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Postings from September 2003
At 01:04 +0200 9/8/03, Rafael Garcia-Suarez wrote:
>Elizabeth Mattijsen wrote:
> > If I build 21021 with:
> > > -Accflags=-DNO_HASH_SEED
>You can always do 'perl -V:ccflags'. That should be there.
You learn something every day. Thanks, Rafael.
I concocted the following check routine. Maybe this needs a home
somewhere in a Util core library somewhere? If so, I'll supply a
patch for the indicated library.
I also made it print something in void context, so you'll be able to
do one-liners such as:
perl -Mwhatever -e is_hash_randomized
(if is_hash_randomized in module whatever.pm would be exported, of course)
Liz
The code:
#---------------------------------------------------------------------------
# is_hash_randomized
#
# OUT: 1 undef (random sequence) or defined (repeatable with seed)
#
# Prints a string when called in void context.
sub is_hash_randomized {
# If we're called in void context
# Call ourselves to get status
# Show the world what it is
# We're done now
if (!defined wantarray) {
my $seed = is_hash_randomized();
print defined $seed ?
qq{Repeatable hash sequences with seed "$seed".\n} :
qq{Unrepeatable hash sequences.\n};
return;
}
# We don't have any random sequences yet, as if seed "0"
return 0 if $] < 5.008001;
# Get the -Accflags= settings using this Perl executor
open my $handle, "$^X -V:ccflags |"
or die "Could not execute $^X -V:ccflags: $!\n";
my $ccflags = <$handle>;
close $handle;
# Return repeatable default if random sequences compiled out
# Return random if switch settings reversed and environment variable set
# Return whatever the environment variable indicates
return 0 if $ccflags =~ m#-DNO_HASH_SEED#;
return if $ccflags =~ m#-DUSE_HASH_SEED_EXPLICIT#
and exists $ENV{PERL_HASH_SEED};
$ENV{PERL_HASH_SEED};
} #is_hash_randomized
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