lix/scripts/nix-push.in

#! @perl@ -w @perlFlags@

use strict;
use File::Basename;
use File::Temp qw(tempdir);
use File::Path qw(mkpath);
use File::stat;
use File::Copy;
use Nix::Config;
use Nix::Store;

my $hashAlgo = "sha256";

my $tmpDir = tempdir("nix-push.XXXXXX", CLEANUP => 1, TMPDIR => 1)
    or die "cannot create a temporary directory";

my $nixExpr = "$tmpDir/create-nars.nix";

my $curl = "$Nix::Config::curl --fail --silent";
my $extraCurlFlags = ${ENV{'CURL_FLAGS'}};
$curl = "$curl $extraCurlFlags" if defined $extraCurlFlags;


# Parse the command line.
my $compressionType = "xz";
my $force = 0;
my $destDir;
my @roots;

sub showSyntax {
    print STDERR <<EOF
Usage: nix-push --dest DIR PATHS...

`nix-push' packs the closure of PATHS into a set of NAR archives
stored in DIR.
EOF
    ; # `
    exit 1;
}

for (my $n = 0; $n < scalar @ARGV; $n++) {
    my $arg = $ARGV[$n];

    if ($arg eq "--help") {
        showSyntax;
    } elsif ($arg eq "--bzip2") {
        $compressionType = "bzip2";
    } elsif ($arg eq "--force") {
        $force = 1;
    } elsif ($arg eq "--dest") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
        $destDir = $ARGV[$n];
        mkpath($destDir, 0, 0755);
    } elsif (substr($arg, 0, 1) eq "-") {
        showSyntax;
    } else {
        push @roots, $arg;
    }
}
        
showSyntax if !defined $destDir;


# From the given store paths, determine the set of requisite store
# paths, i.e, the paths required to realise them.
my %storePaths;

foreach my $path (@roots) {
    die unless $path =~ /^\//;

    # Get all paths referenced by the normalisation of the given 
    # Nix expression.
    my $pid = open(READ,
        "$Nix::Config::binDir/nix-store --query --requisites --force-realise " .
        "--include-outputs '$path'|") or die;
    
    while (<READ>) {
        chomp;
        die "bad: $_" unless /^\//;
        $storePaths{$_} = "";
    }

    close READ or die "nix-store failed: $?";
}

my @storePaths = keys %storePaths;


# Create a list of Nix derivations that turn each path into a Nix
# archive.
open NIX, ">$nixExpr";
print NIX "[";

foreach my $storePath (@storePaths) {
    die unless ($storePath =~ /\/[0-9a-z]{32}[^\"\\\$]*$/);

    # Construct a Nix expression that creates a Nix archive.
    my $nixexpr = 
        "(import <nix/nar.nix> " .
        "{ storePath = builtins.storePath \"$storePath\"; hashAlgo = \"$hashAlgo\"; compressionType = \"$compressionType\"; }) ";
    
    print NIX $nixexpr;
}

print NIX "]";
close NIX;


# Build the Nix expression.
print STDERR "building compressed archives...\n";
my @narPaths;
my $pid = open(READ, "$Nix::Config::binDir/nix-build $nixExpr -o $tmpDir/result |")
    or die "cannot run nix-build";
while (<READ>) {
    chomp;
    die unless /^\//;
    push @narPaths, $_;
}
close READ or die "nix-build failed: $?";


# Copy the archives and the corresponding info files.
print STDERR "copying archives...\n";

my $totalNarSize = 0;
my $totalCompressedSize = 0;

for (my $n = 0; $n < scalar @storePaths; $n++) {
    my $storePath = $storePaths[$n];
    my $narDir = $narPaths[$n];
    my $baseName = basename $storePath;

    # Get info about the store path.
    my ($deriver, $narHash, $time, $narSize, $refs) = queryPathInfo($storePath, 1);

    # In some exceptional cases (such as VM tests that use the Nix
    # store of the host), the database doesn't contain the hash.  So
    # compute it.
    if ($narHash =~ /^sha256:0*$/) {
        my $nar = "$tmpDir/nar";
        system("$Nix::Config::binDir/nix-store --dump $storePath > $nar") == 0
            or die "cannot dump $storePath\n";
        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --base32 --flat $nar`;
        die "cannot hash `$nar'" if $? != 0;
        chomp $narHash;
        $narHash = "sha256:$narHash";
        $narSize = stat("$nar")->size;
        unlink $nar or die;
    }

    $totalNarSize += $narSize;
    
    # Get info about the compressed NAR.
    open HASH, "$narDir/nar-compressed-hash" or die "cannot open nar-compressed-hash";
    my $compressedHash = <HASH>;
    chomp $compressedHash;
    $compressedHash =~ /^[0-9a-z]+$/ or die "invalid hash";
    close HASH;

    my $narName = "$compressedHash.nar." . ($compressionType eq "xz" ? "xz" : "bz2");

    my $narFile = "$narDir/$narName";
    (-f $narFile) or die "NAR file for $storePath not found";

    my $compressedSize = stat($narFile)->size;    
    $totalCompressedSize += $compressedSize;

    printf STDERR "%s [%.2f MiB, %.1f%%]\n", $storePath,
        $compressedSize / (1024 * 1024), $compressedSize / $narSize * 100;

    # Copy the compressed NAR.
    my $dst = "$destDir/$narName";
    if (! -f $dst) {
        my $tmp = "$destDir/.tmp.$$.$narName";
        copy($narFile, $tmp) or die "cannot copy $narFile to $tmp: $!\n";
        rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
    }

    # Write the info file.
    my $info;
    $info .= "StorePath: $storePath\n";
    $info .= "URL: $narName\n";
    $info .= "Compression: $compressionType\n";
    $info .= "FileHash: sha256:$compressedHash\n";
    $info .= "FileSize: $compressedSize\n";
    $info .= "NarHash: $narHash\n";
    $info .= "NarSize: $narSize\n";
    $info .= "References: " . join(" ", map { basename $_ } @{$refs}) . "\n";
    if (defined $deriver) {
        $info .= "Deriver: " . basename $deriver . "\n";
        if (isValidPath($deriver)) {
            my $drv = derivationFromPath($deriver);
            $info .= "System: $drv->{platform}\n";
        }
    }

    my $pathHash = substr(basename($storePath), 0, 32);
    
    $dst = "$destDir/$pathHash.narinfo";
    if ($force || ! -f $dst) {
        my $tmp = "$destDir/.tmp.$$.$pathHash.narinfo";
        open INFO, ">$tmp" or die;
        print INFO "$info" or die;
        close INFO or die;
        rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
    }
}

printf STDERR "total compressed size %.2f MiB, %.1f%%\n",
    $totalCompressedSize / (1024 * 1024), $totalCompressedSize / $totalNarSize * 100;