Add support for tarball flake inputs

For example,

  $ nix flake info https://github.com/edolstra/dwarffs/archive/master.tar.gz

Fixes #2929.

1 files changed, 91 insertions, 0 deletions

diff --git a/src/libstore/fetchers/tarball.cc b/src/libstore/fetchers/tarball.cc
new file mode 100644
index 000000000..e82066089
--- /dev/null
+++ b/src/libstore/fetchers/tarball.cc
@@ -0,0 +1,91 @@
+#include "fetchers.hh"
+#include "download.hh"
+#include "globals.hh"
+#include "parse.hh"
+#include "store-api.hh"
+
+namespace nix::fetchers {
+
+struct TarballInput : Input
+{
+    ParsedURL url;
+    std::optional<Hash> hash;
+
+    bool operator ==(const Input & other) const override
+    {
+        auto other2 = dynamic_cast<const TarballInput *>(&other);
+        return
+            other2
+            && to_string() == other2->to_string()
+            && hash == other2->hash;
+    }
+
+    bool isImmutable() const override
+    {
+        return (bool) hash;
+    }
+
+    std::string to_string() const override
+    {
+        auto url2(url);
+        if (narHash)
+            url2.query.insert_or_assign("narHash", narHash->to_string(SRI));
+        return url2.to_string();
+    }
+
+    std::pair<Tree, std::shared_ptr<const Input>> fetchTreeInternal(nix::ref<Store> store) const override
+    {
+        CachedDownloadRequest request(url.to_string());
+        request.unpack = true;
+        request.getLastModified = true;
+        request.name = "source";
+
+        auto res = getDownloader()->downloadCached(store, request);
+
+        auto input = std::make_shared<TarballInput>(*this);
+
+        auto storePath = store->parseStorePath(res.storePath);
+
+        input->narHash = store->queryPathInfo(storePath)->narHash;
+
+        return {
+            Tree {
+                .actualPath = res.path,
+                .storePath = std::move(storePath),
+                .lastModified = *res.lastModified
+            },
+            input
+        };
+    }
+};
+
+struct TarballInputScheme : InputScheme
+{
+    std::unique_ptr<Input> inputFromURL(const ParsedURL & url) override
+    {
+        if (url.scheme != "file" && url.scheme != "http" && url.scheme != "https") return nullptr;
+
+        if (!hasSuffix(url.path, ".zip")
+            && !hasSuffix(url.path, ".tar")
+            && !hasSuffix(url.path, ".tar.gz")
+            && !hasSuffix(url.path, ".tar.xz")
+            && !hasSuffix(url.path, ".tar.bz2"))
+            return nullptr;
+
+        auto input = std::make_unique<TarballInput>();
+        input->type = "tarball";
+        input->url = url;
+
+        auto narHash = url.query.find("narHash");
+        if (narHash != url.query.end()) {
+            // FIXME: require SRI hash.
+            input->narHash = Hash(narHash->second);
+        }
+
+        return input;
+    }
+};
+
+static auto r1 = OnStartup([] { registerInputScheme(std::make_unique<TarballInputScheme>()); });
+
+}