Support piping data to client stdin

Pass the client stdin fd to the server and open a fifo buffer
from it.

Fixes #3394

src/buffer_utils.cc

@@ -265,4 +265,15 @@ Vector<String> undo_group_as_strings(const Buffer::UndoGroup& undo_group)
     return res;
 }
 
+String generate_buffer_name(StringView pattern)
+{
+    auto& buffer_manager = BufferManager::instance();
+    for (int i = 0; true; ++i)
+    {
+        String name = format(pattern, i);
+        if (buffer_manager.get_buffer_ifp(name) == nullptr)
+            return name;
+    }
+}
+
 }

src/buffer_utils.hh

@@ -87,6 +87,8 @@ void write_to_debug_buffer(StringView str);
 Vector<String> history_as_strings(const Vector<Buffer::HistoryNode>& history);
 Vector<String> undo_group_as_strings(const Buffer::UndoGroup& undo_group);
 
+String generate_buffer_name(StringView pattern);
+
 }
 
 #endif // buffer_utils_hh_INCLUDED

src/commands.cc

@@ -356,16 +356,8 @@ void edit(const ParametersParser& parser, Context& context, const ShellContext&)
        (parser.get_switch("debug") ? Buffer::Flags::Debug : Buffer::Flags::None);
 
     auto& buffer_manager = BufferManager::instance();
-    auto generate_scratch_name = [&] {
-        for (int i = 0; true; ++i)
-        {
-            String name = format("*scratch-{}*", i);
-            if (buffer_manager.get_buffer_ifp(name) == nullptr)
-                return name;
-        }
-    };
     const auto& name = parser.positional_count() > 0 ?
-        parser[0] : (scratch ? generate_scratch_name() : context.buffer().name());
+        parser[0] : (scratch ? generate_buffer_name("*scratch-{}*") : context.buffer().name());
 
     Buffer* buffer = buffer_manager.get_buffer_ifp(name);
     if (scratch)

src/main.cc

@@ -661,9 +661,21 @@ int run_client(StringView session, StringView name, StringView client_init,
 {
     try
     {
+        Optional<int> stdin_fd;
+        if (not isatty(0))
+        {
+            // move stdin to another fd, and restore tty as stdin
+            stdin_fd = dup(0);
+            int tty = open("/dev/tty", O_RDONLY);
+            dup2(tty, 0);
+            close(tty);
+        }
+
         EventManager event_manager;
         RemoteClient client{session, name, make_ui(ui_type), getpid(), get_env_vars(),
-                            client_init, std::move(init_coord)};
+                            client_init, std::move(init_coord), stdin_fd};
+        stdin_fd.map(close);
+
         if (suspend)
             raise(SIGTSTP);
         while (not client.exit_status() and client.is_ui_ok())

src/optional.hh

@@ -60,11 +60,12 @@ public:
     bool operator!=(const Optional& other) const { return !(*this == other); }
 
     template<typename... Args>
-    void emplace(Args&&... args)
+    T& emplace(Args&&... args)
     {
         destruct_ifn();
         new (&m_value) T{std::forward<Args>(args)...};
         m_valid = true;
+        return m_value;
     }
 
     T& operator*()

src/remote.cc

@@ -261,25 +261,56 @@ public:
         return Reader<T>::read(*this);
     }
 
+    Optional<int> ancillary_fd()
+    {
+        auto res = m_ancillary_fd;
+        m_ancillary_fd.reset();
+        return res;
+    }
+
+    ~MsgReader()
+    {
+        m_ancillary_fd.map(close);
+    }
+
     void reset()
     {
         m_stream.resize(0);
         m_write_pos = 0;
         m_read_pos = header_size;
+        m_ancillary_fd.map(close);
     }
 
 private:
     void read_from_socket(int sock, size_t size)
     {
         kak_assert(m_write_pos + size <= m_stream.size());
-        int res = ::read(sock, m_stream.data() + m_write_pos, size);
+        iovec io{m_stream.data() + m_write_pos, size};
+        alignas(cmsghdr) char fdbuf[CMSG_SPACE(sizeof(int))];
+
+        msghdr msg{};
+        msg.msg_iov = &io;
+        msg.msg_iovlen = 1;
+        msg.msg_control = fdbuf;
+        msg.msg_controllen = sizeof(fdbuf);
+
+        int res = recvmsg(sock, &msg, MSG_CMSG_CLOEXEC);
         if (res <= 0)
             throw disconnected{format("socket read failed: {}", strerror(errno))};
+
         m_write_pos += res;
+
+        if (cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
+            cmsg && cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS && cmsg->cmsg_len == CMSG_LEN(sizeof(int)))
+        {
+            m_ancillary_fd.map(close);
+            memcpy(&m_ancillary_fd.emplace(), CMSG_DATA(cmsg), sizeof(int));
+        }
     }
 
     static constexpr uint32_t header_size = sizeof(MessageType) + sizeof(uint32_t);
     Vector<char, MemoryDomain::Remote> m_stream;
+    Optional<int> m_ancillary_fd;
     uint32_t m_write_pos = 0;
     uint32_t m_read_pos = header_size;
 };
@@ -398,14 +429,32 @@ private:
     RemoteBuffer  m_send_buffer;
 };
 
-static bool send_data(int fd, RemoteBuffer& buffer)
+static bool send_data(int fd, RemoteBuffer& buffer, Optional<int> ancillary_fd = {})
 {
     while (not buffer.empty() and fd_writable(fd))
     {
-      int res = ::write(fd, buffer.data(), buffer.size());
-      if (res <= 0)
-          throw disconnected{format("socket write failed: {}", strerror(errno))};
-      buffer.erase(buffer.begin(), buffer.begin() + res);
+        iovec io{buffer.data(), buffer.size()};
+        alignas(cmsghdr) char fdbuf[CMSG_SPACE(sizeof(int))];
+
+        msghdr msg{};
+        msg.msg_iov = &io;
+        msg.msg_iovlen = 1;
+        if (ancillary_fd)
+        {
+            msg.msg_control = fdbuf;
+            msg.msg_controllen = sizeof(fdbuf);
+
+            cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
+            cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+            cmsg->cmsg_level = SOL_SOCKET;
+            cmsg->cmsg_type = SCM_RIGHTS;
+            memcpy(CMSG_DATA(cmsg), &*ancillary_fd, sizeof(int));
+        }
+
+        int res = sendmsg(fd, &msg, 0);
+        if (res <= 0)
+              throw disconnected{format("socket write failed: {}", strerror(errno))};
+         buffer.erase(buffer.begin(), buffer.begin() + res);
     }
     return buffer.empty();
 }
@@ -592,7 +641,7 @@ bool check_session(StringView session)
 
 RemoteClient::RemoteClient(StringView session, StringView name, std::unique_ptr<UserInterface>&& ui,
                            int pid, const EnvVarMap& env_vars, StringView init_command,
-                           Optional<BufferCoord> init_coord)
+                           Optional<BufferCoord> init_coord, Optional<int> stdin_fd)
     : m_ui(std::move(ui))
 {
     int sock = connect_to(session);
@@ -601,6 +650,7 @@ RemoteClient::RemoteClient(StringView session, StringView name, std::unique_ptr<
         MsgWriter msg{m_send_buffer, MessageType::Connect};
         msg.write(pid, name, init_command, init_coord, m_ui->dimensions(), env_vars);
     }
+    send_data(sock, m_send_buffer, stdin_fd);
 
     m_ui->set_on_key([this](Key key){
         MsgWriter msg(m_send_buffer, MessageType::Key);
@@ -750,6 +800,10 @@ private:
                 auto init_coord = m_reader.read<Optional<BufferCoord>>();
                 auto dimensions = m_reader.read<DisplayCoord>();
                 auto env_vars = m_reader.read<HashMap<String, String, MemoryDomain::EnvVars>>();
+
+                if (auto stdin_fd = m_reader.ancillary_fd())
+                    create_fifo_buffer(generate_buffer_name("*stdin-{}*"), *stdin_fd, Buffer::Flags::None);
+
                 auto* ui = new RemoteUI{sock, dimensions};
                 ClientManager::instance().create_client(
                     std::unique_ptr<UserInterface>(ui), pid, std::move(name),

src/remote.hh

@@ -32,7 +32,7 @@ class RemoteClient
 public:
     RemoteClient(StringView session, StringView name, std::unique_ptr<UserInterface>&& ui,
                  int pid, const EnvVarMap& env_vars, StringView init_command,
-                 Optional<BufferCoord> init_coord);
+                 Optional<BufferCoord> init_coord, Optional<int> stdin_fd);
 
     bool is_ui_ok() const;
     const Optional<int>& exit_status() const { return m_exit_status; }