gnu/105221: grep(1): `grep -w -F ""` issue

Dorr H. Clark dclark at
Thu Oct 9 06:53:13 UTC 2008


The behavior described in 105221 is due to 'grep' looping 
infinitely within Fexecute() of revision 1.25 of search.c. 

When used with the combination of '-w' and '-F' and 
the empty string, 'grep' enters a inescapable "while(1)" block 

A proposed fix then, is to immediately fail the search for a match 
when grep is called with this combination of options if the
string to match is zero-length (and thus, trivially does not match
the non-empty input!).

David K Lam

Dorr H. Clark

Graduate School of Engineering
Santa Clara University
Santa Clara, CA

--- /usr/src/gnu/usr.bin/grep/search.c	2006-02-19 04:27:39.000000000 +0000
+++ search.c	2008-08-21 00:29:38.000000000 +0000
@@ -959,6 +959,10 @@
       else if (match_words)
+          if(beg[len-1] == eol)
+            break;
 	  while (1)
 	      int word_match = 0;


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