Created attachment 812625 [details]
Suggested patch for BZ1009306

Description of problem:
When making a (*env)->NewStringUTF jni call on 32 bit, the const char *bytes parameter appends an extra character to the string.  I could not reproduce this issue on 64 bit.  Before applying the attached patch (meant to address issues found BZ1009306) the call seems to append various extra strings, however after the patch it is always reproducible with only one extra character ("\003")


Version-Release number of selected component (if applicable):
I've reproduced this on Fedora 19 with java-1.7.0 and on RHEL6.5 with java-1.6.0 i386 variants 

How reproducible:
always


Steps to Reproduce:
1. compile the jni tests included in icedtea6/7 (it is advisable to add the -g compile flag on line ~680) 
2. stap -I/usr/lib/jvm/java/tapset/ -e 'probe hotspot.jni.GetStringUTFLength.return { printf("%sret=%d\n",name,ret) }' -c 'export LD_LIBRARY_PATH=.:/usr/lib/jvm/java/jre/lib/i386/server && ./JNIStapTest GetStringUTFLength
3.
4. 

Actual results:
GetStringUTFLengthret=16
GetStringUTFLengthret=33
GetStringUTFLengthret=32
GetStringUTFLengthret=32
GetStringUTFLengthret=7


Expected results:
GetStringUTFLengthret=16
GetStringUTFLengthret=33
GetStringUTFLengthret=32
GetStringUTFLengthret=32
GetStringUTFLengthret=6


Additional info:
by running gdb on JNIStapTest, it is possible to step through to the JNI call and see the extra character being appended.  This is causing the GetSTringUTFLengthret=7 (instead of the expected 6)

ie,

[lberk@localhost tapset]$ LD_LIBRARY_PATH=.:/usr/lib/jvm/java/jre/lib/i386/server gdb --args ./JNIStapTest GetStringUTFLength
(gdb) b 646
Breakpoint 1 at 0x804a8d4: file ./JNIStapTest.c, line 646.
(gdb) r
Starting program: /home/lberk/icedtea7/test/tapset/./JNIStapTest GetStringUTFLength
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[New Thread 0x8be53b40 (LWP 31352)]
[New Thread 0x8bdd2b40 (LWP 31353)]
[New Thread 0x8bba4b40 (LWP 31354)]
[New Thread 0x8a1d2b40 (LWP 31355)]
[New Thread 0x8a181b40 (LWP 31356)]
[New Thread 0x89dffb40 (LWP 31357)]
[New Thread 0x89daeb40 (LWP 31358)]
[New Thread 0x89d2db40 (LWP 31359)]
[New Thread 0x89cacb40 (LWP 31360)]
[New Thread 0x89c5bb40 (LWP 31361)]

Breakpoint 1, main (argc=2, argv=0xbffff464) at ./JNIStapTest.c:646
646         char string_chars[6] = {0x57,0x4F,0x52,0x44,0xC0,0x80};
(gdb) n
647         jstring aString = (*env)->NewStringUTF(env, string_chars);
(gdb) p string_chars
$1 = "WORD\300\200"
(gdb) s
jni_NewStringUTF (env=0x805ad28, bytes=0xbffff0de "WORD\300\200\003") at /usr/src/debug/java-1.7.0-openjdk-1.7.0.60-2.4.2.7.fc19.i386/openjdk/hotspot/src/share/vm/prims/jni.cpp:3317
3317    JNI_ENTRY(jstring, jni_NewStringUTF(JNIEnv *env, const char *bytes))

the equivalent run on an 86_64/amd64 jvm is below (where the extra character isn't added:

[root@hp-dl360egen8-01 tapset]# LD_LIBRARY_PATH=.:/usr/lib/jvm/java/jre/lib/amd64/server gdb --args ./JNIStapTest GetStringUTFLength
(gdb) b 649
Breakpoint 1 at 0x402c03: file ./JNIStapTest.c, line 649.
(gdb) r
Starting program: /root/icedtea6/test/tapset/JNIStapTest GetStringUTFLength
[Thread debugging using libthread_db enabled]
[New Thread 0x7ffff2935700 (LWP 28784)]
[New Thread 0x7ffff2834700 (LWP 28785)]
[New Thread 0x7ffff2733700 (LWP 28786)]
[New Thread 0x7ffff2632700 (LWP 28787)]
[New Thread 0x7ffff2531700 (LWP 28788)]
[New Thread 0x7ffff2430700 (LWP 28789)]
[New Thread 0x7ffff232f700 (LWP 28790)]
[New Thread 0x7ffff222e700 (LWP 28791)]
[New Thread 0x7ffff212d700 (LWP 28792)]
[New Thread 0x7ffff202c700 (LWP 28793)]
[New Thread 0x7ffff1f2b700 (LWP 28794)]
[New Thread 0x7ffff1e2a700 (LWP 28795)]
[New Thread 0x7ffff1d29700 (LWP 28796)]
[New Thread 0x7ffff1c28700 (LWP 28797)]
[New Thread 0x7ffff1b27700 (LWP 28798)]
[New Thread 0x7ffff1a26700 (LWP 28799)]
[New Thread 0x7ffff1925700 (LWP 28800)]
[New Thread 0x7ffff1824700 (LWP 28801)]
[New Thread 0x7ffff1723700 (LWP 28802)]
[New Thread 0x7ffff1622700 (LWP 28803)]
[New Thread 0x7ffff1521700 (LWP 28804)]
[New Thread 0x7ffff1420700 (LWP 28805)]
[New Thread 0x7ffff131f700 (LWP 28806)]
[New Thread 0x7fffeb7f7700 (LWP 28807)]
[New Thread 0x7fffeb6f6700 (LWP 28808)]
[New Thread 0x7fffeb5f5700 (LWP 28809)]
[New Thread 0x7fffeb4f4700 (LWP 28810)]
[New Thread 0x7fffeb3f3700 (LWP 28811)]
[New Thread 0x7fffeb2f2700 (LWP 28812)]
[New Thread 0x7fffeb1f1700 (LWP 28813)]
[New Thread 0x7fffeb0f0700 (LWP 28814)]

Breakpoint 1, main (argc=2, argv=0x7fffffffe188) at ./JNIStapTest.c:649
649         char string_chars[6] = {0x57,0x4F,0x52,0x44,0xC0,0x80};
(gdb) n
650         jstring aString = (*env)->NewStringUTF(env, string_chars);
(gdb) p string_chars
$1 = "WORD\300\200"
(gdb) s
jni_NewStringUTF (env=0x6129d0, bytes=0x7fffffffdbb0 "WORD\300\200")
    at /usr/src/debug/icedtea6-1.11.11.90/openjdk/hotspot/src/share/vm/prims/jni.cpp:2086
2086    JNI_ENTRY(jstring, jni_NewStringUTF(JNIEnv *env, const char *bytes))
(gdb) p bytes
$2 = 0x7fffffffdbb0 "WORD\300\200"