lib/libcompat/regexp/regsub.c

   1 /* $DragonFly: src/lib/libcompat/regexp/regsub.c,v 1.2 2004/10/25 19:38:02 drhodus Exp $                                                                */
   2 /*
   3  * regsub
   4  *
   5  *      Copyright (c) 1986 by University of Toronto.
   6  *      Written by Henry Spencer.  Not derived from licensed software.
   7  *
   8  *      Permission is granted to anyone to use this software for any
   9  *      purpose on any computer system, and to redistribute it freely,
  10  *      subject to the following restrictions:
  11  *
  12  *      1. The author is not responsible for the consequences of use of
  13  *              this software, no matter how awful, even if they arise
  14  *              from defects in it.
  15  *
  16  *      2. The origin of this software must not be misrepresented, either
  17  *              by explicit claim or by omission.
  18  *
  19  *      3. Altered versions must be plainly marked as such, and must not
  20  *              be misrepresented as being the original software.
  21  */
  22 #include <regexp.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include "regmagic.h"
  26
  27 #ifndef CHARBITS
  28 #define UCHARAT(p)      ((int)*(unsigned char *)(p))
  29 #else
  30 #define UCHARAT(p)      ((int)*(p)&CHARBITS)
  31 #endif
  32
  33 /*
  34  - regsub - perform substitutions after a regexp match
  35  */
  36 void
  37 regsub(prog, source, dest)
  38 const regexp *prog;
  39 const char *source;
  40 char *dest;
  41 {
  42         char *src;
  43         char *dst;
  44         char c;
  45         int no;
  46         int len;
  47         extern char *strncpy();
  48
  49         if (prog == NULL || source == NULL || dest == NULL) {
  50                 regerror("NULL parm to regsub");
  51                 return;
  52         }
  53         if (UCHARAT(prog->program) != MAGIC) {
  54                 regerror("damaged regexp fed to regsub");
  55                 return;
  56         }
  57
  58         src = (char *)source;
  59         dst = dest;
  60         while ((c = *src++) != '\0') {
  61                 if (c == '&')
  62                         no = 0;
  63                 else if (c == '\\' && '0' <= *src && *src <= '9')
  64                         no = *src++ - '0';
  65                 else
  66                         no = -1;
  67                 if (no < 0) {   /* Ordinary character. */
  68                         if (c == '\\' && (*src == '\\' || *src == '&'))
  69                                 c = *src++;
  70                         *dst++ = c;
  71                 } else if (prog->startp[no] != NULL && prog->endp[no] != NULL) {
  72                         len = prog->endp[no] - prog->startp[no];
  73                         (void) strncpy(dst, prog->startp[no], len);
  74                         dst += len;
  75                         if (len != 0 && *(dst-1) == '\0') {     /* strncpy hit NUL. */
  76                                 regerror("damaged match string");
  77                                 return;
  78                         }
  79                 }
  80         }
  81         *dst++ = '\0';
  82 }