[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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