lib/libcompat/regexp/regsub.c

   1 /* $DragonFly: src/lib/libcompat/regexp/regsub.c,v 1.3 2008/09/30 16:57:04 swildner 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(const regexp *prog, const char *source, char *dest)
  38 {
  39         char *src;
  40         char *dst;
  41         char c;
  42         int no;
  43         int len;
  44         extern char *strncpy();
  45
  46         if (prog == NULL || source == NULL || dest == NULL) {
  47                 regerror("NULL parm to regsub");
  48                 return;
  49         }
  50         if (UCHARAT(prog->program) != MAGIC) {
  51                 regerror("damaged regexp fed to regsub");
  52                 return;
  53         }
  54
  55         src = (char *)source;
  56         dst = dest;
  57         while ((c = *src++) != '\0') {
  58                 if (c == '&')
  59                         no = 0;
  60                 else if (c == '\\' && '0' <= *src && *src <= '9')
  61                         no = *src++ - '0';
  62                 else
  63                         no = -1;
  64                 if (no < 0) {   /* Ordinary character. */
  65                         if (c == '\\' && (*src == '\\' || *src == '&'))
  66                                 c = *src++;
  67                         *dst++ = c;
  68                 } else if (prog->startp[no] != NULL && prog->endp[no] != NULL) {
  69                         len = prog->endp[no] - prog->startp[no];
  70                         (void) strncpy(dst, prog->startp[no], len);
  71                         dst += len;
  72                         if (len != 0 && *(dst-1) == '\0') {     /* strncpy hit NUL. */
  73                                 regerror("damaged match string");
  74                                 return;
  75                         }
  76                 }
  77         }
  78         *dst++ = '\0';
  79 }