	if (ri == 0)
205			bb_error_msg_and_die("division by zero");
206			if (op == '/')
207	niro	532	return li / ri;
208	niro	816	return li % ri;
209	niro	532	}
210
211			/* Do the : operator.
212			SV is the VALUE for the lhs (the string),
213			PV is the VALUE for the rhs (the pattern). */
214
215	niro	816	static VALUE docolon(VALUE sv, VALUE *pv)
216	niro	532	{
217			VALUE *v;
218			regex_t re_buffer;
219			const int NMATCH = 2;
220			regmatch_t re_regs[NMATCH];
221
222			tostring(sv);
223			tostring(pv);
224
225			if (pv->u.s[0] == '^') {
226	niro	816	bb_error_msg("\
227	niro	532	warning: unportable BRE: `%s': using `^' as the first character\n\
228			of a basic regular expression is not portable; it is being ignored", pv->u.s);
229			}
230
231			memset(&re_buffer, 0, sizeof(re_buffer));
232			memset(re_regs, 0, sizeof(*re_regs));
233	niro	816	xregcomp(&re_buffer, pv->u.s, 0);
234	niro	532
235			/* expr uses an anchored pattern match, so check that there was a
236			* match and that the match starts at offset 0. */
237	niro	816	if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
238			&& re_regs[0].rm_so == 0
239			) {
240	niro	532	/* Were \(...\) used? */
241			if (re_buffer.re_nsub > 0) {
242			sv->u.s[re_regs[1].rm_eo] = '\0';
243			v = str_value(sv->u.s + re_regs[1].rm_so);
244	niro	816	} else {
245	niro	532	v = int_value(re_regs[0].rm_eo);
246	niro	816	}
247	niro	532	} else {
248			/* Match failed -- return the right kind of null. */
249			if (re_buffer.re_nsub > 0)
250			v = str_value("");
251			else
252			v = int_value(0);
253			}
254	niro	816	//FIXME: sounds like here is a bit missing: regfree(&re_buffer);
255	niro	532	return v;
256			}
257
258			/* Handle bare operands and ( expr ) syntax. */
259
260			static VALUE *eval7(void)
261			{
262			VALUE *v;
263
264	niro	816	if (!*G.args)
265	niro	532	bb_error_msg_and_die("syntax error");
266
267			if (nextarg("(")) {
268	niro	816	G.args++;
269	niro	532	v = eval();
270			if (!nextarg(")"))
271			bb_error_msg_and_die("syntax error");
272	niro	816	G.args++;
273	niro	532	return v;
274			}
275
276			if (nextarg(")"))
277			bb_error_msg_and_die("syntax error");
278
279	niro	816	return str_value(*G.args++);
280	niro	532	}
281
282			/* Handle match, substr, index, length, and quote keywords. */
283
284			static VALUE *eval6(void)
285			{
286	niro	816	static const char keywords[] ALIGN1 =
287			"quote\0""length\0""match\0""index\0""substr\0";
288	niro	532
289	niro	816	VALUE r, i1, *i2;
290			VALUE l = l; / silence gcc */
291			VALUE v = v; / silence gcc */
292			int key = G.args ? index_in_strings(keywords, G.args) + 1 : 0;
293
294			if (key == 0) /* not a keyword */
295			return eval7();
296			G.args++; /* We have a valid token, so get the next argument. */
297			if (key == 1) { /* quote */
298			if (!*G.args)
299	niro	532	bb_error_msg_and_die("syntax error");
300	niro	816	return str_value(*G.args++);
301			}
302			if (key == 2) { /* length */
303	niro	532	r = eval6();
304			tostring(r);
305			v = int_value(strlen(r->u.s));
306			freev(r);
307	niro	816	} else
308	niro	532	l = eval6();
309	niro	816
310			if (key == 3) { /* match */
311	niro	532	r = eval6();
312			v = docolon(l, r);
313			freev(l);
314			freev(r);
315	niro	816	}
316			if (key == 4) { /* index */
317	niro	532	r = eval6();
318			tostring(l);
319			tostring(r);
320			v = int_value(strcspn(l->u.s, r->u.s) + 1);
321			if (v->u.i == (arith_t) strlen(l->u.s) + 1)
322			v->u.i = 0;
323			freev(l);
324			freev(r);
325	niro	816	}
326			if (key == 5) { /* substr */
327	niro	532	i1 = eval6();
328			i2 = eval6();
329			tostring(l);
330			if (!toarith(i1) \|\| !toarith(i2)
331	niro	816	\|\| i1->u.i > (arith_t) strlen(l->u.s)
332			\|\| i1->u.i <= 0 \|\| i2->u.i <= 0)
333	niro	532	v = str_value("");
334			else {
335			v = xmalloc(sizeof(VALUE));
336	niro	816	v->type = STRING;
337	niro	532	v->u.s = xstrndup(l->u.s + i1->u.i - 1, i2->u.i);
338			}
339			freev(l);
340			freev(i1);
341			freev(i2);
342	niro	816	}
343			return v;
344
345	niro	532	}
346
347			/* Handle : operator (pattern matching).
348			Calls docolon to do the real work. */
349
350			static VALUE *eval5(void)
351			{
352			VALUE l, r, *v;
353
354			l = eval6();
355			while (nextarg(":")) {
356	niro	816	G.args++;
357	niro	532	r = eval6();
358			v = docolon(l, r);
359			freev(l);
360			freev(r);
361			l = v;
362			}
363			return l;
364			}
365
366			/* Handle , /, % operators. /
367
368			static VALUE *eval4(void)
369			{
370			VALUE l, r;
371			int op;
372			arith_t val;
373
374			l = eval5();
375			while (1) {
376	niro	816	op = nextarg("*");
377			if (!op) { op = nextarg("/");
378			if (!op) { op = nextarg("%");
379			if (!op) return l;
380			}}
381			G.args++;
382	niro	532	r = eval5();
383			val = arithmetic_common(l, r, op);
384			freev(l);
385			freev(r);
386			l = int_value(val);
387			}
388			}
389
390			/* Handle +, - operators. */
391
392			static VALUE *eval3(void)
393			{
394			VALUE l, r;
395			int op;
396			arith_t val;
397
398			l = eval4();
399			while (1) {
400	niro	816	op = nextarg("+");
401			if (!op) {
402			op = nextarg("-");
403			if (!op) return l;
404			}
405			G.args++;
406	niro	532	r = eval4();
407			val = arithmetic_common(l, r, op);
408			freev(l);
409			freev(r);
410			l = int_value(val);
411			}
412			}
413
414			/* Handle comparisons. */
415
416			static VALUE *eval2(void)
417			{
418			VALUE l, r;
419			int op;
420			arith_t val;
421
422			l = eval3();
423			while (1) {
424	niro	816	op = nextarg("<");
425			if (!op) { op = nextarg("<=");
426			if (!op) { op = nextarg("=");
427			if (!op) { op = nextarg("==");
428			if (!op) { op = nextarg("!=");
429			if (!op) { op = nextarg(">=");
430			if (!op) { op = nextarg(">");
431			if (!op) return l;
432			}}}}}}
433			G.args++;
434	niro	532	r = eval3();
435			toarith(l);
436			toarith(r);
437			val = cmp_common(l, r, op);
438			freev(l);
439			freev(r);
440			l = int_value(val);
441			}
442			}
443
444			/* Handle &. */
445
446			static VALUE *eval1(void)
447			{
448			VALUE l, r;
449
450			l = eval2();
451			while (nextarg("&")) {
452	niro	816	G.args++;
453	niro	532	r = eval2();
454			if (null(l) \|\| null(r)) {
455			freev(l);
456			freev(r);
457			l = int_value(0);
458			} else
459			freev(r);
460			}
461			return l;
462			}
463
464			/* Handle \|. */
465
466			static VALUE *eval(void)
467			{
468			VALUE l, r;
469
470			l = eval1();
471			while (nextarg("\|")) {
472	niro	816	G.args++;
473	niro	532	r = eval1();
474			if (null(l)) {
475			freev(l);
476			l = r;
477			} else
478			freev(r);
479			}
480			return l;
481			}
482	niro	816
483			int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
484			int expr_main(int argc, char **argv)
485			{
486			VALUE *v;
487
488			if (argc == 1) {
489			bb_error_msg_and_die("too few arguments");
490			}
491
492			G.args = argv + 1;
493
494			v = eval();
495			if (*G.args)
496			bb_error_msg_and_die("syntax error");
497
498			if (v->type == INTEGER)
499			printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
500			else
501			puts(v->u.s);
502
503			fflush_stdout_and_exit(null(v));
504			}