From scozens@pwj.co.jp

Yes, I *know* the regexp is incorrect. (at least, for what I wanted
it to do - brainfart.) But it shouldn't lead to a segfault - or
should it?

bash-2.03$ perl -lne 'print if /\b(\w+)\s+$1\b/' files.tex
*** some lines of text here ***

[main] D​:\usr\local\bin\perl.exe 1028 (0) handle_exceptions​: Exception​:
STATUS_ACCESS_VIOLATION
[main] perl 1028 (0) handle_exceptions​: Dumping stack trace to
perl.exe.core

Things to note​:
  Different files die on different lines, but I cannot see anything
in common with the lines it barfs on.
  Further investigation shows that changing the line it blows up on
and the line above makes no difference - it seems to be based on the
line number in a file, but then on one file it dies on line 28, on
another, line 19, on another, line 68.
  `Simple' files, like `foo bar\nbaz bar\nfoo quux\n...<repeat for 50
lines>' work fine.
  There's no commonality about what's in $1 either. Real
hair-tearing-out stuff.
  No attempt yet to verify on other platforms - sorry, I'm
trapped at work.

  For those of you who like that sort of thing, here's the stack
trace​:
[main] perl 1074 (0) exception​: trapped!
[main] perl 1074 (0) exception​: code 0xC0000005 at 0x61053637
[main] perl 1074 (0) exception​: ax 0x43 bx 0xA037110 cx 0x42 dx 0x0
[main] perl 1074 (0) exception​: si 0xA037110 di 0x1 bp 0x248FBC0 sp
0x248FBB8
[main] perl 1074 (0) exception​: exception is​: STATUS_ACCESS_VIOLATION
[main] perl 1074 (0) stack​: Stack trace​:
[main] perl 1074 (0) stack​: frame 0​: sp = 0x248F9CC, pc = 0x6100A2C3
[main] perl 1074 (0) stack​: frame 1​: sp = 0x248FA08, pc = 0x77F84C92
[main] perl 1074 (0) stack​: frame 2​: sp = 0x248FA2C, pc = 0x77F7967F
[main] perl 1074 (0) stack​: frame 3​: sp = 0x248FAB8, pc = 0x77F6626E
[main] perl 1074 (0) stack​: frame 4​: sp = 0x248FBC0, pc = 0x61A0A924
[main] perl 1074 (0) stack​: frame 5​: sp = 0x248FBE0, pc = 0x619FA516
[main] perl 1074 (0) stack​: frame 6​: sp = 0x248FC10, pc = 0x619F9A2F
[main] perl 1074 (0) stack​: frame 7​: sp = 0x248FC3C, pc = 0x61A09303
[main] perl 1074 (0) stack​: frame 8​: sp = 0x248FD44, pc = 0x61A015AB
[main] perl 1074 (0) stack​: frame 9​: sp = 0x248FD70, pc = 0x61A00F6D
[main] perl 1074 (0) stack​: frame 10​: sp = 0x248FD78, pc = 0x619C2BFF
[main] perl 1074 (0) stack​: frame 11​: sp = 0x248FD84, pc = 0x61A1C433
[main] perl 1074 (0) stack​: frame 12​: sp = 0x248FD94, pc = 0x61A1C383
[main] perl 1074 (0) stack​: frame 13​: sp = 0x248FDC4, pc = 0x619C292D
[main] perl 1074 (0) stack​: frame 14​: sp = 0x248FEF8, pc = 0x4010BC
[main] perl 1074 (0) stack​: frame 15​: sp = 0x248FF08, pc = 0x61004402
[main] perl 1074 (0) stack​: End of stack trace (more stack frames may be
present)

Enjoy,
Simon

Site configuration information for perl 5.00562:

Configured by 02552 at Fri Oct 22 17:31:02  1999.

Summary of my perl5 (revision 5.0 version 5 subversion 62) configuration:
  Platform:
    osname=cygwin_nt-4.0, osvers=20.1, archname=cygwin
    uname='cygwin_nt-4.0 scozens 20.1 (0.311) 1998-12-3 20:39:18 i586
unknown '
    config_args='-der'
    hint=previous, useposix=true, d_sigaction=define
    usethreads=undef useperlio=undef d_sfio=undef
    use64bits=undef usemultiplicity=undef
  Compiler:
    cc='gcc', optimize='-O', gccversion=egcs-2.91.57 19980901 (egcs-1.1
release)
    cppflags='-DCYGWIN
-I/cygnus/cygwin-b20/H-586-cygwin32/i586-cygwin32/include
-I/usr/local/include -fno-strict-aliasing'
    ccflags ='-DCYGWIN
-I/cygnus/cygwin-b20/H-586-cygwin32/i586-cygwin32/include
-I/usr/local/include -fno-strict-aliasing'
    stdchar='char', d_stdstdio=undef, usevfork=false
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    alignbytes=8, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='ld2', ldflags =' -L/usr/local/lib'
    libpth=/cygnus/cygwin-b20/H-i586-cygwin32/i586-cygwin32/lib
/usr/local/lib
    libs=-lcygwin -lm -lkernel32
    libc=/usr/lib/libc.a, so=dll, useshrplib=true, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_cygwin.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -L/usr/local/lib'

Locally applied patches:



@INC for perl 5.00562:
    /usr/local/lib/perl5/5.00562/cygwin
    /usr/local/lib/perl5/5.00562
    /usr/local/lib/site_perl/5.00562/cygwin
    /usr/local/lib/site_perl
    .


Environment for perl 5.00562:
    HOME=/WINNT/Profiles/02552/\xE3\x83\x87\xE3\x82�$B9c�(B\x82�$(D??�(B\x83\x88\xE3\x83\x83\xE3\x83\x97
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=/usr/local/bin:/usr/bin:/miktex/miktex/bin:/cygnus/CYGWIN~1/H-I586~1/b
in:/PROGRA~1/ORACLE/bin:/WINNT/SYSTEM32:/WINNT:/abas/teamasset://c/bin/lanm
an.dos/netprog://c/dos
    PERL_BADLANG (unset)
    SHELL=/bin/sh

From [Unknown Contact. See original ticket]

scozens@​pwj.co.jp writes​:

bash-2.03$ perl -lne 'print if /\b(\w+)\s+$1\b/' files.tex

What is "wrong" about this REx?

 Different files die on different lines\, but I cannot see anything

in common with the lines it barfs on.
Further investigation shows that changing the line it blows up on
and the line above makes no difference - it seems to be based on the
line number in a file, but then on one file it dies on line 28, on
another, line 19, on another, line 68.

This looks pretty similar to a bug Larry found, but cannot be the same
bug. However, without a test file this report is useless.

Hope this helps,
Ilya

From [Unknown Contact. See original ticket]

scozens@​pwj.co.jp writes​:

bash-2.03$ perl -lne 'print if /\b(\w+)\s+$1\b/' files.tex

I see​: you used $1 instead of \1. Then it is the same bug as one
which Larry reported. You may want to apply the patch I sent a week
ago nevertheless.

http​://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1999-11/msg00025.html

Ilya