[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

4 files changed, 72 insertions, 35 deletions

diff --git a/lib/kernel/doc/src/logger_std_h.xml b/lib/kernel/doc/src/logger_std_h.xml
index fcd180abd6..8c5a476d86 100644
--- a/lib/kernel/doc/src/logger_std_h.xml
+++ b/lib/kernel/doc/src/logger_std_h.xml
@@ -59,14 +59,21 @@
       <item>
 	<p>This has the value <c>standard_io</c>, <c>standard_error</c>,
 	<c>{file,LogFileName}</c>, or <c>{file,LogFileName,LogFileOpts}</c>.</p>
-	<p>If <c>LogFileOpts</c> is specified, it replaces the default
-	  list of options used when opening the log file. The default
-	  list is <c>[raw,append,delayed_write]</c>. One reason to do
-	  so can be to change <c>append</c> to, for
-	  example, <c>write</c>, ensuring that the old log is
-	  truncated when a node is restarted. See the reference manual
-	  for <seealso marker="file#open-2"><c>file:open/2</c></seealso>
-	  for more information about file options.</p>
+	<p><c>LogFileOpts</c> specify the file options used when
+	  opening the log file,
+	  see <seealso marker="file#open-2"><c>file:open/2</c></seealso>.
+	  If <c>LogFileOpts</c> is not specified, the default option
+	  list used is <c>[raw,append,delayed_write]</c>. If <c>LogFileOpts</c>
+	  is specified, it replaces the default options list with the
+	  following adjustments:</p>
+	<list>
+	  <item>
+	    If <c>raw</c> is not found in the list, it is added
+	  </item>
+	  <item>
+	    It <c>write</c>, <c>append</c> or <c>exclusice</c> are not
+	    found in the list, <c>append</c> is added</item>
+	</list>
 	<p>Log files are always UTF-8 encoded. The encoding can not be
 	  changed by setting the option <c>{encoding,Encoding}</c>
 	  in <c>LogFileOpts</c>.</p>
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.
 
diff --git a/lib/kernel/test/logger_SUITE.erl b/lib/kernel/test/logger_SUITE.erl
index 2dad651f9c..ce0c2efa10 100644
--- a/lib/kernel/test/logger_SUITE.erl
+++ b/lib/kernel/test/logger_SUITE.erl
@@ -1047,8 +1047,9 @@ kernel_config(Config) ->
     ok = rpc:call(Node,application,unset_env,[kernel,logger]),
     ok = rpc:call(Node,logger,internal_init_logger,[]),
     ok = rpc:call(Node,logger,add_handlers,[kernel]),
+    DefModes = [raw,append,delayed_write],
     #{primary:=#{filter_default:=log,filters:=[]},
-      handlers:=[#{id:=default,filters:=DF,config:=#{type:={file,F}}}],
+      handlers:=[#{id:=default,filters:=DF,config:=#{type:={file,F,DefModes}}}],
       module_levels:=[]} = rpc:call(Node,logger,get_config,[]),
 
     %% Same, but using 'logger' parameter instead of 'error_logger'
@@ -1060,26 +1061,26 @@ kernel_config(Config) ->
     ok = rpc:call(Node,logger,internal_init_logger,[]),
     ok = rpc:call(Node,logger,add_handlers,[kernel]),
     #{primary:=#{filter_default:=log,filters:=[]},
-      handlers:=[#{id:=default,filters:=DF,config:=#{type:={file,F}}}],
+      handlers:=[#{id:=default,filters:=DF,config:=#{type:={file,F,DefModes}}}],
       module_levels:=[]} = rpc:call(Node,logger,get_config,[]),
 
     %% Same, but with type={file,File,Modes}
     ok = rpc:call(Node,logger,remove_handler,[default]),% so it can be added again
     ok = rpc:call(Node,application,unset_env,[kernel,error_logger]),
-    M = [raw,write,delayed_write],
+    M = [raw,write],
     ok = rpc:call(Node,application,set_env,[kernel,logger,
                                             [{handler,default,logger_std_h,
                                               #{config=>#{type=>{file,F,M}}}}]]),
     ok = rpc:call(Node,logger,internal_init_logger,[]),
     ok = rpc:call(Node,logger,add_handlers,[kernel]),
     #{primary:=#{filter_default:=log,filters:=[]},
-      handlers:=[#{id:=default,filters:=DF,config:=#{type:={file,F,M}}}],
+      handlers:=[#{id:=default,filters:=DF,
+                   config:=#{type:={file,F,[delayed_write|M]}}}],
       module_levels:=[]} = rpc:call(Node,logger,get_config,[]),
 
     %% Same, but with disk_log handler
     ok = rpc:call(Node,logger,remove_handler,[default]),% so it can be added again
     ok = rpc:call(Node,application,unset_env,[kernel,error_logger]),
-    M = [raw,write,delayed_write],
     ok = rpc:call(Node,application,set_env,[kernel,logger,
                                             [{handler,default,logger_disk_log_h,
                                               #{config=>#{file=>F}}}]]),
diff --git a/lib/kernel/test/logger_std_h_SUITE.erl b/lib/kernel/test/logger_std_h_SUITE.erl
index ba491ac5fa..8cadb1083b 100644
--- a/lib/kernel/test/logger_std_h_SUITE.erl
+++ b/lib/kernel/test/logger_std_h_SUITE.erl
@@ -257,9 +257,10 @@ errors(Config) ->
     end,
 
     {error,
-     {handler_not_added,{open_failed,Log,_}}} =
+     {handler_not_added,
+      {invalid_config,logger_std_h,#{type:={file,Log,bad_file_opt}}}}} =
         logger:add_handler(myh3,logger_std_h,
-                           #{config=>#{type=>{file,Log,[bad_file_opt]}}}),
+                           #{config=>#{type=>{file,Log,bad_file_opt}}}),
 
     ok = logger:notice(?msg).
 
@@ -607,11 +608,14 @@ reconfig(cleanup, _Config) ->
 file_opts(Config) ->
     Dir = ?config(priv_dir,Config),
     Log = filename:join(Dir, lists:concat([?FUNCTION_NAME,".log"])),
-    BadFileOpts = [raw],
-    BadType = {file,Log,BadFileOpts},
-    {error,{handler_not_added,{open_failed,Log,enoent}}} =
-        logger:add_handler(?MODULE, logger_std_h,
-                           #{config => #{type => BadType}}),
+    MissingAccess = [raw],
+    Type1 = {file,Log,MissingAccess},
+    ok = logger:add_handler(?MODULE, logger_std_h,
+                            #{config => #{type => Type1}}),
+    {ok,#{config:=#{type:={file,Log,Modes1}}}} =
+        logger:get_handler_config(?MODULE),
+    [append,delayed_write,raw] = lists:sort(Modes1),
+    ok = logger:remove_handler(?MODULE),
 
     OkFileOpts = [raw,append],
     OkType = {file,Log,OkFileOpts},
@@ -622,9 +626,10 @@ file_opts(Config) ->
                               filters=>?DEFAULT_HANDLER_FILTERS([?MODULE]),
                               formatter=>{?MODULE,self()}}),
 
-    #{cb_state := #{handler_state := #{type := OkType}}} =
+    ModType = {file,Log,[delayed_write|OkFileOpts]},
+    #{cb_state := #{handler_state := #{type := ModType}}} =
         logger_olp:info(h_proc_name()),
-    {ok,#{config := #{type := OkType}}} = logger:get_handler_config(?MODULE),
+    {ok,#{config := #{type := ModType}}} = logger:get_handler_config(?MODULE),
     logger:notice(M1=?msg,?domain),
     ?check(M1),
     B1 = ?bin(M1),