<div dir="ltr">Hey Neil,<br><br>I hope that this helps you!<br><br>The start of the lttng metadata file will start with some binary data if it is generated by a tracing session, The binary correlates to a 32 bit magic number, a uuid, with 16 sections of 8 bit ints, a 32 bit checksum, a 32 bit content size, a 32 bit packet size, some 8 bit ints representing the compression scheme, the encryption scheme, the checksum, the major release number of the Common Trace Format(CTF) in use and the minor release number of the CTF in use.<br><br>Everything after that binary data is the textual representation of the CTF metadata, which is sent in packets, I think. The "corrupt" areas you see in the text is the end of a packet that was created by lttng and start of a new packet that was created by lttng, again, I think, I'm not an expert on this part of the CTF. I know that the start of the CTF metadata can have the binary I described, however.<br><br>Its all part of the CTF, the guys pointed me to this on their IRC channel, maybe it could help you?<br><br><a href="http://diamon.org/docs/ctf/v1.8.2/">http://diamon.org/docs/ctf/v1.8.2/</a><br><br>Sorry I rambled, I enjoy the theory behind the CTF! :D <br><br>The segmentation fault is still an issue though. :(</div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Mar 5, 2015 at 10:50 AM, Neil Bryan <span dir="ltr"><<a href="mailto:Neil.Bryan@ttp.com" target="_blank">Neil.Bryan@ttp.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal">Hello LTTng devs,<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I am experiencing a strange problem with what I believe is corrupt metadata. This is seen on v2.6.0 of LTTng.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">If I try and parse recovered traces using Babeltrace, it fails with a segmentation fault.
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">nbryan@meteorubuntu-OptiPlex-7010:/data/nbryan/Meteor/altera_trace$ babeltrace --help<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">BabelTrace Trace Viewer and Converter 1.0.0-rc1<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">nbryan@meteorubuntu-OptiPlex-7010:/data/nbryan/Meteor/altera_trace$ babeltrace auto-20150304-091109/<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">Segmentation fault (core dumped)<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I thought it may be worth a look at the metadata file and I observed the following (these are just three examples):<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Environment:<u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">env {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> hostname = "socfpga_cyclone5";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> domain = "kernel";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> sysname = "Linux";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> kernel_release = "3.10.31-ltsi-05035-g801a40f";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> kernel_version = "#3 SMP Tue Mar 3 17:31:45 GMT 2015";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> tracer_name = "lttng-modules";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> tracer_major = 2;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> tracer_minor = 6;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> tracer_patchlevel = 0;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">};<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">event {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> name = "syscall_exit_recvmmsg";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> id = 921;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> stream_id = 0;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> fields := struct {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signe WСu?©)2ѕИN№d™Џ‰n® и Ђ d = 0; encoding = none; base = 16; } _mmsg;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _timeout;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> };<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">};<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">Decoded binary values:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,00h,01h,08h<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">event {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> name = "syscall_exit_getcpu";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> id = 903;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> stream_id = 0;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> fields := struct {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _cpup;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _nodep;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 0; encoding = none; base = WСu?©)2ѕИN№d™Џ‰n® и Ђ 16; } _tcache;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> };<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">};<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">Decoded binary values:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,00h,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,01h,08h<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">event {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> name = "syscall_exit_fstatat64";<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> id = 886;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> stream_id = 0;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> fields := struct {<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _ret;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 1; encod WСu?©)2ѕИN№d™Џ‰n® и Ђ ing = none; base = 10; } _dfd;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> string _filename;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 0; encoding = none; base = 16; } _statbuf;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> integer { size = 32; align = 32; signed = 1; encoding = none; base = 10; } _flag;<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> };<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">};<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">Decoded binary values:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,00h,57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,E8h,7Fh,00h,00h,00h,80h,00h,00h,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">00h,00h,00h,01h,08h<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">In a metadata file containing 7200 lines, I see this corruption 74 times.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I also notice that the header of the metadata file contains something very similar:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">57h,1Dh,D1h,75h,3Fh,ADh,A9h,29h,32h,BEh,C8h,4Eh,B9h,64h,99h,8Fh,14h,89h,6Eh,AEh,00h,00h,00h,00h,D8h,27h,00h,00h,00h,80h,00h,00h,00h,00h,00h,01h,08h<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">This appears identical to the other instances, less the first three 00h bytes.
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Now it may be intentional to squirt binary data into what is essentially a text file, but it looks suspicious. Can anyone shed any light on what is happening here?<u></u><u></u></p>
<p class="MsoNormal">Is the metadata file supposed to have any binary data in it at all?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks,<span class="HOEnZb"><font color="#888888"><u></u><u></u></font></span></p><span class="HOEnZb"><font color="#888888">
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Neil.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
</font></span></div>
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<br></blockquote></div><br></div>