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      1 /*	$NetBSD: re.c,v 1.22 2025/09/17 20:35:11 rillig Exp $	*/
      2 
      3 /* re.c: This file contains the regular expression interface routines for
      4    the ed line editor. */
      5 /*-
      6  * Copyright (c) 1993 Andrew Moore, Talke Studio.
      7  * All rights reserved.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     28  * SUCH DAMAGE.
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 #ifndef lint
     33 #if 0
     34 static char *rcsid = "@(#)re.c,v 1.6 1994/02/01 00:34:43 alm Exp";
     35 #else
     36 __RCSID("$NetBSD: re.c,v 1.22 2025/09/17 20:35:11 rillig Exp $");
     37 #endif
     38 #endif /* not lint */
     39 
     40 #include <stdarg.h>
     41 #include "ed.h"
     42 
     43 
     44 char errmsg[MAXPATHLEN + 40] = "";
     45 
     46 void
     47 seterrmsg(const char *fmt, ...)
     48 {
     49 	va_list ap;
     50 
     51 	va_start(ap, fmt);
     52 	vsnprintf(errmsg, sizeof(errmsg), fmt, ap);
     53 	va_end(ap);
     54 }
     55 
     56 /* get_compiled_pattern: return pointer to compiled pattern from command
     57    buffer */
     58 pattern_t *
     59 get_compiled_pattern(void)
     60 {
     61 	static pattern_t *expr = NULL;
     62 
     63 	char *exps;
     64 	char delimiter;
     65 	int n;
     66 
     67 	if ((delimiter = *ibufp) == ' ') {
     68 		seterrmsg("invalid pattern delimiter");
     69 		return NULL;
     70 	} else if (delimiter == '\n' || *++ibufp == '\n' || *ibufp == delimiter) {
     71 		if (!expr) seterrmsg("no previous pattern");
     72 		return expr;
     73 	} else if ((exps = extract_pattern(delimiter)) == NULL)
     74 		return NULL;
     75 	/* buffer alloc'd && not reserved */
     76 	if (expr && !patlock)
     77 		regfree(expr);
     78 	else if ((expr = (pattern_t *) malloc(sizeof(pattern_t))) == NULL) {
     79 		fprintf(stderr, "%s\n", strerror(errno));
     80 		seterrmsg("out of memory");
     81 		return NULL;
     82 	}
     83 	patlock = 0;
     84 	if ((n = regcomp(expr, exps, ere)) != 0) {
     85 		regerror(n, expr, errmsg, sizeof errmsg);
     86 		free(expr);
     87 		return expr = NULL;
     88 	}
     89 	return expr;
     90 }
     91 
     92 
     93 /* extract_pattern: copy a pattern string from the command buffer; return
     94    pointer to the copy */
     95 char *
     96 extract_pattern(int delimiter)
     97 {
     98 	static char *lhbuf = NULL;	/* buffer */
     99 	static int lhbufsz = 0;		/* buffer size */
    100 
    101 	char *nd;
    102 	int len;
    103 
    104 	for (nd = ibufp; *nd != delimiter && *nd != '\n'; nd++)
    105 		switch (*nd) {
    106 		default:
    107 			break;
    108 		case '[':
    109 			if ((nd = parse_char_class(nd + 1)) == NULL) {
    110 				seterrmsg("unbalanced brackets ([])");
    111 				return NULL;
    112 			}
    113 			break;
    114 		case '\\':
    115 			if (*++nd == '\n') {
    116 				seterrmsg("trailing backslash (\\)");
    117 				return NULL;
    118 			}
    119 			break;
    120 		}
    121 	len = nd - ibufp;
    122 	REALLOC(lhbuf, lhbufsz, len + 1, NULL);
    123 	memcpy(lhbuf, ibufp, len);
    124 	lhbuf[len] = '\0';
    125 	ibufp = nd;
    126 	return (isbinary) ? NUL_TO_NEWLINE(lhbuf, len) : lhbuf;
    127 }
    128 
    129 
    130 /* parse_char_class: expand a POSIX character class */
    131 char *
    132 parse_char_class(char *s)
    133 {
    134 	int c, d;
    135 
    136 	if (*s == '^')
    137 		s++;
    138 	if (*s == ']')
    139 		s++;
    140 	for (; *s != ']' && *s != '\n'; s++)
    141 		if (*s == '[' && ((d = *(s+1)) == '.' || d == ':' || d == '='))
    142 			for (s++, c = *++s; *s != ']' || c != d; s++)
    143 				if ((c = *s) == '\n')
    144 					return NULL;
    145 	return  (*s == ']') ? s : NULL;
    146 }
    147