[Bug exp/12347] New: Scripted strcmp() returns incorrect, constant value

[Bug exp/12347] New: Scripted strcmp() returns incorrect, constant value

[twists at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12347

           Summary: Scripted strcmp() returns incorrect, constant value
           Product: gdb
           Version: unknown
            Status: NEW
          Severity: normal
          Priority: P2
         Component: exp
        AssignedTo: unassigned@sourceware.org
        ReportedBy: twists@gmail.com


Created attachment 5165
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5165
repro test case

The glibc function strchr() is returning a constant nonsense value when used by
gdb.

The original test case:

    perl -e 'system "gdb -p $$"'
    (gdb) set print pretty on
    (gdb) p $patchlevel_sv = *PL_patchlevel
    $1 = {
      sv_any = 0x9199030,
      sv_refcnt = 1,
      sv_flags = 17412,
      sv_u = {
        svu_pv = 0x919fe98 "v5.12.2",
        svu_iv = 152698520,
        svu_uv = 152698520,
        svu_rv = 0x919fe98,
        svu_array = 0x919fe98,
        svu_hash = 0x919fe98,
        svu_gp = 0x919fe98
      }
    }
    (gdb) p $patchlevel = $patchlevel_sv->sv_u.svu_pv
    $2 = 0x919fe98 "v5.12.2"
    (gdb) p strcmp($patchlevel, "v5.10")
    $3 = 3998896
    (gdb) p strcmp($patchlevel, "v5.12")
    $4 = 3998896

An automated, minimal test is attached in gdb-strcmp-repro.tar.gz:

    tar xzf gdb-strcmp-repro.tar.gz
    cd gdb-strcmp-repro
    make

The internet complaint at
http://old.nabble.com/call-strcmp-tt28828726.html#a28828726 might also be an
instance of this.

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[Bug exp/12347] Scripted strcmp() returns incorrect, constant value

[twists at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12347

--- Comment #1 from Josh Jore <twists at gmail dot com> 2010-12-27 01:09:37 UTC ---
I'm using version 7.2-1ubuntu3 as provided by the Ubuntu package repository.
Also fails when I build the latest CVS rev.

$ gdb -v
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.

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[Bug exp/12347] Scripted strcmp() returns incorrect, constant value

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=12347

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> 2010-12-27 08:42:52 UTC ---
strcmp is the IFUNC symbol.

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[Bug exp/12347] Scripted strcmp() returns incorrect, constant value

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12347

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jan.kratochvil at redhat
                   |                            |dot com
         Resolution|                            |FIXED
   Target Milestone|---                         |7.3

--- Comment #3 from Jan Kratochvil <jan.kratochvil at redhat dot com> 2011-06-02 13:17:20 UTC ---
This is fixed in FSF GDB HEAD and GDB 7.3-prerelease branch.
[patch 0/7] STT_GNU_IFUNC support
http://sourceware.org/ml/gdb-patches/2011-03/msg00937.html

You can download a GDB snapshot before gdb-7.3 gets released these days/weeks.
http://www.gnu.org/software/gdb/current/

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