Fix inverted logic case in file uploads.

pe/filesrv/fserve.erl

@@ -1,9 +1,52 @@
 -module(fserve).
--export([start/0]).
+-export([start/0, file_serve/2, put/2, get/1]).
 -include("./msg.hrl").
 
 start () ->
-    file_serve(#{}, #{}).
+    spawn(fserve, file_serve, [#{}, sets:new()]).
 
 file_serve(Names, DataStore) ->
-    throw (not_implemented).
+    receive
+	#upload{client=Client, data=Data} -> 
+	    case upload(DataStore, Data) of
+		{ok, UpdatedDataStore, CAS_ID} -> 
+		    Client ! CAS_ID,
+		    file_serve(Names, UpdatedDataStore);
+		{error, Reason} -> throw(Reason)
+	    end;
+	#stop{client=Client} ->
+	    io:format("Shutdown message received from ~w~n", [Client]);
+	#dump{client=Client} ->
+	    io:format("Dumping store.~n"),
+	    Client ! {Names, DataStore},
+	    file_serve(Names, DataStore)
+    end.
+
+put(DataStore, Data)  ->
+    <<HashBinary:256/big-unsigned-integer>> = crypto:hash(sha256, Data),
+    Hash = integer_to_list(HashBinary, 16),
+    case sets:is_element(Hash, DataStore) of
+	false ->
+	    Path = "data/" ++ Hash,
+	    case file:write_file(Path, Data) of
+		ok -> 
+		    io:format("Wrote ~s to file ~s~n", [Hash, Path]),
+		    {ok, sets:add_element(Hash, DataStore), Hash};
+		{error, Reason} -> {error, Reason}
+	    end;
+	true -> 
+	    io:format("Receive request to store previously stored ~s~n", [Hash]),
+	    {ok, DataStore, Hash}
+    end.
+    
+get(ID) ->
+    Path = "data/" ++ ID,
+    file:read_file(Path).
+
+upload(DataStore, Data) ->
+    case fserve:put(DataStore, Data) of
+	{ok, UpdatedDataStore, ID} ->
+	    io:format("Successfully stored file.~n"),
+	    {ok, UpdatedDataStore, ID};
+	{error, Reason} -> {error, Reason}
+    end.

pe/filesrv/msg.hrl

@@ -14,3 +14,9 @@
 
 % fetch obtains the data referenced by an alternative name.
 -record(fetch, {client, name}).
+
+% stop tells the server to shutdown.
+-record(stop, {client}).
+
+% dump tells the server to send the current state of the system.
+-record(dump, {client}).