path: root/scripts/nix-channel.in

#! @perl@ -w @perlFlags@

use utf8;
use strict;
use File::Basename;
use File::Path qw(mkpath);
use Nix::Config;
use Nix::Manifest;

binmode STDERR, ":encoding(utf8)";

Nix::Config::readConfig;

my $manifestDir = $Nix::Config::manifestDir;


# Turn on caching in nix-prefetch-url.
my $channelCache = "$Nix::Config::stateDir/channel-cache";
mkdir $channelCache, 0755 unless -e $channelCache;
$ENV{'NIX_DOWNLOAD_CACHE'} = $channelCache if -W $channelCache;

# Figure out the name of the `.nix-channels' file to use.
my $home = $ENV{"HOME"} or die '$HOME not set\n';
my $channelsList = "$home/.nix-channels";
my $nixDefExpr = "$home/.nix-defexpr";

# Figure out the name of the channels profile.
my $userName = getpwuid($<) || $ENV{"USER"} or die "cannot figure out user name";
my $profile = "$Nix::Config::stateDir/profiles/per-user/$userName/channels";
mkpath(dirname $profile, 0, 0755);

my %channels;


# Reads the list of channels.
sub readChannels {
    return if (!-f $channelsList);
    open CHANNELS, "<$channelsList" or die "cannot open ‘$channelsList’: $!";
    while (<CHANNELS>) {
        chomp;
        next if /^\s*\#/;
        my ($url, $name) = split ' ', $_;
        $url =~ s/\/*$//; # remove trailing slashes
        $name = basename $url unless defined $name;
        $channels{$name} = $url;
    }
    close CHANNELS;
}


# Writes the list of channels.
sub writeChannels {
    open CHANNELS, ">$channelsList" or die "cannot open ‘$channelsList’: $!";
    foreach my $name (keys %channels) {
        print CHANNELS "$channels{$name} $name\n";
    }
    close CHANNELS;
}


# Adds a channel.
sub addChannel {
    my ($url, $name) = @_;
    readChannels;
    $channels{$name} = $url;
    writeChannels;
}


# Remove a channel.
sub removeChannel {
    my ($name) = @_;
    readChannels;
    my $url = $channels{$name};
    deleteOldManifests($url . "/MANIFEST", undef) if defined $url;
    delete $channels{$name};
    writeChannels;

    system("$Nix::Config::binDir/nix-env --profile '$profile' -e '$name'") == 0
        or die "cannot remove channel ‘$name’\n";
}


# Fetch Nix expressions and pull manifests from the subscribed
# channels.
sub update {
    my @channelNames = @_;

    readChannels;

    # Download each channel.
    my $exprs = "";
    foreach my $name (keys %channels) {
        next if scalar @channelNames > 0 && ! grep { $_ eq $name } @{channelNames};

        my $url = $channels{$name};
        my $origUrl = "$url/MANIFEST";

        # Check if $url is a redirect.  If so, follow it now to ensure
        # consistency if the redirection is changed between
        # downloading the manifest and the tarball.
        my $headers = `$Nix::Config::curl --silent --head '$url'`;
        die "$0: unable to check ‘$url’\n" if $? != 0;
        $headers =~ s/\r//g;
        $url = $1 if $headers =~ /^Location:\s*(.*)\s*$/m;

        # Check if the channel advertises a binary cache.
        my $binaryCacheURL = `$Nix::Config::curl --silent '$url'/binary-cache-url`;
        my $extraAttrs = "";
        my $getManifest = ($Nix::Config::config{"force-manifest"} // "false") eq "true";
        if ($? == 0 && $binaryCacheURL ne "") {
            $extraAttrs .= "binaryCacheURL = \"$binaryCacheURL\"; ";
            deleteOldManifests($origUrl, undef);
        } else {
            $getManifest = 1;
        }

        if ($getManifest) {
            # No binary cache, so pull the channel manifest.
            mkdir $manifestDir, 0755 unless -e $manifestDir;
            die "$0: you do not have write permission to ‘$manifestDir’!\n" unless -W $manifestDir;
            $ENV{'NIX_ORIG_URL'} = $origUrl;
            system("$Nix::Config::binDir/nix-pull", "--skip-wrong-store", "$url/MANIFEST") == 0
                or die "cannot pull manifest from ‘$url’\n";
        }

        # Download the channel tarball.
        my $fullURL = "$url/nixexprs.tar.xz";
        system("$Nix::Config::curl --fail --silent --head '$fullURL' > /dev/null") == 0 or
            $fullURL = "$url/nixexprs.tar.bz2";
        print STDERR "downloading Nix expressions from ‘$fullURL’...\n";
        my ($hash, $path) = `PRINT_PATH=1 QUIET=1 $Nix::Config::binDir/nix-prefetch-url '$fullURL'`;
        die "cannot fetch ‘$fullURL’\n" if $? != 0;
        chomp $path;

        # If the URL contains a version number, append it to the name
        # attribute (so that "nix-env -q" on the channels profile
        # shows something useful).
        my $cname = $name;
        $cname .= $1 if basename($url) =~ /(-\d.*)$/;

        $exprs .= "'f: f { name = \"$cname\"; channelName = \"$name\"; src = builtins.storePath \"$path\"; $extraAttrs }' ";
    }

    # Unpack the channel tarballs into the Nix store and install them
    # into the channels profile.
    print STDERR "unpacking channels...\n";
    system("$Nix::Config::binDir/nix-env --profile '$profile' " .
           "-f '<nix/unpack-channel.nix>' -i -E $exprs --quiet") == 0
           or die "cannot unpack the channels";

    # Make the channels appear in nix-env.
    unlink $nixDefExpr if -l $nixDefExpr; # old-skool ~/.nix-defexpr
    mkdir $nixDefExpr or die "cannot create directory ‘$nixDefExpr’" if !-e $nixDefExpr;
    my $channelLink = "$nixDefExpr/channels";
    unlink $channelLink; # !!! not atomic
    symlink($profile, $channelLink) or die "cannot symlink ‘$channelLink’ to ‘$profile’";
}


die "$0: argument expected\n" if scalar @ARGV == 0;


while (scalar @ARGV) {
    my $arg = shift @ARGV;

    if ($arg eq "--add") {
        die "$0: ‘--add’ requires one or two arguments\n" if scalar @ARGV < 1 || scalar @ARGV > 2;
        my $url = shift @ARGV;
        my $name = shift @ARGV;
        unless (defined $name) {
            $name = basename $url;
            $name =~ s/-unstable//;
            $name =~ s/-stable//;
        }
        addChannel($url, $name);
        last;
    }

    if ($arg eq "--remove") {
        die "$0: ‘--remove’ requires one argument\n" if scalar @ARGV != 1;
        removeChannel(shift @ARGV);
        last;
    }

    if ($arg eq "--list") {
        die "$0: ‘--list’ requires one argument\n" if scalar @ARGV != 0;
        readChannels;
        foreach my $name (keys %channels) {
            print "$name $channels{$name}\n";
        }
        last;
    }

    elsif ($arg eq "--update") {
        update(@ARGV);
        last;
    }

    elsif ($arg eq "--help") {
        exec "man nix-channel" or die;
    }

    elsif ($arg eq "--version") {
        print "nix-channel (Nix) $Nix::Config::version\n";
        exit 0;
    }

    else {
        die "unknown argument ‘$arg’; try ‘--help’\n";
    }
}