package filetest;
+our $VERSION = '1.01';
+
=head1 NAME
filetest - Perl pragma to control the filetest permission operators
=head1 SYNOPSIS
-
+
$can_perhaps_read = -r "file"; # use the mode bits
{
use filetest 'access'; # intuit harder
=head1 DESCRIPTION
This pragma tells the compiler to change the behaviour of the filetest
-permissions operators, the -r -w -x -R -W -X (see L<perlfunc>).
+permission operators, C<-r> C<-w> C<-x> C<-R> C<-W> C<-X>
+(see L<perlfunc>).
-The default behaviour to use the mode bits as returned by the stat()
+The default behaviour is to use the mode bits as returned by the stat()
family of calls. This, however, may not be the right thing to do if
for example various ACL (access control lists) schemes are in use.
For such environments, C<use filetest> may help the permission
when C<use filetest> is in effect, because in some systems
the extended functionality needs to be emulated.
-B<NOTE>: using the file tests is a lost case from the start: there is
-a window open for race conditions (who is to say that the permissions
-will not change between the test and the real operation?). Therefore
-if you are serious about security, just try the real operation and
-test for its success. Think atomicity.
+B<NOTE>: using the file tests for security purposes is a lost cause
+from the start: there is a window open for race conditions (who is to
+say that the permissions will not change between the test and the real
+operation?). Therefore if you are serious about security, just try
+the real operation and test for its success - think in terms of atomic
+operations.
=head2 subpragma access
=cut
+$filetest::hint_bits = 0x00400000; # HINT_FILETEST_ACCESS
+
sub import {
if ( $_[1] eq 'access' ) {
- $^H |= 0x00400000;
+ $^H |= $filetest::hint_bits;
} else {
die "filetest: the only implemented subpragma is 'access'.\n";
}
sub unimport {
if ( $_[1] eq 'access' ) {
- $^H &= ~0x00400000;
+ $^H &= ~$filetest::hint_bits;
} else {
die "filetest: the only implemented subpragma is 'access'.\n";
}