argra****@users*****
argra****@users*****
2012年 10月 10日 (水) 03:42:00 JST
Index: docs/modules/filetest-1.02/filetest.pod
diff -u /dev/null docs/modules/filetest-1.02/filetest.pod:1.1
--- /dev/null Wed Oct 10 03:42:00 2012
+++ docs/modules/filetest-1.02/filetest.pod Wed Oct 10 03:42:00 2012
@@ -0,0 +1,235 @@
+
+=encoding euc-jp
+
+=head1 NAME
+
+=begin original
+
+filetest - Perl pragma to control the filetest permission operators
+
+=end original
+
+filetest - ファイルテストパーミッション演算子を制御する Perl プラグマ
+
+=head1 SYNOPSIS
+
+ $can_perhaps_read = -r "file"; # use the mode bits
+ {
+ use filetest 'access'; # intuit harder
+ $can_really_read = -r "file";
+ }
+ $can_perhaps_read = -r "file"; # use the mode bits again
+
+=head1 DESCRIPTION
+
+=begin original
+
+This pragma tells the compiler to change the behaviour of the filetest
+permission operators, C<-r> C<-w> C<-x> C<-R> C<-W> C<-X>
+(see L<perlfunc>).
+
+=end original
+
+This pragma tells the compiler to change the behaviour of the filetest
+permission operators, C<-r> C<-w> C<-x> C<-R> C<-W> C<-X>
+(see L<perlfunc>).
+(TBT)
+
+=begin original
+
+The default behaviour of file test operators is to use the simple
+mode bits as returned by the stat() family of system calls. However,
+many operating systems have additional features to define more complex
+access rights, for example ACLs (Access Control Lists).
+For such environments, C<use filetest> may help the permission
+operators to return results more consistent with other tools.
+
+=end original
+
+The default behaviour of file test operators is to use the simple
+mode bits as returned by the stat() family of system calls. However,
+many operating systems have additional features to define more complex
+access rights, for example ACLs (Access Control Lists).
+For such environments, C<use filetest> may help the permission
+operators to return results more consistent with other tools.
+(TBT)
+
+=begin original
+
+The C<use filetest> or C<no filetest> statements affect file tests defined in
+their block, up to the end of the closest enclosing block (they are lexically
+block-scoped).
+
+=end original
+
+The C<use filetest> or C<no filetest> statements affect file tests defined in
+their block, up to the end of the closest enclosing block (they are lexically
+block-scoped).
+(TBT)
+
+=begin original
+
+Currently, only the C<access> sub-pragma is implemented. It enables (or
+disables) the use of access() when available, that is, on most UNIX systems and
+other POSIX environments. See details below.
+
+=end original
+
+Currently, only the C<access> sub-pragma is implemented. It enables (or
+disables) the use of access() when available, that is, on most UNIX systems and
+other POSIX environments. See details below.
+(TBT)
+
+=head2 Consider this carefully
+
+=begin original
+
+The stat() mode bits are probably right for most of the files and
+directories found on your system, because few people want to use the
+additional features offered by access(). But you may encounter surprises
+if your program runs on a system that uses ACLs, since the stat()
+information won't reflect the actual permissions.
+
+=end original
+
+The stat() mode bits are probably right for most of the files and
+directories found on your system, because few people want to use the
+additional features offered by access(). But you may encounter surprises
+if your program runs on a system that uses ACLs, since the stat()
+information won't reflect the actual permissions.
+(TBT)
+
+=begin original
+
+There may be a slight performance decrease in the filetest operations
+when the filetest pragma is in effect, because checking bits is very
+cheap.
+
+=end original
+
+There may be a slight performance decrease in the filetest operations
+when the filetest pragma is in effect, because checking bits is very
+cheap.
+(TBT)
+
+=begin original
+
+Also, note that 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. Filetests are more useful for filesystem administrative
+tasks, when you have no need for the content of the elements on disk.
+
+=end original
+
+Also, note that 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. Filetests are more useful for filesystem administrative
+tasks, when you have no need for the content of the elements on disk.
+(TBT)
+
+=head2 The "access" sub-pragma
+
+=begin original
+
+UNIX and POSIX systems provide an abstract access() operating system call,
+which should be used to query the read, write, and execute rights. This
+function hides various distinct approaches in additional operating system
+specific security features, like Access Control Lists (ACLs)
+
+=end original
+
+UNIX and POSIX systems provide an abstract access() operating system call,
+which should be used to query the read, write, and execute rights. This
+function hides various distinct approaches in additional operating system
+specific security features, like Access Control Lists (ACLs)
+(TBT)
+
+=begin original
+
+The extended filetest functionality is used by Perl only when the argument
+of the operators is a filename, not when it is a filehandle.
+
+=end original
+
+The extended filetest functionality is used by Perl only when the argument
+of the operators is a filename, not when it is a filehandle.
+(TBT)
+
+=head2 Limitation with regard to C<_>
+
+=begin original
+
+Because access() does not invoke stat() (at least not in a way visible
+to Perl), B<the stat result cache "_" is not set>. This means that the
+outcome of the following two tests is different. The first has the stat
+bits of C</etc/passwd> in C<_>, and in the second case this still
+contains the bits of C</etc>.
+
+=end original
+
+Because access() does not invoke stat() (at least not in a way visible
+to Perl), B<the stat result cache "_" is not set>. This means that the
+outcome of the following two tests is different. The first has the stat
+bits of C</etc/passwd> in C<_>, and in the second case this still
+contains the bits of C</etc>.
+(TBT)
+
+ { -d '/etc';
+ -w '/etc/passwd';
+ print -f _ ? 'Yes' : 'No'; # Yes
+ }
+
+ { use filetest 'access';
+ -d '/etc';
+ -w '/etc/passwd';
+ print -f _ ? 'Yes' : 'No'; # No
+ }
+
+=begin original
+
+Of course, unless your OS does not implement access(), in which case the
+pragma is simply ignored. Best not to use C<_> at all in a file where
+the filetest pragma is active!
+
+=end original
+
+Of course, unless your OS does not implement access(), in which case the
+pragma is simply ignored. Best not to use C<_> at all in a file where
+the filetest pragma is active!
+(TBT)
+
+=begin original
+
+As a side effect, as C<_> doesn't work, stacked filetest operators
+(C<-f -w $file>) won't work either.
+
+=end original
+
+As a side effect, as C<_> doesn't work, stacked filetest operators
+(C<-f -w $file>) won't work either.
+(TBT)
+
+=begin original
+
+This limitation might be removed in a future version of perl.
+
+=end original
+
+This limitation might be removed in a future version of perl.
+(TBT)
+
+=begin meta
+
+Translate: SHIRAKATA Kentaro <argra****@ub32*****>
+Status: in progress
+
+=end meta
+
+=cut
+