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      1 /*	$NetBSD: regsub.c,v 1.4 2024/01/23 15:32:54 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2015 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christos Zoulas.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 #include <sys/cdefs.h>
     32 #if defined(LIBC_SCCS) && !defined(lint)
     33 __RCSID("$NetBSD: regsub.c,v 1.4 2024/01/23 15:32:54 christos Exp $");
     34 #endif
     35 
     36 #include <sys/param.h>
     37 #include <ctype.h>
     38 #include <stdlib.h>
     39 #include <string.h>
     40 #include <regex.h>
     41 
     42 struct str {
     43 	char *s_ptr;
     44 	size_t s_max;
     45 	size_t s_len;
     46 	int s_fixed;
     47 };
     48 
     49 #define	REINCR	64
     50 
     51 static int
     52 addspace(struct str *s, size_t len)
     53 {
     54 	void *v;
     55 
     56 	if (s->s_max - s->s_len > len)
     57 		return 0;
     58 
     59 	if (s->s_fixed)
     60 		return -1;
     61 
     62 	s->s_max += len + REINCR;
     63 
     64 	v = realloc(s->s_ptr, s->s_max);
     65 	if (v == NULL)
     66 		return -1;
     67 	s->s_ptr = v;
     68 
     69 	return 0;
     70 }
     71 
     72 static void
     73 addchar(struct str *s, int c)
     74 {
     75 	if (addspace(s, 1) == -1)
     76 		s->s_len++;
     77 	else
     78 		s->s_ptr[s->s_len++] = c;
     79 	if (c == 0) {
     80 		--s->s_len;
     81 		s->s_ptr[s->s_max - 1] = c;
     82 	}
     83 }
     84 
     85 static void
     86 addnstr(struct str *s, const char *buf, size_t len)
     87 {
     88 	if (addspace(s, len) != -1)
     89 		memcpy(s->s_ptr + s->s_len, buf, len);
     90 	s->s_len += len;
     91 }
     92 
     93 static int
     94 initstr(struct str *s, char *buf, size_t len)
     95 {
     96 	s->s_max = len;
     97 	s->s_ptr = buf == NULL ? malloc(len) : buf;
     98 	s->s_fixed = buf != NULL;
     99 	s->s_len = 0;
    100 	return s->s_ptr == NULL ? -1 : 0;
    101 }
    102 
    103 static ssize_t
    104 regsub1(char **buf, size_t len, const char *sub,
    105     const regmatch_t *rm, const char *str)
    106 {
    107         ssize_t i;
    108         char c;
    109 	struct str s;
    110 
    111 	if (initstr(&s, *buf, len) == -1)
    112 		return -1;
    113 
    114         while ((c = *sub++) != '\0') {
    115 
    116 		switch (c) {
    117 		case '&':
    118 			i = 0;
    119 			break;
    120 		case '\\':
    121 			if (isdigit((unsigned char)*sub))
    122 				i = *sub++ - '0';
    123 			else
    124 				i = -1;
    125 			break;
    126 		default:
    127 			i = -1;
    128 			break;
    129 		}
    130 
    131                 if (i == -1) {
    132                         if (c == '\\' && (*sub == '\\' || *sub == '&'))
    133                                 c = *sub++;
    134 			addchar(&s, c);
    135                 } else if (rm[i].rm_so != -1 && rm[i].rm_eo != -1) {
    136                         size_t l = (size_t)(rm[i].rm_eo - rm[i].rm_so);
    137 			addnstr(&s, str + (size_t)rm[i].rm_so, l);
    138                 }
    139         }
    140 
    141 	addchar(&s, '\0');
    142 	if (!s.s_fixed) {
    143 		if (s.s_len >= s.s_max) {
    144 			free(s.s_ptr);
    145 			return -1;
    146 		}
    147 		*buf = s.s_ptr;
    148 	}
    149 	return s.s_len;
    150 }
    151 
    152 ssize_t
    153 regnsub(char *buf, size_t len, const char *sub, const regmatch_t *rm,
    154     const char *str)
    155 {
    156 	return regsub1(&buf, len, sub, rm, str);
    157 }
    158 
    159 ssize_t
    160 regasub(char **buf, const char *sub, const regmatch_t *rm, const char *str)
    161 {
    162 	*buf = NULL;
    163 	return regsub1(buf, REINCR, sub, rm, str);
    164 }
    165