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Recover SymbolicMode.pm and rename under PerlPowerTools::* #233
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,210 @@ | ||
| package PerlPowerTools::SymbolicMode; | ||
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| # | ||
| # $Id: SymbolicMode.pm,v 1.1 2004/07/23 20:10:01 cwest Exp $ | ||
| # | ||
| # $Log: SymbolicMode.pm,v $ | ||
| # Revision 1.1 2004/07/23 20:10:01 cwest | ||
| # initial import | ||
| # | ||
| # Revision 1.1 1999/03/07 12:03:54 abigail | ||
| # Initial revision | ||
| # | ||
| # | ||
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| use strict; | ||
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| sub mod ($$) { | ||
| my $symbolic = shift; | ||
| my $file = shift; | ||
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| # Initialization. | ||
| # The 'user', 'group' and 'other' groups. | ||
| my @ugo = qw /u g o/; | ||
| # Bit masks for '[sg]uid', 'sticky', 'read', 'write' and 'execute'. | ||
| # Can't use qw // cause silly Perl doesn't know '2' is a number | ||
| # when dealing with &= ~$bit. | ||
| my %bits = (s => 8, t => 8, r => 4, w => 2, x => 1); | ||
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| # For parsing. | ||
| my $who_re = '[augo]*'; | ||
| my $action_re = '[-+=][rstwxXugo]*'; | ||
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| # Find the current permissions. This is what we start with. | ||
| my $mode = sprintf "%04o" => (stat $file) [2] || 0; | ||
| my $current = substr $mode => -3; # rwx permissions for ugo. | ||
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| my %perms; | ||
| @perms {@ugo} = split // => $current; | ||
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| # Handle the suid, guid and sticky bits. | ||
| # It looks like permission are 4 groups of 3 bits, groups for user, | ||
| # group and others, and a group for the special flags, but they are | ||
| # really 3 groups of 4 bits. Or maybe not. | ||
| # Anyway, this function is greatly simplified by treating them as | ||
| # 3 4-bit groups. The highest bit will be "special" one. suid for | ||
| # the users group, guid for the group group, and the sticky bit | ||
| # for the others group. | ||
| my $special = substr $mode => -4, 1; | ||
| my $bit = 1; | ||
| foreach my $c (reverse @ugo) { | ||
| $perms {$c} |= 8 if $special & $bit; | ||
| $bit <<= 1; | ||
| } | ||
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| # Keep track of the original permissions. | ||
| my %orig = %perms; | ||
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| # Find the umask setting, and store the bits for each group | ||
| # in a hash. | ||
| my %umask; # umask bits. | ||
| @umask {@ugo} = split // => sprintf "%03o" => umask; | ||
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| # Time to parse... | ||
| foreach my $clause (split /,/ => $symbolic) { | ||
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| # Perhaps we should die if we can't parse it? | ||
| return undef unless | ||
| my ($who, $actions) = | ||
| $clause =~ /^($who_re)((?:$action_re)+)$/o; | ||
| # We would rather split the different actions out here, | ||
| # but there doesn't seem to be a way to collect them. | ||
| # /^($who_re)($action_re)+/ only gets the last one. | ||
| # Now, we have to reparse in later. | ||
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| my %who; | ||
| if ($who) { | ||
| $who =~ s/a/ugo/; # Ignore multiple 'a's. | ||
| @who {split // => $who} = undef; | ||
| } | ||
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| # @who will contain who these settings applies to. | ||
| # if who isn't set, it might be masked with the umask, | ||
| # hence, this isn't the final decision. | ||
| # Maybe we don't need this. | ||
| my @who = $who ? keys %who : @ugo; | ||
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| foreach my $action (split /(?=$action_re)/o => $actions) { | ||
| # The first character has to be the operator. | ||
| my $operator = substr $action, 0, 1; | ||
| # And the rest are the permissions. | ||
| my $perms = substr $action, 1; | ||
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| # BSD documentation says 'X' is to be ignored unless | ||
| # the operator is '-'. GNU, HP, SunOS and Solaris handle | ||
| # '-' and '=', while OpenBSD ignores only '-'. | ||
| # Solaris, HP and OpenBSD all turn a file with permission | ||
| # 666 to a file with permission 000 if chmod =X is | ||
| # is applied on it. SunOS and GNU act as if chmod = was | ||
| # applied to it. I cannot find out what the reasoning | ||
| # behind the choices of Solaris, HP and OpenBSD is. | ||
| # GNU and SunOS seem to ignore the 'X', which, after | ||
| # careful studying of the documentation seems to be | ||
| # the right choice. | ||
| # Therefore, remove any 'X' if the operator ain't '+'; | ||
| $perms =~ s/X+//g unless $operator eq '+'; | ||
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| # If there are no permissions, things are simple. | ||
| unless ($perms) { | ||
| # Things like u+ and go- are ignored; only = makes sense. | ||
| next unless $operator eq '='; | ||
| # Clear permissions on u= and go=. | ||
| if ($who) {@perms {keys %who} = (0) x 3;} | ||
| # '=' is special. Sets permissions to the umask. | ||
| else {%perms = %umask;} | ||
| next; | ||
| } | ||
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| # If we arrive here, $perms is a string. | ||
| # We can iterate over the characters. | ||
| foreach (split // => $perms) { | ||
| if ($_ eq 'X') { | ||
| # We know the operator eq '+'. | ||
| # Permission of `X' is special. If used on a regular file, | ||
| # the execution bit will only be turned on if any of the | ||
| # execution bits of the _unmodified_ file are turned on. | ||
| # That is, | ||
| # chmod 600 file; chmod u+x,a+X file; | ||
| # should result in the file having permission 700, not 711. | ||
| # GNU and SunOS get this wrong; | ||
| # Solaris, HP and OpenBSD get it right. | ||
| next unless -d $file || grep {$orig {$_} & 1} @ugo; | ||
| # Now, do as if it's an x. | ||
| $_ = 'x'; | ||
| } | ||
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| if (/[st]/) { | ||
| # BSD man page says operations on 's' and 't' are to | ||
| # be ignored if they operate only on the "other" group. | ||
| # GNU and HP happely accept 'o+t'. Sun rejects 'o+t', | ||
| # but also rejects 'g+t', accepting only 'u+t'. | ||
| # OpenBSD acceps both 'u+t' and 'g+t', ignoring 'o+t'. | ||
| # We do too. | ||
| # OpenBSD however, accepts 'o=t', clearing all the bits | ||
| # of the "other" group. | ||
| # We don't, as that doesn't make any sense, and doesn't | ||
| # confirm to the documentation. | ||
| next if $who =~ /^o+$/; | ||
| } | ||
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| # Determine the $bit for the mask. | ||
| my $bit = /[ugo]/ ? $orig {$_} & ~8 : $bits {$_}; | ||
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| die "Weird permission `$_' found\n" unless defined $bit; | ||
| # Should not happen. | ||
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| # Determine the set on which to operate. | ||
| my @set = $who ? @who : grep {!($umask {$_} & $bit)} @ugo; | ||
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| # If the permission is 's', don't operate on the other group. | ||
| # Unless the operator was '='. But in that case, don't set | ||
| # the 8 bit for 'other'. | ||
| my $equal_s; | ||
| if (/s/) { | ||
| if ($operator eq '=') {$equal_s = 1;} | ||
| else {@set = grep {!/o/} @set or next;} | ||
| } | ||
| # If the permission is 't', only operate on the other group; | ||
| # regardless what the 'who' settings are. | ||
| # Note that for a directory with permissions 1777, and a | ||
| # umask of 002, a chmod =t on HP and Solaris turn the | ||
| # permissions to 1000, GNU and SunOS turn the permissiosn | ||
| # to 1020, while OpenBSD keeps 1777. | ||
| /t/ and @set = qw /o/; | ||
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| # Apply. | ||
| foreach my $s (@set) { | ||
| do {$perms {$s} |= $bit; next} if $operator eq '+'; | ||
| do {$perms {$s} &= ~$bit; next} if $operator eq '-'; | ||
| do {$perms {$s} = $bit; next} if $operator eq '='; | ||
| die "Weird operator `$operator' found\n"; | ||
| # Should not happen. | ||
| } | ||
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| # Special case '=s'. | ||
| $perms {o} &= ~$bit if $equal_s; | ||
| } | ||
| } | ||
| } | ||
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| # Now, translate @perms to an *octal* number. | ||
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| # First, deal with the suid, guid, and sticky bits by collecting | ||
| # the high bits of the ugo permissions. | ||
| my $first = 0; | ||
| $bit = 1; | ||
| for my $c (reverse @ugo) { | ||
| if ($perms {$c} & 8) {$first |= $bit; $perms {$c} &= ~8;} | ||
| $bit <<= 1; | ||
| } | ||
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| join "" => $first, @perms {@ugo}; | ||
| } | ||
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| 1; | ||
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| __END__ |