Re: Bug report: NullPointerException from Driver.connect when passed a Properties with non-string values

Nathaniel,

It's ironic to note that Properties.getProperty() returns null even if
there is a value in the hashtable for the key.

It suggests that it will only return a string.

Either way the solution is to check to make sure the url is for us before
loading up the properties.

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

On Mon, Jan 28, 2013 at 2:43 PM, Nathaniel Waisbrot
<waisbrot(at)highfleet(dot)com>wrote:

> Thanks for the responses, dmp and Dave.
> I agree that it's rather surprising to be getting non-String values for
> the Driver, but I don't think it's actually *required* by any spec that
> they be Strings. The references I'm looking at are:
>
> The connect method of Driver, which takes a Properties:
>
> http://docs.oracle.com/javase/6/docs/api/java/sql/Driver.html#connect%28java.lang.String,%20java.util.Properties%29
>
> The Properties class:
> http://docs.oracle.com/javase/6/docs/api/java/util/Properties.html
>
> Which warns that:
> "Because Properties inherits from Hashtable, the put and putAll
> methods can be applied to a Properties object. Their use is strongly
> discouraged as they allow the caller to insert entries whose keys or values
> are not Strings. The setProperty method should be used instead. If the
> store or save method is called on a "compromised" Properties object that
> contains a non-String key or value, the call will fail. Similarly, the call
> to the propertyNames or list method will fail if it is called on a
> "compromised" Properties object that contains a non-String key."
>
>
> Frustratingly, you need to actually look at the source code of Properties
> to see some undocumented behavior of getProperty:
>
> public String getProperty(String key) {
> Object oval = super.get(key);
> String sval = (oval instanceof String) ? (String)oval : null;
> return ((sval == null) && (defaults != null)) ?
> defaults.getProperty(key) : sval;
> }
>
>
> Note that middle line--the reason that my example program fails is because
> an Object is not of type String, and so getProperty is substituting a null
> value.
>
> I've attached a candidate patch for you: waisbrot-exception.patch checks
> the result of getProperty() and throws a PSQLException if it is null. This
> allows drivers that want to deal with non-string Properties to get a turn
> with the URL, but will cause DriverManager to report the error if no Driver
> can perform the connection.
>
>
>
>
>
>
>
>
> On Jan 28, 2013, at 1:40 PM, Dave Cramer <pg(at)fastcrypt(dot)com> wrote:
>
> > Well ... another interesting stretching of the spec.
> >
> > Driver PropertyInfo values are required to be Strings as per the spec.
> http://docs.oracle.com/javase/1.3/docs/api/java/sql/DriverPropertyInfo.html
> >
> > Your test case is actually a bit misleading as getProperty returns null
> because getString on the empty object returns null.
> >
> > while I'm inclined to accept a patch to fix this, this is clearly 'out
> of spec'
> >
> > Dave Cramer
> >
> > dave.cramer(at)credativ(dot)ca
> > http://www.credativ.ca
> >
> >
> > On Mon, Jan 28, 2013 at 1:16 PM, dmp <danap(at)ttc-cmc(dot)net> wrote:
> > Hello Nathaniel,
> >
> > Any very robust program will try to handle anything the user throws at
> it.
> >
> > In this case you have passed a null value as an argument to the method
> > and it as acted according by giving you a NUllPointerException. Perhaps
> > wrapping this as SQLException may be more easily caught by your app., but
> > would be deceptive in response.
> >
> > Perhaps you could submit a patch for consideration, to the solution you
> > desire. The code may be obtained at GitHub.
> >
> > git clone git://github.com/pgjdbc/pgjdbc.git
> >
> > danap.
> >
> >
> >
> > Nathaniel Waisbrot wrote:
> > I found this while working with another JDBC driver (Stels XML driver).
> The Postgresql driver's connect() method is expecting the passed
> Properties object to have only string values, but this is not actually
> guaranteed to be the case. I think that the PG driver should wrap the
> NullPointerException in a SQLException, which would allow the DriverManager
> to attempt to use other JDBC drivers to make the connection.
> >
> > Here is a simple Java program which will reproduce the problem:
> >
> > ==================
> > import java.sql.DriverManager;
> > import java.util.Properties;
> >
> > public class PGTest {
> > public static void main(String[] args) throws Exception {
> > Class.forName("org.postgresql.Driver");
> > Properties info = new Properties();
> > info.put("foo", new Object()); //
> info.getPropert("foo") will return null
> > DriverManager.getConnection("foo:bar//baz", info);
> > }
> > }
> > ==================
> >
> > and here is the stack trace produced by running that program:
> >
> > ==================
> > Exception in thread "main" java.lang.NullPointerException
> > at java.util.Hashtable.put(Hashtable.java:542)
> > at java.util.Properties.setProperty(Properties.java:161)
> > at org.postgresql.Driver.connect(Driver.java:244)
> > at java.sql.DriverManager.getConnection(DriverManager.java:579)
> > at java.sql.DriverManager.getConnection(DriverManager.java:190)
> > at PGTest.main(PGTest.java:9)
> > ==================
> >
> > I'm using postgresql-9.2-1002.jdbc4.jar, with Java 7, running on Mac OS
> 10.8.2. Output of java -version:
> > java version "1.7.0_07"
> > Java(TM) SE Runtime Environment (build 1.7.0_07-b10)
> > Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode)
> >
> >
> >
> >
> >
> >
> > --
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> >
>
>
>