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Subject: Patch 7.4.593

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From: Bram Moolenaar <Bram@moolenaar.net>

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------------

Patch 7.4.593

Problem:    Crash when searching for "x\{0,90000}". (Dominique Pelle)

Solution:   Bail out from the NFA engine when the max limit is much higher

	    than the min limit.

Files:	    src/regexp_nfa.c, src/regexp.c, src/vim.h

*** ../vim-7.4.592/src/regexp_nfa.c	2015-01-18 16:46:28.983828439 +0100

--- src/regexp_nfa.c	2015-01-27 12:47:42.515592198 +0100

***************

*** 244,249 ****

--- 244,252 ----

  static char_u e_misplaced[] = N_("E866: (NFA regexp) Misplaced %c");

  static char_u e_ill_char_class[] = N_("E877: (NFA regexp) Invalid character class: %ld");

+ /* re_flags passed to nfa_regcomp() */

+ static int nfa_re_flags;

+ 

  /* NFA regexp \ze operator encountered. */

  static int nfa_has_zend;

***************

*** 2011,2020 ****

  	     *  <atom>*  */

  	    if (minval == 0 && maxval == MAX_LIMIT)

  	    {

! 		if (greedy)

  		    /* \{}, \{0,} */

  		    EMIT(NFA_STAR);

! 		else

  		    /* \{-}, \{-0,} */

  		    EMIT(NFA_STAR_NONGREEDY);

  		break;

--- 2014,2023 ----

  	     *  <atom>*  */

  	    if (minval == 0 && maxval == MAX_LIMIT)

  	    {

! 		if (greedy)		/* { { (match the braces) */

  		    /* \{}, \{0,} */

  		    EMIT(NFA_STAR);

! 		else			/* { { (match the braces) */

  		    /* \{-}, \{-0,} */

  		    EMIT(NFA_STAR_NONGREEDY);

  		break;

***************

*** 2030,2035 ****

--- 2033,2044 ----

  		return OK;

  	    }

+ 	    /* The engine is very inefficient (uses too many states) when the

+ 	     * maximum is much larger than the minimum.  Bail out if we can

+ 	     * use the other engine. */

+ 	    if ((nfa_re_flags & RE_AUTO) && maxval > minval + 200)

+ 		return FAIL;

+ 

  	    /* Ignore previous call to nfa_regatom() */

  	    post_ptr = post_start + my_post_start;

  	    /* Save parse state after the repeated atom and the \{} */

***************

*** 7046,7051 ****

--- 7055,7061 ----

  	return NULL;

      nfa_regengine.expr = expr;

+     nfa_re_flags = re_flags;

      init_class_tab();

*** ../vim-7.4.592/src/regexp.c	2014-11-20 23:07:00.515474686 +0100

--- src/regexp.c	2015-01-27 12:49:02.170719494 +0100

***************

*** 8081,8087 ****

       * First try the NFA engine, unless backtracking was requested.

       */

      if (regexp_engine != BACKTRACKING_ENGINE)

!         prog = nfa_regengine.regcomp(expr, re_flags);

      else

  	prog = bt_regengine.regcomp(expr, re_flags);

--- 8081,8088 ----

       * First try the NFA engine, unless backtracking was requested.

       */

      if (regexp_engine != BACKTRACKING_ENGINE)

!         prog = nfa_regengine.regcomp(expr,

! 		re_flags + (regexp_engine == AUTOMATIC_ENGINE ? RE_AUTO : 0));

      else

  	prog = bt_regengine.regcomp(expr, re_flags);

***************

*** 8105,8120 ****

  #endif

  	/*

  	 * If the NFA engine failed, try the backtracking engine.

! 	 * Disabled for now, both engines fail on the same patterns.

! 	 * Re-enable when regcomp() fails when the pattern would work better

! 	 * with the other engine.

! 	 *

  	if (regexp_engine == AUTOMATIC_ENGINE)

  	{

  	    prog = bt_regengine.regcomp(expr, re_flags);

- 	    regexp_engine == BACKTRACKING_ENGINE;

  	}

- 	 */

      }

      if (prog != NULL)

--- 8106,8119 ----

  #endif

  	/*

  	 * If the NFA engine failed, try the backtracking engine.

! 	 * The NFA engine also fails for patterns that it can't handle well

! 	 * but are still valid patterns, thus a retry should work.

! 	 */

  	if (regexp_engine == AUTOMATIC_ENGINE)

  	{

+ 	    regexp_engine = BACKTRACKING_ENGINE;

  	    prog = bt_regengine.regcomp(expr, re_flags);

  	}

      }

      if (prog != NULL)

*** ../vim-7.4.592/src/vim.h	2014-12-08 04:16:26.269702835 +0100

--- src/vim.h	2015-01-27 12:41:57.483371986 +0100

***************

*** 1020,1025 ****

--- 1020,1026 ----

  #define RE_MAGIC	1	/* 'magic' option */

  #define RE_STRING	2	/* match in string instead of buffer text */

  #define RE_STRICT	4	/* don't allow [abc] without ] */

+ #define RE_AUTO		8	/* automatic engine selection */

  #ifdef FEAT_SYN_HL

  /* values for reg_do_extmatch */

*** ../vim-7.4.592/src/version.c	2015-01-27 11:26:11.041183653 +0100

--- src/version.c	2015-01-27 12:52:44.720281369 +0100

***************

*** 743,744 ****

--- 743,746 ----

  {   /* Add new patch number below this line */

+ /**/

+     593,

  /**/

-- 

hundred-and-one symptoms of being an internet addict:

121. You ask for e-mail adresses instead of telephone numbers.

 /// Bram Moolenaar -- Bram@Moolenaar.net -- http://www.Moolenaar.net   \\\

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