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Postings from November 1999
Hi!
> [...]
> > Nope. All I say is that you MUST NOT free() memory which hasn't been
> > malloc()ed before. The memory block which perl tries to free() in
> > Safefree() is the original block passed via exec(2). This block
> > hasn't been malloc()ed and therefore perl must not free() it.
>
> Let me restate things to syncronize our understanding:
>
> a) Perl uses PL_origenviron variable to understand when environ is malloc()ed.
>
> You do not claim that this scheme is broken (though AFAICS, it will
> work correct only if perl_parse is called only once).
On the contrary: I do believe that the check
(environ == PL_origenviron) /* need we copy environment? */
is broken. This test would only be OK if perl itself could guarantee
that no extension module modifies environ behind the scene.
> b) Perl thinks that if environ is malloc()ed, then environ[i] is malloc()ed;
>
> You claim that this assumption is unwarranted. This claim looks correct.
See above.
> However, in view of the above two statements your patch is still
> broken, since AFAICS it does not address existence of two different
> questions.
My patch is definitely broken since mg.c:magic_clear_all_env() has to
be fixed also. Since there are two different functions preformig the
"need we copy environment?" check, the IMHO correct fix would need
a global variable which indicates wether perl has already copied
the environment.
The following two testcases show the bug on my Solaris 5.5.1 box with
perl5.00503, Term-ReadLine-Gnu-1.07 and readline-4.0:
-----------------------------------------------------------------
#!/tmp/perl/bin/perl
# dumps core if LINES and COLUMNS aren't defined in the env:
#0 0xef5cc5a0 in _free_unlocked ()
#1 0xef5cc560 in free ()
#2 0x507b8 in Perl_safefree (where=0xeffffa79) at util.c:173
#3 0x550f4 in Perl_magic_clear_all_env (sv=0x0, mg=0xc98e0) at mg.c:785
#....
use Term::ReadLine;
$RL = new Term::ReadLine 'foo';
undef %ENV;
-----------------------------------------------------------------
#!/tmp/perl/bin/perl
# dumps core if LINES and COLUMNS aren't defined in the env:
#0 0xef5cc5a0 in _free_unlocked ()
#1 0xef5cc560 in free ()
#2 0x507b8 in Perl_safefree (where=0xeffffcff) at util.c:173
#3 0x52af8 in Perl_my_setenv (nam=0xd0128 "PATH", val=0xd1890 "/foobar")
# at util.c:1443
#....
use Term::ReadLine;
$RL = new Term::ReadLine 'foo';
$ENV{PATH} = "/foobar";
-----------------------------------------------------------------
I'm not familiar with the perl source so I leave it up to you to
invent a correct patch.
Regards,
Joerg
--
Gaertner Datensysteme 38114 Braunschweig
Joerg Schumacher Hamburger Str. 273a
Tel: 0531-2335555 Fax: 0531-2335556
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