On Fri, Jul 08, 2005 at 09:36:19AM +0100, Steve Hay wrote:
> The crash is deliberately forced by win32_checkTLS(), but I don't
> understand for what reason. PerlEnvGetenv() takes an IPerlEnv* and uses
> the IPERL2HOST() macro (which is set to IPerlEnv2Host()) to locate the
> CPerlHost* which that IPerlEnv* is a member of. It then calls
> win32_checkTLS() to check that the host_perl in the CPerlHost* that has
> been found is my_perl. Evidently, in this case host_perl != my_perl, so
> it bombs out.
>
> Does anyone know what this my_perl is? What is the purpose of the
> host_perl != my_perl check, and why might it be failing?
my_perl is a pointer to the current perl interpreter; in a threaded build,
it's normally passed as an extra 1st arg to most functions (that's what all
the pTHX/aTHX stuff is for); functions that don't get it passed can
have 'dTHX;' at their start, which declares my_perl and determines it from
thread-local storage (this is slow).
win32_checkTLS() appears to be sanity checking that the passed host_perl is
the same as the my_perl determined by dTHX; since is this happening during the
middle of cloning, this isn't likely to be the case.
The real question is why is PerlIO_debug() getting called for the first time
during cloning? On my system, it's getting called much earlier, during
perl_parse(). A second possibility is that it's not being called for the
first time, but that in this code:
PerlIO_debug(const char *fmt, ...)
{
va_list ap;
dSYS;
va_start(ap, fmt);
if (!PL_perlio_debug_fd && !PL_tainting && PL_uid == PL_euid && PL_gid
== PL_egid) {
const char *s = PerlEnv_getenv("PERLIO_DEBUG");
if (s && *s)
PL_perlio_debug_fd = PerlLIO_open3(s, O_WRONLY | O_CREAT |
O_APPEND, 0666);
else
PL_perlio_debug_fd = -1;
for some reason PerlLIO_open3() is setting PL_perlio_debug_fd to 0, so
that each time PerlIO_debug is called, it will still do a
PerlEnv_getenv("PERLIO_DEBUG"). Perhaps?
Can you detemine when PerlIO_debug() is being called, and if whether it's
calling PerlLIO_open3() and whether that's rturning 0?
--
The perl5 internals are a complete mess. It's like Jenga - to get the
perl5 tower taller and do something new you select a block somewhere in
the middle, with trepidation pull it out slowly, and then carefully
balance it somewhere new, hoping the whole edifice won't collapse as a
result.
- Nicholas Clark, based on an original by Simon Cozens.
