Filename	/usr/lib/perl5/5.14/filetest.pm
Statements	Executed 5 statements in 29µs

Subroutines

Calls	P	F	Exclusive Time	Inclusive Time	Subroutine
1	1	1	8µs	8µs	filetest::::importfiletest::import
0	0	0	0s	0s	filetest::::unimportfiletest::unimport

Call graph for these subroutines as a Graphviz dot language file.

Line	State ments	Time on line	Calls	Time in subs	Code
1					package filetest;
2
3	1	2µs			our $VERSION = '1.02';
4
5					=head1 NAME
6
7					filetest - Perl pragma to control the filetest permission operators
8
9					=head1 SYNOPSIS
10
11					$can_perhaps_read = -r "file"; # use the mode bits
12					{
13					use filetest 'access'; # intuit harder
14					$can_really_read = -r "file";
15					}
16					$can_perhaps_read = -r "file"; # use the mode bits again
17
18					=head1 DESCRIPTION
19
20					This pragma tells the compiler to change the behaviour of the filetest
21					permission operators, C<-r> C<-w> C<-x> C<-R> C<-W> C<-X>
22					(see L<perlfunc>).
23
24					The default behaviour of file test operators is to use the simple
25					mode bits as returned by the stat() family of system calls. However,
26					many operating systems have additional features to define more complex
27					access rights, for example ACLs (Access Control Lists).
28					For such environments, C<use filetest> may help the permission
29					operators to return results more consistent with other tools.
30
31					The C<use filetest> or C<no filetest> statements affect file tests defined in
32					their block, up to the end of the closest enclosing block (they are lexically
33					block-scoped).
34
35					Currently, only the C<access> sub-pragma is implemented. It enables (or
36					disables) the use of access() when available, that is, on most UNIX systems and
37					other POSIX environments. See details below.
38
39					=head2 Consider this carefully
40
41					The stat() mode bits are probably right for most of the files and
42					directories found on your system, because few people want to use the
43					additional features offered by access(). But you may encounter surprises
44					if your program runs on a system that uses ACLs, since the stat()
45					information won't reflect the actual permissions.
46
47					There may be a slight performance decrease in the filetest operations
48					when the filetest pragma is in effect, because checking bits is very
49					cheap.
50
51					Also, note that using the file tests for security purposes is a lost cause
52					from the start: there is a window open for race conditions (who is to
53					say that the permissions will not change between the test and the real
54					operation?). Therefore if you are serious about security, just try
55					the real operation and test for its success - think in terms of atomic
56					operations. Filetests are more useful for filesystem administrative
57					tasks, when you have no need for the content of the elements on disk.
58
59					=head2 The "access" sub-pragma
60
61					UNIX and POSIX systems provide an abstract access() operating system call,
62					which should be used to query the read, write, and execute rights. This
63					function hides various distinct approaches in additional operating system
64					specific security features, like Access Control Lists (ACLs)
65
66					The extended filetest functionality is used by Perl only when the argument
67					of the operators is a filename, not when it is a filehandle.
68
69					=head2 Limitation with regard to C<_>
70
71					Because access() does not invoke stat() (at least not in a way visible
72					to Perl), B<the stat result cache "_" is not set>. This means that the
73					outcome of the following two tests is different. The first has the stat
74					bits of C</etc/passwd> in C<_>, and in the second case this still
75					contains the bits of C</etc>.
76
77					{ -d '/etc';
78					-w '/etc/passwd';
79					print -f _ ? 'Yes' : 'No'; # Yes
80					}
81
82					{ use filetest 'access';
83					-d '/etc';
84					-w '/etc/passwd';
85					print -f _ ? 'Yes' : 'No'; # No
86					}
87
88					Of course, unless your OS does not implement access(), in which case the
89					pragma is simply ignored. Best not to use C<_> at all in a file where
90					the filetest pragma is active!
91
92					As a side effect, as C<_> doesn't work, stacked filetest operators
93					(C<-f -w $file>) won't work either.
94
95					This limitation might be removed in a future version of perl.
96
97					=cut
98
99	1	500ns			$filetest::hint_bits = 0x00400000; # HINT_FILETEST_ACCESS
100
101					# spent 8µs within filetest::import which was called: # once (8µs+0s) by installer::download::BEGIN@42 at line 45 of /cygdrive/c/lo/libo-master/instsetoo_native/util/C:/lo/libo-master/solenv/bin/modules/installer/download.pm sub import {
102	2	14µs			if ( $_[1] eq 'access' ) {
103					$^H |= $filetest::hint_bits;
104					} else {
105					die "filetest: the only implemented subpragma is 'access'.\n";
106					}
107					}
108
109					sub unimport {
110					if ( $_[1] eq 'access' ) {
111					$^H &= ~$filetest::hint_bits;
112					} else {
113					die "filetest: the only implemented subpragma is 'access'.\n";
114					}
115					}
116
117	1	12µs			1;