90 lines
2.2 KiB
Perl
Executable File
90 lines
2.2 KiB
Perl
Executable File
#! /usr/bin/perl -w
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use strict;
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my $pkglist = $ENV{"NIX_ACTIVATIONS"};
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$pkglist or die "NIX_ACTIVATIONS not set";
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my $linkdir = $ENV{"NIX_LINKS"};
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$linkdir or die "NIX_LINKS not set";
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my @dirs = ("bin", "sbin", "lib");
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# Figure out a generation number.
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my $nr = 1;
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while (-e "$linkdir/$nr") { $nr++; }
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my $gendir = "$linkdir/$nr";
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print "populating $gendir\n";
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# Create the subdirectories.
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mkdir $gendir;
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foreach my $dir (@dirs) {
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mkdir "$gendir/$dir";
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}
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# For each activated package, create symlinks.
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sub createLinks {
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my $srcdir = shift;
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my $dstdir = shift;
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my @srcfiles = glob("$srcdir/*");
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foreach my $srcfile (@srcfiles) {
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my $basename = $srcfile;
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$basename =~ s/^.*\///g; # strip directory
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my $dstfile = "$dstdir/$basename";
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if (-d $srcfile) {
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# !!! hack for resolving name clashes
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if (!-e $dstfile) {
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mkdir($dstfile) or
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die "error creating directory $dstfile";
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}
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-d $dstfile or die "$dstfile is not a directory";
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createLinks($srcfile, $dstfile);
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} elsif (-l $dstfile) {
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my $target = readlink($dstfile);
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die "collission between $srcfile and $target";
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} else {
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print "linking $dstfile to $srcfile\n";
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symlink($srcfile, $dstfile) or
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die "error creating link $dstfile";
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}
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}
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}
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open PKGS, "< $pkglist";
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while (<PKGS>) {
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chomp;
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my $hash = $_;
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my $pkgdir = `nix getpkg $hash`;
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if ($?) { die "`nix getpkg' failed"; }
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chomp $pkgdir;
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print "merging $pkgdir\n";
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foreach my $dir (@dirs) {
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createLinks("$pkgdir/$dir", "$gendir/$dir");
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}
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}
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close PKGS;
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# Make $gendir the current generation by pointing $linkdir/current to
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# it. The rename() system call is supposed to be essentially atomic
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# on Unix. That is, if we have links `current -> X' and `new_current
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# -> Y', and we rename new_current to current, a process accessing
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# current will see X or Y, but never a file-not-found or other error
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# condition. This is sufficient to atomically switch the current link
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# tree.
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my $current = "$linkdir/current";
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print "switching $current to $gendir\n";
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my $tmplink = "$linkdir/new_current";
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symlink($gendir, $tmplink) or die "cannot create $tmplink";
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rename($tmplink, $current) or die "cannot rename $tmplink";
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