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#include "lix/libfetchers/fetchers.hh"
#include "lix/libfetchers/cache.hh"
#include "lix/libstore/content-address.hh"
#include "lix/libstore/filetransfer.hh"
#include "lix/libstore/globals.hh"
#include "lix/libfetchers/builtin-fetchers.hh"
#include "lix/libstore/store-api.hh"
#include "lix/libutil/archive.hh"
#include "lix/libutil/async-io.hh"
#include "lix/libutil/async.hh"
#include "lix/libutil/tarfile.hh"
#include "lix/libstore/temporary-dir.hh"
#include "lix/libutil/types.hh"
#include "lix/libutil/split.hh"
namespace nix::fetchers {
/* Note [Recursive hashing of file inputs]:
* We recursively hash `file` inputs to be consistent with the way that we look
* up the paths in binary caches (which is assumed all over the place in
* flakes, like in `nix flake archive`).
*
* It would also be easier to always hash downloadFile outputs as recursive,
* but there are a *whole bunch* of random usages of downloadFile for stuff
* from channel tarballs to GitHub API that I haven't fully figured out what
* they are doing or what the implications are for changing them. It seems that
* for things that are not directly *themselves* flake inputs, the intent is
* that they are flat-hashed, but flake inputs are always assumed
* recursive-hashed.
*
* So we make the flake usage of it do the thing that's right for flakes, and
* everything else we leave as before.
*
* Quoth Dr. Eelco Dolstra: https://github.com/NixOS/nix/pull/6548#discussion_r877921756
* > A problem with the use of downloadFile() is that it uses
* > FileIngestionMethod::Flat instead of FileIngestionMethod::Recursive.
* > Currently it's assumed that all flake inputs use recursive+sha256 with a
* > name of "source". This allows inputs to be substituted using the narHash
* > attribute in the lock file (see Input::computeStorePath()). However, the
* > lazy trees branch will probably remove the ability to substitute inputs
* > anyway...
*
* In other words, the feature was supposed to have been implemented consistent
* with other flake input types as recursive-hashed, but it was forgotten
* before merging it into CppNix, and was later fixed by some version between
* 2.19 and 2.24, which we are now consistent with.
*
* See: https://github.com/edolstra/flake-compat/pull/44
*/
kj::Promise<Result<DownloadFileResult>> downloadFile(
ref<Store> store,
const std::string & url,
const std::string & name,
bool locked,
Headers headers,
FileIngestionMethod ingestionMethod)
try {
// FIXME: check store
Attrs inAttrs({
{"type", "file"},
{"url", url},
{"name", name},
{"ingestionMethod", uint64_t(ingestionMethod)},
});
auto cached = TRY_AWAIT(getCache()->lookupExpired(store, inAttrs));
auto useCached = [&]() -> DownloadFileResult
{
return {
.storePath = std::move(cached->storePath),
.etag = getStrAttr(cached->infoAttrs, "etag"),
.effectiveUrl = getStrAttr(cached->infoAttrs, "url"),
.immutableUrl = maybeGetStrAttr(cached->infoAttrs, "immutableUrl"),
};
};
if (cached && !cached->expired)
co_return useCached();
if (cached)
headers.emplace_back("If-None-Match", getStrAttr(cached->infoAttrs, "etag"));
FileTransferResult res;
std::string data;
try {
auto [meta, content] = TRY_AWAIT(getFileTransfer()->download(url, {headers}));
res = std::move(meta);
data = TRY_AWAIT(content->drain());
} catch (FileTransferError & e) {
if (cached) {
printTaggedWarning("%s; using cached version", Uncolored(e.msg()));
co_return useCached();
} else
throw;
}
// FIXME: write to temporary file. or stream it. or like. anything but load
// the entire thing in memory.
Attrs infoAttrs({
{"etag", res.etag},
{"url", res.effectiveUri},
});
if (res.immutableUrl)
infoAttrs.emplace("immutableUrl", *res.immutableUrl);
std::optional<StorePath> storePath;
if (res.cached) {
assert(cached);
storePath = std::move(cached->storePath);
} else {
StringSink sink;
sink << dumpString(data);
auto flatHash = [&]() { return hashString(HashType::SHA256, data); };
// See Note [Recursive hashing of file inputs].
auto narHash = hashString(HashType::SHA256, sink.s);
ValidPathInfo info {
*store,
name,
FixedOutputInfo {
.method = ingestionMethod,
.hash = ingestionMethod == FileIngestionMethod::Flat ? flatHash() : narHash,
.references = {},
},
narHash,
};
info.narSize = sink.s.size();
auto source = AsyncStringInputStream { sink.s };
TRY_AWAIT(store->addToStore(info, source, NoRepair, NoCheckSigs));
storePath = std::move(info.path);
}
getCache()->add(
store,
inAttrs,
infoAttrs,
*storePath,
locked);
if (url != res.effectiveUri)
getCache()->add(
store,
{
{"type", "file"},
{"url", res.effectiveUri},
{"name", name},
},
infoAttrs,
*storePath,
locked);
co_return DownloadFileResult{
.storePath = std::move(*storePath),
.etag = res.etag,
.effectiveUrl = res.effectiveUri,
.immutableUrl = res.immutableUrl,
};
} catch (...) {
co_return result::current_exception();
}
kj::Promise<Result<DownloadTarballResult>> downloadTarball(
ref<Store> store,
const std::string & url,
const std::string & name,
bool locked,
const Headers & headers)
try {
Attrs inAttrs({
{"type", "tarball"},
{"url", url},
{"name", name},
});
auto cached = TRY_AWAIT(getCache()->lookupExpired(store, inAttrs));
if (cached && !cached->expired)
co_return DownloadTarballResult{
.tree = Tree { .actualPath = store->toRealPath(cached->storePath), .storePath = std::move(cached->storePath) },
.lastModified = (time_t) getIntAttr(cached->infoAttrs, "lastModified"),
.immutableUrl = maybeGetStrAttr(cached->infoAttrs, "immutableUrl"),
};
auto res = TRY_AWAIT(downloadFile(store, url, name, locked, headers));
std::optional<StorePath> unpackedStorePath;
time_t lastModified;
if (cached && res.etag != "" && getStrAttr(cached->infoAttrs, "etag") == res.etag) {
unpackedStorePath = std::move(cached->storePath);
lastModified = getIntAttr(cached->infoAttrs, "lastModified");
} else {
Path tmpDir = createTempDir();
AutoDelete autoDelete(tmpDir, true);
unpackTarfile(store->toRealPath(res.storePath), tmpDir);
auto members = readDirectory(tmpDir);
if (members.size() != 1)
throw nix::Error("tarball '%s' contains an unexpected number of top-level files", url);
auto topDir = tmpDir + "/" + members.begin()->name;
lastModified = lstat(topDir).st_mtime;
unpackedStorePath = TRY_AWAIT(
store->addToStoreRecursive(name, *prepareDump(topDir), HashType::SHA256, NoRepair)
);
}
Attrs infoAttrs({
{"lastModified", uint64_t(lastModified)},
{"etag", res.etag},
});
if (res.immutableUrl)
infoAttrs.emplace("immutableUrl", *res.immutableUrl);
getCache()->add(
store,
inAttrs,
infoAttrs,
*unpackedStorePath,
locked);
co_return DownloadTarballResult{
.tree = Tree { .actualPath = store->toRealPath(*unpackedStorePath), .storePath = std::move(*unpackedStorePath) },
.lastModified = lastModified,
.immutableUrl = res.immutableUrl,
};
} catch (...) {
co_return result::current_exception();
}
// FIXME: some of these only apply to TarballInputScheme.
static const std::set<std::string> allowedCurlAttrs = {
"lastModified",
"name",
"rev",
"revCount",
"unpack",
"url",
};
// An input scheme corresponding to a curl-downloadable resource.
struct CurlInputScheme : InputScheme
{
const std::set<std::string> transportUrlSchemes = {"file", "http", "https"};
const std::set<std::string> & allowedAttrs() const override {
return allowedCurlAttrs;
}
bool hasTarballExtension(std::string_view path) const
{
return path.ends_with(".zip") || path.ends_with(".tar")
|| path.ends_with(".tgz") || path.ends_with(".tar.gz")
|| path.ends_with(".tar.xz") || path.ends_with(".tar.bz2")
|| path.ends_with(".tar.zst");
}
virtual bool isValidURL(const ParsedURL & url, bool requireTree) const = 0;
std::optional<Input> inputFromURL(const ParsedURL & _url, bool requireTree) const override
{
if (!isValidURL(_url, requireTree))
return std::nullopt;
auto url = _url;
Attrs attrs;
attrs.emplace("type", schemeType());
url.scheme = parseUrlScheme(url.scheme).transport;
emplaceURLQueryIntoAttrs(url, attrs, {"revCount", "lastModified"}, {});
attrs.emplace("url", url.to_string());
return inputFromAttrs(attrs);
}
Attrs preprocessAttrs(const Attrs & attrs) const override
{
for (auto & [name, value] : attrs)
if (name != "type" && name != "narHash" && !allowedAttrs().contains(name))
throw UnsupportedAttributeError("unsupported tarball input attribute '%s'. If you wanted to fetch a tarball with a query parameter, please use '{ type = \"tarball\"; url = \"...\"; }'", name);
return attrs;
}
ParsedURL toURL(const Input & input) const override
{
auto url = parseURL(getStrAttr(input.attrs, "url"));
// NAR hashes are preferred over file hashes since tar/zip
// files don't have a canonical representation.
if (auto narHash = input.getNarHash())
url.query.insert_or_assign("narHash", narHash->to_string());
return url;
}
bool isLockedByRev() const override { return false; }
bool hasAllInfo(const Input & input) const override
{
return true;
}
};
struct FileInputScheme : CurlInputScheme
{
std::string schemeType() const override { return "file"; }
bool isValidURL(const ParsedURL & url, bool requireTree) const override
{
auto parsedUrlScheme = parseUrlScheme(url.scheme);
return transportUrlSchemes.count(std::string(parsedUrlScheme.transport))
&& (parsedUrlScheme.application
? parsedUrlScheme.application.value() == schemeType()
: (!requireTree && !hasTarballExtension(url.path)));
}
kj::Promise<Result<std::pair<StorePath, Input>>>
fetch(ref<Store> store, const Input & input) override
try {
auto file =
// See Note [Recursive hashing of file inputs].
TRY_AWAIT(downloadFile(store, getStrAttr(input.attrs, "url"), input.getName(), false, {}, FileIngestionMethod::Recursive));
co_return {std::move(file.storePath), input};
} catch (...) {
co_return result::current_exception();
}
};
struct TarballInputScheme : CurlInputScheme
{
std::string schemeType() const override { return "tarball"; }
bool isValidURL(const ParsedURL & url, bool requireTree) const override
{
auto parsedUrlScheme = parseUrlScheme(url.scheme);
return transportUrlSchemes.count(std::string(parsedUrlScheme.transport))
&& (parsedUrlScheme.application
? parsedUrlScheme.application.value() == schemeType()
: (requireTree || hasTarballExtension(url.path)));
}
kj::Promise<Result<std::pair<StorePath, Input>>>
fetch(ref<Store> store, const Input & _input) override
try {
Input input(_input);
auto url = getStrAttr(input.attrs, "url");
auto result = TRY_AWAIT(downloadTarball(store, url, input.getName(), false));
if (result.immutableUrl) {
auto immutableInput = Input::fromURL(*result.immutableUrl);
// FIXME: would be nice to support arbitrary flakerefs
// here, e.g. git flakes.
if (immutableInput.getType() != "tarball")
throw Error("tarball 'Link' headers that redirect to non-tarball URLs are not supported");
input = immutableInput;
}
if (result.lastModified && !input.attrs.contains("lastModified"))
input.attrs.insert_or_assign("lastModified", uint64_t(result.lastModified));
co_return {result.tree.storePath, std::move(input)};
} catch (...) {
co_return result::current_exception();
}
};
std::unique_ptr<InputScheme> makeFileInputScheme()
{
return std::make_unique<FileInputScheme>();
}
std::unique_ptr<InputScheme> makeTarballInputScheme()
{
return std::make_unique<TarballInputScheme>();
}
}
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