lix/scripts/nix-channel.in
Eelco Dolstra ce86a9a0ae * nix-channel: fail if we don't have write permission to the manifests
directory.  Previously in this situation we did add the Nix
  expressions from the channel to allow installation from source, but
  this doesn't work for binary-only channels and leads to confusing
  error messages.
2012-02-02 12:25:56 +00:00

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#! @perl@ -w @perlFlags@
use strict;
use Nix::Config;
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 = $ENV{"HOME"};
die '$HOME not set' unless defined $home;
my $channelsList = "$home/.nix-channels";
my $nixDefExpr = "$home/.nix-defexpr";
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;
next if /^\s*\#/;
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;
# Create the manifests directory if it doesn't exist.
mkdir $manifestDir, 0755 unless -e $manifestDir;
# Do we have write permission to the manifests directory?
die "$0: you do not have write permission to `$manifestDir'!\n" unless -W $manifestDir;
# Pull cache manifests.
foreach my $url (@channels) {
#print "pulling cache manifest from `$url'\n";
system("$Nix::Config::binDir/nix-pull", "--skip-wrong-store", "$url/MANIFEST") == 0
or die "cannot pull cache manifest from `$url'";
}
# Create a Nix expression that fetches and unpacks the channel Nix
# expressions.
my $inputs = "[";
foreach my $url (@channels) {
$url =~ /\/([^\/]+)\/?$/;
my $channelName = $1;
$channelName = "unnamed" unless defined $channelName;
my $fullURL = "$url/nixexprs.tar.bz2";
print "downloading Nix expressions from `$fullURL'...\n";
$ENV{"PRINT_PATH"} = 1;
$ENV{"QUIET"} = 1;
my ($hash, $path) = `$Nix::Config::binDir/nix-prefetch-url '$fullURL'`;
die "cannot fetch `$fullURL'" if $? != 0;
chomp $path;
$inputs .= '"' . $channelName . '"' . " " . $path . " ";
}
$inputs .= "]";
# Figure out a name for the GC root.
my $userName = getpwuid($<);
die "who ARE you? go away" unless defined $userName;
my $rootFile = "$Nix::Config::stateDir/gcroots/per-user/$userName/channels";
# Build the Nix expression.
print "unpacking channel Nix expressions...\n";
my $outPath = `\\
$Nix::Config::binDir/nix-build --out-link '$rootFile' --drv-link '$rootFile'.tmp \\
'<nix/unpack-channel.nix>' \\
--argstr system @system@ --arg inputs '$inputs'`
or die "cannot unpack the channels";
chomp $outPath;
unlink "$rootFile.tmp";
# 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 $channelLink; # !!! not atomic
symlink($outPath, $channelLink) or die "cannot symlink `$channelLink' to `$outPath'";
}
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'";
}
}