Previously working REGEX match now fails

Question

As part of cleaning up config files in a build script, we have something like this:

Regex.IsMatch(LongStringOfFilecontents, @"Password=""[0-9a-zA-Z]*""")

and

Regex.IsMatch(LongStringOfFilecontents, @"Password2=""[0-9a-zA-Z]*""")

When a match is found, the passwords are replaced with a dummy value before the app is released.

The problem is that it now finds "Password" but not "Password2" or "Password1".

This C# .NET 3.5 code has been in use for several years, has been run hundreds of times, and has not been changed. As recently as a few days ago it was run successfully. As of this morning it chokes on "Password2". The config file really does contain both Password="some arbitrary value" and Password2="some arbitrary value".

I suspected that "d2" might be taken as a pattern, but it is not inside a {}, and as mentioned, it has behaved correctly for several years.

I have tested against a possible timeout and that does not seem to be the issue. I have tried the CaseInsensitive Option, which should not matter anyway ([a-zA-Z], right?) and that also has no effect.

It fails on two different (Win 7 Professional, 64 bit, SP1) machines, but works as expected on an XP machine (SP 3).

Unless this was the result of this morning's Windows 7 Automatic Update I'm baffled.

Here's the complete context:

ReplaceInFile(filename, @"Password1=""[0-9a-zA-Z]*""", @"Password1=""REPLACE_ME""");


        private static bool ReplaceInFile(string filename, string regexp, string replacement)
    {
        try
        {
            if (File.Exists(filename))
            {
                string oldContents = null;
                using (StreamReader reader = new StreamReader(filename, true))
                {
                    oldContents = reader.ReadToEnd();
                }
                if (Regex.IsMatch(oldContents, regexp))
                {
                    string newContents = Regex.Replace(oldContents, regexp, replacement);
                    if (oldContents != newContents)
                    {
                        File.WriteAllText(filename, newContents);
                        return true;
                    }
                }
                else
                {
                    BuildFailed("DID NOT FIND " + regexp + " in " + filename + " Case-SeNsiTive?");
                }
            }
            return false;
        }
        catch (Exception ex)
        {
            BuildFailed(ex.Message);
            return false;
        }
    }

And here's a small portion of the large file that it being examined:

<Kirk Enabled="1" Type="8000" Password1="test_pwd" Password2="dev_pwd" UserName1="admin" UserName2="GW-DECT/admin" DutyCycle="1" TcpPort="10000" ServerIP="localhost" />

Answer 1

I think your problem is more likely to be the contents of the password does not match [0-9a-zA-Z] rather than anything with the Password= or Password2= part. Most likely there is a non alpha-numeric character in that password.

Answer 2

Give this regex a try (using on RegexPal.com seemed to work). I did escape the equal sign.

@"Password[1-3]\\=""[0-9a-zA-Z]*"""

Here was my test text:

Password1="Blah"
Password2="blah2"
Password3="045and2"