AIX: add istat parser as stat is absent

[FelixMarxIBM]

Fixes #1667

Why:

• stat is absent on AIX

What:

• use istat instead and pasre the Owner of the output

Example output

# ls -al /tmp/.com_ibm_tools_attach/
total 24
drwxrwxrwt    3 root     system         4096 Jul 02 06:21 .
drwxrwxrwt   45 bin      bin            8192 Jul 02 06:20 ..
drwx--x--t    2 testuser staff           256 Jul 02 06:21 8061236
-rw-rw-rw-    1 root     system            0 Jan 16 2020  _attachlock
-rw-rw-rw-    1 root     system            0 Nov 21 2023  _controller
-rw-rw-rw-    1 root     system            0 Jan 16 2020  _master
-rwxrwxrwx    1 root     system            0 Jan 16 2020  _notifier

The istat command does not offer an output to only get the Owner PID, therefore we have to use a Pattern matcher to get it.

# istat /tmp/.com_ibm_tools_attach/8061236
Inode 45058 on device 10/7      Directory
Protection: rwx--x--x   Sticky
Owner: 205(testuser)            Group: 1(staff)
Link count:   2         Length 256 bytes

Last updated:   Tue Jul  2 06:21:53 EDT 2024
Last modified:  Tue Jul  2 06:21:53 EDT 2024
Last accessed:  Tue Jul  2 06:21:52 EDT 2024

The Exception that is seen prior to this fix on AIX:

2024-06-13T04:24:37.828-05:00 | ERROR | instana-executor-thread-30-7     | ExternalAttach   | com.instana.agent - 1.1.723 | java.lang.IllegalStateException: Unable to execute stat command
	at net.bytebuddy.agent.VirtualMachine$ForOpenJ9$Dispatcher$ForJnaPosixEnvironment.getOwnerIdOf(VirtualMachine.java:2182)
	at net.bytebuddy.agent.VirtualMachine$ForOpenJ9.attach(VirtualMachine.java:1695)
	at net.bytebuddy.agent.VirtualMachine$ForOpenJ9.attach(VirtualMachine.java:1663)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:90)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
	at java.lang.reflect.Method.invoke(Method.java:508)
	at com.instana.agent.loader.AgentLoaderAttach.attach(AgentLoaderAttach.java:398)
	at com.instana.agent.loader.AgentLoaderAttach.run(AgentLoaderAttach.java:150)
	at com.instana.agent.loader.AgentLoaderAttach.parseArgsAndRun(AgentLoaderAttach.java:100)
	at com.instana.agent.loader.AgentLoaderAttach.main(AgentLoaderAttach.java:83)
Caused by: java.io.IOException: Cannot run program "stat": error=2, A file or directory in the path name does not exist.
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1059)
	at java.lang.Runtime.exec(Runtime.java:631)
	at java.lang.Runtime.exec(Runtime.java:496)
	at net.bytebuddy.agent.VirtualMachine$ForOpenJ9$Dispatcher$ForJnaPosixEnvironment.getOwnerIdOf(VirtualMachine.java:2153)
	... 10 more
Caused by: java.io.IOException: error=2, A file or directory in the path name does not exist.
	at java.lang.UNIXProcess.forkAndExec(Native Method)
	at java.lang.UNIXProcess.<init>(UNIXProcess.java:291)
	at java.lang.ProcessImpl.start(ProcessImpl.java:167)
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1040)
	... 13 more

[FelixMarxIBM]

After creating a temp build with these attach-tools, the attachment works without any issues:

2024-07-02T06:39:30.350-04:00 | INFO  | instana-executor-thread-2-3      | ExternalAttach   | com.instana.agent - 1.1.727 | Executing: su testuser -c "/opt/java/semeru/jdk8u402-b06/bin/java -Xms16m -Xmx16m -Dcom.ibm.tools.attach.enable=no -Duser.dir=/ -cp /tmp/.instana/attach-tools-1.14.18.jar:/tmp/.instana/javaagent-loader-1.3.62.jar com.instana.agent.loader.AgentLoaderAttach agent=/tmp/.instana/javaagent-loader-1.3.62.jar verify=true pid=8061246 host=127.0.0.1 port=42699 boot=/com.instana.agent.artifact/com.instana/instrumentation-boot/1.1.29/jar shared=/com.instana.agent.artifact/com.instana/instrumentation-shared/1.0.141/jar inMemoryClassLoader=true agentSocket=true"
2024-07-02T06:39:32.300-04:00 | INFO  | nstana-socket-client-thread--6-4 | tClientIdDecoder | com.instana.agent - 1.1.727 | 8061246:com.instana.agent.main.javaagentloader connection established
2024-07-02T06:39:32.333-04:00 | INFO  | instana-executor-thread-2-3      | aagentLoaderImpl | com.instana.agent - 1.1.727 | Initial attach to JVM with PID 8061246 successful

[raphw]

Looks good. I'm currently on vacation but will merge once I'm on a machine again.