aboutsummaryrefslogblamecommitdiffstats
path: root/lib/ssh/src/ssh_sftp.erl
blob: bab688f226e21209ce26f2a1f58ca0b959c63af3 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215

                   
  
                                                        
  




                                                                      
  



                                                                         
  


















                                                                             

                                                                            










                                                                          
                        
                                                                                                            








                                                                                    

                                    









                  











                                                                                           
















                                                                      
                                                 


                                                  
                                                                         







                                                                      
                                                                









                                   

                                                               
                                                          

                                                                
                                                                                    







                                                                      
                                                                







                                   


                                                     











                                                
                                              
               
                










                                                        

                                               


































































                                                                                                     

 
































































































































































































                                                                             
                                                                             






































                                                                          

                                                              







                                                                    

                                         
                  
                                                                        
                
                                     













                                                                      
                                                                            


                                                                     

                                                                          









                                                                             





                                      








                                                                    







































































                                                                               
                                                                                           



















                                                                           
                                                                                   









                                                              
                                 











                                                                
                                 








































































































































                                                                              


                                                                                 












































                                                                       








                                                         













                                                                               





                                              





















































































































































































































































































































































                                                                                             
 










































































































































































































                                                                                                              




                                                 
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2005-2014. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%

%%

%%% Description: SFTP protocol front-end

-module(ssh_sftp).

-behaviour(ssh_channel).

-include_lib("kernel/include/file.hrl").
-include("ssh.hrl").
-include("ssh_xfer.hrl").

%% API

-export([start_channel/1, start_channel/2, start_channel/3, stop_channel/1]).

-export([open/3, open_tar/3, opendir/2, close/2, readdir/2, pread/4, read/3,
         open/4, open_tar/4, opendir/3, close/3, readdir/3, pread/5, read/4,
	 apread/4, aread/3, pwrite/4, write/3, apwrite/4, awrite/3,
	 pwrite/5, write/4, 
	 position/3, real_path/2, read_file_info/2, get_file_info/2,
	 position/4, real_path/3, read_file_info/3, get_file_info/3,
	 write_file_info/3, read_link_info/2, read_link/2, make_symlink/3,
	 write_file_info/4, read_link_info/3, read_link/3, make_symlink/4,
	 rename/3, delete/2, make_dir/2, del_dir/2, send_window/1,
	 rename/4, delete/3, make_dir/3, del_dir/3, send_window/2,
	 recv_window/1, list_dir/2, read_file/2, write_file/3,
	 recv_window/2, list_dir/3, read_file/3, write_file/4]).

%% ssh_channel callbacks
-export([init/1, handle_call/3, handle_cast/2, code_change/3, handle_msg/2, handle_ssh_msg/2, terminate/2]).
%% TODO: Should be placed elsewhere ssh_sftpd should not call functions in ssh_sftp!
-export([info_to_attr/1, attr_to_info/1]).

-record(state, 
	{
	  xf,
	  rep_buf = <<>>,
	  req_id,
	  req_list = [],  %% {ReqId, Fun}
	  inf,   %% list of fileinf,
	  opts
	 }).

-record(fileinf,
	{
	  handle, 
	  offset,
	  size,
	  mode
	 }).

-record(bufinf,
	{
	  mode,			 % read | write  (=from or to buffer by user)
	  crypto_state,
	  crypto_fun,            % For encode or decode depending on the mode field
	  size = 0,		 % # bytes "before" the current buffer for the postion call

	  chunksize,		 % The size of the chunks to be sent or received
	  enc_text_buf = <<>>,	 % Encrypted text
	  plain_text_buf = <<>>	 % Decrypted text
	}).
	  
-define(FILEOP_TIMEOUT, infinity).

-define(NEXT_REQID(S),
	S#state { req_id = (S#state.req_id + 1) band 16#ffffffff}).

-define(XF(S), S#state.xf).
-define(REQID(S), S#state.req_id).

%%====================================================================
%% API
%%====================================================================
start_channel(Cm) when is_pid(Cm) ->
    start_channel(Cm, []);
start_channel(Host) when is_list(Host) ->
    start_channel(Host, []).					 
start_channel(Cm, Opts) when is_pid(Cm) ->
    Timeout = proplists:get_value(timeout, Opts, infinity),
    {_, SftpOpts} = handle_options(Opts, [], []),
    case ssh_xfer:attach(Cm, []) of
	{ok, ChannelId, Cm} -> 
	    case ssh_channel:start(Cm, ChannelId, 
				   ?MODULE, [Cm, ChannelId, SftpOpts]) of
		{ok, Pid} ->
		    case wait_for_version_negotiation(Pid, Timeout) of
			ok ->
			    {ok, Pid}; 
			TimeOut ->
			    TimeOut
		    end;
		{error, Reason} ->
		    {error, format_channel_start_error(Reason)};
		ignore ->
		    {error, ignore}
	    end;
	Error ->
	    Error
    end;

start_channel(Host, Opts) ->
    start_channel(Host, 22, Opts).
start_channel(Host, Port, Opts) ->
    {SshOpts, SftpOpts} = handle_options(Opts, [], []),
    Timeout = proplists:get_value(timeout, SftpOpts, infinity),
    case ssh_xfer:connect(Host, Port, SshOpts, Timeout) of
	{ok, ChannelId, Cm} ->
	    case ssh_channel:start(Cm, ChannelId, ?MODULE, [Cm, 
							    ChannelId, SftpOpts]) of
		{ok, Pid} ->
		    case wait_for_version_negotiation(Pid, Timeout) of
			ok ->
			    {ok, Pid, Cm};
			TimeOut ->
			    TimeOut
		    end;
		{error, Reason} ->
		    {error, format_channel_start_error(Reason)};
		ignore ->
		    {error, ignore}
	    end;
	Error ->
	    Error	    
    end.

stop_channel(Pid) ->
    case is_process_alive(Pid) of
	true ->
	    OldValue = process_flag(trap_exit, true),
	    link(Pid),
	    exit(Pid, ssh_sftp_stop_channel),
	    receive 
		{'EXIT', Pid, normal} ->
		    ok
	    after 5000 ->
		    exit(Pid, kill),
		    receive 
			{'EXIT', Pid, killed} ->
			    ok
		    end
	    end,
	    process_flag(trap_exit, OldValue),
	    ok;
	false ->
	    ok
    end.

wait_for_version_negotiation(Pid, Timeout) ->
    call(Pid, wait_for_version_negotiation, Timeout).

open(Pid, File, Mode) ->
    open(Pid, File, Mode, ?FILEOP_TIMEOUT).
open(Pid, File, Mode, FileOpTimeout) ->
    call(Pid, {open, false, File, Mode}, FileOpTimeout).

open_tar(Pid, File, Mode) ->
    open_tar(Pid, File, Mode, ?FILEOP_TIMEOUT).
open_tar(Pid, File, Mode, FileOpTimeout) ->
    case {lists:member(write,Mode),
	  lists:member(read,Mode),
	  Mode -- [read,write]} of
	{true,false,[]} ->
	    {ok,Handle} = open(Pid, File, [write], FileOpTimeout),
	    erl_tar:init(Pid, write,
			 fun(write, {_,Data}) ->
				 write_to_remote_tar(Pid, Handle, to_bin(Data), FileOpTimeout);
			    (position, {_,Pos}) -> 
				 position(Pid, Handle, Pos, FileOpTimeout);
			    (close, _) -> 
				 close(Pid, Handle, FileOpTimeout)
			 end);
	{true,false,[{crypto,{CryptoInitFun,CryptoEncryptFun,CryptoEndFun}}]} ->
	    {ok,SftpHandle} = open(Pid, File, [write], FileOpTimeout),
	    BI = #bufinf{mode = write,
			 crypto_fun = CryptoEncryptFun},
	    {ok,BufHandle} = open_buf(Pid, CryptoInitFun, BI, FileOpTimeout),
	    erl_tar:init(Pid, write,
			 fun(write, {_,Data}) ->
				 write_buf(Pid, SftpHandle, BufHandle,  to_bin(Data), FileOpTimeout);
			    (position, {_,Pos}) ->
				 position_buf(Pid, SftpHandle, BufHandle, Pos, FileOpTimeout);
			    (close, _) ->
				 {ok,#bufinf{
					plain_text_buf = PlainBuf0,
					enc_text_buf = EncBuf0,
					crypto_state = CState0
				       }}  = call(Pid, {get_bufinf,BufHandle}, FileOpTimeout),
				 {ok,EncTextTail} = CryptoEndFun(PlainBuf0, CState0),
				 EncTextBuf = <<EncBuf0/binary, EncTextTail/binary>>,
				 case write(Pid, SftpHandle, EncTextBuf, FileOpTimeout) of
				     ok ->
					 call(Pid, {erase_bufinf,BufHandle}, FileOpTimeout),
					 close(Pid, SftpHandle, FileOpTimeout);
				     Other ->
					 Other
				 end
			 end);
	{false,true,[]} ->
	    {ok,Handle} = open(Pid, File, [read,binary], FileOpTimeout),
	    erl_tar:init(Pid, read,
			 fun(read2, {_,Len}) ->
				 read_repeat(Pid, Handle, Len, FileOpTimeout);
			    (position, {_,Pos}) -> 
				 position(Pid, Handle, Pos, FileOpTimeout);
			    (close, _) -> 
				 close(Pid, Handle, FileOpTimeout)
			 end);
	{false,true,[{crypto,{CryptoInitFun,CryptoDecryptFun}}]} ->
	    {ok,SftpHandle} = open(Pid, File, [read,binary], FileOpTimeout),
	    BI = #bufinf{mode = read,
			 crypto_fun = CryptoDecryptFun},
	    {ok,BufHandle} = open_buf(Pid, CryptoInitFun, BI, FileOpTimeout),
	    erl_tar:init(Pid, read,
			 fun(read2, {_,Len}) ->
				 read_buf(Pid, SftpHandle, BufHandle, Len, FileOpTimeout);
			    (position, {_,Pos}) -> 
				 position_buf(Pid, SftpHandle, BufHandle, Pos, FileOpTimeout);
			    (close, _) -> 
				 call(Pid, {erase_bufinf,BufHandle}, FileOpTimeout),
				 close(Pid, SftpHandle, FileOpTimeout)
                         end);
	_ ->
	    {error,{illegal_mode,Mode}}
    end.


opendir(Pid, Path) ->
    opendir(Pid, Path, ?FILEOP_TIMEOUT).
opendir(Pid, Path, FileOpTimeout) ->
    call(Pid, {opendir, false, Path}, FileOpTimeout).

close(Pid, Handle) ->
    close(Pid, Handle, ?FILEOP_TIMEOUT).
close(Pid, Handle, FileOpTimeout) ->
    call(Pid, {close,false,Handle}, FileOpTimeout).

readdir(Pid,Handle) ->
    readdir(Pid,Handle, ?FILEOP_TIMEOUT).
readdir(Pid,Handle, FileOpTimeout) ->
    call(Pid, {readdir,false,Handle}, FileOpTimeout).

pread(Pid, Handle, Offset, Len) ->
    pread(Pid, Handle, Offset, Len, ?FILEOP_TIMEOUT).
pread(Pid, Handle, Offset, Len, FileOpTimeout) ->
    call(Pid, {pread,false,Handle, Offset, Len}, FileOpTimeout).

read(Pid, Handle, Len) ->
    read(Pid, Handle, Len, ?FILEOP_TIMEOUT).
read(Pid, Handle, Len, FileOpTimeout) ->
    call(Pid, {read,false,Handle, Len}, FileOpTimeout).    

%% TODO this ought to be a cast! Is so in all practial meaning
%% even if it is obscure!
apread(Pid, Handle, Offset, Len) ->
    call(Pid, {pread,true,Handle, Offset, Len}, infinity).

%% TODO this ought to be a cast! 
aread(Pid, Handle, Len) ->
    call(Pid, {read,true,Handle, Len}, infinity).    

pwrite(Pid, Handle, Offset, Data) ->
    pwrite(Pid, Handle, Offset, Data, ?FILEOP_TIMEOUT).
pwrite(Pid, Handle, Offset, Data, FileOpTimeout) ->
    call(Pid, {pwrite,false,Handle,Offset,Data}, FileOpTimeout).

write(Pid, Handle, Data) ->
    write(Pid, Handle, Data, ?FILEOP_TIMEOUT).
write(Pid, Handle, Data, FileOpTimeout) ->
    call(Pid, {write,false,Handle,Data}, FileOpTimeout).

%% TODO this ought to be a cast! Is so in all practial meaning
%% even if it is obscure!
apwrite(Pid, Handle, Offset, Data) ->
    call(Pid, {pwrite,true,Handle,Offset,Data}, infinity).

%% TODO this ought to be a cast!  Is so in all practial meaning
%% even if it is obscure!
awrite(Pid, Handle, Data) ->
    call(Pid, {write,true,Handle,Data}, infinity).

position(Pid, Handle, Pos) ->
    position(Pid, Handle, Pos, ?FILEOP_TIMEOUT).
position(Pid, Handle, Pos, FileOpTimeout) ->
    call(Pid, {position, Handle, Pos}, FileOpTimeout).

real_path(Pid, Path) ->
    real_path(Pid, Path, ?FILEOP_TIMEOUT).
real_path(Pid, Path, FileOpTimeout) ->
    call(Pid, {real_path, false, Path}, FileOpTimeout).

read_file_info(Pid, Name) ->
    read_file_info(Pid, Name, ?FILEOP_TIMEOUT).
read_file_info(Pid, Name, FileOpTimeout) ->
    call(Pid, {read_file_info,false,Name}, FileOpTimeout).

get_file_info(Pid, Handle) ->
    get_file_info(Pid, Handle, ?FILEOP_TIMEOUT).
get_file_info(Pid, Handle, FileOpTimeout) ->
    call(Pid, {get_file_info,false,Handle}, FileOpTimeout).

write_file_info(Pid, Name, Info) ->
    write_file_info(Pid, Name, Info, ?FILEOP_TIMEOUT).
write_file_info(Pid, Name, Info, FileOpTimeout) ->
    call(Pid, {write_file_info,false,Name, Info}, FileOpTimeout).

read_link_info(Pid, Name) ->
    read_link_info(Pid, Name, ?FILEOP_TIMEOUT).
read_link_info(Pid, Name, FileOpTimeout) ->
    call(Pid, {read_link_info,false,Name}, FileOpTimeout).

read_link(Pid, LinkName) ->
    read_link(Pid, LinkName, ?FILEOP_TIMEOUT).
read_link(Pid, LinkName, FileOpTimeout) ->
    case call(Pid, {read_link,false,LinkName}, FileOpTimeout) of
	 {ok, [{Name, _Attrs}]} ->
	    {ok, Name};
	ErrMsg ->
	    ErrMsg
    end.

make_symlink(Pid, Name, Target) ->
    make_symlink(Pid, Name, Target, ?FILEOP_TIMEOUT).
make_symlink(Pid, Name, Target, FileOpTimeout) ->
    call(Pid, {make_symlink,false, Name, Target}, FileOpTimeout).
 
rename(Pid, FromFile, ToFile) ->
    rename(Pid, FromFile, ToFile, ?FILEOP_TIMEOUT).
rename(Pid, FromFile, ToFile, FileOpTimeout) ->
    call(Pid, {rename,false,FromFile, ToFile}, FileOpTimeout).

delete(Pid, Name) ->
    delete(Pid, Name, ?FILEOP_TIMEOUT).
delete(Pid, Name, FileOpTimeout) ->
    call(Pid, {delete,false,Name}, FileOpTimeout).

make_dir(Pid, Name) ->
    make_dir(Pid, Name, ?FILEOP_TIMEOUT).
make_dir(Pid, Name, FileOpTimeout) ->
    call(Pid, {make_dir,false,Name}, FileOpTimeout).

del_dir(Pid, Name) ->
    del_dir(Pid, Name, ?FILEOP_TIMEOUT).
del_dir(Pid, Name, FileOpTimeout) ->
    call(Pid, {del_dir,false,Name}, FileOpTimeout).

%% TODO : send_window and recv_window  - Really needed? Not documented!
%% internal use maybe should be handled in other way!
send_window(Pid) ->
    send_window(Pid, ?FILEOP_TIMEOUT).
send_window(Pid, FileOpTimeout) ->
    call(Pid, send_window, FileOpTimeout).

recv_window(Pid) ->
    recv_window(Pid, ?FILEOP_TIMEOUT).
recv_window(Pid, FileOpTimeout) ->
    call(Pid, recv_window, FileOpTimeout).


list_dir(Pid, Name) ->
    list_dir(Pid, Name, ?FILEOP_TIMEOUT).

list_dir(Pid, Name, FileOpTimeout) ->
    case opendir(Pid, Name, FileOpTimeout) of
	{ok,Handle} ->
	    Res = do_list_dir(Pid, Handle, FileOpTimeout, []),
	    close(Pid, Handle, FileOpTimeout),
	    case Res of
		{ok, List} ->
		    NList = lists:foldl(fun({Nm, _Info},Acc) -> 
					  [Nm|Acc] end, 
				  [], List),
		    {ok,NList};
		Error -> Error
	    end;
	Error ->
	    Error
    end.

do_list_dir(Pid, Handle, FileOpTimeout, Acc) ->
    case readdir(Pid, Handle, FileOpTimeout) of
	{ok, []} ->
	    {ok, Acc};
	{ok, Names} ->
	    do_list_dir(Pid, Handle, FileOpTimeout, Acc ++ Names);
	eof ->
	    {ok, Acc};
	Error ->
	    Error
    end.


read_file(Pid, Name) ->
    read_file(Pid, Name, ?FILEOP_TIMEOUT).

read_file(Pid, Name, FileOpTimeout) ->
    case open(Pid, Name, [read, binary], FileOpTimeout) of
	{ok, Handle} ->
	    {ok,{_WindowSz,PacketSz}} = recv_window(Pid, FileOpTimeout),
	    Res = read_file_loop(Pid, Handle, PacketSz, FileOpTimeout, []),
	    close(Pid, Handle),
	    Res;
	Error ->
	    Error
    end.

read_file_loop(Pid, Handle, PacketSz, FileOpTimeout, Acc) ->
    case read(Pid, Handle, PacketSz, FileOpTimeout) of
	{ok, Data}  ->
	    read_file_loop(Pid, Handle, PacketSz, FileOpTimeout, [Data|Acc]);
	eof ->
	    {ok, list_to_binary(lists:reverse(Acc))};
	Error ->
	    Error
    end.

write_file(Pid, Name, List) ->
    write_file(Pid, Name, List, ?FILEOP_TIMEOUT).

write_file(Pid, Name, List, FileOpTimeout) when is_list(List) ->
    write_file(Pid, Name, unicode:characters_to_binary(List), FileOpTimeout);
write_file(Pid, Name, Bin, FileOpTimeout) ->
    case open(Pid, Name, [write, binary], FileOpTimeout) of
	{ok, Handle} ->
	    {ok,{_Window,Packet}} = send_window(Pid, FileOpTimeout),
	    Res = write_file_loop(Pid, Handle, 0, Bin, size(Bin), Packet,
				  FileOpTimeout),
	    close(Pid, Handle, FileOpTimeout),
	    Res;
	Error ->
	    Error
    end.

write_file_loop(_Pid, _Handle, _Pos, _Bin, 0, _PacketSz,_FileOpTimeout) ->
    ok;
write_file_loop(Pid, Handle, Pos, Bin, Remain, PacketSz, FileOpTimeout) ->
    if Remain >= PacketSz ->
	    <<_:Pos/binary, Data:PacketSz/binary, _/binary>> = Bin,
	    case write(Pid, Handle, Data, FileOpTimeout) of
		ok ->
		    write_file_loop(Pid, Handle, 
				    Pos+PacketSz, Bin, Remain-PacketSz,
				    PacketSz, FileOpTimeout);
		Error ->
		    Error
	    end;
       true ->
	    <<_:Pos/binary, Data/binary>> = Bin,
	    write(Pid, Handle, Data, FileOpTimeout)
    end.

%%====================================================================
%% SSh channel callbacks 
%%====================================================================

%%--------------------------------------------------------------------
%% Function: init(Args) -> {ok, State} 
%%                        
%% Description: 
%%--------------------------------------------------------------------
init([Cm, ChannelId, Options]) ->
    Timeout = proplists:get_value(timeout, Options, infinity),
    erlang:monitor(process, Cm),
    case ssh_connection:subsystem(Cm, ChannelId, "sftp", Timeout) of
	success ->
	    Xf = #ssh_xfer{cm = Cm,
			       channel = ChannelId},
	    {ok, #state{xf = Xf,
			req_id = 0, 
			rep_buf = <<>>,
			inf = new_inf(),
			opts = Options}};
	failure ->
	    {stop, {shutdown, "server failed to start sftp subsystem"}};
	Error ->
	    {stop, {shutdown, Error}}
    end.
    
%%--------------------------------------------------------------------
%% Function: handle_call/3
%% Description: Handling call messages
%% Returns: {reply, Reply, State}          |
%%          {reply, Reply, State, Timeout} |
%%          {noreply, State}               |
%%          {noreply, State, Timeout}      |
%%          {stop, Reason, Reply, State}   | (terminate/2 is called)
%%          {stop, Reason, State}            (terminate/2 is called)
%%--------------------------------------------------------------------
handle_call({{timeout, infinity}, wait_for_version_negotiation}, From,
	    #state{xf = #ssh_xfer{vsn = undefined} = Xf} = State) ->
    {noreply, State#state{xf = Xf#ssh_xfer{vsn = {wait, From, undefined}}}};

handle_call({{timeout, Timeout}, wait_for_version_negotiation}, From,
	    #state{xf = #ssh_xfer{vsn = undefined} = Xf} = State) ->
    TRef = erlang:send_after(Timeout, self(), {timeout, undefined, From}),
    {noreply, State#state{xf = Xf#ssh_xfer{vsn = {wait, From, TRef}}}};

handle_call({_, wait_for_version_negotiation}, _, State) ->
    {reply, ok, State};
	    
handle_call({{timeout, infinity}, Msg}, From, State) ->
    do_handle_call(Msg, From, State);
handle_call({{timeout, Timeout}, Msg}, From,  #state{req_id = Id} = State) ->
    timer:send_after(Timeout, {timeout, Id, From}),
    do_handle_call(Msg, From, State).

handle_cast(_,State) ->
    {noreply, State}.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

do_handle_call({get_bufinf,BufHandle}, _From, S=#state{inf=I0}) ->
    {reply, dict:find(BufHandle,I0), S};

do_handle_call({put_bufinf,BufHandle,B}, _From, S=#state{inf=I0}) ->
    {reply, ok, S#state{inf=dict:store(BufHandle,B,I0)}};

do_handle_call({erase_bufinf,BufHandle}, _From, S=#state{inf=I0}) ->
    {reply, ok, S#state{inf=dict:erase(BufHandle,I0)}};

do_handle_call({open, Async,FileName,Mode}, From, #state{xf = XF} = State) ->
    {Access,Flags,Attrs} = open_mode(XF#ssh_xfer.vsn, Mode),
    ReqID = State#state.req_id,
    ssh_xfer:open(XF, ReqID, FileName, Access, Flags, Attrs),
    case Async of
	true ->
	    {reply, {async,ReqID},
	     update_request_info(ReqID, State,
		      fun({ok,Handle},State1) ->
			      open2(ReqID,FileName,Handle,Mode,Async,
				    From,State1);
			 (Rep,State1) ->
			      async_reply(ReqID, Rep, From, State1)
		      end)};
	false ->
	    {noreply,
	     update_request_info(ReqID, State,
		      fun({ok,Handle},State1) ->
			      open2(ReqID,FileName,Handle,Mode,Async,
				    From,State1);
			 (Rep,State1) ->
			      sync_reply(Rep, From, State1)
		      end)}
    end;

do_handle_call({opendir,Async,Path}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:opendir(?XF(State), ReqID, Path),
    make_reply(ReqID, Async, From, State);

do_handle_call({readdir,Async,Handle}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:readdir(?XF(State), ReqID, Handle),
    make_reply(ReqID, Async, From, State);

do_handle_call({close,_Async,Handle}, From, State) ->
    %% wait until all operations on handle are done
    case get_size(Handle, State) of
	undefined ->
	    ReqID = State#state.req_id,
	    ssh_xfer:close(?XF(State), ReqID, Handle),
	    make_reply_post(ReqID, false, From, State,
			    fun(Rep, State1) ->
				    {Rep, erase_handle(Handle, State1)}
			    end);
	_ ->
	    case lseek_position(Handle, cur, State) of
		{ok,_} ->
		    ReqID = State#state.req_id,
		    ssh_xfer:close(?XF(State), ReqID, Handle),
		    make_reply_post(ReqID, false, From, State,
				    fun(Rep, State1) ->
					    {Rep, erase_handle(Handle, State1)}
				    end);
		Error ->
		    {reply, Error, State}
	    end
    end;

do_handle_call({pread,Async,Handle,At,Length}, From, State) ->
    case lseek_position(Handle, At, State) of
	{ok,Offset} ->
	    ReqID = State#state.req_id,
	    ssh_xfer:read(?XF(State),ReqID,Handle,Offset,Length),
	    %% To get multiple async read to work we must update the offset
	    %% before the operation begins
	    State1 = update_offset(Handle, Offset+Length, State),
	    make_reply_post(ReqID,Async,From,State1,
			    fun({ok,Data}, State2) ->
				    case get_mode(Handle, State2) of
					binary -> {{ok,Data}, State2};
					text ->
					    {{ok,unicode:characters_to_list(Data)}, State2}
				    end;
			       (Rep, State2) -> 
				    {Rep, State2}
			    end);
	Error ->
	    {reply, Error, State}
    end;

do_handle_call({read,Async,Handle,Length}, From, State) ->
    case lseek_position(Handle, cur, State) of
	{ok,Offset} ->
	    ReqID = State#state.req_id,
	    ssh_xfer:read(?XF(State),ReqID,Handle,Offset,Length),
	    %% To get multiple async read to work we must update the offset
	    %% before the operation begins
	    State1 = update_offset(Handle, Offset+Length, State),
	    make_reply_post(ReqID,Async,From,State1,
			    fun({ok,Data}, State2) ->
				    case get_mode(Handle, State2) of
					binary -> {{ok,Data}, State2};
					text -> {{ok,binary_to_list(Data)}, State2}
				    end;
			       (Rep, State2) -> {Rep, State2}
			    end);
	Error ->
	    {reply, Error, State}
    end;

do_handle_call({pwrite,Async,Handle,At,Data0}, From, State) ->
    case lseek_position(Handle, At, State) of
	{ok,Offset} ->
	    Data = to_bin(Data0),
	    ReqID = State#state.req_id,
	    Size = size(Data),
	    ssh_xfer:write(?XF(State),ReqID,Handle,Offset,Data),
	    State1 = update_size(Handle, Offset+Size, State),
	    make_reply(ReqID, Async, From, State1);
	Error ->
	    {reply, Error, State}
    end;

do_handle_call({write,Async,Handle,Data0}, From, State) ->
    case lseek_position(Handle, cur, State) of
	{ok,Offset} ->
	    Data = to_bin(Data0),
	    ReqID = State#state.req_id,
	    Size = size(Data),
	    ssh_xfer:write(?XF(State),ReqID,Handle,Offset,Data),
	    State1 = update_offset(Handle, Offset+Size, State),
	    make_reply(ReqID, Async, From, State1);
	Error ->
	    {reply, Error, State}
    end;

do_handle_call({position,Handle,At}, _From, State) ->
    %% We could make this auto sync when all request to Handle is done?
    case lseek_position(Handle, At, State) of
	{ok,Offset} ->
	    {reply, {ok, Offset}, update_offset(Handle, Offset, State)};
	Error ->
	    {reply, Error, State}
    end;

do_handle_call({rename,Async,FromFile,ToFile}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:rename(?XF(State),ReqID,FromFile,ToFile,[overwrite]),
    make_reply(ReqID, Async, From, State);

do_handle_call({delete,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:remove(?XF(State), ReqID, Name),
    make_reply(ReqID, Async, From, State);

do_handle_call({make_dir,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:mkdir(?XF(State), ReqID, Name,
		   #ssh_xfer_attr{ type = directory }),
    make_reply(ReqID, Async, From, State);

do_handle_call({del_dir,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:rmdir(?XF(State), ReqID, Name),
    make_reply(ReqID, Async, From, State);

do_handle_call({real_path,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:realpath(?XF(State), ReqID, Name),
    make_reply(ReqID, Async, From, State);

do_handle_call({read_file_info,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:stat(?XF(State), ReqID, Name, all),
    make_reply(ReqID, Async, From, State);

do_handle_call({get_file_info,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:fstat(?XF(State), ReqID, Name, all),
    make_reply(ReqID, Async, From, State);

do_handle_call({read_link_info,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:lstat(?XF(State), ReqID, Name, all),
    make_reply(ReqID, Async, From, State);

do_handle_call({read_link,Async,Name}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:readlink(?XF(State), ReqID, Name),
    make_reply(ReqID, Async, From, State);

do_handle_call({make_symlink, Async, Path, TargetPath}, From, State) ->
    ReqID = State#state.req_id,
    ssh_xfer:symlink(?XF(State), ReqID, Path, TargetPath),
    make_reply(ReqID, Async, From, State);

do_handle_call({write_file_info,Async,Name,Info}, From, State) ->
    ReqID = State#state.req_id,
    A = info_to_attr(Info),
    ssh_xfer:setstat(?XF(State), ReqID, Name, A),
    make_reply(ReqID, Async, From, State);

%% TODO: Do we really want this format? Function send_window
%% is not documented and seems to be used only inernaly! 
%% It is backwards compatible for now.
do_handle_call(send_window, _From, State) ->
    XF = State#state.xf,
     [{send_window,{{win_size, Size0},{packet_size, Size1}}}] =
	ssh:channel_info(XF#ssh_xfer.cm,  XF#ssh_xfer.channel, [send_window]),
    {reply, {ok, {Size0, Size1}}, State};

%% TODO: Do we really want this format? Function recv_window
%% is not documented and seems to be used only inernaly! 
%% It is backwards compatible for now.
do_handle_call(recv_window, _From, State) ->
    XF = State#state.xf,
    [{recv_window,{{win_size, Size0},{packet_size, Size1}}}] =
	ssh:channel_info(XF#ssh_xfer.cm,  XF#ssh_xfer.channel, [recv_window]),
    {reply, {ok, {Size0, Size1}}, State};

%% Backwards compatible
do_handle_call(stop, _From, State) ->
    {stop, shutdown, ok, State};

do_handle_call(Call, _From, State) ->    
    {reply, {error, bad_call, Call, State}, State}.

%%--------------------------------------------------------------------
%% Function: handle_ssh_msg(Args) -> {ok, State} | {stop, ChannelId, State}
%%                        
%% Description: Handles channel messages
%%--------------------------------------------------------------------
handle_ssh_msg({ssh_cm, _ConnectionManager, 
		{data, _ChannelId, 0, Data}}, #state{rep_buf = Data0} = 
	       State0) ->
    State = handle_reply(State0, <<Data0/binary,Data/binary>>),
    {ok, State};

handle_ssh_msg({ssh_cm, _ConnectionManager, 
		{data, _ChannelId, 1, Data}}, State) ->
    error_logger:format("ssh: STDERR: ~s\n", [binary_to_list(Data)]),
    {ok, State};

handle_ssh_msg({ssh_cm, _ConnectionManager, {eof, _ChannelId}}, State) ->
    {ok, State};

handle_ssh_msg({ssh_cm, _, {signal, _, _}}, State) ->
    %% Ignore signals according to RFC 4254 section 6.9.
    {ok, State};

handle_ssh_msg({ssh_cm, _, {exit_signal, ChannelId, _, Error, _}}, 
	       State0) ->
    State = reply_all(State0, {error, Error}),
    {stop, ChannelId,  State};

handle_ssh_msg({ssh_cm, _, {exit_status, ChannelId, Status}}, State0) ->
    State = reply_all(State0, {error, {exit_status, Status}}),
    {stop, ChannelId, State}.

%%--------------------------------------------------------------------
%% Function: handle_msg(Args) -> {ok, State} | {stop, ChannelId, State}
%%                        
%% Description: Handles channel messages
%%--------------------------------------------------------------------
handle_msg({ssh_channel_up, _, _}, #state{opts = Options, xf = Xf} = State) ->
    Version = proplists:get_value(sftp_vsn, Options, ?SSH_SFTP_PROTOCOL_VERSION),
    ssh_xfer:protocol_version_request(Xf, Version),
    {ok, State};

%% Version negotiation timed out
handle_msg({timeout, undefined, From}, 
	   #state{xf = #ssh_xfer{channel = ChannelId}} = State) ->
    ssh_channel:reply(From, {error, timeout}),
    {stop, ChannelId, State};

handle_msg({timeout, Id, From}, #state{req_list = ReqList0} = State) ->
    case lists:keysearch(Id, 1, ReqList0) of
	false ->
	    {ok, State};
	_ ->
	    ReqList = lists:keydelete(Id, 1, ReqList0),
	    ssh_channel:reply(From, {error, timeout}),
	    {ok, State#state{req_list = ReqList}}
    end;

%% Connection manager goes down
handle_msg({'DOWN', _Ref, _Type, _Process, _},  
	   #state{xf = #ssh_xfer{channel = ChannelId}} = State) ->
    {stop, ChannelId, State};
 
%% Stopped by user
handle_msg({'EXIT', _, ssh_sftp_stop_channel}, 
	   #state{xf = #ssh_xfer{channel = ChannelId}} = State) ->
    {stop, ChannelId, State};

handle_msg(_, State) ->
    {ok, State}.
%%--------------------------------------------------------------------
%% Function: terminate(Reason, State) -> void()
%% Description: Called when the channel process is terminated
%%--------------------------------------------------------------------
%% Backwards compatible
terminate(shutdown, #state{xf = #ssh_xfer{cm = Cm}} = State) ->
    reply_all(State, {error, closed}),
    ssh:close(Cm);

terminate(_Reason, State) ->
    reply_all(State, {error, closed}).

%%====================================================================
%% Internal functions
%%====================================================================
handle_options([], Sftp, Ssh) ->
    {Ssh, Sftp};
handle_options([{timeout, _} = Opt | Rest], Sftp, Ssh) ->
    handle_options(Rest, [Opt | Sftp], Ssh);
handle_options([{sftp_vsn, _} = Opt| Rest], Sftp, Ssh) ->
    handle_options(Rest, [Opt | Sftp], Ssh);
handle_options([Opt | Rest], Sftp, Ssh) ->
    handle_options(Rest, Sftp, [Opt | Ssh]).

call(Pid, Msg, TimeOut) ->
    ssh_channel:call(Pid, {{timeout, TimeOut}, Msg}, infinity).

handle_reply(State, <<?UINT32(Len),Reply:Len/binary,Rest/binary>>) ->
    do_handle_reply(State, Reply, Rest);
handle_reply(State, Data) -> 
     State#state{rep_buf = Data}.

do_handle_reply(#state{xf = Xf} = State, 
		<<?SSH_FXP_VERSION, ?UINT32(Version), BinExt/binary>>, Rest) ->
    Ext = ssh_xfer:decode_ext(BinExt),
    case Xf#ssh_xfer.vsn of
	undefined ->
	    ok;
	{wait, From, TRef} ->
	    if is_reference(TRef) ->
		    erlang:cancel_timer(TRef);
	       true ->
		    ok
	    end,
	    ssh_channel:reply(From, ok)
    end,    
    State#state{xf = Xf#ssh_xfer{vsn = Version, ext = Ext}, rep_buf = Rest};

do_handle_reply(State0, Data, Rest) ->
    case catch ssh_xfer:xf_reply(?XF(State0), Data) of
	{'EXIT', _Reason} ->
	    handle_reply(State0, Rest);
	XfReply ->
	    State = handle_req_reply(State0, XfReply),
	    handle_reply(State, Rest)
    end.

handle_req_reply(State0, {_, ReqID, _} = XfReply) ->
    case lists:keysearch(ReqID, 1, State0#state.req_list) of
	false ->
	    State0;
	{value,{_,Fun}} ->
	    List = lists:keydelete(ReqID, 1, State0#state.req_list),
	    State1 = State0#state { req_list = List },
	    case catch Fun(xreply(XfReply),State1) of
		{'EXIT', _} -> 
		    State1;
		State -> 
		    State
	    end
    end.

xreply({handle,_,H}) -> {ok, H};
xreply({data,_,Data}) -> {ok, Data};
xreply({name,_,Names}) -> {ok, Names};
xreply({attrs, _, A}) -> {ok, attr_to_info(A)};
xreply({extended_reply,_,X}) -> {ok, X};
xreply({status,_,{ok, _Err, _Lang, _Rep}}) -> ok;
xreply({status,_,{eof, _Err, _Lang, _Rep}}) -> eof;
xreply({status,_,{Stat, _Err, _Lang, _Rep}}) -> {error, Stat};
xreply({Code, _, Reply}) -> {Code, Reply}.

update_request_info(ReqID, State, Fun) ->
    List = [{ReqID,Fun} | State#state.req_list],
    ID = (State#state.req_id + 1) band 16#ffffffff,
    State#state { req_list = List, req_id = ID }.

async_reply(ReqID, Reply, _From={To,_}, State) ->
    To ! {async_reply, ReqID, Reply},
    State.

sync_reply(Reply, From, State) ->
    catch (ssh_channel:reply(From, Reply)),
    State.

open2(OrigReqID,FileName,Handle,Mode,Async,From,State) ->
    I0 = State#state.inf,
    FileMode = case lists:member(binary, Mode) orelse lists:member(raw, Mode) of
		   true -> binary;
		   false -> text
	       end,
    I1 = add_new_handle(Handle, FileMode, I0),
    State0 = State#state{inf = I1},
    ReqID = State0#state.req_id,
    ssh_xfer:stat(State0#state.xf, ReqID, FileName, [size]),
    case Async of
	true ->
	    update_request_info(ReqID, State0,
				fun({ok,FI},State1) ->
					Size = FI#file_info.size,
					State2 = if is_integer(Size) ->
							 put_size(Handle, Size, State1);
						    true ->
							 State1
						 end,
					async_reply(OrigReqID, {ok,Handle}, From, State2);
				   (_, State1) ->
					async_reply(OrigReqID, {ok,Handle}, From, State1)
				end);
	false ->
	    update_request_info(ReqID, State0,
				fun({ok,FI},State1) ->
					Size = FI#file_info.size,
					State2 = if is_integer(Size) ->
							 put_size(Handle, Size, State1);
						    true ->
							 State1
						 end,
					sync_reply({ok,Handle}, From, State2);
				   (_, State1) ->
					sync_reply({ok,Handle}, From, State1)
				end)
    end.

reply_all(State, Reply) ->
    List = State#state.req_list,
    lists:foreach(fun({_ReqID,Fun}) ->
		    catch Fun(Reply,State)
	    end, List),
    State#state {req_list = []}.

make_reply(ReqID, true, From, State) ->
    {reply, {async, ReqID},
     update_request_info(ReqID, State,
			 fun(Reply,State1) -> 
				 async_reply(ReqID,Reply,From,State1)
			 end)};

make_reply(ReqID, false, From, State) ->
    {noreply, 
     update_request_info(ReqID, State,
			 fun(Reply,State1) -> 
				 sync_reply(Reply, From, State1) 
			 end)}.

make_reply_post(ReqID, true, From, State, PostFun) ->
    {reply, {async, ReqID},
     update_request_info(ReqID, State,
			 fun(Reply,State1) ->
				 case catch PostFun(Reply, State1) of
				     {'EXIT',_} ->
					 async_reply(ReqID,Reply, From, State1);
				     {Reply1, State2} ->
					 async_reply(ReqID,Reply1, From, State2)
				 end
			 end)};

make_reply_post(ReqID, false, From, State, PostFun) ->
    {noreply,
     update_request_info(ReqID, State,
			 fun(Reply,State1) ->
				 case catch PostFun(Reply, State1) of
				     {'EXIT',_} ->
					 sync_reply(Reply, From, State1);
				     {Reply1, State2} ->
					 sync_reply(Reply1, From, State2)
				 end
			 end)}.

%% convert: file_info -> ssh_xfer_attr
info_to_attr(I) when is_record(I, file_info) ->
    #ssh_xfer_attr { permissions = I#file_info.mode,
		     size = I#file_info.size,
		     type = I#file_info.type,
		     owner = I#file_info.uid,
		     group = I#file_info.gid,
		     atime = datetime_to_unix(I#file_info.atime),
		     mtime = datetime_to_unix(I#file_info.mtime),
		     createtime = datetime_to_unix(I#file_info.ctime)}.

%% convert: ssh_xfer_attr -> file_info
attr_to_info(A) when is_record(A, ssh_xfer_attr) ->
    #file_info{
      size   = A#ssh_xfer_attr.size,
      type   = A#ssh_xfer_attr.type,
      access = read_write, %% FIXME: read/write/read_write/none
      atime  = unix_to_datetime(A#ssh_xfer_attr.atime),
      mtime  = unix_to_datetime(A#ssh_xfer_attr.mtime),
      ctime  = unix_to_datetime(A#ssh_xfer_attr.createtime),
      mode   = A#ssh_xfer_attr.permissions,
      links  = 1,
      major_device = 0,
      minor_device = 0,
      inode  = 0,
      uid    = A#ssh_xfer_attr.owner,
      gid    = A#ssh_xfer_attr.group}.


%% Added workaround for sftp timestam problem. (Timestamps should be
%% in UTC but they where not) .  The workaround uses a deprecated
%% function i calandar.  This will work as expected most of the time
%% but has problems for the same reason as
%% calendar:local_time_to_universal_time/1. We consider it better that
%% the timestamps work as expected most of the time instead of none of
%% the time. Hopfully the file-api will be updated so that we can
%% solve this problem in a better way in the future.

unix_to_datetime(undefined) ->
    undefined;
unix_to_datetime(UTCSecs) ->
    UTCDateTime = 
	calendar:gregorian_seconds_to_datetime(UTCSecs + 62167219200),
    erlang:universaltime_to_localtime(UTCDateTime).

datetime_to_unix(undefined) ->
    undefined;
datetime_to_unix(LocalDateTime) ->    
    UTCDateTime = erlang:localtime_to_universaltime(LocalDateTime),
    calendar:datetime_to_gregorian_seconds(UTCDateTime) - 62167219200.


open_mode(Vsn,Modes) when Vsn >= 5 ->
    open_mode5(Modes);
open_mode(_Vsn, Modes) ->
    open_mode3(Modes).

open_mode5(Modes) ->
    A = #ssh_xfer_attr{type = regular},
    {Fl, Ac} = case {lists:member(write, Modes),
		     lists:member(read, Modes),
		     lists:member(append, Modes)} of
		   {_, _, true} ->
		       {[append_data],
			[read_attributes,
			 append_data, write_attributes]};
		   {true, false, false} ->
		       {[create_truncate],
			[write_data, write_attributes]};
		   {true, true, _} ->
		       {[open_or_create],
			[read_data, read_attributes,
			 write_data, write_attributes]};
		   {false, true, _} ->
		       {[open_existing],
			[read_data, read_attributes]}
	       end,
    {Ac, Fl, A}.

open_mode3(Modes) ->
    A = #ssh_xfer_attr{type = regular},
    Fl = case {lists:member(write, Modes),
	       lists:member(read, Modes),
	       lists:member(append, Modes)} of
	     {_, _, true} ->
		 [append];
	     {true, false, false} ->
		 [write, creat, trunc];
	     {true, true, _} ->
		 [read, write];
	     {false, true, _} ->
		 [read]
	 end,
    {[], Fl, A}.

%% accessors for inf dict
new_inf() -> dict:new().

add_new_handle(Handle, FileMode, Inf) ->
    dict:store(Handle, #fileinf{offset=0, size=0, mode=FileMode}, Inf).

update_size(Handle, NewSize, State) ->
    OldSize = get_size(Handle, State),
    if NewSize > OldSize ->
	    put_size(Handle, NewSize, State);
       true ->
	    State
    end.

%% set_offset(Handle, NewOffset) ->
%%     put({offset,Handle}, NewOffset).

update_offset(Handle, NewOffset, State0) ->
    State1 = put_offset(Handle, NewOffset, State0),
    update_size(Handle, NewOffset, State1).

%% access size and offset for handle
put_size(Handle, Size, State) ->
    Inf0 = State#state.inf,
    case dict:find(Handle, Inf0) of
	{ok, FI} ->
	    State#state{inf=dict:store(Handle, FI#fileinf{size=Size}, Inf0)};
	_ ->
	    State#state{inf=dict:store(Handle, #fileinf{size=Size,offset=0},
				       Inf0)}
    end.

put_offset(Handle, Offset, State) ->
    Inf0 = State#state.inf,
    case dict:find(Handle, Inf0) of
	{ok, FI} ->
	    State#state{inf=dict:store(Handle, FI#fileinf{offset=Offset},
				       Inf0)};
	_ ->
	    State#state{inf=dict:store(Handle, #fileinf{size=Offset,
							offset=Offset}, Inf0)}
    end.

get_size(Handle, State) ->
    case dict:find(Handle, State#state.inf) of
	{ok, FI} ->
	    FI#fileinf.size;
	_ ->
	    undefined
    end.

%% get_offset(Handle, State) ->
%%     {ok, FI} = dict:find(Handle, State#state.inf),
%%     FI#fileinf.offset.

get_mode(Handle, State) ->
    case dict:find(Handle, State#state.inf) of
	{ok, FI} ->
	    FI#fileinf.mode;
	_ ->
	    undefined
    end.

erase_handle(Handle, State) ->
    FI = dict:erase(Handle, State#state.inf),
    State#state{inf = FI}.

%%
%% Caluclate a integer offset
%%
lseek_position(Handle, Pos, State) ->
    case dict:find(Handle, State#state.inf) of
	{ok, #fileinf{offset=O, size=S}} ->
	    lseek_pos(Pos, O, S);
	_ ->
	    {error, einval}
    end.

lseek_pos(_Pos, undefined, _) ->
    {error, einval};
lseek_pos(Pos, _CurOffset, _CurSize)
  when is_integer(Pos) andalso 0 =< Pos andalso Pos < ?SSH_FILEXFER_LARGEFILESIZE ->
    {ok,Pos};
lseek_pos(bof, _CurOffset, _CurSize) ->
    {ok,0};
lseek_pos(cur, CurOffset, _CurSize) ->
    {ok,CurOffset};
lseek_pos(eof, _CurOffset, CurSize) ->
    {ok,CurSize};
lseek_pos({bof, Offset}, _CurOffset, _CurSize)
  when is_integer(Offset) andalso 0 =< Offset andalso Offset < ?SSH_FILEXFER_LARGEFILESIZE ->
    {ok, Offset};
lseek_pos({cur, Offset}, CurOffset, _CurSize)
  when is_integer(Offset) andalso -(?SSH_FILEXFER_LARGEFILESIZE) =< Offset andalso
       Offset < ?SSH_FILEXFER_LARGEFILESIZE ->
    NewOffset = CurOffset + Offset,
    if NewOffset < 0 ->
	    {ok, 0};
       true ->
	    {ok, NewOffset}
    end;
lseek_pos({eof, Offset}, _CurOffset, CurSize) 
  when is_integer(Offset) andalso -(?SSH_FILEXFER_LARGEFILESIZE) =< Offset andalso
       Offset < ?SSH_FILEXFER_LARGEFILESIZE ->
    NewOffset = CurSize + Offset,
    if NewOffset < 0 ->
	    {ok, 0};
       true ->
	    {ok, NewOffset}
    end;
lseek_pos(_, _, _) ->
    {error, einval}. 

%%%================================================================
%%%
to_bin(Data) when is_list(Data) -> list_to_binary(Data);
to_bin(Data) when is_binary(Data) -> Data.


read_repeat(Pid, Handle, Len, FileOpTimeout) ->
    {ok,{_WindowSz,PacketSz}} = recv_window(Pid, FileOpTimeout),
    read_rpt(Pid, Handle, Len, PacketSz, FileOpTimeout, <<>>).

read_rpt(Pid, Handle, WantedLen, PacketSz, FileOpTimeout, Acc) when WantedLen > 0 ->
    case read(Pid, Handle, min(WantedLen,PacketSz), FileOpTimeout) of
	{ok, Data}  ->
	    read_rpt(Pid, Handle, WantedLen-size(Data), PacketSz, FileOpTimeout, <<Acc/binary, Data/binary>>);
	eof ->
	    {ok, Acc};
	Error ->
	    Error
    end;
read_rpt(_Pid, _Handle, WantedLen, _PacketSz, _FileOpTimeout, Acc) when WantedLen >= 0 ->
    {ok,Acc}.


write_to_remote_tar(_Pid, _SftpHandle, <<>>, _FileOpTimeout) ->
    ok;
write_to_remote_tar(Pid, SftpHandle, Bin, FileOpTimeout) ->
    {ok,{_Window,Packet}} = send_window(Pid, FileOpTimeout),
    write_file_loop(Pid, SftpHandle, 0, Bin, size(Bin), Packet, FileOpTimeout).

position_buf(Pid, SftpHandle, BufHandle, Pos, FileOpTimeout) ->
    {ok,#bufinf{mode = Mode,
		plain_text_buf = Buf0,
		size = Size}} = call(Pid, {get_bufinf,BufHandle}, FileOpTimeout),
    case Pos of
	{cur,0} when Mode==write ->
	    {ok,Size+size(Buf0)};
	
	{cur,0} when Mode==read ->
	    {ok,Size};
	
	_ when Mode==read, is_integer(Pos) ->
	    Skip = Pos-Size,
	    if 
		Skip < 0 ->
		    {error, cannot_rewind};
		Skip == 0 ->
		    %% Optimization
		    {ok,Pos};
		Skip > 0 ->
		    case read_buf(Pid, SftpHandle, BufHandle, Skip, FileOpTimeout) of
			%% A bit innefficient to fetch the bufinf again, but there are lots of
			%% other more important optimizations waiting....
			{ok,_} ->
			    {ok,Pos};
			 Other ->
			    Other
		    end
	    end;

	_ ->
	    {error,{not_yet_implemented,{pos,Pos}}}
      end.

read_buf(Pid, SftpHandle, BufHandle, WantedLen, FileOpTimeout) ->
    {ok,{_Window,Packet}} = send_window(Pid, FileOpTimeout),
    {ok,B0}  = call(Pid, {get_bufinf,BufHandle}, FileOpTimeout),
    case do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, B0) of
	{ok,ResultBin,B} ->
	    call(Pid, {put_bufinf,BufHandle,B}, FileOpTimeout),
	    {ok,ResultBin};
	{error,Error} ->
	    {error,Error};
	{eof,B} ->
	    call(Pid, {put_bufinf,BufHandle,B}, FileOpTimeout),
	    eof
      end.

do_the_read_buf(_Pid, _SftpHandle, WantedLen, _Packet, _FileOpTimeout, 
		B=#bufinf{plain_text_buf=PlainBuf0,
			  size = Size})
    when size(PlainBuf0) >= WantedLen ->
    %% We already have the wanted number of bytes decoded and ready!
    <<ResultBin:WantedLen/binary, PlainBuf/binary>> = PlainBuf0,
    {ok,ResultBin,B#bufinf{plain_text_buf=PlainBuf,
			   size = Size + WantedLen}};

do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, 
		B0=#bufinf{plain_text_buf = PlainBuf0,
			   enc_text_buf = EncBuf0,
			   chunksize = undefined
			  })
  when size(EncBuf0) > 0 ->
    %% We have (at least) one decodable byte waiting for decodeing.
    {ok,DecodedBin,B} = apply_crypto(EncBuf0, B0),
    do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, 
		    B#bufinf{plain_text_buf = <<PlainBuf0/binary, DecodedBin/binary>>,
			     enc_text_buf = <<>>
			    });
    
do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, 
		B0=#bufinf{plain_text_buf = PlainBuf0,
			   enc_text_buf = EncBuf0,
			   chunksize = ChunkSize0
			  })
  when size(EncBuf0) >= ChunkSize0 ->
    %% We have (at least) one chunk of decodable bytes waiting for decodeing.
    <<ToDecode:ChunkSize0/binary, EncBuf/binary>> = EncBuf0,
    {ok,DecodedBin,B} = apply_crypto(ToDecode, B0),
    do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, 
		    B#bufinf{plain_text_buf = <<PlainBuf0/binary, DecodedBin/binary>>,
			     enc_text_buf = EncBuf
			    });
    
do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout, B=#bufinf{enc_text_buf = EncBuf0}) ->
    %% We must read more bytes and append to the buffer of encoded bytes.
    case read(Pid, SftpHandle, Packet, FileOpTimeout) of
	{ok,EncryptedBin} ->
	    do_the_read_buf(Pid, SftpHandle, WantedLen, Packet, FileOpTimeout,
			    B#bufinf{enc_text_buf = <<EncBuf0/binary, EncryptedBin/binary>>});
	eof ->
	    {eof,B};
	Other ->
	    Other
    end.


write_buf(Pid, SftpHandle, BufHandle, PlainBin, FileOpTimeout) ->
    {ok,{_Window,Packet}} = send_window(Pid, FileOpTimeout),
    {ok,B0=#bufinf{plain_text_buf=PTB}}  = call(Pid, {get_bufinf,BufHandle}, FileOpTimeout),
    case do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout, 
			  B0#bufinf{plain_text_buf = <<PTB/binary,PlainBin/binary>>}) of
	{ok, B} ->
	    call(Pid, {put_bufinf,BufHandle,B}, FileOpTimeout),
	    ok;
	{error,Error} ->
	    {error,Error}
    end.

do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout, 
		 B=#bufinf{enc_text_buf = EncBuf0,
			   size = Size})
  when size(EncBuf0) >= Packet ->
    <<BinToWrite:Packet/binary, EncBuf/binary>> = EncBuf0,
    case write(Pid, SftpHandle, BinToWrite, FileOpTimeout) of
	ok ->
	    do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout,
			     B#bufinf{enc_text_buf = EncBuf,
				      size = Size + Packet});
	Other ->
	    Other
    end;

do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout,
		 B0=#bufinf{plain_text_buf = PlainBuf0,
			    enc_text_buf = EncBuf0,
			    chunksize = undefined})
  when size(PlainBuf0) > 0 ->
     {ok,EncodedBin,B} = apply_crypto(PlainBuf0, B0),
     do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout,
		     B#bufinf{plain_text_buf = <<>>,
			      enc_text_buf = <<EncBuf0/binary, EncodedBin/binary>>});

do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout,
		 B0=#bufinf{plain_text_buf = PlainBuf0,
			    enc_text_buf = EncBuf0,
			    chunksize = ChunkSize0
			   })
  when size(PlainBuf0) >= ChunkSize0 ->
    <<ToEncode:ChunkSize0/binary, PlainBuf/binary>> = PlainBuf0,
    {ok,EncodedBin,B} = apply_crypto(ToEncode, B0),
    do_the_write_buf(Pid, SftpHandle, Packet, FileOpTimeout,
		     B#bufinf{plain_text_buf = PlainBuf,
			      enc_text_buf = <<EncBuf0/binary, EncodedBin/binary>>});

do_the_write_buf(_Pid, _SftpHandle, _Packet, _FileOpTimeout, B) ->
    {ok,B}.

apply_crypto(In, B=#bufinf{crypto_state = CState0,
			   crypto_fun = F}) ->
    case F(In,CState0) of
	{ok,EncodedBin,CState} -> 
	    {ok, EncodedBin, B#bufinf{crypto_state=CState}};
	{ok,EncodedBin,CState,ChunkSize} -> 
	    {ok, EncodedBin, B#bufinf{crypto_state=CState,
				      chunksize=ChunkSize}}
    end.

open_buf(Pid, CryptoInitFun, BufInfo0, FileOpTimeout) ->
    case CryptoInitFun() of
	{ok,CryptoState} ->
	    open_buf1(Pid, BufInfo0, FileOpTimeout, CryptoState, undefined);
	{ok,CryptoState,ChunkSize} ->
	    open_buf1(Pid, BufInfo0, FileOpTimeout, CryptoState, ChunkSize);
	Other ->
	    Other
    end.

open_buf1(Pid, BufInfo0, FileOpTimeout, CryptoState, ChunkSize) ->
    BufInfo = BufInfo0#bufinf{crypto_state = CryptoState,
			      chunksize = ChunkSize},
    BufHandle = make_ref(),
    call(Pid, {put_bufinf,BufHandle,BufInfo}, FileOpTimeout),
    {ok,BufHandle}.

format_channel_start_error({shutdown, Reason}) ->
    Reason;
format_channel_start_error(Reason) ->
    Reason.