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| author | Jarkko Hietaniemi <jhi@iki.fi> | 2003-07-27 20:21:40 +0000 |
|---|---|---|
| committer | Jarkko Hietaniemi <jhi@iki.fi> | 2003-07-27 20:21:40 +0000 |
| commit | 4546b9e60350d925ea9a8210378c9e1a79f4a7ab (patch) | |
| tree | f7989045aae0c5d7e38662b15ee435cd2d244332 /pod/perlrun.pod | |
| parent | dcc7f48117e0d8d95c3ad7e7d270188fbf5e9ec8 (diff) | |
| download | perl-4546b9e60350d925ea9a8210378c9e1a79f4a7ab.tar.gz | |
We now return to your normally scheduled hash randomisation.
p4raw-id: //depot/perl@20242
Diffstat (limited to 'pod/perlrun.pod')
| -rw-r--r-- | pod/perlrun.pod | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/pod/perlrun.pod b/pod/perlrun.pod index 024184ac86..d8ed107ac7 100644 --- a/pod/perlrun.pod +++ b/pod/perlrun.pod @@ -1111,20 +1111,19 @@ PERL_ENCODING environment variable is consulted for an encoding name. =item PERL_HASH_SEED (Since Perl 5.8.1.) Used to randomise Perl's internal hash function. +To emulate the pre-5.8.1 behaviour, set to an integer (zero means +exactly the same order as 5.8.0). "Pre-5.8.1" means, among other +things, that hash keys will be ordered the same between different runs +of Perl. -The default behaviour is B<not> to randomise if the PERL_HASH_SEED is -unset. If Perl has been compiled with C<-DUSE_HASH_SEED>, the default -behaviour B<is> to randomise. If Perl hash been compiled with -C<-DNO_HASH_SEED>, the hash randomisation is completely disabled. - -If PERL_HASH_SEED is set to a numeric (positive integer) string, -that is used as the seed. +The default behaviour is to randomise unless the PERL_HASH_SEED is set. +If Perl has been compiled with C<-DUSE_HASH_SEED_EXPLICIT>, the default +behaviour is B<not> to randomise unless the PERL_HASH_SEED is set. If PERL_HASH_SEED is unset or set to a non-numeric string, Perl uses the pseudorandom seed supplied by the operating system and libraries. - -The seed being set means that each different run of Perl will have -a different ordering of the results of keys(), values(), and each(). +This means that each different run of Perl will have a different +ordering of the results of keys(), values(), and each(). See L<perlsec/"Algorithmic Complexity Attacks"> for more information. |