| File::chmod - Implements symbolic and ls chmod modes |
File::chmod - Implements symbolic and ls chmod modes
This is File::chmod v0.32.
use File::chmod;
# chmod takes all three types
# these all do the same thing
chmod(0666,@files);
chmod("=rw",@files);
chmod("-rw-rw-rw-",@files);
# or
use File::chmod qw( symchmod lschmod );
chmod(0666,@files); # this is the normal chmod
symchmod("=rw",@files); # takes symbolic modes only
lschmod("-rw-rw-rw-",@files); # takes "ls" modes only
# more functions, read on to understand
File::chmod is a utility that allows you to bypass system calls or bit
processing of a file's permissions. It overloads the chmod() function
with its own that gets an octal mode, a symbolic mode (see below), or
an ``ls'' mode (see below). If you wish not to overload chmod(), you can
export symchmod() and lschmod(), which take, respectively, a symbolic
mode and an ``ls'' mode.
Symbolic modes are thoroughly described in your chmod(1) man page, but
here are a few examples.
# NEW: if $UMASK is true, symchmod() applies a bit-mask found in $MASK
chmod("+x","file1","file2"); # overloaded chmod(), that is...
# turns on the execute bit for all users on those two files
chmod("o=,g-w","file1","file2");
# removes 'other' permissions, and the write bit for 'group'
chmod("=u","file1","file2");
# sets all bits to those in 'user'
``ls'' modes are the type produced on the left-hand side of an ls -l on a
directory. Examples are:
chmod("-rwxr-xr-x","file1","file2");
# the 0755 setting; user has read-write-execute, group and others
# have read-execute priveleges
chmod("-rwsrws---","file1","file2");
# sets read-write-execute for user and group, none for others
# also sets set-uid and set-gid bits
The regular chmod() and lschmod() are absolute; that is, they are not
appending to or subtracting from the current file mode. They set it,
regardless of what it had been before. symchmod() is useful for allowing
the modifying of a file's permissions without having to run a system call
or determining the file's permissions, and then combining that with whatever
bits are appropriate. It also operates separately on each file.
An added feature to version 0.30 is the $UMASK variable, explained below; if
symchmod() is called and this variable is true, then the function uses the
(also new) $MASK variable (which defaults to umask()) as a mask against the
new mode. This is documented below more clearly.
Exported by default:
chmod(MODE,FILES)getchmod(MODE,FILES)
@newmodes = getchmod("+x","file1","file2");
# @newmodes holds the octal permissons of the files'
# modes, if they were to be sent through chmod("+x"...)
Exported by request:
symchmod(MODE,FILES)lschmod(MODE,FILES)getsymchmod(MODE,FILES)getlschmod(MODE,FILES)getmod(FILES)
chmod() on your system. Otherwise, the functions will not report errors.
Example: a file can not have file-locking and the set-gid bits on at the
same time. If $File::chmod::DEBUG is true, the function will report an
error. If not, you are not warned of the conflict. It is set to 1 as
default.
umask() at compile time. Is only applied if
$UMASK is true.
getsymchmod() whether or not to apply the umask
found in $MASK. It defaults to true.
Note: this section was started with version 0.30.
This is an in-depth look at the changes being made from version to version.
getsymchmod() was doing some crazy ish. That's about all I can say.
I did a great deal of debugging, and fixed it up. It ALL had to do with two
things:
$or = (/+=/ ? 1 : 0); # should have been /[+=]/
/u/ && $ok ? u_or() : u_not(); # should have been /u/ and $ok
map() incorrectly in getmod(). Fixed that.
symchmod() function now honors the $UMASK and $MASK variables. $UMASK is
a boolean which indicates whether or not to honor the $MASK variable. $MASK
holds a umask, and it defaults to umask(). $UMASK defaults to true. These
variables are NOT exported. They must explictly set (i.e. $File::chmod::UMASK
= 0).
determine_mode() to mode(). However, if you happen
to be using determine_mode() somewhere, mode() will be called, but you'll also
get a warning about deprecation.
Renamed internal functions {or,not}_{l,s,t} to {l,s,t}_{or,not}. This is to
keep in standard with the OTHER 6 pairs of bitwise functions, such as r_or()
and g_not(). I don't know WHY the others had 'not' or 'or' in the front.
warn() were not guarded by the $DEBUG variable, and now they
are. Also, for some reason, I left a debugging check (that didn't check to
see if $DEBUG was true) in getsymchmod(), line 118. It printed ``ENTERING /g/''.
It's gone now.
# or_s sub, File/chmod.pm, v0.21, line 330
($VAL & 00100) && do {
$DEBUG && warn("execute bit must be on for set-uid"); 1;
} && next;
Aside from me using '&&' more than enough (changed in the new code), this is broken. This is now fixed.
not_l() function (now renamed to l_not()) used to take the file mode and
bit-wise NOT it with ~02000. However, it did not check if the file was locked
vs. set-gid. Now, the function is $VAL &= ~02000 if not $VAL & 00010;.
use vars qw( ... );, but never given a value, and the
%r, %w, and %x hashes had a 'full' key which never got used. And the hashes
themselves weren't really needed anyway. Here is a list of the variables no
longer in use, and what they have been replaced with (if any):
$S nothing $U, $G, $O $W %r, %w, %x octal numbers @files @_ (I had @files = @_; in nearly EVERY sub) $c $_
getmod() subroutine, um, nearly ALL of the getsymchmod()
function, now that I look at it.
Here's part of the getsymchmod() rewrite:
for ($c){
if (/u/){
u_or() if $MODE eq "+" or $MODE eq "=";
u_not() if $MODE eq "-";
}
...
}
# changed to
/u/ && $or ? u_or() : u_and(); # note: operating on $_, $c isn't used anymore # note: $or holds 1 if the $MODE was + or =, 0 if $MODE was - # note: previous was redundant. didn't need $MODE eq "-" check # because u_or() and u_not() both go to the next character
This is only good on Unix-like boxes. I would like people to help me work on
File::chmod for any OS that deserves it. If you would like to help, please
email me (address below) with the OS and any information you might have on how
chmod() should work on it; if you don't have any specific information, but
would still like to help, hey, that's good too. I have the following
information (from perlport):
Jeff japhy Pinyan, japhy.734+CPAN@gmail.com, CPAN ID: PINYAN
Stat::lsMode (by Mark-James Dominus, CPAN ID: MJD) chmod(1) manpage perldoc -f chmod perldoc -f stat
Copyright (C) 2007 by Jeff Pinyan
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.
| File::chmod - Implements symbolic and ls chmod modes |