Add 'nix store prefetch-{file,tarball}'

These replace nix-prefetch-url and nix-prefetch-url --unpack,
respectively.

4 files changed, 415 insertions, 1 deletions

diff --git a/src/nix/local.mk b/src/nix/local.mk
index f37b73384..23c08fc86 100644
--- a/src/nix/local.mk
+++ b/src/nix/local.mk
@@ -12,7 +12,6 @@ nix_SOURCES := \
   $(wildcard src/nix-daemon/*.cc) \
   $(wildcard src/nix-env/*.cc) \
   $(wildcard src/nix-instantiate/*.cc) \
-  $(wildcard src/nix-prefetch-url/*.cc) \
   $(wildcard src/nix-store/*.cc) \
 
 nix_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/libexpr -I src/libmain
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
new file mode 100644
index 000000000..969299489
--- /dev/null
+++ b/src/nix/prefetch.cc
@@ -0,0 +1,352 @@
+#include "command.hh"
+#include "common-args.hh"
+#include "shared.hh"
+#include "store-api.hh"
+#include "filetransfer.hh"
+#include "finally.hh"
+#include "progress-bar.hh"
+#include "tarfile.hh"
+#include "attr-path.hh"
+#include "eval-inline.hh"
+#include "legacy.hh"
+
+#include <nlohmann/json.hpp>
+
+using namespace nix;
+
+/* If ‘url’ starts with ‘mirror://’, then resolve it using the list of
+   mirrors defined in Nixpkgs. */
+string resolveMirrorUrl(EvalState & state, string url)
+{
+    if (url.substr(0, 9) != "mirror://") return url;
+
+    std::string s(url, 9);
+    auto p = s.find('/');
+    if (p == std::string::npos) throw Error("invalid mirror URL '%s'", url);
+    std::string mirrorName(s, 0, p);
+
+    Value vMirrors;
+    // FIXME: use nixpkgs flake
+    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("unknown mirror name '%s'", mirrorName);
+    state.forceList(*mirrorList->value);
+
+    if (mirrorList->value->listSize() < 1)
+        throw Error("mirror URL '%s' did not expand to anything", url);
+
+    auto mirror = state.forceString(*mirrorList->value->listElems()[0]);
+    return mirror + (hasSuffix(mirror, "/") ? "" : "/") + string(s, p + 1);
+}
+
+std::tuple<StorePath, Hash> prefetchFile(
+    ref<Store> store,
+    std::string_view url,
+    std::optional<std::string> name,
+    HashType hashType,
+    std::optional<Hash> expectedHash,
+    bool unpack,
+    bool executable)
+{
+    auto ingestionMethod = unpack || executable ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
+
+    /* Figure out a name in the Nix store. */
+    if (!name) {
+        name = baseNameOf(url);
+        if (name->empty())
+            throw Error("cannot figure out file name for '%s'", url);
+    }
+
+    std::optional<StorePath> storePath;
+    std::optional<Hash> hash;
+
+    /* If an expected hash is given, the file may already exist in
+       the store. */
+    if (expectedHash) {
+        hashType = expectedHash->type;
+        storePath = store->makeFixedOutputPath(ingestionMethod, *expectedHash, *name);
+        if (store->isValidPath(*storePath))
+            hash = expectedHash;
+        else
+            storePath.reset();
+    }
+
+    if (!storePath) {
+
+        AutoDelete tmpDir(createTempDir(), true);
+        Path tmpFile = (Path) tmpDir + "/tmp";
+
+        /* Download the file. */
+        {
+            auto mode = 0600;
+            if (executable)
+                mode = 0700;
+
+            AutoCloseFD fd = open(tmpFile.c_str(), O_WRONLY | O_CREAT | O_EXCL, mode);
+            if (!fd) throw SysError("creating temporary file '%s'", tmpFile);
+
+            FdSink sink(fd.get());
+
+            FileTransferRequest req(url);
+            req.decompress = false;
+            getFileTransfer()->download(std::move(req), sink);
+        }
+
+        /* Optionally unpack the file. */
+        if (unpack) {
+            Activity act(*logger, lvlChatty, actUnknown,
+                fmt("unpacking '%s'", url));
+            Path unpacked = (Path) tmpDir + "/unpacked";
+            createDirs(unpacked);
+            unpackTarfile(tmpFile, unpacked);
+
+            /* If the archive unpacks to a single file/directory, then use
+               that as the top-level. */
+            auto entries = readDirectory(unpacked);
+            if (entries.size() == 1)
+                tmpFile = unpacked + "/" + entries[0].name;
+            else
+                tmpFile = unpacked;
+        }
+
+        Activity act(*logger, lvlChatty, actUnknown,
+            fmt("adding '%s' to the store", url));
+
+        auto info = store->addToStoreSlow(*name, tmpFile, ingestionMethod, hashType, expectedHash);
+        storePath = info.path;
+        assert(info.ca);
+        hash = getContentAddressHash(*info.ca);
+    }
+
+    return {storePath.value(), hash.value()};
+}
+
+static int main_nix_prefetch_url(int argc, char * * argv)
+{
+    {
+        HashType ht = htSHA256;
+        std::vector<string> args;
+        bool printPath = getEnv("PRINT_PATH") == "1";
+        bool fromExpr = false;
+        string attrPath;
+        bool unpack = false;
+        bool executable = false;
+        std::optional<std::string> name;
+
+        struct MyArgs : LegacyArgs, MixEvalArgs
+        {
+            using LegacyArgs::LegacyArgs;
+        };
+
+        MyArgs myArgs(std::string(baseNameOf(argv[0])), [&](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);
+            }
+            else if (*arg == "--print-path")
+                printPath = true;
+            else if (*arg == "--attr" || *arg == "-A") {
+                fromExpr = true;
+                attrPath = getArg(*arg, arg, end);
+            }
+            else if (*arg == "--unpack")
+                unpack = true;
+            else if (*arg == "--executable")
+                executable = true;
+            else if (*arg == "--name")
+                name = getArg(*arg, arg, end);
+            else if (*arg != "" && arg->at(0) == '-')
+                return false;
+            else
+                args.push_back(*arg);
+            return true;
+        });
+
+        myArgs.parseCmdline(argvToStrings(argc, argv));
+
+        initPlugins();
+
+        if (args.size() > 2)
+            throw UsageError("too many arguments");
+
+        Finally f([]() { stopProgressBar(); });
+
+        if (isatty(STDERR_FILENO))
+          startProgressBar();
+
+        auto store = openStore();
+        auto state = std::make_unique<EvalState>(myArgs.searchPath, store);
+
+        Bindings & autoArgs = *myArgs.getAutoArgs(*state);
+
+        /* If -A is given, get the URL from the specified Nix
+           expression. */
+        string url;
+        if (!fromExpr) {
+            if (args.empty())
+                throw UsageError("you must specify a URL");
+            url = args[0];
+        } else {
+            Path path = resolveExprPath(lookupFileArg(*state, args.empty() ? "." : args[0]));
+            Value vRoot;
+            state->evalFile(path, vRoot);
+            Value & v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot).first);
+            state->forceAttrs(v);
+
+            /* Extract the URL. */
+            auto attr = v.attrs->find(state->symbols.create("urls"));
+            if (attr == v.attrs->end())
+                throw Error("attribute set does not contain a 'urls' attribute");
+            state->forceList(*attr->value);
+            if (attr->value->listSize() < 1)
+                throw Error("'urls' list is empty");
+            url = state->forceString(*attr->value->listElems()[0]);
+
+            /* Extract the hash mode. */
+            attr = v.attrs->find(state->symbols.create("outputHashMode"));
+            if (attr == v.attrs->end())
+                printInfo("warning: this does not look like a fetchurl call");
+            else
+                unpack = state->forceString(*attr->value) == "recursive";
+
+            /* Extract the name. */
+            if (!name) {
+                attr = v.attrs->find(state->symbols.create("name"));
+                if (attr != v.attrs->end())
+                    name = state->forceString(*attr->value);
+            }
+        }
+
+        std::optional<Hash> expectedHash;
+        if (args.size() == 2)
+            expectedHash = Hash::parseAny(args[1], ht);
+
+        auto [storePath, hash] = prefetchFile(
+            store, resolveMirrorUrl(*state, url), name, ht, expectedHash, unpack, executable);
+
+        stopProgressBar();
+
+        if (!printPath)
+            printInfo("path is '%s'", store->printStorePath(storePath));
+
+        std::cout << printHash16or32(hash) << std::endl;
+        if (printPath)
+            std::cout << store->printStorePath(storePath) << std::endl;
+
+        return 0;
+    }
+}
+
+static RegisterLegacyCommand r_nix_prefetch_url("nix-prefetch-url", main_nix_prefetch_url);
+
+struct CmdStorePrefetch : 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)
+    {
+        addFlag({
+            .longName = "name",
+            .description = "store path name",
+            .labels = {"name"},
+            .handler = {&name}
+        });
+
+        addFlag({
+            .longName = "expected-hash",
+            .description = unpack ? "expected NAR hash of the unpacked tarball" : "expected hash of the file",
+            .labels = {"hash"},
+            .handler = {[&](std::string s) {
+                expectedHash = Hash::parseAny(s, hashType);
+            }}
+        });
+
+        addFlag(Flag::mkHashTypeFlag("hash-type", &hashType));
+
+        expectArg("url", &url);
+    }
+
+    Category category() override { return catUtility; }
+
+    void run(ref<Store> store) override
+    {
+        auto [storePath, hash] = prefetchFile(store, url, name, hashType, expectedHash, unpack, executable);
+
+        if (json) {
+            auto res = nlohmann::json::object();
+            res["storePath"] = store->printStorePath(storePath);
+            res["hash"] = hash.to_string(SRI, true);
+            logger->cout(res.dump());
+        } else {
+            notice("Downloaded '%s' to '%s' (hash '%s').",
+                url,
+                store->printStorePath(storePath),
+                hash.to_string(SRI, true));
+        }
+    }
+};
+
+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"});
diff --git a/src/nix/store-prefetch-file.md b/src/nix/store-prefetch-file.md
new file mode 100644
index 000000000..1663b847b
--- /dev/null
+++ b/src/nix/store-prefetch-file.md
@@ -0,0 +1,32 @@
+R""(
+
+# Examples
+
+* Download a file to the Nix store:
+
+  ```console
+  # nix store prefetch-file https://releases.nixos.org/nix/nix-2.3.10/nix-2.3.10.tar.xz
+  Downloaded 'https://releases.nixos.org/nix/nix-2.3.10/nix-2.3.10.tar.xz' to
+  '/nix/store/vbdbi42hgnc4h7pyqzp6h2yf77kw93aw-source' (hash
+  'sha256-qKheVd5D0BervxMDbt+1hnTKE2aRWC8XCAwc0SeHt6s=').
+  ```
+
+* Download a file and get the SHA-512 hash:
+
+  ```console
+  # nix store prefetch-file --json --hash-type sha512 \
+      https://releases.nixos.org/nix/nix-2.3.10/nix-2.3.10.tar.xz \
+    | jq -r .hash
+  sha512-6XJxfym0TNH9knxeH4ZOvns6wElFy3uahunl2hJgovACCMEMXSy42s69zWVyGJALXTI+86tpDJGlIcAySEKBbA==
+  ```
+
+# Description
+
+This command downloads the file *url* to the Nix store. It prints out
+the resulting store path and the cryptographic hash of the contents of
+the file.
+
+The name component of the store path defaults to the last component of
+*url*, but this can be overriden using `--name`.
+
+)""
diff --git a/src/nix/store-prefetch-tarball.md b/src/nix/store-prefetch-tarball.md
new file mode 100644
index 000000000..535d7e022
--- /dev/null
+++ b/src/nix/store-prefetch-tarball.md
@@ -0,0 +1,31 @@
+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`.
+
+)""