From eb95f6951e7a4abd2b7685b2de07de90b90ee0d2 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Thu, 25 Sep 2014 08:35:07 +0200
Subject: perm: Don't crash if file content is different, tell caller instead.
 Better error handling.

---
 src/perm.erl | 54 +++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 19 deletions(-)

(limited to 'src/perm.erl')

diff --git a/src/perm.erl b/src/perm.erl
index 2ce5b46..34f431c 100644
--- a/src/perm.erl
+++ b/src/perm.erl
@@ -6,17 +6,25 @@
 -module(perm).
 -export([ensurefile/3]).
 
-fsync(Name) ->
-    fsyncport:fsync(Name).
+fsync([]) ->
+    ok;
+fsync([Name | Rest]) ->
+    case fsyncport:fsync(Name) of
+	ok ->
+	    fsync(Rest);
+	{error, Error} ->
+	    {error, Error}
+    end.
 
 readfile_and_verify(Name, Content) ->
     case file:read_file(Name) of
         {ok, ContentsReadBinary} ->
             ContentsRead = binary_to_list(ContentsReadBinary),
-            if Content == ContentsRead ->
+            if
+                Content == ContentsRead ->
                     ok;
-               true ->
-                    {error, "File contents differ"}
+                true ->
+                    differ
             end;
         {error, Error} ->
             {error, Error}
@@ -72,24 +80,32 @@ tempfilename(Base) ->
 			     MegaSecs * 1000000 + Secs, MicroSecs]),
     Filename.
 
+exit_with_error(Error, Message) ->
+    io:format("~s: ~w~n", [Message, Error]),
+    exit({perm, fileerror, Message, Error}).
+
+check_error(ReturnValue, ErrorMessage) ->
+    case ReturnValue of
+        ok ->
+            ok;
+        {error, Error} ->
+            exit_with_error(Error, ErrorMessage)
+    end.
+
 ensurefile(Rootdir, Key, Content) ->
     {Dirs, Path} = path_for_key(Rootdir, Key),
     case readfile_and_verify(Path, Content) of
 	ok ->
-	    lists:foreach(fun (Dir) -> fsync(Dir) end, [Path, Rootdir | Dirs]);
+	    check_error(fsync([Path, Rootdir | Dirs]), "Error in fsync");
+        differ ->
+            differ;
 	{error, enoent} ->
-            case make_dirs([Rootdir, Rootdir ++ "nursery/"] ++ Dirs) of
-		ok ->
-		    NurseryName = Rootdir ++ "nursery/" ++
-                        tempfilename(hex:bin_to_hexstr(Key)),
-		    _Result = writefile(Path, NurseryName, Content),
-		    lists:foreach(fun (Dir) ->
-                                          fsync(Dir)
-                                  end,
-                                  [Path, Rootdir | Dirs]); %% XXX check results
-		{error, Error} ->
-		    io:format("Error creating directory: ~w~n", [Error])
-	    end;
+            check_error(make_dirs([Rootdir, Rootdir ++ "nursery/"] ++ Dirs),
+                        "Error creating directory"),
+            NurseryName = Rootdir ++ "nursery/" ++
+                tempfilename(hex:bin_to_hexstr(Key)),
+            _Result = writefile(Path, NurseryName, Content),
+            check_error(fsync([Path, Rootdir | Dirs]), "Error in fsync");
 	{error, Error} ->
-	    exit({perm, fileerror, "Error reading file", Error})
+            exit_with_error(Error, "Error reading file")
     end.
-- 
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