mirror of
https://github.com/privatevoid-net/nix-super.git
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167e36a5c3
This prevents unnecessary and slow rebuilds of NARs that already exist in the binary cache.
113 lines
4.1 KiB
Text
Executable file
113 lines
4.1 KiB
Text
Executable file
#! @perl@ -w @perlFlags@
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use strict;
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use File::Basename;
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use File::Temp qw(tempdir);
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use File::stat;
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use Nix::Store;
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use Nix::Config;
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use Nix::Utils;
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my $url = shift;
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my $expHash = shift;
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my $hashType = $ENV{'NIX_HASH_ALGO'} || "sha256";
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my $cacheDir = $ENV{'NIX_DOWNLOAD_CACHE'};
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if (!defined $url || $url eq "") {
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print STDERR <<EOF
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Usage: nix-prefetch-url URL [EXPECTED-HASH]
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EOF
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;
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exit 1;
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}
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my $tmpDir = tempdir("nix-prefetch-url.XXXXXX", CLEANUP => 1, TMPDIR => 1)
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or die "cannot create a temporary directory";
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# Hack to support the mirror:// scheme from Nixpkgs.
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if ($url =~ /^mirror:\/\//) {
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system("$Nix::Config::binDir/nix-build '<nixpkgs>' -A resolveMirrorURLs --argstr url '$url' -o $tmpDir/urls > /dev/null") == 0
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or die "$0: nix-build failed; maybe \$NIX_PATH is not set properly\n";
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my @expanded = split ' ', readFile("$tmpDir/urls");
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die "$0: cannot resolve ‘$url’" unless scalar @expanded > 0;
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print STDERR "$url expands to $expanded[0]\n";
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$url = $expanded[0];
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}
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# Handle escaped characters in the URI. `+', `=' and `?' are the only
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# characters that are valid in Nix store path names but have a special
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# meaning in URIs.
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my $name = basename $url;
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die "cannot figure out file name for ‘$url’\n" if $name eq "";
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$name =~ s/%2b/+/g;
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$name =~ s/%3d/=/g;
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$name =~ s/%3f/?/g;
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my $finalPath;
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my $hash;
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# If the hash was given, a file with that hash may already be in the
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# store.
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if (defined $expHash) {
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$finalPath = makeFixedOutputPath(0, $hashType, $expHash, $name);
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if (isValidPath($finalPath)) { $hash = $expHash; } else { $finalPath = undef; }
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}
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# If we don't know the hash or a file with that hash doesn't exist,
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# download the file and add it to the store.
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if (!defined $finalPath) {
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my $tmpFile = "$tmpDir/$name";
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# Optionally do timestamp-based caching of the download.
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# Actually, the only thing that we cache in $NIX_DOWNLOAD_CACHE is
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# the hash and the timestamp of the file at $url. The caching of
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# the file *contents* is done in Nix store, where it can be
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# garbage-collected independently.
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my ($cachedTimestampFN, $cachedHashFN, @cacheFlags);
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if (defined $cacheDir) {
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my $urlHash = hashString("sha256", 1, $url);
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writeFile "$cacheDir/$urlHash.url", $url;
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$cachedHashFN = "$cacheDir/$urlHash.$hashType";
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$cachedTimestampFN = "$cacheDir/$urlHash.stamp";
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@cacheFlags = ("--time-cond", $cachedTimestampFN) if -f $cachedHashFN && -f $cachedTimestampFN;
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}
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# Perform the download.
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my @curlFlags = ("curl", $url, "-o", $tmpFile, "--fail", "--location", "--max-redirs", "20", "--disable-epsv", "--cookie-jar", "$tmpDir/cookies", "--remote-time", (split " ", ($ENV{NIX_CURL_FLAGS} || "")));
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(system $Nix::Config::curl @curlFlags, @cacheFlags) == 0 or die "$0: download of ‘$url’ failed\n";
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if (defined $cacheDir && ! -e $tmpFile) {
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# Curl didn't create $tmpFile, so apparently there's no newer
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# file on the server.
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$hash = readFile $cachedHashFN or die;
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$finalPath = makeFixedOutputPath(0, $hashType, $hash, $name);
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unless (isValidPath $finalPath) {
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print STDERR "cached contents of ‘$url’ disappeared, redownloading...\n";
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$finalPath = undef;
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(system $Nix::Config::curl @curlFlags) == 0 or die "$0: download of ‘$url’ failed\n";
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}
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}
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if (!defined $finalPath) {
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# Compute the hash.
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$hash = hashFile($hashType, $hashType ne "md5", $tmpFile);
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if (defined $cacheDir) {
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writeFile $cachedHashFN, $hash;
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my $st = stat($tmpFile) or die;
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open STAMP, ">$cachedTimestampFN" or die; close STAMP;
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utime($st->atime, $st->mtime, $cachedTimestampFN) or die;
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}
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# Add the downloaded file to the Nix store.
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$finalPath = addToStore($tmpFile, 0, $hashType);
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}
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die "$0: hash mismatch for ‘$url’\n" if defined $expHash && $expHash ne $hash;
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}
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print STDERR "path is ‘$finalPath’\n" unless $ENV{'QUIET'};
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print "$hash\n";
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print "$finalPath\n" if $ENV{'PRINT_PATH'};
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