'Grep patch'

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List: busybox
Subject: Grep patch
From: "Borin, Rogerio" <rogerio.borin () avocent ! com>
Date: 2007-10-26 20:54:54
Message-ID: DCA754113E788947A6111339A04702251ABA87 () hsv-email2 ! corp ! avocent ! com
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Hello,

 

I'm sending a patch to grep which was not working correctly when
multiple patterns were used.

In the main searching loop the program read a line of text and then in
an inner loop it tried to match against each of the patterns. However,
if a match were found it didn't stop the inner loop, in a way that only
the last pattern was honored. The patched just added a 'break' to this
loop.

 

The bug was only visible when using -F flag (literal matching) because
the variable 'ret' was never reset when this flag was not passed (normal
regexp matching).

 

In order to experience the bug, try 'grep -F -e "txt1" -e "txt2"
input.txt', where input.txt is:

--------

txt1

txt2

--------

The output will be 'txt2' only.

 

Regards,

 

Rogerio

 


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<div class=Section1>

Hello,<o:p></o:p>

<o:p>&nbsp;</o:p>

I&#8217;m
sending a patch to grep which was not working correctly when multiple patterns
were used.<o:p></o:p>

In
the main searching loop the program read a line of text and then in an inner
loop it tried to match against each of the patterns. However, if a match were found
it didn&#8217;t stop the inner loop, in a way that only the last pattern was
honored. The patched just added a &#8216;break&#8217; to this \
loop.<o:p></o:p>

<o:p>&nbsp;</o:p>

The
bug was only visible when using &#8211;F flag (literal matching) because the
variable &#8216;ret&#8217; was never reset when this flag was not passed
(normal regexp matching).<o:p></o:p>

<o:p>&nbsp;</o:p>

In
order to experience the bug, try &#8216;grep &#8211;F &#8211;e &#8220;txt1&#8221;
&#8211;e &#8220;txt2&#8221; input.txt&#8217;, where input.txt \
is:<o:p></o:p>

--------<o:p></o:p>

txt1<o:p></o:p>

txt2<o:p></o:p>

--------<o:p></o:p>

The
output will be &#8216;txt2&#8217; only.<o:p></o:p>

<o:p>&nbsp;</o:p>

Regards,<o:p></o:p>

<o:p>&nbsp;</o:p>

Rogerio<o:p></o:p>

<o:p>&nbsp;</o:p>

</div>

</body>

</html>


["grep.patch" (application/octet-stream)]

--- busybox-1.7.1/findutils/grep.c	2007-10-26 18:29:01.000000000 -0200
+++ busybox-1.7.1-grep/findutils/grep.c	2007-10-26 18:29:09.000000000 -0200
@@ -162,9 +162,11 @@
 			gl = (grep_list_data_t *)pattern_ptr->data;
 			if (FGREP_FLAG) {
 				ret = strstr(line, gl->pattern) != NULL;
+				if (ret)
+					break;
 			} else {
 				/*
-				 * test for a postitive-assertion match (regexec returns success (0)
+				 * test for a positive-assertion match (regexec returns success (0)
 				 * and the user did not specify invert search), or a negative-assertion
 				 * match (regexec returns failure (REG_NOMATCH) and the user specified
 				 * invert search)
@@ -176,16 +178,19 @@
 				regmatch.rm_so = 0;
 				regmatch.rm_eo = 0;
 				if (regexec(&(gl->preg), line, 1, &regmatch, 0) == 0) {
-					if (!(option_mask32 & OPT_w))
+					if (!(option_mask32 & OPT_w)) {
 						ret = 1;
-					else {
+						break;
+					} else {
 						char c = ' ';
 						if (regmatch.rm_so)
 							c = line[regmatch.rm_so - 1];
 						if (!isalnum(c) && c != '_') {
 							c = line[regmatch.rm_eo];
-							if (!c || (!isalnum(c) && c != '_'))
+							if (!c || (!isalnum(c) && c != '_')) {
 								ret = 1;
+								break;
+							}
 						}
 					}
 				}


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