feat(3p/nix): Implement AddToStore rpc client r/1594

Implement the AddToStore RPC client method, which uses an
AddToStorePathWriterSink (the dual of the AddToStorePathReaderSource on
the server side) to hook into the dumpPath machinery (which we should
refactor not to use sinks or sources, but not yet) and write dumped
paths as binary data over gRPC. With this commit and sandboxing
disabled, the following derivation builds cleanly:

    derivation {
      name = "test";
      builder = ./build.sh;
      system = "x86_64-linux";
    }

where build.sh has chmod +x and contains:

    #!/bin/sh
    echo 1 > $out

Change-Id: I94cab86f0825a3a9993262a9807130645c13bf44
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1638
Reviewed-by: kanepyork <rikingcoding@gmail.com>
Tested-by: BuildkiteCI

4 files changed, 69 insertions, 2 deletions

diff --git a/third_party/nix/src/libstore/rpc-store.cc b/third_party/nix/src/libstore/rpc-store.cc
index f0abdd42efa9..0b57127610ad 100644
--- a/third_party/nix/src/libstore/rpc-store.cc
+++ b/third_party/nix/src/libstore/rpc-store.cc
@@ -1,6 +1,7 @@
 #include "rpc-store.hh"
 
 #include <algorithm>
+#include <filesystem>
 #include <memory>
 
 #include <absl/status/status.h>
@@ -20,6 +21,7 @@
 #include "libproto/worker.grpc.pb.h"
 #include "libproto/worker.pb.h"
 #include "libstore/store-api.hh"
+#include "libutil/archive.hh"
 #include "libutil/hash.hh"
 #include "libutil/types.hh"
 
@@ -54,6 +56,32 @@ T FillFrom(const U& src) {
   return result;
 }
 
+class AddToStorePathWriterSink : public BufferedSink {
+ public:
+  explicit AddToStorePathWriterSink(
+      std::unique_ptr<
+          grpc_impl::ClientWriter<class nix::proto::AddToStoreRequest>>&&
+          writer)
+      : writer_(std::move(writer)), good_(true) {}
+
+  bool good() override { return good_; }
+
+  void write(const unsigned char* data, size_t len) override {
+    proto::AddToStoreRequest req;
+    req.set_data(data, len);
+    if (!writer_->Write(req)) {
+      good_ = false;
+    }
+  }
+
+  grpc::Status Finish() { return writer_->Finish(); }
+
+ private:
+  std::unique_ptr<grpc_impl::ClientWriter<class nix::proto::AddToStoreRequest>>
+      writer_;
+  bool good_;
+};
+
 constexpr absl::StatusCode GRPCStatusCodeToAbsl(grpc::StatusCode code) {
   switch (code) {
     case grpc::StatusCode::OK:
@@ -304,7 +332,29 @@ void RpcStore::addToStore(const ValidPathInfo& info,
 Path RpcStore::addToStore(const std::string& name, const Path& srcPath,
                           bool recursive, HashType hashAlgo, PathFilter& filter,
                           RepairFlag repair) {
-  throw Unsupported(absl::StrCat("Not implemented ", __func__));
+  if (repair != 0u) {
+    throw Error(
+        "repairing is not supported when building through the Nix daemon");
+  }
+
+  ClientContext ctx;
+  proto::StorePath response;
+  auto writer = stub_->AddToStore(&ctx, &response);
+
+  proto::AddToStoreRequest metadata_req;
+  metadata_req.mutable_meta()->set_base_name(name);
+  // TODO(grfn): what is fixed?
+  metadata_req.mutable_meta()->set_fixed(!(hashAlgo == htSHA256 && recursive));
+  metadata_req.mutable_meta()->set_recursive(recursive);
+  metadata_req.mutable_meta()->set_hash_type(HashTypeToProto(hashAlgo));
+  writer->Write(metadata_req);
+
+  AddToStorePathWriterSink sink(std::move(writer));
+  dumpPath(std::filesystem::absolute(srcPath), sink);
+  sink.flush();
+  SuccessOrThrow(sink.Finish());
+
+  return response.path();
 }
 
 Path RpcStore::addTextToStore(const std::string& name,
diff --git a/third_party/nix/src/libutil/hash.cc b/third_party/nix/src/libutil/hash.cc
index 97cc137b11a7..f7ee44728f60 100644
--- a/third_party/nix/src/libutil/hash.cc
+++ b/third_party/nix/src/libutil/hash.cc
@@ -35,6 +35,21 @@ std::optional<HashType> hash_type_from(nix::proto::HashType hash_type) {
   }
 }
 
+nix::proto::HashType HashTypeToProto(HashType hash_type) {
+  switch (hash_type) {
+    case HashType::htMD5:
+      return nix::proto::HashType::MD5;
+    case HashType::htSHA1:
+      return nix::proto::HashType::SHA1;
+    case HashType::htSHA256:
+      return nix::proto::HashType::SHA256;
+    case HashType::htSHA512:
+      return nix::proto::HashType::SHA512;
+    default:
+      return nix::proto::HashType::UNKNOWN;
+  }
+}
+
 void Hash::init() {
   if (type == htMD5) {
     hashSize = md5HashSize;
diff --git a/third_party/nix/src/libutil/hash.hh b/third_party/nix/src/libutil/hash.hh
index bc32f9146373..4d52702aee75 100644
--- a/third_party/nix/src/libutil/hash.hh
+++ b/third_party/nix/src/libutil/hash.hh
@@ -16,6 +16,8 @@ enum HashType : char { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 };
 
 std::optional<HashType> hash_type_from(nix::proto::HashType hash_type);
 
+nix::proto::HashType HashTypeToProto(HashType hash_type);
+
 const int md5HashSize = 16;
 const int sha1HashSize = 20;
 const int sha256HashSize = 32;
diff --git a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
index b3ecc9d5b9a1..fe580b08a214 100644
--- a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
+++ b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
@@ -146,7 +146,7 @@ class WorkerServiceImpl final : public WorkerService::Service {
           proto::AddToStoreRequest metadata_request;
           auto has_metadata = reader->Read(&metadata_request);
 
-          if (!has_metadata || metadata_request.has_meta()) {
+          if (!has_metadata || !metadata_request.has_meta()) {
             return Status(grpc::StatusCode::INVALID_ARGUMENT,
                           "Metadata must be set before sending file content");
           }