nix store prefetch-tarball -> nix flake prefetch

src/nix/flake-prefetch.md

@@ -0,0 +1,28 @@
+R""(
+
+# Examples
+
+* Download a tarball and unpack it:
+
+  ```console
+  # nix flake prefetch https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz
+  Downloaded 'https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz?narHash=sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY='
+  to '/nix/store/sl5vvk8mb4ma1sjyy03kwpvkz50hd22d-source' (hash
+  'sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY=').
+  ```
+
+* Download the `dwarffs` flake (looked up in the flake registry):
+
+  ```console
+  # nix flake prefetch dwarffs --json
+  {"hash":"sha256-VHg3MYVgQ12LeRSU2PSoDeKlSPD8PYYEFxxwkVVDRd0="
+  ,"storePath":"/nix/store/hang3792qwdmm2n0d9nsrs5n6bsws6kv-source"}
+  ```
+
+# Description
+
+This command downloads the source tree denoted by flake reference
+*flake-url*. Note that this does not need to be a flake (i.e. it does
+not have to contain a `flake.nix` file).
+
+)""

src/nix/flake.cc

@@ -960,6 +960,45 @@ struct CmdFlakeShow : FlakeCommand
     }
 };
 
+struct CmdFlakePrefetch : FlakeCommand, MixJSON
+{
+    CmdFlakePrefetch()
+    {
+    }
+
+    std::string description() override
+    {
+        return "download the source tree denoted by a flake reference into the Nix store";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "flake-prefetch.md"
+          ;
+    }
+
+    void run(ref<Store> store) override
+    {
+        auto originalRef = getFlakeRef();
+        auto resolvedRef = originalRef.resolve(store);
+        auto [tree, lockedRef] = resolvedRef.fetchTree(store);
+        auto hash = store->queryPathInfo(tree.storePath)->narHash;
+
+        if (json) {
+            auto res = nlohmann::json::object();
+            res["storePath"] = store->printStorePath(tree.storePath);
+            res["hash"] = hash.to_string(SRI, true);
+            logger->cout(res.dump());
+        } else {
+            notice("Downloaded '%s' to '%s' (hash '%s').",
+                lockedRef.to_string(),
+                store->printStorePath(tree.storePath),
+                hash.to_string(SRI, true));
+        }
+    }
+};
+
 struct CmdFlake : NixMultiCommand
 {
     CmdFlake()
@@ -973,6 +1012,7 @@ struct CmdFlake : NixMultiCommand
                 {"clone", []() { return make_ref<CmdFlakeClone>(); }},
                 {"archive", []() { return make_ref<CmdFlakeArchive>(); }},
                 {"show", []() { return make_ref<CmdFlakeShow>(); }},
+                {"prefetch", []() { return make_ref<CmdFlakePrefetch>(); }},
             })
     {
     }

src/nix/prefetch.cc

@@ -246,17 +246,15 @@ static int main_nix_prefetch_url(int argc, char * * argv)
 
 static RegisterLegacyCommand r_nix_prefetch_url("nix-prefetch-url", main_nix_prefetch_url);
 
-struct CmdStorePrefetch : StoreCommand, MixJSON
+struct CmdStorePrefetchFile : StoreCommand, MixJSON
 {
     std::string url;
     bool executable = false;
-    bool unpack;
     std::optional<std::string> name;
     HashType hashType = htSHA256;
     std::optional<Hash> expectedHash;
 
-    CmdStorePrefetch(bool unpack)
-        : unpack(unpack)
+    CmdStorePrefetchFile()
     {
         addFlag({
             .longName = "name",
@@ -267,7 +265,7 @@ struct CmdStorePrefetch : StoreCommand, MixJSON
 
         addFlag({
             .longName = "expected-hash",
-            .description = unpack ? "expected NAR hash of the unpacked tarball" : "expected hash of the file",
+            .description = "expected hash of the file",
             .labels = {"hash"},
             .handler = {[&](std::string s) {
                 expectedHash = Hash::parseAny(s, hashType);
@@ -276,14 +274,31 @@ struct CmdStorePrefetch : StoreCommand, MixJSON
 
         addFlag(Flag::mkHashTypeFlag("hash-type", &hashType));
 
+        addFlag({
+            .longName = "executable",
+            .description = "make the resulting file executable",
+            .handler = {&executable, true},
+        });
+
         expectArg("url", &url);
     }
 
     Category category() override { return catUtility; }
 
+    std::string description() override
+    {
+        return "download a file into the Nix store";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "store-prefetch-file.md"
+          ;
+    }
     void run(ref<Store> store) override
     {
-        auto [storePath, hash] = prefetchFile(store, url, name, hashType, expectedHash, unpack, executable);
+        auto [storePath, hash] = prefetchFile(store, url, name, hashType, expectedHash, false, executable);
 
         if (json) {
             auto res = nlohmann::json::object();
@@ -299,54 +314,4 @@ struct CmdStorePrefetch : StoreCommand, MixJSON
     }
 };
 
-struct CmdStorePrefetchFile : CmdStorePrefetch
-{
-    CmdStorePrefetchFile()
-        : CmdStorePrefetch(false)
-    {
-        name = "source";
-
-        addFlag({
-            .longName = "executable",
-            .description = "make the resulting file executable",
-            .handler = {&executable, true},
-        });
-    }
-
-    std::string description() override
-    {
-        return "download a file into the Nix store";
-    }
-
-    std::string doc() override
-    {
-        return
-          #include "store-prefetch-file.md"
-          ;
-    }
-};
-
 static auto rCmdStorePrefetchFile = registerCommand2<CmdStorePrefetchFile>({"store", "prefetch-file"});
-
-struct CmdStorePrefetchTarball : CmdStorePrefetch
-{
-    CmdStorePrefetchTarball()
-        : CmdStorePrefetch(true)
-    {
-        name = "source";
-    }
-
-    std::string description() override
-    {
-        return "download and unpack a tarball into the Nix store";
-    }
-
-    std::string doc() override
-    {
-        return
-          #include "store-prefetch-tarball.md"
-          ;
-    }
-};
-
-static auto rCmdStorePrefetchTarball = registerCommand2<CmdStorePrefetchTarball>({"store", "prefetch-tarball"});

src/nix/store-prefetch-tarball.md

@@ -1,31 +0,0 @@
-R""(
-
-# Examples
-
-* Download a tarball and unpack it:
-
-  ```console
-  # nix store prefetch-tarball https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz
-  Downloaded 'https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz'
-  to '/nix/store/sl5vvk8mb4ma1sjyy03kwpvkz50hd22d-source' (hash
-  'sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY=').
-  ```
-
-* Download a tarball and unpack it, unless it already exists in the
-  Nix store:
-
-  ```console
-  # nix store prefetch-tarball https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.5.tar.xz \
-      --expected-hash sha256-3XYHZANT6AFBV0BqegkAZHbba6oeDkIUCDwbATLMhAY=
-  ```
-
-# Description
-
-This command downloads a tarball or zip file from *url*, unpacks it,
-and adds the unpacked tree to the Nix store. It prints out the
-resulting store path and the NAR hash of that store path.
-
-The name component of the store path defaults to `source`, but this
-can be overriden using `--name`.
-
-)""