nix-prefetch-url: Rewrite in C++

This commit is contained in:
Eelco Dolstra 2015-10-01 16:47:43 +02:00
parent bdc4a0b54d
commit bec3c31608
6 changed files with 141 additions and 133 deletions

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@ -13,6 +13,7 @@ makefiles = \
src/nix-collect-garbage/local.mk \
src/download-via-ssh/local.mk \
src/nix-log2xml/local.mk \
src/nix-prefetch-url/local.mk \
src/bsdiff-4.3/local.mk \
perl/local.mk \
scripts/local.mk \

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@ -4,7 +4,6 @@ nix_bin_scripts := \
$(d)/nix-copy-closure \
$(d)/nix-generate-patches \
$(d)/nix-install-package \
$(d)/nix-prefetch-url \
$(d)/nix-pull \
$(d)/nix-push

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@ -1,132 +0,0 @@
#! @perl@ -w @perlFlags@
use utf8;
use strict;
use File::Basename;
use File::stat;
use Nix::Store;
use Nix::Config;
use Nix::Utils;
binmode STDERR, ":encoding(utf8)";
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 $tmpDir = mkTempDir("nix-prefetch-url");
# Hack to support the mirror:// scheme from Nixpkgs.
if ($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'};

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@ -202,6 +202,7 @@ public:
AutoDelete(const Path & p, bool recursive = true);
~AutoDelete();
void cancel();
operator Path() const { return path; }
};

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@ -0,0 +1,7 @@
programs += nix-prefetch-url
nix-prefetch-url_DIR := $(d)
nix-prefetch-url_SOURCES := $(d)/nix-prefetch-url.cc
nix-prefetch-url_LIBS = libmain libexpr libstore libutil libformat

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@ -0,0 +1,132 @@
#include "hash.hh"
#include "shared.hh"
#include "download.hh"
#include "store-api.hh"
#include "eval.hh"
#include "eval-inline.hh"
#include "common-opts.hh"
#include <iostream>
using namespace nix;
/* If uri starts with mirror://, then resolve it using the list of
mirrors defined in Nixpkgs. */
string resolveMirrorUri(EvalState & state, string uri)
{
if (string(uri, 0, 9) != "mirror://") return uri;
string s(uri, 9);
auto p = s.find('/');
if (p == string::npos) throw Error("invalid mirror URI");
string mirrorName(s, 0, p);
Value vMirrors;
state.eval(state.parseExprFromString("import <nixpkgs/pkgs/build-support/fetchurl/mirrors.nix>", "."), vMirrors);
state.forceAttrs(vMirrors);
auto mirrorList = vMirrors.attrs->find(state.symbols.create(mirrorName));
if (mirrorList == vMirrors.attrs->end())
throw Error(format("unknown mirror name %1%") % mirrorName);
state.forceList(*mirrorList->value);
if (mirrorList->value->listSize() < 1)
throw Error(format("mirror URI %1% did not expand to anything") % uri);
string mirror = state.forceString(*mirrorList->value->listElems()[0]);
return mirror + (hasSuffix(mirror, "/") ? "" : "/") + string(s, p + 1);
}
int main(int argc, char * * argv)
{
return handleExceptions(argv[0], [&]() {
initNix();
initGC();
HashType ht = htSHA256;
std::vector<string> args;
Strings searchPath;
parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) {
if (*arg == "--help")
showManPage("nix-prefetch-url");
else if (*arg == "--version")
printVersion("nix-prefetch-url");
else if (*arg == "--type") {
string s = getArg(*arg, arg, end);
ht = parseHashType(s);
if (ht == htUnknown)
throw UsageError(format("unknown hash type %1%") % s);
}
else if (parseSearchPathArg(arg, end, searchPath))
;
else if (*arg != "" && arg->at(0) == '-')
return false;
else
args.push_back(*arg);
return true;
});
if (args.size() < 1 || args.size() > 2)
throw UsageError("nix-prefetch-url expects one argument");
store = openStore();
EvalState state(searchPath);
/* Figure out a name in the Nix store. */
auto uri = args[0];
auto name = baseNameOf(uri);
if (name.empty())
throw Error(format("cannot figure out file name for %1%") % uri);
/* If an expected hash is given, the file may already exist in
the store. */
Hash hash, expectedHash(ht);
Path storePath;
if (args.size() == 2) {
expectedHash = parseHash16or32(ht, args[1]);
storePath = makeFixedOutputPath(false, ht, expectedHash, name);
if (store->isValidPath(storePath))
hash = expectedHash;
else
storePath.clear();
}
if (storePath.empty()) {
auto actualUri = resolveMirrorUri(state, uri);
if (uri != actualUri)
printMsg(lvlInfo, format("%1% expands to %2%") % uri % actualUri);
/* Download the file. */
auto result = downloadFile(actualUri);
/* Copy the file to the Nix store. FIXME: if RemoteStore
implemented addToStoreFromDump() and downloadFile()
supported a sink, we could stream the download directly
into the Nix store. */
AutoDelete tmpDir(createTempDir(), true);
Path tmpFile = (Path) tmpDir + "/tmp";
writeFile(tmpFile, result.data);
/* FIXME: inefficient; addToStore() will also hash
this. */
hash = hashString(ht, result.data);
if (expectedHash != Hash(ht) && expectedHash != hash)
throw Error(format("hash mismatch for %1%") % uri);
storePath = store->addToStore(name, tmpFile, false, ht);
}
printMsg(lvlInfo, format("path is %1%") % storePath);
std::cout << printHash16or32(hash) << std::endl;
if (getEnv("PRINT_PATH") != "")
std::cout << storePath << std::endl;
});
}