[Bug translator/14297] New: stap -l and pn() fail to expand complex wildcards

[Bug translator/14297] New: stap -l and pn() fail to expand complex wildcards

[smakarov at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

             Bug #: 14297
           Summary: stap -l and pn() fail to expand complex wildcards
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap@sourceware.org
        ReportedBy: smakarov@redhat.com
    Classification: Unclassified


Features such as stap -l and pn() currently use a series of hacks and
heuristics to obtain the name of the probe point *with* wildcard expansions
applied but *without* alias expansions or anything else that results in
tapset-internal probe points being visible. These heuristics fail when wildcard
expansion and alias expansion alternate in complicated ways, e.g.

[root:/opt/codebase/systemtap]:stap$ stap -l
'process("stap").library("*").plt("a*")'
process("stap").library("*").plt("a*")?

[root:/opt/codebase/systemtap]:stap$ stap -l "syscall.open.return.max*(30)"
syscall.open.return.max*(30)

(The latter example is not supported in current systemtap, but will be
available after enhancement PR12210 is completed.)

Essentially, because some wildcard expansion may happen after tapset-internal
probe points are revealed by the derivation, the heuristics choose a derivation
stage which still contains wildcards.

Hence, rather than the current heuristics, some kind of comprehensive and
correct mechanism for constructing the "user-friendly" probe point name needs
to be added.

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[smakarov at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

Serguei Makarov <smakarov at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jistone at redhat dot com,
                   |                            |smakarov at redhat dot com

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[fche at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fche at redhat dot com

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> 2013-05-14 15:34:08 UTC ---
The plt probes in specific synthesize probes that allow the plt("*") component
to survive into the descendent generation.  That's a related bug.

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[fche at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #2 from Frank Ch. Eigler <fche at redhat dot com> 2013-05-15 02:13:15 UTC ---
commit 8159bf5

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[jistone at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

Josh Stone <jistone at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

--- Comment #3 from Josh Stone <jistone at redhat dot com> 2013-05-15 04:26:46 UTC ---
This has caused a regression for aliases:

$ stap -l syscall.open
derived_probe with no locations


Less critical, the plt output seems oddly inconsistent:

$ stap -l 'process("stap").plt("write")' 
process("stap").plt("write")

$ stap -l 'process("stap").plt("writ?")' 
process("stap").plt("writ?")

$ stap -l 'process("stap").plt("writ[e]")' 
process("stap").plt("writ[e]")

$ stap -l 'process("stap").plt("writ*")' 
process("stap").plt("write").statement(4243536)?

i.e. only the last form got wildcard expanded, but that exposed the statement
address too.  I'd think we want every wildcard-expanded form to list like the
first plain one did.

(and why does the derived plt get marked '?' optional?  It seems to have been
this way forever, but I don't see the reason.)

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[jistone at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

--- Comment #4 from Josh Stone <jistone at redhat dot com> 2013-05-15 04:39:22 UTC ---
Also weird to me:

$ stap -l 'process("stap").plt' 
process("stap").plt

$ stap -l 'process("stap").pl*'
process("stap").plt("CERT_AddExtension").statement(4246512)?
process("stap").plt("CERT_AsciiToName").statement(4244352)?
process("stap").plt("CERT_ChangeCertTrust").statement(4248304)?
process("stap").plt("CERT_CreateCertificate").statement(4246528)?
...

I'd expect the "pl*" to simply expand to "plt", and then list the same way as
the first version does.  Maybe you could argue that both forms should spell out
all the names, but not with the statements IMO.

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[Bug translator/14297] stap -l and pn() fail to expand complex wildcards

[fche at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14297

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #5 from Frank Ch. Eigler <fche at redhat dot com> 2013-05-15 17:52:58 UTC ---
commits up to 76ff513 fix & test this

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