[pcre-dev] [Bug 669] pcrecpp:: QuoteMeta does not behave as …

Top Page
Delete this message
Author: Craig Silverstein
Date:  
To: pcre-dev
Subject: [pcre-dev] [Bug 669] pcrecpp:: QuoteMeta does not behave as expected when there are embedded null bytes
------- You are receiving this mail because: -------
You are on the CC list for the bug.

http://bugs.exim.org/show_bug.cgi?id=669




--- Comment #2 from Craig Silverstein <csilvers@???>  2008-02-14 21:36:26 ---
Actually, I think I prefer solution 2:
}   2) The pcrecpp interface should magically translate embedded
}      null to \x00 so that libpcre matches on them as expected.


It's not been a goal of QuoteMeta to behave exactly like perl's
QuoteMeta (Philip: should it be?), so I have no problem special-casing
our handling of NUL. It's also a much simpler diff (which I include
below).

Philip, what do you think?

craig

--cut here--

Index: pcrecpp.h
===================================================================
--- pcrecpp.h   (revision 320)
+++ pcrecpp.h   (working copy)
@@ -620,6 +620,9 @@
   //           1.5-2.0?
   // may become:
   //           1\.5\-2\.0\?
+  // Note QuoteMeta behaves the same as perl's QuoteMeta function,
+  // *except* that it escapes the NUL character (\0) as backslash + 0,
+  // rather than backslash + NUL.
   static string QuoteMeta(const StringPiece& unquoted);



Index: pcrecpp.cc
===================================================================
--- pcrecpp.cc  (revision 320)
+++ pcrecpp.cc  (working copy)
@@ -441,21 +441,27 @@
   // Note that it's legal to escape a character even if it has no
   // special meaning in a regular expression -- so this function does
   // that.  (This also makes it identical to the perl function of the
-  // same name; see `perldoc -f quotemeta`.)
+  // same name; see `perldoc -f quotemeta`.)  The one exception is
+  // escaping NUL: rather than doing backslash + NUL, like perl does,
+  // we do '\0', because pcre itself doesn't take embedded NUL chars.
   for (int ii = 0; ii < unquoted.size(); ++ii) {
     // Note that using 'isalnum' here raises the benchmark time from
     // 32ns to 58ns:
-    if ((unquoted[ii] < 'a' || unquoted[ii] > 'z') &&
-        (unquoted[ii] < 'A' || unquoted[ii] > 'Z') &&
-        (unquoted[ii] < '0' || unquoted[ii] > '9') &&
-        unquoted[ii] != '_' &&
-        // If this is the part of a UTF8 or Latin1 character, we need
-        // to copy this byte without escaping.  Experimentally this is
-        // what works correctly with the regexp library.
-        !(unquoted[ii] & 128)) {
+    if (unquoted[ii] == '\0') {
+      result += "\\0";
+    } else if ((unquoted[ii] < 'a' || unquoted[ii] > 'z') &&
+               (unquoted[ii] < 'A' || unquoted[ii] > 'Z') &&
+               (unquoted[ii] < '0' || unquoted[ii] > '9') &&
+               unquoted[ii] != '_' &&
+               // If this is the part of a UTF8 or Latin1 character, we need
+               // to copy this byte without escaping.  Experimentally this is
+               // what works correctly with the regexp library.
+               !(unquoted[ii] & 128)) {
       result += '\\';
+      result += unquoted[ii];
+    } else {
+      result += unquoted[ii];
     }
-    result += unquoted[ii];
   }


return result;
Index: pcrecpp_unittest.cc
===================================================================
--- pcrecpp_unittest.cc (revision 320)
+++ pcrecpp_unittest.cc (working copy)
@@ -497,6 +497,7 @@
TestQuoteMeta("((a|b)c?d*e+[f-h]i)");
TestQuoteMeta("((?!)xxx).*yyy");
TestQuoteMeta("([");
+ TestQuoteMeta(string("foo\0bar", 7));
}

static void TestQuoteMetaSimpleNegative() {


--
Configure bugmail: http://bugs.exim.org/userprefs.cgi?tab=email