Clean up vm CredentialPipe

This code is needlessly complicated for what it does.  Even with the
intent, which is secure buffer cleanup, it's trivial to encase all this
into a single class that accepts the strings by rvalue reference, then
cleans them up afterward.

Doing this also cleans up a potential lifetime problem, where if the
unix socket returned immediately, it would've invalidated the buffers
that were being sent.  It also moves to async_write, instead of
async_write_some.  The former could in theory fail if the socket blocks
(unlikely in this scenario) but it's good to handle anyway.

Tested: Need some help here.  There's no backend for this, so we might
just have to rely on inspection.

Change-Id: I9032d458f8eb7a0689bee575aae611641bacee26
Signed-off-by: Ed Tanous <edtanous@google.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/test/include/credential_pipe_test.cpp b/test/include/credential_pipe_test.cpp
new file mode 100644
index 0000000000..c5b544bc0c
--- /dev/null
+++ b/test/include/credential_pipe_test.cpp
@@ -0,0 +1,41 @@
+#include "credential_pipe.hpp"
+
+#include <boost/asio/io_context.hpp>
+#include <boost/beast/core/file_posix.hpp>
+
+#include <string>
+
+#include <gmock/gmock.h>
+
+using ::testing::ElementsAre;
+
+static void handler(boost::asio::io_context& io,
+                    const boost::system::error_code& ec, size_t sent)
+{
+    io.stop();
+    EXPECT_FALSE(ec);
+    EXPECT_EQ(sent, 18);
+}
+
+TEST(CredentialsPipe, BasicSend)
+{
+    boost::beast::file_posix file;
+    {
+        boost::asio::io_context io;
+        CredentialsPipe pipe(io);
+        file.native_handle(dup(pipe.fd()));
+        ASSERT_GT(file.native_handle(), 0);
+        pipe.asyncWrite("username", "password",
+                        std::bind_front(handler, std::ref(io)));
+        io.run();
+    }
+    std::array<char, 18> buff{};
+    boost::system::error_code ec;
+    size_t r = file.read(buff.data(), buff.size(), ec);
+    ASSERT_FALSE(ec);
+    ASSERT_EQ(r, 18);
+
+    EXPECT_THAT(buff,
+                ElementsAre('u', 's', 'e', 'r', 'n', 'a', 'm', 'e', '\0', 'p',
+                            'a', 's', 's', 'w', 'o', 'r', 'd', '\0'));
+}