1 files changed, 130 insertions, 0 deletions
diff --git a/scripts/nix-prefetch-url.in b/scripts/nix-prefetch-url.in
new file mode 100755
index 000000000000..bcd9197bcff1
--- /dev/null
+++ b/scripts/nix-prefetch-url.in
@@ -0,0 +1,130 @@
+#! @perl@ -w @perlFlags@
+
+use strict;
+use File::Basename;
+use File::Temp qw(tempdir);
+use File::stat;
+use Nix::Store;
+use Nix::Config;
+use Nix::Utils;
+
+my $hashType = $ENV{'NIX_HASH_ALGO'} || "sha256"; # obsolete
+my $cacheDir = $ENV{'NIX_DOWNLOAD_CACHE'};
+
+my @args;
+my $arg;
+while ($arg = shift) {
+    if ($arg eq "--help") {
+        exec "man nix-prefetch-url" or die;
+    } elsif ($arg eq "--type") {
+        $hashType = shift;
+        die "$0: `$arg' requires an argument\n" unless defined $hashType;
+    } elsif (substr($arg, 0, 1) eq "-") {
+        die "$0: unknown flag `$arg'\n";
+    } else {
+        push @args, $arg;
+    }
+}
+
+my $url = $args[0];
+my $expHash = $args[1];
+
+
+if (!defined $url || $url eq "") {
+    print STDERR <<EOF
+Usage: nix-prefetch-url URL [EXPECTED-HASH]
+EOF
+    ;
+    exit 1;
+}
+
+my $tmpDir = tempdir("nix-prefetch-url.XXXXXX", CLEANUP => 1, TMPDIR => 1)
+    or die "cannot create a temporary directory";
+
+# Hack to support the mirror:// scheme from Nixpkgs.
+if ($url =~ /^mirror:\/\//) {
+    system("$Nix::Config::binDir/nix-build '<nixpkgs>' -A resolveMirrorURLs --argstr url '$url' -o $tmpDir/urls > /dev/null") == 0
+        or die "$0: nix-build failed; maybe \$NIX_PATH is not set properly\n";
+    my @expanded = split ' ', readFile("$tmpDir/urls");
+    die "$0: cannot resolve ‘$url’" unless scalar @expanded > 0;
+    print STDERR "$url expands to $expanded[0]\n";
+    $url = $expanded[0];
+}
+
+# Handle escaped characters in the URI.  `+', `=' and `?' are the only
+# characters that are valid in Nix store path names but have a special
+# meaning in URIs.
+my $name = basename $url;
+die "cannot figure out file name for ‘$url’\n" if $name eq ""; 
+$name =~ s/%2b/+/g;
+$name =~ s/%3d/=/g;
+$name =~ s/%3f/?/g;
+
+my $finalPath;
+my $hash;
+
+# If the hash was given, a file with that hash may already be in the
+# store.
+if (defined $expHash) {
+    $finalPath = makeFixedOutputPath(0, $hashType, $expHash, $name);
+    if (isValidPath($finalPath)) { $hash = $expHash; } else { $finalPath = undef; }
+}
+
+# If we don't know the hash or a file with that hash doesn't exist,
+# download the file and add it to the store.
+if (!defined $finalPath) {
+
+    my $tmpFile = "$tmpDir/$name";
+    
+    # Optionally do timestamp-based caching of the download.
+    # Actually, the only thing that we cache in $NIX_DOWNLOAD_CACHE is
+    # the hash and the timestamp of the file at $url.  The caching of
+    # the file *contents* is done in Nix store, where it can be
+    # garbage-collected independently.
+    my ($cachedTimestampFN, $cachedHashFN, @cacheFlags);
+    if (defined $cacheDir) {
+        my $urlHash = hashString("sha256", 1, $url);
+        writeFile "$cacheDir/$urlHash.url", $url;
+        $cachedHashFN = "$cacheDir/$urlHash.$hashType";
+        $cachedTimestampFN = "$cacheDir/$urlHash.stamp";
+        @cacheFlags = ("--time-cond", $cachedTimestampFN) if -f $cachedHashFN && -f $cachedTimestampFN;
+    }
+    
+    # Perform the download.
+    my @curlFlags = ("curl", $url, "-o", $tmpFile, "--fail", "--location", "--max-redirs", "20", "--disable-epsv", "--cookie-jar", "$tmpDir/cookies", "--remote-time", (split " ", ($ENV{NIX_CURL_FLAGS} || "")));
+    (system $Nix::Config::curl @curlFlags, @cacheFlags) == 0 or die "$0: download of ‘$url’ failed\n";
+
+    if (defined $cacheDir && ! -e $tmpFile) {
+        # Curl didn't create $tmpFile, so apparently there's no newer
+        # file on the server.
+        $hash = readFile $cachedHashFN or die;
+        $finalPath = makeFixedOutputPath(0, $hashType, $hash, $name);
+        unless (isValidPath $finalPath) {
+            print STDERR "cached contents of ‘$url’ disappeared, redownloading...\n";
+            $finalPath = undef;
+            (system $Nix::Config::curl @curlFlags) == 0 or die "$0: download of ‘$url’ failed\n";
+        }
+    }
+
+    if (!defined $finalPath) {
+        
+        # Compute the hash.
+        $hash = hashFile($hashType, $hashType ne "md5", $tmpFile);
+
+        if (defined $cacheDir) {
+            writeFile $cachedHashFN, $hash;
+            my $st = stat($tmpFile) or die;
+            open STAMP, ">$cachedTimestampFN" or die; close STAMP;
+            utime($st->atime, $st->mtime, $cachedTimestampFN) or die;
+        }
+    
+        # Add the downloaded file to the Nix store.
+        $finalPath = addToStore($tmpFile, 0, $hashType);
+    }
+
+    die "$0: hash mismatch for ‘$url’\n" if defined $expHash && $expHash ne $hash;
+}
+
+print STDERR "path is ‘$finalPath’\n" unless $ENV{'QUIET'};
+print "$hash\n";
+print "$finalPath\n" if $ENV{'PRINT_PATH'};