Add Transport:sendfile/4,/5

Adds offset based sendfile to transports. Same behaviour as
file:sendfile/4,/5 except socket and file arguments are reversed and
either a raw file or a filename can be used.

sendfile/2,/4,/5 now compulsory callbacks in ranch_transport.

ranch_tcp:sendfile/2 now defaults to a chunk_size of 8191 - the default
for ranch_ssl:sendfile/2. The same default is used for both
ranch_tcp:sendfile/4,5 and ranch_ssl:sendfile/4,5.

1 files changed, 108 insertions, 0 deletions

diff --git a/src/ranch_transport.erl b/src/ranch_transport.erl
index 38dca5a..6168b35 100644
--- a/src/ranch_transport.erl
+++ b/src/ranch_transport.erl
@@ -15,8 +15,12 @@
 %% @private
 -module(ranch_transport).
 
+-export([sendfile/6]).
+
 -type socket() :: any().
 -type opts() :: any().
+-type sendfile_opts() :: [{chunk_size, non_neg_integer()}].
+-export_type([sendfile_opts/0]).
 
 %% Name of the transport.
 -callback name() -> atom().
@@ -55,6 +59,19 @@
 %% Send data on a socket.
 -callback send(socket(), iodata()) -> ok | {error, atom()}.
 
+%% Send a file on a socket.
+-callback sendfile(socket(), file:name())
+	-> {ok, non_neg_integer()} | {error, atom()}.
+
+%% Send part of a file on a socket.
+-callback sendfile(socket(), file:name() | file:fd(), non_neg_integer(),
+		non_neg_integer()) -> {ok, non_neg_integer()} | {error, atom()}.
+
+%% Send part of a file on a socket.
+-callback sendfile(socket(), file:name() | file:fd(), non_neg_integer(),
+		non_neg_integer(), sendfile_opts())
+	-> {ok, non_neg_integer()} | {error, atom()}.
+
 %% Set options on the given socket.
 -callback setopts(socket(), opts()) -> ok | {error, atom()}.
 
@@ -75,3 +92,94 @@
 
 %% Close the given socket.
 -callback close(socket()) -> ok.
+
+%% @doc Send part of a file on a socket.
+%%
+%% A fallback for transports that don't have a native sendfile implementation.
+%% Note that the ordering of arguments is different from file:sendfile/5 and
+%% that this function accepts either a raw file or a file name.
+%%
+%% @see file:sendfile/5
+-spec sendfile(module(), socket(), file:filename_all() | file:fd(),
+		non_neg_integer(), non_neg_integer(), sendfile_opts())
+	-> {ok, non_neg_integer()} | {error, atom()}.
+sendfile(Transport, Socket, Filename, Offset, Bytes, Opts)
+		when is_list(Filename) orelse is_atom(Filename)
+		orelse is_binary(Filename) ->
+	ChunkSize = chunk_size(Opts),
+	case file:open(Filename, [read, raw, binary]) of
+		{ok, RawFile} ->
+			_ = case Offset of
+				0 ->
+					ok;
+				_ ->
+					{ok, _} = file:position(RawFile, {bof, Offset})
+			end,
+			try
+				sendfile_loop(Transport, Socket, RawFile, Bytes, 0, ChunkSize)
+			after
+				ok = file:close(RawFile)
+			end;
+		{error, _Reason} = Error ->
+			Error
+	end;
+sendfile(Transport, Socket, RawFile, Offset, Bytes, Opts) ->
+	ChunkSize = chunk_size(Opts),
+	Initial2 = case file:position(RawFile, {cur, 0}) of
+		{ok, Offset} ->
+			Offset;
+		{ok, Initial} ->
+			{ok, _} = file:position(RawFile, {bof, Offset}),
+			Initial
+		end,
+	case sendfile_loop(Transport, Socket, RawFile, Bytes, 0, ChunkSize) of
+		{ok, _Sent} = Result ->
+			{ok, _} = file:position(RawFile, {bof, Initial2}),
+			Result;
+		{error, _Reason} = Error ->
+			Error
+	end.
+
+-spec chunk_size(sendfile_opts()) -> pos_integer().
+chunk_size(Opts) ->
+	case lists:keyfind(chunk_size, 1, Opts) of
+		{chunk_size, ChunkSize}
+				when is_integer(ChunkSize) andalso ChunkSize > 0 ->
+			ChunkSize;
+		{chunk_size, 0} ->
+			16#1FFF;
+		false ->
+			16#1FFF
+	end.
+
+-spec sendfile_loop(module(), socket(), file:fd(), non_neg_integer(),
+		non_neg_integer(), pos_integer())
+	-> {ok, non_neg_integer()} | {error, term()}.
+sendfile_loop(_Transport, _Socket, _RawFile, Sent, Sent, _ChunkSize)
+		when Sent =/= 0 ->
+	%% All requested data has been read and sent, return number of bytes sent.
+	{ok, Sent};
+sendfile_loop(Transport, Socket, RawFile, Bytes, Sent, ChunkSize) ->
+	ReadSize = read_size(Bytes, Sent, ChunkSize),
+	case file:read(RawFile, ReadSize) of
+		{ok, IoData} ->
+			case Transport:send(Socket, IoData) of
+				ok ->
+					Sent2 = iolist_size(IoData) + Sent,
+					sendfile_loop(Transport, Socket, RawFile, Bytes, Sent2,
+						ChunkSize);
+				{error, _Reason} = Error ->
+					Error
+			end;
+		eof ->
+			{ok, Sent};
+		{error, _Reason} = Error ->
+			Error
+	end.
+
+-spec read_size(non_neg_integer(), non_neg_integer(), non_neg_integer()) ->
+	non_neg_integer().
+read_size(0, _Sent, ChunkSize) ->
+	ChunkSize;
+read_size(Bytes, Sent, ChunkSize) ->
+	min(Bytes - Sent, ChunkSize).