update-alternatives 0.93.72
Here is the script, as promised in my other message:
#!/usr/bin/perl --
use POSIX; &ENOENT;
$version= '0.93.72'; # This line modified by Makefile
sub usageversion {
print(STDERR <<END)
Debian GNU/Linux update-alternatives $version. Copyright (C) 1995
Ian Jackson. This is free software; see the GNU General Public Licence
version 2 or later for copying conditions. There is NO warranty.
Usage: update-alternatives --install <link> <name> <path> <priority>
[--slave <link> <name> <path>] ...
update-alternatives --remove <name> <path>
update-alternatives --auto <name>
update-alternatives --display <name>
<name> is the name in /etc/alternatives.
<path> is the name referred to.
<link> is the link pointing to /etc/alternatives/<name>.
Options: --verbose|--quiet --test --help --version
--altdir <directory> --admindir <directory>
END
|| &quit("failed to write usage: $!");
}
sub quit { print STDERR "update-alternatives: @_\n"; exit(2); }
sub badusage { print STDERR "update-alternatives: @_\n\n"; &usageversion; exit(2); }
$altdir= '/etc/alternatives';
$admindir= '/var/lib/dpkg/alternatives';
$testmode= 0;
$verbosemode= 0;
$mode='';
$manual= 'auto';
$|=1;
sub checkmanymodes {
return unless $mode;
&badusage("two modes specified: $_ and --$mode");
}
while (@ARGV) {
$_= shift(@ARGV);
last if m/^--$/;
if (!m/^--/) {
&quit("unknown argument \`$_'");
} elsif (m/^--(help|version)$/) {
&usageversion; exit(0);
} elsif (m/^--test$/) {
$testmode= 1;
} elsif (m/^--verbose$/) {
$verbosemode= +1;
} elsif (m/^--quiet$/) {
$verbosemode= -1;
} elsif (m/^--install$/) {
&checkmanymodes;
@ARGV >= 4 || &badusage("--install needs <link> <name> <path> <priority>");
($alink,$name,$apath,$apriority,@ARGV) = @ARGV;
$mode= 'install';
} elsif (m/^--remove$/) {
&checkmanymodes;
@ARGV >= 2 || &badusage("--remove needs <name> <path>");
($name,$apath,@ARGV) = @ARGV;
$mode= 'remove';
} elsif (m/^--(display|auto)$/) {
&checkmanymodes;
@ARGV || &badusage("--$1 needs <name>");
$mode= $1;
$name= shift(@ARGV);
} elsif (m/^--slave$/) {
@ARGV >= 3 || &badusage("--slave needs <link> <name> <path>");
($slink,$sname,$spath,@ARGV) = @ARGV;
defined($aslavelink{$sname}) && &badusage("slave name $sname duplicated");
$aslavelinkcount{$slink}++ && &badusage("slave link $slink duplicated");
$aslavelink{$sname}= $slink;
$aslavepath{$sname}= $spath;
} elsif (m/^--altdir$/) {
@ARGV && &badusage("--altdir needs a <directory> argument");
$altdir= shift(@ARGV);
} elsif (m/^--admindir$/) {
@ARGV && &badusage("--admindir needs a <directory> argument");
$admindir= shift(@ARGV);
} else {
&badusage("unknown option \`$_'");
}
}
defined($aslavelink{$name}) && &badusage("name $name is both primary and slave");
$aslavelinkcount{$alink} && &badusage("link $link is both primary and slave");
$mode || &badusage("need --display, --install, --remove or --auto");
$mode eq 'install' || !%slavelink || &badusage("--slave only allowed with --install");
if (open(AF,"$admindir/$name")) {
$manual= &gl("manflag");
$manual eq 'auto' || $manual eq 'manual' || &badfmt("manflag");
$link= &gl("link");
while (($sname= &gl("sname")) ne '') {
push(@slavenames,$sname);
defined($slavenum{$sname}) && &badfmt("duplicate slave $tsname");
$slavenum{$sname}= $#slavenames;
$slink= &gl("slink");
$slink eq $link && &badfmt("slave link same as main link $link");
$slavelinkcount{$slink}++ && &badfmt("duplicate slave link $slink");
push(@slavelinks,$slink);
}
while (($version= &gl("version")) ne '') {
defined($versionnum{$version}) && &badfmt("duplicate path $tver");
push(@versions,$version);
$versionnum{$version}= $i= $#versions;
$priority= &gl("priority");
$priority =~ m/^\d+$/ || &badfmt("priority $version $priority");
$priorities[$i]= $priority;
for ($j=0; $j<=$#slavenames; $j++) {
$slavepath{$i,$j}= &gl("spath");
}
}
close(AF);
$dataread=1;
} elsif ($! != &ENOENT) {
&quit("failed to open $admindir/$name: $!");
}
if ($mode eq 'display') {
if (!$dataread) {
&pr("No alternatives for $name.");
} else {
&pr("$name - status is $manual.");
if (defined($linkname= readlink("$altdir/$name"))) {
&pr(" link currently points to $linkname");
} elsif ($! == &ENOENT) {
&pr(" link currently absent");
} else {
&pr(" link unreadable - $!");
}
$best= '';
for ($i=0; $i<=$#versions; $i++) {
if ($best eq '' || $priorities[$i] > $bestpri) {
$best= $versions[$i]; $bestpri= $priorities[$i];
}
&pr("$versions[$i] - priority $priorities[$i]");
for ($j=0; $j<=$#slavenames; $j++) {
next unless length($tspath= $slavepath{$i,$j});
&pr(" slave $slavenames[$j]: $tspath");
}
}
if ($best eq '') {
&pr("No versions available.");
} else {
&pr("Current \`best' version is $best.");
}
}
exit 0;
}
$best= '';
for ($i=0; $i<=$#versions; $i++) {
if ($best eq '' || $priorities[$i] > $bestpri) {
$best= $versions[$i]; $bestpri= $priorities[$i];
}
}
if (defined($linkname= readlink("$altdir/$name"))) {
if ($linkname eq $best) {
$state= 'expected';
} elsif (defined($linkname2= readlink("$altdir/$name.dpkg-tmp"))) {
$state= 'expected-inprogress';
} else {
$state= 'unexpected';
}
} elsif ($! == &ENOENT) {
$state= 'nonexistent';
} else {
$state= 'unexpected';
}
# Possible values for:
# $manual manual, auto
# $state expected, expected-inprogress, unexpected, nonexistent
# $mode auto, install, remove
# all independent
if ($mode eq 'auto') {
&pr("Setting up automatic selection of $name.");
unlink("$altdir/$name.dpkg-tmp") || $! == &ENOENT ||
&quit("unable to remove $altdir/$name.dpkg-tmp: $!");
unlink("$altdir/$name") || $! == &ENOENT ||
&quit("unable to remove $altdir/$name.dpkg-tmp: $!");
$state= 'nonexistent';
$manual= 'auto';
} elsif ($state eq 'nonexistent') {
if ($mode eq 'manual') {
&pr("$altdir/$name has been deleted, returning to automatic selection.");
$mode= 'auto';
}
}
# $manual manual, auto
# $state expected, expected-inprogress, unexpected, nonexistent
# $mode auto, install, remove
# mode=auto <=> state=nonexistent
if ($state eq 'unexpected' && $manual eq 'auto') {
&pr("$altdir/$name has been changed (manually or by a script).\n".
"Switching to manual updates only.");
$manual= 'manual';
}
# $manual manual, auto
# $state expected, expected-inprogress, unexpected, nonexistent
# $mode auto, install, remove
# mode=auto <=> state=nonexistent
# state=unexpected => manual=manual
if ($mode eq 'install') {
if ($link ne $alink && $link ne '') {
&pr("Renaming $name link from $link to $alink.");
rename($link,$alink) || $! == &ENOENT ||
&quit("unable to rename $link to $alink: $!");
}
$link= $alink;
if (!defined($i= $versionnum{$apath})) {
push(@versions,$apath);
$versionnum{$apath}= $i= $#versions;
}
$priorities[$i]= $apriority;
for $sname (keys %aslavelink) {
if (!defined($j= $slavenum{$sname})) {
push(@slavenames,$sname);
$slavenum{$sname}= $j= $#slavenames;
}
$oldslavelink= $slavelinks[$j];
$newslavelink= $aslavelink{$sname};
$slavelinkcount{$oldslavelink}-- if $oldslavelink ne '';
$slavelinkcount{$newslavelink}++ &&
&quit("slave link name $newslavelink duplicated");
if ($newslavelink ne $oldslavelink && $oldslavelink ne '') {
&pr("Renaming $sname slave link from $oldslavelink to $newslavelink.");
rename($oldslavelink,$newslavelink) || $! == &ENOENT ||
&quit("unable to rename $oldslavelink to $newslavelink: $!");
}
$slavelinks[$j]= $newslavelink;
}
for ($j=0; $j<=$#slavenames; $j++) {
$slavepath{$i,$j}= $aslavepath{$slavenames[$j]};
}
}
if ($mode eq 'remove') {
if (defined($i= $versionnum{$apath})) {
$k= $#versions;
$versionnum{$versions[$k]}= $i;
delete $versionnum{$versions[$i]};
$versions[$i]= $versions[$k]; $#versions--;
$priorities[$i]= $priorities[$k]; $#priorities--;
for ($j=0; $j<=$#slavenames; $j++) {
$slavepath{$i,$j}= $slavepath{$k,$j};
delete $slavepath{$k,$j};
}
} else {
&pr("Alternative $apath for $name not registered, not removing.");
}
}
for ($j=0; $j<=$#slavenames; $j++) {
for ($i=0; $i<=$#versions; $i++) {
last if $slavepath{$i,$j} ne '';
}
if ($i > $#versions) {
&pr("Discarding obsolete slave link $slavenames[$j] ($slavelinks[$j]).");
unlink($slavenames[$j]) || $! == &ENOENT ||
&quit("unable to remove $slavenames[$j]: $!");
unlink($slavelinks[$j]) || $! == &ENOENT ||
&quit("unable to remove $slavelinks[$j]: $!");
$k= $#slavenames;
$slavenum{$slavenames[$k]}= $j;
delete $slavenum{$slavenames[$j]};
$slavelinkcount{$slavelinks[$j]}--;
$slavenames[$j]= $slavenames[$k]; $#slavenames--;
$slavelinks[$j]= $slavelinks[$k]; $#slavelinks--;
for ($i=0; $i<=$#versions; $i++) {
$slavepath{$i,$j}= $slavepath{$i,$k};
delete $slavepath{$i,$k};
}
}
}
if ($manual eq 'manual') {
&pr("Automatic updates of $altdir/$name are disabled, leaving it alone.");
&pr("To return to automatic updates use \`update-alternatives --auto $name'.");
} else {
if ($state eq 'expected-inprogress') {
&pr("Recovering from previous failed update of $name ...");
rename("$altdir/$name.dpkg-tmp","$altdir/$name") ||
&quit("unable to rename $altdir/$name.dpkg-tmp to $altdir/$name: $!");
$state= 'expected';
}
}
# $manual manual, auto
# $state expected, expected-inprogress, unexpected, nonexistent
# $mode auto, install, remove
# mode=auto <=> state=nonexistent
# state=unexpected => manual=manual
# manual=auto => state!=expected-inprogress && state!=unexpected
open(AF,">$admindir/$name.dpkg-new") ||
&quit("unable to open $admindir/$name.dpkg-new for write: $!");
&paf($manual);
&paf($link);
for ($j=0; $j<=$#slavenames; $j++) {
&paf($slavenames[$j]);
&paf($slavelinks[$j]);
}
&paf('');
$best= '';
for ($i=0; $i<=$#versions; $i++) {
if ($best eq '' || $priorities[$i] > $bestpri) {
$best= $versions[$i]; $bestpri= $priorities[$i]; $bestnum= $i;
}
&paf($versions[$i]);
&paf($priorities[$i]);
for ($j=0; $j<=$#slavenames; $j++) {
&paf($slavepath{$i,$j});
}
}
&paf('');
close(AF) || &quit("unable to close $admindir/$name.dpkg-new: $!");
if ($manual eq 'auto') {
if ($best eq '') {
&pr("Last package providing $name ($link) removed, deleting it.");
unlink("$altdir/$name") || $! == &ENOENT ||
&quit("unable to remove $altdir/$name: $!");
unlink("$link") || $! == &ENOENT ||
&quit("unable to remove $altdir/$name: $!");
unlink("$admindir/$name.dpkg-new") ||
&quit("unable to remove $admindir/$name.dpkg-new: $!");
unlink("$admindir/$name") || $! == &ENOENT ||
&quit("unable to remove $admindir/$name: $!");
exit(0);
} else {
if (!defined($linkname= readlink($link)) && $! != &ENOENT) {
&pr("warning: $link is supposed to be a symlink to $altdir/$name\n".
" (or nonexistent); however, readlink failed: $!");
} elsif ($linkname ne "$altdir/$name") {
unlink("$link.dpkg-tmp") || $! == &ENOENT ||
&quit("unable to ensure $link.dpkg-tmp nonexistent: $!");
symlink("$altdir/$name","$link.dpkg-tmp") ||
&quit("unable to make $link.dpkg-tmp a symlink to $altdir/$name: $!");
rename("$link.dpkg-tmp",$link) ||
&quit("unable to install $link.dpkg-tmp as $link: $!");
}
&pr("Updating $name ($link) to point to $best.");
unlink("$altdir/$name.dpkg-tmp") || $! == &ENOENT ||
&quit("unable to ensure $altdir/$name.dpkg-tmp nonexistent: $!");
symlink($best,"$altdir/$name.dpkg-tmp");
}
}
rename("$admindir/$name.dpkg-new","$admindir/$name") ||
&quit("unable to rename $admindir/$name.dpkg-new to $admindir/$name: $!");
if ($manual eq 'auto') {
rename("$altdir/$name.dpkg-tmp","$altdir/$name") ||
&quit("unable to install $altdir/$name.dpkg-tmp as $altdir/$name");
for ($j=0; $j<=$#slavenames; $j++) {
$sname= $slavenames[$j];
$slink= $slavelinks[$j];
if (!defined($linkname= readlink($slink)) && $! != &ENOENT) {
&pr("warning: $slink is supposed to be a slave symlink to\n".
" $altdir/$sname, or nonexistent; however, readlink failed: $!");
} elsif ($linkname ne "$altdir/$sname") {
unlink("$slink.dpkg-tmp") || $! == &ENOENT ||
&quit("unable to ensure $slink.dpkg-tmp nonexistent: $!");
symlink("$altdir/$sname","$slink.dpkg-tmp") ||
&quit("unable to make $slink.dpkg-tmp a symlink to $altdir/$sname: $!");
rename("$slink.dpkg-tmp",$slink) ||
&quit("unable to install $slink.dpkg-tmp as $slink: $!");
}
$spath= $slavepath{$bestnum,$j};
unlink("$altdir/$sname.dpkg-tmp") || $! == &ENOENT ||
&quit("unable to ensure $altdir/$sname.dpkg-tmp nonexistent: $!");
if ($spath eq '') {
&pr("Removing $sname ($slink), not appropriate with $best.");
unlink("$altdir/$sname") || $! == &ENOENT ||
&quit("unable to remove $altdir/$sname: $!");
} else {
&pr("Updating $sname ($slink) to point to $spath.");
symlink("$spath","$altdir/$sname.dpkg-tmp") ||
&quit("unable to make $altdir/$sname.dpkg-tmp a symlink to $spath: $!");
rename("$altdir/$sname.dpkg-tmp","$altdir/$sname") ||
&quit("unable to install $altdir/$sname.dpkg-tmp as $altdir/$sname: $!");
}
}
}
sub pr { print(STDOUT "@_\n") || &quit("error writing stdout: $!"); }
sub paf {
$_[0] =~ m/\n/ && &quit("newlines prohibited in update-alternatives files ($_[0])");
print(AF "$_[0]\n") || &quit("error writing stdout: $!");
}
sub gl {
$!=0; $_= <AF>;
length($_) || &quit("error or eof reading $admindir/$name for $_[0] ($!)");
s/\n$// || &badfmt("missing newline after $_[0]");
$_;
}
sub badfmt {
&quit("internal error: $admindir/$name corrupt: $_[0]");
}
exit(0);
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