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tr(1): plug leak in genclass()

If we have already generated a given character class we don't need to
do it again.  We can also return some of the memory we allocated for
the class.  NCHARS is an upper bound, most character classes are
small.

This fixes a small leak in genclass().

While here, switch to an ANSI function definition.

Thread: https://marc.info/?l=openbsd-tech&m=163571942030440&w=2

ok millert@

/*	$OpenBSD: str.c,v 1.14 2021/11/02 03:09:15 cheloha Exp $	*/
/*	$NetBSD: str.c,v 1.7 1995/08/31 22:13:47 jtc Exp $	*/

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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 <sys/types.h>

#include <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <err.h>

#include "extern.h"

static int	backslash(STR *);
static int	bracket(STR *);
static int	c_class(const void *, const void *);
static void	genclass(STR *);
static void	genequiv(STR *);
static int	genrange(STR *);
static void	genseq(STR *);

int
next(s)
	STR *s;
{
	int ch;

	switch (s->state) {
	case EOS:
		return (0);
	case INFINITE:
		return (1);
	case NORMAL:
		switch (ch = *s->str) {
		case '\0':
			s->state = EOS;
			return (0);
		case '\\':
			s->lastch = backslash(s);
			break;
		case '[':
			if (bracket(s))
				return (next(s));
			/* FALLTHROUGH */
		default:
			++s->str;
			s->lastch = ch;
			break;
		}

		/* We can start a range at any time. */
		if (s->str[0] == '-' && genrange(s))
			return (next(s));
		return (1);
	case RANGE:
		if (s->cnt-- == 0) {
			s->state = NORMAL;
			return (next(s));
		}
		++s->lastch;
		return (1);
	case SEQUENCE:
		if (s->cnt-- == 0) {
			s->state = NORMAL;
			return (next(s));
		}
		return (1);
	case SET:
		if ((s->lastch = s->set[s->cnt++]) == OOBCH) {
			s->state = NORMAL;
			return (next(s));
		}
		return (1);
	default:
		return 0;
	}
	/* NOTREACHED */
}

static int
bracket(s)
	STR *s;
{
	char *p;

	switch (s->str[1]) {
	case ':':				/* "[:class:]" */
		if ((p = strstr((char *)s->str + 2, ":]")) == NULL)
			return (0);
		*p = '\0';
		s->str += 2;
		genclass(s);
		s->str = (unsigned char *)p + 2;
		return (1);
	case '=':				/* "[=equiv=]" */
		if ((p = strstr((char *)s->str + 2, "=]")) == NULL)
			return (0);
		s->str += 2;
		genequiv(s);
		return (1);
	default:				/* "[\###*n]" or "[#*n]" */
		if ((p = strpbrk((char *)s->str + 2, "*]")) == NULL)
			return (0);
		if (p[0] != '*' || strchr(p, ']') == NULL)
			return (0);
		s->str += 1;
		genseq(s);
		return (1);
	}
	/* NOTREACHED */
}

typedef struct {
	char *name;
	int (*func)(int);
	int *set;
} CLASS;

static CLASS classes[] = {
	{ "alnum",  isalnum,  },
	{ "alpha",  isalpha,  },
	{ "blank",  isblank,  },
	{ "cntrl",  iscntrl,  },
	{ "digit",  isdigit,  },
	{ "graph",  isgraph,  },
	{ "lower",  islower,  },
	{ "print",  isprint,  },
	{ "punct",  ispunct,  },
	{ "space",  isspace,  },
	{ "upper",  isupper,  },
	{ "xdigit", isxdigit, },
};

static void
genclass(STR *s)
{
	CLASS *cp, tmp;
	size_t len;
	int i;

	tmp.name = (char *)s->str;
	if ((cp = (CLASS *)bsearch(&tmp, classes, sizeof(classes) /
	    sizeof(CLASS), sizeof(CLASS), c_class)) == NULL)
		errx(1, "unknown class %s", s->str);

	/*
	 * Generate the set of characters in the class if we haven't
	 * already done so.
	 */
	if (cp->set == NULL) {
		cp->set = reallocarray(NULL, NCHARS + 1, sizeof(*cp->set));
		if (cp->set == NULL)
			err(1, NULL);
		len = 0;
		for (i = 0; i < NCHARS; i++) {
			if (cp->func(i)) {
				cp->set[len] = i;
				len++;
			}
		}
		cp->set[len] = OOBCH;
		len++;
		cp->set = reallocarray(cp->set, len, sizeof(*cp->set));
		if (cp->set == NULL)
			err(1, NULL);
	}

	s->cnt = 0;
	s->state = SET;
	s->set = cp->set;
}

static int
c_class(a, b)
	const void *a, *b;
{
	return (strcmp(((CLASS *)a)->name, ((CLASS *)b)->name));
}

/*
 * English doesn't have any equivalence classes, so for now
 * we just syntax check and grab the character.
 */
static void
genequiv(s)
	STR *s;
{
	if (*s->str == '\\') {
		s->equiv[0] = backslash(s);
		if (*s->str != '=')
			errx(1, "misplaced equivalence equals sign");
	} else {
		s->equiv[0] = s->str[0];
		if (s->str[1] != '=')
			errx(1, "misplaced equivalence equals sign");
	}
	s->str += 2;
	s->cnt = 0;
	s->state = SET;
	s->set = s->equiv;
}

static int
genrange(s)
	STR *s;
{
	int stopval;
	unsigned char *savestart;

	savestart = s->str;
	stopval = *++s->str == '\\' ? backslash(s) : *s->str++;
	if (stopval < (u_char)s->lastch) {
		s->str = savestart;
		return (0);
	}
	s->cnt = stopval - s->lastch + 1;
	s->state = RANGE;
	--s->lastch;
	return (1);
}

static void
genseq(s)
	STR *s;
{
	char *ep;

	if (s->which == STRING1)
		errx(1, "sequences only valid in string2");

	if (*s->str == '\\')
		s->lastch = backslash(s);
	else
		s->lastch = *s->str++;
	if (*s->str != '*')
		errx(1, "misplaced sequence asterisk");

	switch (*++s->str) {
	case '\\':
		s->cnt = backslash(s);
		break;
	case ']':
		s->cnt = 0;
		++s->str;
		break;
	default:
		if (isdigit(*s->str)) {
			s->cnt = strtol((char *)s->str, &ep, 0);
			if (*ep == ']') {
				s->str = (unsigned char *)ep + 1;
				break;
			}
		}
		errx(1, "illegal sequence count");
		/* NOTREACHED */
	}

	s->state = s->cnt ? SEQUENCE : INFINITE;
}

/*
 * Translate \??? into a character.  Up to 3 octal digits, if no digits either
 * an escape code or a literal character.
 */
static int
backslash(STR *s)
{
	size_t i;
	int ch, val;

	assert(*s->str == '\\');
	s->str++;

	/* Empty escapes become plain backslashes. */
	if (*s->str == '\0') {
		s->state = EOS;
		return ('\\');
	}

	val = 0;
	for (i = 0; i < 3; i++) {
		if (s->str[i] < '0' || '7' < s->str[i])
			break;
		val = val * 8 + s->str[i] - '0';
	}
	if (i > 0) {
		if (val > UCHAR_MAX)
			errx(1, "octal value out of range: %d", val);
		s->str += i;
		return (val);
	}

	ch = *s->str++;
	switch (ch) {
		case 'a':			/* escape characters */
			return ('\7');
		case 'b':
			return ('\b');
		case 'f':
			return ('\f');
		case 'n':
			return ('\n');
		case 'r':
			return ('\r');
		case 't':
			return ('\t');
		case 'v':
			return ('\13');
		default:			/* \x" -> x */
			return (ch);
	}
}