Replace the static error string in ZIP_Put_In_Cache0 with on stack memory

[Sean Chou]

Hi all,

    I would like to suggest to replace the static error string in
ZIP_Put_In_Cache0 with on stack memory. Because it takes more time to
modify a string than an int typed error number, it opens a window larger
than int typed error number and might bring in race in multi-thread user
cases.

    I wrote a simple c testcase for JNI call "ZIP_Open", which shows that
it is easy to cause a race. In my machine, the testcase fails several time
with only 2 threads.

    The testcase is attached, it needs jdk shared libs to compile and run.
compile: gcc test_zip_open.c -I j2sdk-image/include/ -I
j2sdk-image/include/linux/ j2sdk-image/jre/lib/i386/lib*.so
j2sdk-image/jre/lib/i386/client/libjvm.so -pthread

run: please include the libs in LD_LIBRARY_PATH  , it is easy to catch the
error case with grep ////

Following is a simple output from my tests:
zhouyx at zhouyx-workstation:/media/data/GiveBack/OJDK-482/i386$ ./a.out 1 |
grep ////
////////////////////////// method1 pmsg :Permission denied
zhouyx at zhouyx-workstation:/media/data/GiveBack/OJDK-482/i386$ ./a.out 10 |
grep ////
//////////////////////// method2 pmsg :No such file or directory
//////////////////////// method2 pmsg :No such file or directory
//////////////////////// method2 pmsg :No such file or directory
zhouyx at zhouyx-workstation:/media/data/GiveBack/OJDK-482/i386$ ./a.out 100 |
grep ////
////////////////////////// method1 pmsg :Permission denied
////////////////////////// method1 pmsg :Permission denied
//////////////////////// method2 pmsg :No such file or directory
//////////////////////// method2 pmsg :No such file or directory
////////////////////////// method1 pmsg :Permission denied


    The modification is here:
http://cr.openjdk.java.net/~zhouyx/OJDK-482/webrev.00/  .
    It puts the error string on stack and return a dup one.

    Please take a look and give some comments, thanks.

-- 
Best Regards,
Sean Chou