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;
} FIX_ALIASING;
#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)
{
	enum { NMATCH = 2 };
	VALUE *v;
	regex_t re_buffer;
	regmatch_t re_regs[NMATCH];

	tostring(sv);
	tostring(pv);

	if (pv->u.s[0] == '^') {
		bb_error_msg(
"warning: '%s': using '^' as the first character\n"
"of a basic regular expression is not portable; it is 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 && re_regs[1].rm_so >= 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);
	}
	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 UNUSED_PARAM, char **argv)
{
	VALUE *v;

	xfunc_error_retval = 2; /* coreutils compat */
	G.args = argv + 1;
	if (*G.args == NULL) {
		bb_error_msg_and_die("too few arguments");
	}
	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	/* 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	#include "libbb.h"
29	#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	/* The kinds of value we can have. */
48	enum {
49	INTEGER,
50	STRING
51	};
52
53	/* A value is.... */
54	struct valinfo {
55	smallint type; /* Which kind. */
56	union { /* The value itself. */
57	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	struct globals {
65	char **args;
66	} FIX_ALIASING;
67	#define G ((struct globals)&bb_common_bufsiz1)
68
69	/* forward declarations */
70	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	v = xzalloc(sizeof(VALUE));
80	if (INTEGER) /* otherwise xzaaloc did it already */
81	v->type = INTEGER;
82	v->u.i = i;
83	return v;
84	}
85
86	/* Return a VALUE for S. */
87
88	static VALUE str_value(const char s)
89	{
90	VALUE *v;
91
92	v = xzalloc(sizeof(VALUE));
93	if (STRING) /* otherwise xzaaloc did it already */
94	v->type = STRING;
95	v->u.s = xstrdup(s);
96	return v;
97	}
98
99	/* Free VALUE V, including structure components. */
100
101	static void freev(VALUE *v)
102	{
103	if (v->type == STRING)
104	free(v->u.s);
105	free(v);
106	}
107
108	/* Return nonzero if V is a null-string or zero-number. */
109
110	static int null(VALUE *v)
111	{
112	if (v->type == INTEGER)
113	return v->u.i == 0;
114	/* STRING: */
115	return v->u.s[0] == '\0' \|\| LONE_CHAR(v->u.s, '0');
116	}
117
118	/* Coerce V to a STRING value (can't fail). */
119
120	static void tostring(VALUE *v)
121	{
122	if (v->type == INTEGER) {
123	v->u.s = xasprintf("%" PF_REZ "d", PF_REZ_TYPE v->u.i);
124	v->type = STRING;
125	}
126	}
127
128	/* Coerce V to an INTEGER value. Return 1 on success, 0 on failure. */
129
130	static bool toarith(VALUE *v)
131	{
132	if (v->type == STRING) {
133	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	v->type = INTEGER;
144	}
145	return 1;
146	}
147
148	/* Return str[0]+str[1] if the next token matches STR exactly.
149	STR must not be NULL. */
150
151	static int nextarg(const char *str)
152	{
153	if (G.args == NULL \|\| strcmp(G.args, str) != 0)
154	return 0;
155	return (unsigned char)str[0] + (unsigned char)str[1];
156	}
157
158	/* The comparison operator handling functions. */
159
160	static int cmp_common(VALUE l, VALUE r, int op)
161	{
162	arith_t ll, rr;
163
164	ll = l->u.i;
165	rr = r->u.i;
166	if (l->type == STRING \|\| r->type == STRING) {
167	tostring(l);
168	tostring(r);
169	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	if (op == '<')
175	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	}
187
188	/* The arithmetic operator handling functions. */
189
190	static arith_t arithmetic_common(VALUE l, VALUE r, int op)
191	{
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	if (op == '-')
201	return li - ri;
202	if (op == '*')
203	return li * ri;
204	if (ri == 0)
205	bb_error_msg_and_die("division by zero");
206	if (op == '/')
207	return li / ri;
208	return li % ri;
209	}
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	static VALUE docolon(VALUE sv, VALUE *pv)
216	{
217	enum { NMATCH = 2 };
218	VALUE *v;
219	regex_t re_buffer;
220	regmatch_t re_regs[NMATCH];
221
222	tostring(sv);
223	tostring(pv);
224
225	if (pv->u.s[0] == '^') {
226	bb_error_msg(
227	"warning: '%s': using '^' as the first character\n"
228	"of a basic regular expression is not portable; it is ignored", pv->u.s);
229	}
230
231	memset(&re_buffer, 0, sizeof(re_buffer));
232	memset(re_regs, 0, sizeof(re_regs));
233	xregcomp(&re_buffer, pv->u.s, 0);
234
235	/* expr uses an anchored pattern match, so check that there was a
236	* match and that the match starts at offset 0. */
237	if (regexec(&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH
238	&& re_regs[0].rm_so == 0
239	) {
240	/* Were \(...\) used? */
241	if (re_buffer.re_nsub > 0 && re_regs[1].rm_so >= 0) {
242	sv->u.s[re_regs[1].rm_eo] = '\0';
243	v = str_value(sv->u.s + re_regs[1].rm_so);
244	} else {
245	v = int_value(re_regs[0].rm_eo);
246	}
247	} 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	regfree(&re_buffer);
255	return v;
256	}
257
258	/* Handle bare operands and ( expr ) syntax. */
259
260	static VALUE *eval7(void)
261	{
262	VALUE *v;
263
264	if (!*G.args)
265	bb_error_msg_and_die("syntax error");
266
267	if (nextarg("(")) {
268	G.args++;
269	v = eval();
270	if (!nextarg(")"))
271	bb_error_msg_and_die("syntax error");
272	G.args++;
273	return v;
274	}
275
276	if (nextarg(")"))
277	bb_error_msg_and_die("syntax error");
278
279	return str_value(*G.args++);
280	}
281
282	/* Handle match, substr, index, length, and quote keywords. */
283
284	static VALUE *eval6(void)
285	{
286	static const char keywords[] ALIGN1 =
287	"quote\0""length\0""match\0""index\0""substr\0";
288
289	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	bb_error_msg_and_die("syntax error");
300	return str_value(*G.args++);
301	}
302	if (key == 2) { /* length */
303	r = eval6();
304	tostring(r);
305	v = int_value(strlen(r->u.s));
306	freev(r);
307	} else
308	l = eval6();
309
310	if (key == 3) { /* match */
311	r = eval6();
312	v = docolon(l, r);
313	freev(l);
314	freev(r);
315	}
316	if (key == 4) { /* index */
317	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	}
326	if (key == 5) { /* substr */
327	i1 = eval6();
328	i2 = eval6();
329	tostring(l);
330	if (!toarith(i1) \|\| !toarith(i2)
331	\|\| i1->u.i > (arith_t) strlen(l->u.s)
332	\|\| i1->u.i <= 0 \|\| i2->u.i <= 0)
333	v = str_value("");
334	else {
335	v = xmalloc(sizeof(VALUE));
336	v->type = STRING;
337	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	}
343	return v;
344
345	}
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	G.args++;
357	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	op = nextarg("*");
377	if (!op) { op = nextarg("/");
378	if (!op) { op = nextarg("%");
379	if (!op) return l;
380	}}
381	G.args++;
382	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	op = nextarg("+");
401	if (!op) {
402	op = nextarg("-");
403	if (!op) return l;
404	}
405	G.args++;
406	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	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	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	G.args++;
453	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	G.args++;
473	r = eval1();
474	if (null(l)) {
475	freev(l);
476	l = r;
477	} else
478	freev(r);
479	}
480	return l;
481	}
482
483	int expr_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
484	int expr_main(int argc UNUSED_PARAM, char **argv)
485	{
486	VALUE *v;
487
488	xfunc_error_retval = 2; /* coreutils compat */
489	G.args = argv + 1;
490	if (*G.args == NULL) {
491	bb_error_msg_and_die("too few arguments");
492	}
493	v = eval();
494	if (*G.args)
495	bb_error_msg_and_die("syntax error");
496	if (v->type == INTEGER)
497	printf("%" PF_REZ "d\n", PF_REZ_TYPE v->u.i);
498	else
499	puts(v->u.s);
500	fflush_stdout_and_exit(null(v));
501	}