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[openssh.git] / match.c

/*

match.c

Author: Tatu Ylonen <ylo@cs.hut.fi>

Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                   All rights reserved

Created: Thu Jun 22 01:17:50 1995 ylo

Simple pattern matching, with '*' and '?' as wildcards.

*/

#include "includes.h"
RCSID("$Id$");

#include "ssh.h"

/* Returns true if the given string matches the pattern (which may contain
   ? and * as wildcards), and zero if it does not match. */
	  
int match_pattern(const char *s, const char *pattern)
{
  while (1)
    {
      /* If at end of pattern, accept if also at end of string. */
      if (!*pattern)
        return !*s;

      /* Process '*'. */
      if (*pattern == '*')
        {
	  /* Skip the asterisk. */
	  pattern++;

	  /* If at end of pattern, accept immediately. */
          if (!*pattern)
            return 1;

	  /* If next character in pattern is known, optimize. */
          if (*pattern != '?' && *pattern != '*')
            {
	      /* Look instances of the next character in pattern, and try
		 to match starting from those. */
              for (; *s; s++)
                if (*s == *pattern &&
                    match_pattern(s + 1, pattern + 1))
                  return 1;
	      /* Failed. */
              return 0;
            }

	  /* Move ahead one character at a time and try to match at each
	     position. */
          for (; *s; s++)
            if (match_pattern(s, pattern))
              return 1;
	  /* Failed. */
          return 0;
        }

      /* There must be at least one more character in the string.  If we are
	 at the end, fail. */
      if (!*s)
        return 0;

      /* Check if the next character of the string is acceptable. */
      if (*pattern != '?' && *pattern != *s)
	return 0;
      
      /* Move to the next character, both in string and in pattern. */
      s++;
      pattern++;
    }
  /*NOTREACHED*/
}