make xfer() a member function, and add tests

5 files changed, 127 insertions, 28 deletions

diff --git a/libnvxx/nv_list.cc b/libnvxx/nv_list.cc
index 6eadd36..eace039 100644
--- a/libnvxx/nv_list.cc
+++ b/libnvxx/nv_list.cc
@@ -130,20 +130,6 @@ nv_list::recv(int fd, int flags)
 		std::error_code(errno, std::system_category()));
 }
 
-nv_list
-nv_list::xfer(int fd, nv_list &&nvl, int flags)
-{
-	if (auto *nv = ::nvlist_xfer(fd, nvl.__m_nv, flags);
-	    nv != nullptr) {
-		// nvlist_xfer destroys the original list
-		nvl.__m_nv = nullptr;
-		return (nv_list(nv));
-	}
-
-	throw std::system_error(
-		std::error_code(errno, std::system_category()));
-}
-
 namespace __detail {
 
 /*
@@ -164,6 +150,22 @@ __nv_list::operator const_nv_list() const
 	return (const_nv_list(__m_nv));
 }
 
+nv_list
+__nv_list::xfer(int fd, int flags) &&
+{
+	__throw_if_error();
+
+	auto *nv = ::nvlist_xfer(fd, __m_nv, flags);
+	// nvlist_xfer always destroys the original list
+	__m_nv = nullptr;
+
+	if (nv != nullptr)
+		return (nv_list(nv));
+
+	throw std::system_error(
+		std::error_code(errno, std::system_category()));
+}
+
 void
 __nv_list::free(std::string_view key)
 {
diff --git a/libnvxx/nvxx.3 b/libnvxx/nvxx.3
index 37db659..c5ef02f 100644
--- a/libnvxx/nvxx.3
+++ b/libnvxx/nvxx.3
@@ -134,6 +134,8 @@ struct nv_list : <unspecified> {
 
 	operator const_nv_list() const;
 
+	nv_list xfer(int fd, int flags = 0) &&;
+
 	void add_null(std::string_view key);
 	void add_bool(std::string_view key, bool value);
 	void add_number(std::string_view key, std::uint64_t);
@@ -603,6 +605,25 @@ If the nvlist is already in the error state, then an exception of type
 is thrown and the error state is not changed.
 .Pp
 The
+.Fn xfer
+function sends this nvlist over a socket as if by
+.Fn send ,
+and then receives a new nvlist from the same socket as if by
+.Fn recv ,
+which is returned.
+If
+.Fa flags
+is non-zero, the specified flags will be used to create the returned nvlist.
+The nvlist being sent is left in the empty state.
+If the nvlist is in the error state, an exception of type
+.Vt nv_error_state
+is thrown.
+If an operating system error occurs while writing to or reading from the file
+descriptor, an exception of type
+.Vt std::system_error
+is thrown and the nvlist being sent is left in the empty state.
+.Pp
+The
 .Fn add_null ,
 .Fn add_bool ,
 .Fn add_number ,
diff --git a/libnvxx/nvxx_base.h b/libnvxx/nvxx_base.h
index 43e53cf..06d213e 100644
--- a/libnvxx/nvxx_base.h
+++ b/libnvxx/nvxx_base.h
@@ -214,6 +214,16 @@ struct __nv_list : virtual __nv_list_base {
 	 */
 	operator const_nv_list() const;
 
+	/*
+	 * Send this nv_list over a file descriptor and receive another nv_list
+	 * in response, which is returned, by calling nvlist_xfer(). On
+	 * failure, throws std::system_error.
+	 *
+	 * The source nv_list is moved-from and is left in an undefined state.
+	 * The returned nv_list is owning.
+	 */
+	[[nodiscard]] nv_list xfer(int __fd, int __flags = 0) &&;
+
 	/* add */
 
 	void add_null(std::string_view);
@@ -434,16 +444,6 @@ struct nv_list final
 	 */
 	[[nodiscard]] static auto recv(int __fd, int __flags = 0) -> nv_list;
 
-	/*
-	 * Send an nv_list over a file descriptor and receive another nv_list
-	 * in response, which is returned, by calling nvlist_xfer(). On
-	 * failure, throws std::system_error.
-	 *
-	 * The source nv_list is moved-from and is left in an undefined state.
-	 * The returned nv_list is owning.
-	 */
-	[[nodiscard]] static nv_list xfer(int, nv_list &&, int);
-
 	void add_bool_range(std::string_view __key,
 			    std::ranges::range auto &&__value)
 	{
diff --git a/libnvxx/tests/Makefile b/libnvxx/tests/Makefile
index 3ea8a5a..384f8a8 100644
--- a/libnvxx/tests/Makefile
+++ b/libnvxx/tests/Makefile
@@ -9,6 +9,6 @@ CXXSTD=			c++23
 CXXFLAGS+=		-W -Wall -Wextra
 CFLAGS+=		-I${.CURDIR:H}
 LDFLAGS+=		-lprivateatf-c++ -L${.OBJDIR:H} -lnvxx
-LDFLAGS.nvxx_basic+=	-lnv
+LDFLAGS.nvxx_basic+=	-lnv -lpthread
 
 .include <bsd.test.mk>
diff --git a/libnvxx/tests/nvxx_basic.cc b/libnvxx/tests/nvxx_basic.cc
index dbca98c..ca70fec 100644
--- a/libnvxx/tests/nvxx_basic.cc
+++ b/libnvxx/tests/nvxx_basic.cc
@@ -10,6 +10,7 @@
 #include <span>
 #include <string>
 #include <string_view>
+#include <thread>
 
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -526,8 +527,6 @@ TEST_CASE(nvxx_send_recv)
 
 TEST_CASE(nvxx_send_error)
 {
-	using namespace std::literals;
-
 	auto nvl = bsd::nv_list();
 	nvl.set_error(std::errc::invalid_argument);
 
@@ -556,6 +555,79 @@ TEST_CASE(nvxx_send_empty)
 }
 
 /*
+ * xfer
+ */
+
+TEST_CASE(nvxx_xfer)
+{
+	using namespace std::literals;
+	auto constexpr send_key = "test"sv;
+	auto constexpr send_value = 42u;
+	auto constexpr resp_key = "response"sv;
+
+	auto fds = std::array<int, 2>{};
+	auto ret = ::socketpair(AF_UNIX, SOCK_STREAM, 0, &fds[0]);
+	ATF_REQUIRE_EQ(0, ret);
+
+	bsd::nv_fd fd0(fds[0]);
+	bsd::nv_fd fd1(fds[1]);
+
+	/*
+	 * testing xfer() is a bit tricky because it blocks waiting for a
+	 * response.  create a thread that receives a list and sends its own in
+	 * response.
+	 */
+
+	auto respond_thread = std::thread([&] {
+		auto nvl2 = bsd::nv_list::recv(fd1.get());
+
+		auto resp_nvl = bsd::nv_list();
+		resp_nvl.add_number(resp_key, nvl2.get_number(send_key));
+		resp_nvl.send(fd1.get());
+	});
+
+	auto send_nvl = bsd::nv_list();
+	send_nvl.add_number(send_key, send_value);
+
+	auto nvl2 = std::move(send_nvl).xfer(fd0.get());
+	ATF_REQUIRE_EQ(send_value, nvl2.get_number(resp_key));
+
+	ATF_REQUIRE_THROW(std::logic_error, send_nvl.ptr());
+
+	respond_thread.join();
+}
+
+TEST_CASE(nvxx_xfer_error)
+{
+	auto nvl = bsd::nv_list();
+	nvl.set_error(std::errc::invalid_argument);
+
+	auto fds = std::array<int, 2>{};
+	auto ret = ::socketpair(AF_UNIX, SOCK_STREAM, 0, &fds[0]);
+	ATF_REQUIRE_EQ(0, ret);
+
+	bsd::nv_fd fd0(fds[0]);
+	bsd::nv_fd fd1(fds[1]);
+
+	ATF_REQUIRE_THROW(bsd::nv_error_state, (void)std::move(nvl).xfer(fd0.get()));
+}
+
+TEST_CASE(nvxx_xfer_empty)
+{
+	auto nvl = bsd::nv_list();
+	auto nvl2 = std::move(nvl);
+
+	auto fds = std::array<int, 2>{};
+	auto ret = ::socketpair(AF_UNIX, SOCK_STREAM, 0, &fds[0]);
+	ATF_REQUIRE_EQ(0, ret);
+
+	bsd::nv_fd fd0(fds[0]);
+	bsd::nv_fd fd1(fds[1]);
+
+	ATF_REQUIRE_THROW(std::logic_error, (void)std::move(nvl).xfer(fd0.get()));
+}
+
+/*
  * exists(_type)
  */
 
@@ -2107,11 +2179,15 @@ ATF_INIT_TEST_CASES(tcs)
 	ATF_ADD_TEST_CASE(tcs, nvxx_unpack);
 	ATF_ADD_TEST_CASE(tcs, nvxx_unpack_range);
 
-	ATF_ADD_TEST_CASE(tcs, nvxx_send_non_socket);
 	ATF_ADD_TEST_CASE(tcs, nvxx_send_recv);
+	ATF_ADD_TEST_CASE(tcs, nvxx_send_non_socket);
 	ATF_ADD_TEST_CASE(tcs, nvxx_send_empty);
 	ATF_ADD_TEST_CASE(tcs, nvxx_send_error);
 
+	ATF_ADD_TEST_CASE(tcs, nvxx_xfer);
+	ATF_ADD_TEST_CASE(tcs, nvxx_xfer_empty);
+	ATF_ADD_TEST_CASE(tcs, nvxx_xfer_error);
+
 	ATF_ADD_TEST_CASE(tcs, nvxx_exists);
 	ATF_ADD_TEST_CASE(tcs, nvxx_exists_nul_key);
 	ATF_ADD_TEST_CASE(tcs, nvxx_exists_type);