about summary refs log tree commit diff
path: root/scripts/nix-channel.in
blob: 63a56616b130fbac756b3cccfc2f82003cd74b99 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
#! @perl@ -w

use strict;

my $rootsDir = "@localstatedir@/nix/gcroots/channels";

my $stateDir = $ENV{"NIX_STATE_DIR"};
$stateDir = "@localstatedir@/nix" unless defined $stateDir;


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

my @channels;


# Reads the list of channels from the file $channelsList;
sub readChannels {
    return if (!-f $channelsList);
    open CHANNELS, "<$channelsList" or die "cannot open `$channelsList': $!";
    while (<CHANNELS>) {
        chomp;
        push @channels, $_;
    }
    close CHANNELS;
}


# Writes the list of channels to the file $channelsList;
sub writeChannels {
    open CHANNELS, ">$channelsList" or die "cannot open `$channelsList': $!";
    foreach my $url (@channels) {
        print CHANNELS "$url\n";
    }
    close CHANNELS;
}


# Adds a channel to the file $channelsList;
sub addChannel {
    my $url = shift;
    readChannels;
    foreach my $url2 (@channels) {
        return if $url eq $url2;
    }
    push @channels, $url;
    writeChannels;
}


# Remove a channel from the file $channelsList;
sub removeChannel {
    my $url = shift;
    my @left = ();
    readChannels;
    foreach my $url2 (@channels) {
        push @left, $url2 if $url ne $url2;
    }
    @channels = @left;
    writeChannels;
}


# Fetch Nix expressions and pull cache manifests from the subscribed
# channels.
sub update {
    readChannels;

    # Get rid of all the old substitutes.
    system "@bindir@/nix-store --clear-substitutes";
    die "cannot clear substitutes" if ($? != 0);

    # Remove all the old manifests.
    for my $manifest (glob "$stateDir/manifests/*.nixmanifest") {
        unlink $manifest or die "cannot remove `$manifest': $!";
    }

    # Pull cache manifests.
    foreach my $url (@channels) {
        print "pulling cache manifest from `$url'\n";
        system "@bindir@/nix-pull '$url'/MANIFEST";
        die "cannot pull cache manifest from `$url'" if ($? != 0);
    }

    # Create a Nix expression that fetches and unpacks the channel Nix
    # expressions.

    my $nixExpr = "[";
    foreach my $url (@channels) {
        my $fullURL = "$url/nixexprs.tar.bz2";
        $ENV{"PRINT_PATH"} = 1;
        my ($hash, $path) = `@bindir@/nix-prefetch-url '$fullURL' 2> /dev/null`;
        die "cannot fetch `$fullURL'" if $? != 0;
        chomp $path;
        $nixExpr .= $path . " ";
    }
    $nixExpr .= "]";

    $nixExpr =
        "(import @datadir@/nix/corepkgs/channels/unpack.nix) " .
        "{inputs = $nixExpr; system = \"@system@\";}";

    # Figure out a name for the GC root.
    my $userName = getpwuid($<);
    die "who ARE you? go away" unless defined $userName;

    my $rootFile = "$rootsDir/$userName";
    
    # Instantiate the Nix expression.
    my $storeExpr = `echo '$nixExpr' | @bindir@/nix-instantiate --add-root '$rootFile'.tmp -`
        or die "cannot instantiate Nix expression";
    chomp $storeExpr;

    # Build the resulting derivation.
    my $outPath = `@bindir@/nix-store --add-root '$rootFile' -r '$storeExpr'`
        or die "cannot realise store expression";
    chomp $outPath;

    unlink "$rootFile.tmp";

    # Make it the default Nix expression for `nix-env'.
    system "@bindir@/nix-env --import '$outPath'";
    die "cannot pull set default Nix expression to `$outPath'" if ($? != 0);
}


sub usageError {
    print STDERR <<EOF;
Usage:
  nix-channel --add URL
  nix-channel --remove URL
  nix-channel --list
  nix-channel --update
EOF
    exit 1;
}


usageError if scalar @ARGV == 0;


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

    if ($arg eq "--add") {
        usageError if scalar @ARGV != 1;
        addChannel (shift @ARGV);
        last;
    }

    if ($arg eq "--remove") {
        usageError if scalar @ARGV != 1;
        removeChannel (shift @ARGV);
        last;
    }

    if ($arg eq "--list") {
        usageError if scalar @ARGV != 0;
        readChannels;
        foreach my $url (@channels) {
            print "$url\n";
        }
        last;
    }

    elsif ($arg eq "--update") {
        usageError if scalar @ARGV != 0;
        update;
        last;
    }
    
    elsif ($arg eq "--help") {
        usageError;
    }

    else {
        die "unknown argument `$arg'; try `--help'";
    }
}