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regsub.c revision 1.8 
      1 /*
      2  * regsub
      3  *
      4  *	Copyright (c) 1986 by University of Toronto.
      5  *	Written by Henry Spencer.  Not derived from licensed software.
      6  *
      7  *	Permission is granted to anyone to use this software for any
      8  *	purpose on any computer system, and to redistribute it freely,
      9  *	subject to the following restrictions:
     10  *
     11  *	1. The author is not responsible for the consequences of use of
     12  *		this software, no matter how awful, even if they arise
     13  *		from defects in it.
     14  *
     15  *	2. The origin of this software must not be misrepresented, either
     16  *		by explicit claim or by omission.
     17  *
     18  *	3. Altered versions must be plainly marked as such, and must not
     19  *		be misrepresented as being the original software.
     20  */
     21 
     22 #include <sys/cdefs.h>
     23 #ifndef lint
     24 __RCSID("$NetBSD: regsub.c,v 1.8 1999/05/06 17:09:31 christos Exp $");
     25 #endif /* not lint */
     26 
     27 #include <regexp.h>
     28 #include <stdio.h>
     29 #include <string.h>
     30 #include "regmagic.h"
     31 
     32 #ifndef CHARBITS
     33 #define	UCHARAT(p)	((int)*(unsigned char *)(p))
     34 #else
     35 #define	UCHARAT(p)	((int)*(p)&CHARBITS)
     36 #endif
     37 
     38 /*
     39  - regsub - perform substitutions after a regexp match
     40  */
     41 void
     42 __compat_regsub(prog, source, dest)
     43 const regexp *prog;
     44 const char *source;
     45 char *dest;
     46 {
     47 	char *src;
     48 	char *dst;
     49 	char c;
     50 	int no;
     51 	int len;
     52 
     53 	if (prog == NULL || source == NULL || dest == NULL) {
     54 		regerror("NULL parm to regsub");
     55 		return;
     56 	}
     57 	if (UCHARAT(prog->program) != MAGIC) {
     58 		regerror("damaged regexp fed to regsub");
     59 		return;
     60 	}
     61 
     62 	/* LINTED const castaway */
     63 	src = (char *)source;
     64 	dst = dest;
     65 	while ((c = *src++) != '\0') {
     66 		if (c == '&')
     67 			no = 0;
     68 		else if (c == '\\' && '0' <= *src && *src <= '9')
     69 			no = *src++ - '0';
     70 		else
     71 			no = -1;
     72  		if (no < 0) {	/* Ordinary character. */
     73  			if (c == '\\' && (*src == '\\' || *src == '&'))
     74  				c = *src++;
     75  			*dst++ = c;
     76  		} else if (prog->startp[no] != NULL && prog->endp[no] != NULL) {
     77 			len = prog->endp[no] - prog->startp[no];
     78 			(void) strncpy(dst, prog->startp[no], (size_t)len);
     79 			dst += len;
     80 			if (len != 0 && *(dst-1) == '\0') {	/* strncpy hit NUL. */
     81 				regerror("damaged match string");
     82 				return;
     83 			}
     84 		}
     85 	}
     86 	*dst++ = '\0';
     87 }
     88