Implement file:sendfile

Allow Erlang code to use sendfile() where available by wrapping it as
file:sendfile/4 and file:sendfile/2.

sendfile(2) - Linux man page:
"sendfile() copies data between one file descriptor and another.
Because this copying is done within the kernel, sendfile() is more
efficient than the combination of read(2) and write(2), which would
require transferring data to and from user space."

1 files changed, 86 insertions, 1 deletions

diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl
index 77fc7e73f9..67458ae77d 100644
--- a/lib/kernel/test/file_SUITE.erl
+++ b/lib/kernel/test/file_SUITE.erl
@@ -86,6 +86,8 @@
 
 -export([standard_io/1,mini_server/1]).
 
+-export([sendfile/0, sendfile/1, sendfile_server/1]).
+
 %% Debug exports
 -export([create_file_slow/2, create_file/2, create_bin/2]).
 -export([verify_file/2, verify_bin/3]).
@@ -107,7 +109,7 @@ all() ->
      delayed_write, read_ahead, segment_read, segment_write,
      ipread, pid2name, interleaved_read_write, otp_5814,
      large_file, read_line_1, read_line_2, read_line_3,
-     read_line_4, standard_io].
+     read_line_4, standard_io, sendfile].
 
 groups() -> 
     [{dirs, [], [make_del_dir, cur_dir_0, cur_dir_1]},
@@ -3950,3 +3952,86 @@ flush(Msgs) ->
     after 0 ->
 	    lists:reverse(Msgs)
     end.
+
+
+sendfile() ->
+    [{timetrap, {seconds, 5}}].
+
+sendfile_supported({unix,linux}) -> true;
+sendfile_supported({unix,sunos}) -> true;
+sendfile_supported({unix,freebsd}) -> true;
+sendfile_supported({unix,dragonfly}) -> true;
+sendfile_supported({unix,darwin}) -> true;
+%% TODO: enable win32 once TransmitFile based implemenation written properly
+%% sendfile_supported({win32,_}) -> true;
+sendfile_supported(_) -> false.
+
+sendfile(Config) when is_list(Config) ->
+    case sendfile_supported(os:type()) of
+	true ->
+	    ?line Data = ?config(data_dir, Config),
+	    ?line Real = filename:join(Data, "realmen.html"),
+	    Host = "localhost",
+
+	    %% TODO: find another way to test for {error, posix_error()}?
+	    %% Disabled because with driver_select I cannot test for
+	    %% invalid out_fd
+	    %% ?line {error, Error} = file:sendfile(Real, -1),
+	    %% ?line test_server:format("sendfile error = ~p", [Error]),
+	    %% %% Unix ebadf, Windows eio
+	    %% ?line true = Error =:= ebadf orelse Error =:= eio,
+
+	    ?line ok = sendfile_send(Host, Real);
+	false ->
+	    {skip, "sendfile not supported on this platform"}
+    end.
+
+%% TODO: consolidate tests and reduce code
+
+sendfile_send(Host, File) ->
+    {Size, _Md5} = FileInfo = sendfile_file_info(File),
+    spawn_link(?MODULE, sendfile_server, [self()]),
+    receive
+	{server, Port} ->
+	    ?line {ok, Sock} = gen_tcp:connect(Host, Port,
+					       [binary,{packet,0}]),
+	    ?line {ok, Size} = file:sendfile(File, Sock),
+	    ?line ok = gen_tcp:close(Sock),
+	    receive
+		{ok, Bin} ->
+		    ?line FileInfo = sendfile_bin_info(Bin),
+		    ok
+	    end
+    end.
+
+sendfile_server(ClientPid) ->
+    ?line {ok, LSock} = gen_tcp:listen(0, [binary, {packet, 0},
+					   {active, false},
+					   {reuseaddr, true}]),
+    ?line {ok, Port} = inet:port(LSock),
+    ClientPid ! {server, Port},
+    ?line {ok, Sock} = gen_tcp:accept(LSock),
+    ?line {ok, Bin} = sendfile_do_recv(Sock, []),
+    ?line ok = gen_tcp:close(Sock),
+    ClientPid ! {ok, Bin}.
+
+-define(SENDFILE_TIMEOUT, 5000).
+
+sendfile_do_recv(Sock, Bs) ->
+    case gen_tcp:recv(Sock, 0, ?SENDFILE_TIMEOUT) of
+	{ok, B} ->
+	    sendfile_do_recv(Sock, [B|Bs]);
+	{error, closed} ->
+	    {ok, lists:reverse(Bs)}
+    end.
+
+sendfile_file_info(File) ->
+    {ok, #file_info{size = Size}} = file:read_file_info(File),
+    {ok, Data} = file:read_file(File),
+    Md5 = erlang:md5(Data),
+    {Size, Md5}.
+
+sendfile_bin_info(Data) ->
+    Size = lists:foldl(fun(E,Sum) -> size(E) + Sum end, 0, Data),
+    Md5 = erlang:md5(Data),
+    {Size, Md5}.