forked from lix-project/lix
167e36a5c3
This prevents unnecessary and slow rebuilds of NARs that already exist in the binary cache.
114 lines
4.1 KiB
Plaintext
Executable file
114 lines
4.1 KiB
Plaintext
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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