forked from lix-project/lix
![Eelco Dolstra](/assets/img/avatar_default.png)
substitute mechanism) creates a store path by downloading full NAR archives and/or patches specified in the available manifests. Any combination of present paths, full downloads, and patches can be used to construct the target path. In particular, patches can be chained in sequence; and full NAR archives of the target path can be omitted (i.e., patch-only deployment is possible). A shortest path algorithm is used to find the smallest set of files to be downloaded (the edge weights are currently file sizes, but one can imagine taking the network speed to the various source into account). Patches are binary deltas between two store paths. To be precise, they are the output of the `bsdiff' program applied to the NAR archives obtained by dumping (`nix-store --dump') the two store paths. The advantage of diff'ing NAR archives (and not, say, doing file-by-file diffs) is that file renames/moves are handled automatically. The disadvantage is that we cannot optimise creation of unchanged files (by hard-linking).
104 lines
2.4 KiB
Plaintext
104 lines
2.4 KiB
Plaintext
#! @perl@ -w -I@libexecdir@/nix
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use strict;
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use IPC::Open2;
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use POSIX qw(tmpnam);
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use readmanifest;
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my $tmpdir;
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do { $tmpdir = tmpnam(); }
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until mkdir $tmpdir, 0777;
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my $manifest = "$tmpdir/manifest";
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my $confFile = "@sysconfdir@/nix/prebuilts.conf";
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#END { unlink $manifest; rmdir $tmpdir; }
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# Obtain URLs either from the command line or from a configuration file.
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my %storePaths2urls;
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my %urls2hashes;
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my %successors;
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sub processURL {
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my $url = shift;
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$url =~ s/\/$//;
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print "obtaining list of Nix archives at $url...\n";
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system("@curl@ --fail --silent --show-error --location --max-redirs 20 " .
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"'$url' > '$manifest'") == 0
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or die "curl failed: $?";
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readManifest $manifest, \%storePaths2urls, \%urls2hashes, \%successors;
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}
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if (scalar @ARGV > 0) {
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while (@ARGV) {
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my $url = shift @ARGV;
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processURL $url;
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}
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} else {
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open CONFFILE, "<$confFile";
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while (<CONFFILE>) {
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chomp;
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if (/^\s*(\S+)\s*(\#.*)?$/) {
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my $url = $1;
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processURL $url;
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}
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}
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close CONFFILE;
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}
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my $size = scalar (keys %storePaths2urls);
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print "$size store paths in manifest\n";
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# Instantiate a store expression that builds the substitute program
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# (the program that fetches URLs and unpacks them into the store).
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my $nixExpr =
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"(import @datadir@/nix/corepkgs/nix-pull) " .
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"{system = \"@system@\";}";
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print STDERR "instantiating store expression...\n";
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my $storeExpr = `echo '$nixExpr' | @bindir@/nix-instantiate -`
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or die "cannot instantiate Nix expression";
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chomp $storeExpr;
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# Register all substitutes.
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print STDERR "registering substitutes...\n";
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my $pid = open2(\*READ, \*WRITE, "@bindir@/nix-store --substitute")
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or die "cannot run nix-store";
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close READ;
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foreach my $storePath (keys %storePaths2urls) {
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print WRITE "$storePath\n";
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print WRITE "$storeExpr\n";
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print WRITE "/fetch\n";
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print WRITE "2\n";
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print WRITE "$storePaths2urls{$storePath}\n";
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print WRITE "$urls2hashes{$storePaths2urls{$storePath}}\n";
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}
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close WRITE;
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waitpid $pid, 0;
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$? == 0 or die "nix-store failed";
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# Register all successors.
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print STDERR "registering successors...\n";
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my @sucs = %successors;
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while (scalar @sucs > 0) {
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my $n = scalar @sucs;
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if ($n > 256) { $n = 256 };
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my @sucs2 = @sucs[0..$n - 1];
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@sucs = @sucs[$n..scalar @sucs - 1];
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system "@bindir@/nix-store --successor @sucs2";
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if ($?) { die "`nix-store --successor' failed"; }
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}
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