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Reference to constant not read-only #1801

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p5pRT opened this issue Apr 7, 2000 · 1 comment
Closed

Reference to constant not read-only #1801

p5pRT opened this issue Apr 7, 2000 · 1 comment
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distro-mswin32 type-library

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@p5pRT
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p5pRT commented Apr 7, 2000

Migrated from rt.perl.org#3060 (status was 'resolved')

Searchable as RT3060$
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p5pRT commented Apr 7, 2000

From eblood@xmission.com

Created by eblood@xmission.com

When useithreads is defined the following code does not produce
the 'Modification of a read-only value attempted' error.

  sub C () { 1 }
  $r = \C;
  $$r = 2;

The problem is that constants are put on the pad when useithreads
is defined. When toref() creates a reference to a PADTMP it
creates a copy of the SV. It does not, however, copy the
read-only status of the SV.

The following patch corrects this and adds a test case for it.

Inline Patch 
diff -bruN perl.sav/pp.c perl/pp.c
--- perl.sav/pp.c Fri Mar 24 22:24:52 2000
+++ perl/pp.c Fri Apr 07 08:05:42 2000
@@ -510,6 +510,13 @@
  SvTEMP_off(sv);
  (void)SvREFCNT_inc(sv);
     }
+#ifdef USE_ITHREADS
+    else if (SvPADTMP(sv) && SvREADONLY(sv)) {
+ /* Must be a const */
+ sv = newSVsv(sv);
+ SvREADONLY_on(sv);
+    }
+#endif
     else if (SvPADTMP(sv))
  sv = newSVsv(sv);
     else {
diff -bruN perl.sav/t/op/ref.t perl/t/op/ref.t
--- perl.sav/t/op/ref.t Fri Mar 24 22:23:58 2000
+++ perl/t/op/ref.t Fri Apr 07 19:34:38 2000
@@ -1,6 +1,6 @@
 #!./perl

-print "1..56\n";
+print "1..57\n";

 # Test glob operations.

@@ -279,17 +279,33 @@
     print ${\$_} for @a;
 }

+# test if ref to constant is readonly
+
+{
+    eval {
+ sub C () { 1 }
+ my $r = \C;
+ print "# should also generate an error...\n";
+ $$r = 2;
+    };
+    if ($@) {
+ print "# $@";
+ print "ok 54\n" if $@ =~ /^Modification of a read-only/;
+    }
+}
+
 # test global destruction

 package FINALE;

 {
-    $ref3 = bless ["ok 56\n"];  # package destruction
-    my $ref2 = bless ["ok 55\n"]; # lexical destruction
-    local $ref1 = bless ["ok 54\n"]; # dynamic destruction
+    $ref3 = bless ["ok 57\n"];  # package destruction
+    my $ref2 = bless ["ok 56\n"]; # lexical destruction
+    local $ref1 = bless ["ok 55\n"]; # dynamic destruction
     1;     # flush any temp values on stack
 }

 DESTROY {
     print $_[0][0];
 }
+
Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl v5.6.0:

Configured by Eric at Fri Mar 24 12:36:06 2000.

Summary of my perl5 (revision 5 version 6 subversion 0) configuration:
  Platform:
    osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    usethreads=undef use5005threads=undef useithreads=define
usemultiplicity=define
    useperlio=undef d_sfio=undef uselargefiles=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef usesocks=undef
  Compiler:
    cc='cl', optimize='-O1 -MD -DNDEBUG', gccversion=
    cppflags='-DWIN32'
    ccflags
='-O1 -MD -DNDEBUG -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT  -DPERL_
IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DPERL_MSVCRT_READFIX'
    stdchar='char', d_stdstdio=define, usevfork=false
    intsize=4, longsize=4, ptrsize=4, doublesize=8
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=4
    alignbytes=8, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='link', ldflags
'-nologo -nodefaultlib -release  -libpath:"D:\apps\perl56\lib\CORE"  -machin
e:x86'
    libpth="g:\apps\msdevstd\lib" "g:\apps\msdevstd\mfc\lib" "%lib%"
"D:\apps\perl56\lib\CORE"
    libs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib
uuid.lib wsock32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib
msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=yes, libperl=perl56.lib
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ',
ddlflags='-dll -nologo -nodefaultlib -release  -libpath:"D:\apps\perl56\lib\
CORE"  -machine:x86'

Locally applied patches:
    ACTIVEPERL_LOCAL_PATCHES_ENTRY


@INC for perl v5.6.0:
    d:\apps\cmt\lib
    D:/apps/perl56/lib
    D:/apps/perl56/site/lib
    .


Environment for perl v5.6.0:
    HOME=d:\home
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=d:\apps\perl56\bin;D:\WINNT\system32;D:\WINNT;g:\apps\bor\Delphi5\Proje
cts\Bpl;g:\apps\bor\Delphi5\Bin;d:\apps\perl\bin;d:\apps\cmt\nt;d:\bin\nt;d:
\bin;;g:\apps\bor\delphi3\bin;g:\apps\bor\tasm\bin;g:\apps\bor\bp\bin;d:\app
s\iqtools;g:\apps\msdevstd\bin\;g:\apps\bor\bcc55\bin;;d:\rnd;c:\APPS\PERL\B
IN
    PERLLIB=d:\apps\cmt\lib
    PERL_BADLANG (unset)
    SHELL (unset)

@p5pRT p5pRT closed this as completed Nov 28, 2003
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