Fix https://bugzilla.redhat.com/show_bug.cgi?id=324781
See the code comments for details.

Lubomir Rintel <lkundrak@v3.sk>

--- grep-2.5.1a/src/search.c.pcrewrap	2008-10-01 16:38:20.000000000 +0200
+++ grep-2.5.1a/src/search.c	2008-10-01 16:38:20.000000000 +0200
@@ -1241,8 +1241,31 @@
      is just for performance improvement in pcre_exec.  */
   int sub[300];
 
-  int e = pcre_exec (cre, extra, buf, size, 0, 0,
-		     sub, sizeof sub / sizeof *sub);
+  char *line_buf = buf;
+  int line_size = 0;
+  int e = 0;
+
+  /* PCRE can't limit the matching to space between newlines (i.e
+     [^a] will allways match newline, see pcreposix(3) for details),
+     therefore whe have to match each line in the buffer separately */
+  do {
+    /* We're not at the of buffer or end of line, get another char */
+    if (line_buf + line_size < buf + size && line_buf[line_size++] != eolbyte) {
+      continue;
+    }
+
+    /* Match the part of buffer that constitutes a line */
+    e = pcre_exec (cre, extra, line_buf, line_size - 1, 0, 0,
+                   sub, sizeof sub / sizeof *sub);
+
+    /* Don't try other lines if this one matched or returned an error */
+    if (e != PCRE_ERROR_NOMATCH)
+      break;
+
+    /* Wrap up */
+    line_buf += line_size;
+    line_size = 0;
+  } while (line_buf < buf + size);
 
   if (e <= 0)
     {
@@ -1261,8 +1284,8 @@
   else
     {
       /* Narrow down to the line we've found.  */
-      char const *beg = buf + sub[0];
-      char const *end = buf + sub[1];
+      char const *beg = line_buf + sub[0];
+      char const *end = line_buf + sub[1];
       char const *buflim = buf + size;
       char eol = eolbyte;
       if (!exact)
--- grep-2.5.1a/tests/Makefile.am.pcrewrap	2008-10-01 16:47:01.000000000 +0200
+++ grep-2.5.1a/tests/Makefile.am	2008-10-01 16:47:26.000000000 +0200
@@ -4,7 +4,7 @@
 
 TESTS = warning.sh khadafy.sh spencer1.sh bre.sh ere.sh \
         status.sh empty.sh options.sh backref.sh file.sh \
-        fmbtest.sh
+        fmbtest.sh pcrewrap.sh
 EXTRA_DIST = $(TESTS) \
              khadafy.lines khadafy.regexp \
              spencer1.awk spencer1.tests \
--- grep-2.5.1a/tests/Makefile.in.pcrewrap	2008-10-01 16:47:01.000000000 +0200
+++ grep-2.5.1a/tests/Makefile.in	2008-10-01 16:47:34.000000000 +0200
@@ -98,7 +98,7 @@
 
 TESTS = warning.sh khadafy.sh spencer1.sh bre.sh ere.sh \
         status.sh empty.sh options.sh backref.sh file.sh \
-	fmbtest.sh
+	fmbtest.sh pcrewrap.sh
 
 EXTRA_DIST = $(TESTS) \
              khadafy.lines khadafy.regexp \
--- grep-2.5.1a/tests/pcrewrap.sh	2008-09-30 09:16:44.037543374 +0200
+++ grep-2.5.1a/tests/pcrewrap.sh	2008-10-01 16:45:45.000000000 +0200
@@ -0,0 +1,23 @@
+#!/bin/sh
+# Test for bug https://bugzilla.redhat.com/show_bug.cgi?id=324781
+# Lubomir Rintel <lkundrak@v3.sk>
+
+: ${srcdir=.}
+
+failures=0
+
+echo -ne "a\na" | ${GREP} -P '[^a]' > /dev/null 2>&1
+if test $? -ne 1
+then
+        echo "PCRE Wrap: Wrong status code, test \#1 failed"
+        failures=1
+fi
+
+echo -ne "a\na" | ${GREP} -P '[^b].[^b]' > /dev/null 2>&1
+if test $? -ne 1
+then
+        echo "PCRE Wrap: Wrong status code, test \#2 failed"
+        failures=1
+fi
+
+exit $failures