From e03c2bd640e1fc1503e92dfd74991f4205973c61 Mon Sep 17 00:00:00 2001
From: Siri Hansen <siri@erlang.org>
Date: Tue, 5 Mar 2019 11:25:00 +0100
Subject: [logger] Add better control of file modes in logger_std_h

OTP-15602

It is allowed to set file modes for the handler to use when opening
its log file. The given modes were earlier accepted without any
checks, which could make the handler behave unexpectedly. This commit
makes sure that

* if none of write, append or exclusive is given, then append is added
* if raw is not given, it is added
* if delayed_write or {delayed_write,_,_} is not given, then
  delayed_write is added
---
 lib/kernel/src/logger_std_h.erl | 50 ++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 13 deletions(-)

(limited to 'lib/kernel/src')

diff --git a/lib/kernel/src/logger_std_h.erl b/lib/kernel/src/logger_std_h.erl
index 392ac7e67b..c634f86550 100644
--- a/lib/kernel/src/logger_std_h.erl
+++ b/lib/kernel/src/logger_std_h.erl
@@ -136,12 +136,10 @@ check_config(_Name,SetOrUpdate,OldHConfig,NewHConfig0) ->
             {error,{illegal_config_change,?MODULE,WriteOnce,Other}}
     end.
 
-check_config(#{type:=Type}=HConfig) ->
+check_config(HConfig) ->
     case check_h_config(maps:to_list(HConfig)) of
-        ok when is_atom(Type) ->
-            {ok,HConfig#{filesync_repeat_interval=>no_repeat}};
         ok ->
-            {ok,HConfig};
+            {ok,fix_file_opts(HConfig)};
         {error,{Key,Value}} ->
             {error,{invalid_config,?MODULE,#{Key=>Value}}}
     end.
@@ -162,8 +160,40 @@ check_h_config([]) ->
 get_default_config() ->
      #{type => standard_io}.
 
-filesync(_Name, _Mode, #{type := Type}=State) when is_atom(Type) ->
-    {ok,State};
+fix_file_opts(#{type:={file,File}}=HConfig) ->
+    fix_file_opts(HConfig#{type=>{file,File,[raw,append,delayed_write]}});
+fix_file_opts(#{type:={file,File,[]}}=HConfig) ->
+    fix_file_opts(HConfig#{type=>{file,File,[raw,append,delayed_write]}});
+fix_file_opts(#{type:={file,File,Modes}}=HConfig) ->
+    HConfig#{type=>{file,File,fix_modes(Modes)}};
+fix_file_opts(HConfig) ->
+    HConfig#{filesync_repeat_interval=>no_repeat}.
+
+fix_modes(Modes) ->
+    %% Ensure write|append|exclusive
+    Modes1 =
+        case [M || M <- Modes,
+                   lists:member(M,[write,append,exclusive])] of
+            [] -> [append|Modes];
+            _ -> Modes
+        end,
+    %% Ensure raw
+    Modes2 =
+        case lists:member(raw,Modes) of
+            false -> [raw|Modes1];
+            true -> Modes1
+        end,
+    %% Ensure delayed_write
+    case lists:partition(fun(delayed_write) -> true;
+                            ({delayed_write,_,_}) -> true;
+                            (_) -> false
+                         end, Modes2) of
+        {[],_} ->
+            [delayed_write|Modes2];
+        _ ->
+            Modes2
+    end.
+
 filesync(_Name, async, #{file_ctrl_pid := FileCtrlPid} = State) ->
     ok = file_ctrl_filesync_async(FileCtrlPid),
     {ok,State};
@@ -217,12 +247,6 @@ open_log_file(HandlerName, FileInfo) ->
         Error -> Error
     end.
 
-do_open_log_file({file,FileName}) ->
-    do_open_log_file({file,FileName,[raw,append,delayed_write]});
-
-do_open_log_file({file,FileName,[]}) ->
-    do_open_log_file({file,FileName,[raw,append,delayed_write]});
-
 do_open_log_file({file,FileName,Modes}) ->
     try
         case filelib:ensure_dir(FileName) of
@@ -323,7 +347,7 @@ file_ctrl_init(HandlerName, StdDev, Starter) ->
 %% Modify file options to use when re-opening if the inode has
 %% changed. I.e. the file may exist and if so should be appended to.
 set_file_opt_append({file, FileName, Modes}) ->
-    {file, FileName, [append | Modes--[exclusive]]};
+    {file, FileName, [append | Modes--[write,append,exclusive]]};
 set_file_opt_append(FileInfo) ->
     FileInfo.
 
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