net/ipv4/netfilter/regexp/regsub.c

   1 /*
   2  * regsub
   3  * @(#)regsub.c 1.3 of 2 April 86
   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  *
  23  * This code was modified by Ethan Sommer to work within the kernel
  24  * (it now uses kmalloc etc..)
  25  *
  26  */
  27 #include "regexp.h"
  28 #include "regmagic.h"
  29 #include <linux/string.h>
  30
  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 #if 0
  39 //void regerror(char * s)
  40 //{
  41 //        printk("regexp(3): %s", s);
  42 //        /* NOTREACHED */
  43 //}
  44 #endif
  45
  46 /*
  47  - regsub - perform substitutions after a regexp match
  48  */
  49 void
  50 regsub(regexp * prog, char * source, char * dest)
  51 {
  52         register char *src;
  53         register char *dst;
  54         register char c;
  55         register int no;
  56         register int len;
  57
  58         /* Not necessary and gcc doesn't like it -MLS */
  59         /*extern char *strncpy();*/
  60
  61         if (prog == NULL || source == NULL || dest == NULL) {
  62                 regerror("NULL parm to regsub");
  63                 return;
  64         }
  65         if (UCHARAT(prog->program) != MAGIC) {
  66                 regerror("damaged regexp fed to regsub");
  67                 return;
  68         }
  69
  70         src = source;
  71         dst = dest;
  72         while ((c = *src++) != '\0') {
  73                 if (c == '&')
  74                         no = 0;
  75                 else if (c == '\\' && '0' <= *src && *src <= '9')
  76                         no = *src++ - '0';
  77                 else
  78                         no = -1;
  79
  80                 if (no < 0) {   /* Ordinary character. */
  81                         if (c == '\\' && (*src == '\\' || *src == '&'))
  82                                 c = *src++;
  83                         *dst++ = c;
  84                 } else if (prog->startp[no] != NULL && prog->endp[no] != NULL) {
  85                         len = prog->endp[no] - prog->startp[no];
  86                         (void) strncpy(dst, prog->startp[no], len);
  87                         dst += len;
  88                         if (len != 0 && *(dst-1) == '\0') {     /* strncpy hit NUL. */
  89                                 regerror("damaged match string");
  90                                 return;
  91                         }
  92                 }
  93         }
  94         *dst++ = '\0';
  95 }