RFR JDK-8034032 : Check src/macosx/native/java/util/prefs/MacOSXPreferencesFile.m for JNI pending issues

[Chris Hegarty]

This looks ok to me Brent, and I agree with your conservative approach.

-Chris.

On 6 Aug 2014, at 22:45, Brent Christian <brent.christian at oracle.com> wrote:

> Please review my fix for:
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8034032
> Webrev:
> http://cr.openjdk.java.net/~bchristi/8034032/webrev.0/
> 
> 
> Within jdk/src/macosx/native/java/util/prefs/MacOSXPreferencesFile.m,
> there is a pattern of making blocks of toCF() calls, where
> later toCF() calls are made when there could be an exception pending from an earlier toCF() call.
> 
> toCF()creates a CFString from a Java String.  If an error occurs, it will raise an exception by calling the throwIfNull() macro:
> 
> #define throwIfNull(var, msg) \
>    do { \
>        if (var == NULL) { \
>            throwOutOfMemoryError(env, msg); \
>            goto bad##var; \
>        } \
>    } while (0)
> 
> Note: "##var" is substituted for whatever text is serving as "var", and throwIfNull() is meant to jump to the cleanup portion of a function (e.g. "badvar") to do cleanup before exiting.
> 
> This goto behavior is used more as intended elsewhere in MacOSXPreferencesFile.m.  toCF() doesn't have such cleanup to do.
> 
> An example of a series of calls to toCF():
> 
> 650     CFStringRef path = toCF(env, jpath);
> 651     CFStringRef child = toCF(env, jchild);
> 652     CFStringRef name = toCF(env, jname);
> 
> It's not until later that we check that everything turned out OK:
> 
> 661     if (!path  ||  !child  ||  !name) goto badparams;
> 
> If one toCF() call throws an OOME exception, it will still be pending when the next call to toCF() makes a JNI call, (GetStringLength() in this case).
> 
> I believe the right thing to do here is to check the success of each toCF() call before making the next toCF() call.  I've left the existing null checks / 'goto badparams' as is.
> 
> I also clear any pending exceptions in throwOutOfMemoryError().
> 
> Thanks,
> -Brent
>