[perl #57322] ungetc() to :scalar might cause problems

# New Ticket Created by  "Goro Fuji" 
# Please include the string:  [perl #57322]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=57322 >


This is a bug report for perl from garo@goro.nonet,
generated with the help of perlbug 1.36 running under perl 5.10.0.


-----------------------------------------------------------------

ungetc() to :scalar might cause SEGV. Moreover, :scalar's ungetc()
always writes the scalar regardless of the SvREADONLY flag and
the open mode. I think PerlIOScalar_unread() should be removed.

See the attached files (scalar_ungetc.t and scalar.diff).

-----------------------------------------------------------------
---
Flags:
    category=library
    severity=medium
---
Site configuration information for perl 5.10.0:

Configured by garo at Sun Jan  6 08:39:07 JST 2008.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=cygwin, osvers=1.5.25(0.15642), archname=cygwin-thread-multi
    uname='cygwin_nt-5.1 goro 1.5.25(0.15642) 2007-12-14 19:21 i686 cygwin '
    config_args='-de -Dmksymlnks -Doptimize=-O3 -Dusethreads
-Acccdlflags=-s -Alddlflags=-s -Accdlflags=-s -Dman3ext=3pm'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=y, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags ='-DPERL_USE_SAFE_PUTENV -U__STRICT_ANSI__
-fno-strict-aliasing -pipe -Wall -Wextra -Wmissing-prototypes
-Winit-self',
    optimize='-O3',
    cppflags='-DPERL_USE_SAFE_PUTENV -U__STRICT_ANSI__
-fno-strict-aliasing -pipe'
    ccversion='', gccversion='3.4.4 (cygming special, gdc 0.12, using
dmd 0.125)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags =' -Wl,--enable-auto-import
-Wl,--export-all-symbols -Wl,--stack,8388608
-Wl,--enable-auto-image-base -Wl,--enable-auto-import
-L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib /lib
    libs=-ldl -lcrypt
    perllibs=-ldl -lcrypt
    libc=/usr/lib/libc.a, so=dll, useshrplib=true, libperl=libperl.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' -s'
    cccdlflags='  -s', lddlflags=' --shared  -Wl,--enable-auto-import
-Wl,--export-all-symbols -Wl,--stack,8388608
-Wl,--enable-auto-image-base -Wl,--enable-auto-import -s
-L/usr/local/lib'

Locally applied patches:


---
@INC for perl 5.10.0:
    /usr/local/lib/perl5/5.10.0/cygwin-thread-multi
    /usr/local/lib/perl5/5.10.0
    /usr/local/lib/perl5/site_perl/5.10.0/cygwin-thread-multi
    /usr/local/lib/perl5/site_perl/5.10.0
    .

---
Environment for perl 5.10.0:
    HOME=/home/garo
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/parrot/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/usr/local/bin:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/Common7/IDE:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/VC/BIN:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/Common7/Tools:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/Common7/Tools/bin:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/VC/PlatformSDK/bin:/cygdrive/c/Program
Files/Microsoft Visual Studio
8/SDK/v2.0/bin:/cygdrive/c/WINDOWS/Microsoft.NET/Framework/v2.0.50727:/cygdrive/c/Program
Files/Microsoft Visual Studio 8/VC/VCPackages:/cygdrive/c/program
files/imagemagick-6.2.8-q16:/cygdrive/c/ActivePerl5.10/bin:/cygdrive/c/WINDOWS/system32:/cygdrive/c/WINDOWS:/cygdrive/c/WINDOWS/System32/Wbem:/cygdrive/c/Program
Files/ATI Technologies/ATI Control Panel:/cygdrive/c/Program
Files/Microsoft SQL
Server/90/Tools/binn/:/cygdrive/c/PROGRA~1/IBM/IBMHOM~1.04/Outloud:/cygdrive/c/Program
Files/QuickTime/QTSystem/:/cygdrive/c/Program Files/Microsoft Visual
Studio 8/VC/bin:/cygdrive/c/Program Files/R/bin:/cygdrive/c/program
files/imagemagick-6.2.8-q16:/cygdrive/c/ActivePerl5.10/bin:/cygdrive/c/WINDOWS/system32:/cygdrive/c/WINDOWS:/cygdrive/c/WINDOWS/System32/Wbem:/cygdrive/c/Program
Files/ATI Technologies/ATI Control Panel:/cygdrive/c/Program
Files/Microsoft SQL
Server/90/Tools/binn/:/cygdrive/c/PROGRA~1/IBM/IBMHOM~1.04/Outloud:/cygdrive/c/Program
Files/QuickTime/QTSystem/
    PERLIO=:perlio
    PERL_BADLANG (unset)
    SHELL (unset)

• [perl #57322] ungetc() to :scalar might cause problems by Goro Fuji
• Re: [perl #57322] ungetc() to :scalar might cause problems by Nicholas Clark