Introduce new option 'raw' in file_info functions

This option allows the caller not to go through the file server for information
about files guaranteed to be local.

3 files changed, 84 insertions, 38 deletions

diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index 8dae34431b..135e993e54 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -1291,6 +1291,8 @@
 			or before unix time epoch which is 1970-01-01 00:00 UTC. 
 			Default is <c>{time, local}</c>.
 		</p> 
+        <p>If the <c>raw</c> option is set, the file server will not be called
+          and only informations about local files will be returned.</p>
 		<note>
           <p>
 			  Since file times is stored in posix time on most OS it is
@@ -1517,6 +1519,8 @@
           the link will be returned in the <c>file_info</c> record and
           the <c>type</c> field of the record will be set to
           <c>symlink</c>.</p>
+      <p>If the <c>raw</c> option is set, the file server will not be called
+        and only informations about local files will be returned.</p>
         <p>If <c><anno>Name</anno></c> is not a symbolic link, this function returns
           exactly the same result as <c>read_file_info/1</c>.
           On platforms that do not support symbolic links, this function
@@ -1855,6 +1859,8 @@
 			interpret it as universal time and <c>posix</c> must be seconds since
 			or before unix time epoch which is 1970-01-01 00:00 UTC.
 			Default is <c>{time, local}</c>.
+        <p>If the <c>raw</c> option is set, the file server will not be called
+          and only informations about local files will be returned.</p>
 		</p>
         <p>The following fields are used from the record, if they are
           given.</p>
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 20b703e084..680442b7f5 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -114,7 +114,7 @@
 -type sendfile_option() :: {chunk_size, non_neg_integer()}
 			 | {use_threads, boolean()}.
 -type file_info_option() :: {'time', 'local'} | {'time', 'universal'} 
-			  | {'time', 'posix'}.
+			  | {'time', 'posix'} | raw.
 %%% BIFs
 
 -export([file_info/1, native_name_encoding/0]).
@@ -250,7 +250,19 @@ read_file_info(Name) ->
       Reason :: posix() | badarg.
 
 read_file_info(Name, Opts) when is_list(Opts) ->
-    check_and_call(read_file_info, [file_name(Name), Opts]).
+    Args = [file_name(Name), Opts],
+    case check_args(Args) of
+        ok ->
+            case lists:member(raw, Opts) of
+                true ->
+                    [FileName|_] = Args,
+                    ?PRIM_FILE:read_file_info(FileName, Opts);
+                false ->
+                    call(read_file_info, Args)
+            end;
+        Error ->
+            Error
+    end.
 
 -spec altname(Name :: name_all()) -> any().
 
@@ -272,7 +284,19 @@ read_link_info(Name) ->
       Reason :: posix() | badarg.
 
 read_link_info(Name, Opts) when is_list(Opts) ->
-    check_and_call(read_link_info, [file_name(Name),Opts]).
+    Args = [file_name(Name), Opts],
+    case check_args(Args) of
+        ok ->
+            case lists:member(raw, Opts) of
+                true ->
+                    [FileName|_] = Args,
+                    ?PRIM_FILE:read_link_info(FileName, Opts);
+                false ->
+                    call(read_link_info, Args)
+            end;
+        Error ->
+            Error
+    end.
 
 
 -spec read_link(Name) -> {ok, Filename} | {error, Reason} when
@@ -306,7 +330,19 @@ write_file_info(Name, Info = #file_info{}) ->
       Reason :: posix() | badarg.
 
 write_file_info(Name, Info = #file_info{}, Opts) when is_list(Opts) ->
-    check_and_call(write_file_info, [file_name(Name), Info, Opts]).
+    Args = [file_name(Name), Info, Opts],
+    case check_args(Args) of
+        ok ->
+            case lists:member(raw, Opts) of
+                true ->
+                    [FileName|_] = Args,
+                    ?PRIM_FILE:write_file_info(FileName, Info, Opts);
+                false ->
+                    call(write_file_info, Args)
+            end;
+        Error ->
+            Error
+    end.
 
 -spec list_dir(Dir) -> {ok, Filenames} | {error, Reason} when
       Dir :: name_all(),
@@ -392,26 +428,12 @@ write_file(Name, Bin, ModeList) when is_list(ModeList) ->
 %% Obsolete, undocumented, local node only, don't use!.
 %% XXX to be removed.
 raw_read_file_info(Name) ->
-    Args = [file_name(Name)],
-    case check_args(Args) of
-	ok ->
-	    [FileName] = Args,
-	    ?PRIM_FILE:read_file_info(FileName);
-	Error ->
-	    Error
-    end.
+    read_file_info(Name, [raw]).
 
 %% Obsolete, undocumented, local node only, don't use!.
 %% XXX to be removed.
 raw_write_file_info(Name, #file_info{} = Info) ->
-    Args = [file_name(Name)],
-    case check_args(Args) of
-	ok ->
-	    [FileName] = Args,
-	    ?PRIM_FILE:write_file_info(FileName, Info);
-	Error ->
-	    Error
-    end.
+    write_file_info(Name, Info, [raw]).
 
 %%%-----------------------------------------------------------------
 %%% File io server functions.
diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl
index f6d6cd94ab..f97bc3baf4 100644
--- a/lib/kernel/test/file_SUITE.erl
+++ b/lib/kernel/test/file_SUITE.erl
@@ -1236,9 +1236,10 @@ file_info_basic_file(Config) when is_list(Config) ->
 
     %% Test that the file has the expected attributes.
     %% The times are tricky, so we will save them to a separate test case.
-    ?line {ok,#file_info{size=Size,type=Type,access=Access,
-			 atime=AccessTime,mtime=ModifyTime}} =
-	?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo} = ?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo} = ?FILE_MODULE:read_file_info(Name, [raw]),
+    #file_info{size=Size,type=Type,access=Access,
+                         atime=AccessTime,mtime=ModifyTime} = FileInfo,
     ?line io:format("Access ~p, Modify ~p", [AccessTime, ModifyTime]),
     ?line Size = 7,
     ?line Type = regular,
@@ -1280,9 +1281,10 @@ file_info_basic_directory(Config) when is_list(Config) ->
     test_server:timetrap_cancel(Dog).
 
 test_directory(Name, ExpectedAccess) ->
-    ?line {ok,#file_info{size=Size,type=Type,access=Access,
-			 atime=AccessTime,mtime=ModifyTime}} =
-	?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo} = ?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo} = ?FILE_MODULE:read_file_info(Name, [raw]),
+    #file_info{size=Size,type=Type,access=Access,
+               atime=AccessTime,mtime=ModifyTime} = FileInfo,
     ?line io:format("Testing directory ~s", [Name]),
     ?line io:format("Directory size is ~p", [Size]),
     ?line io:format("Access ~p", [Access]),
@@ -1307,11 +1309,11 @@ file_info_bad(doc) -> [];
 file_info_bad(Config) when is_list(Config) ->
     ?line Dog = test_server:timetrap(test_server:seconds(5)),
     ?line RootDir = filename:join([?config(priv_dir, Config)]),
-    ?line {error, enoent} = 
-	?FILE_MODULE:read_file_info(
-	  filename:join(RootDir, 
-			atom_to_list(?MODULE)++ "_nonexistent")),
+    FileName = filename:join(RootDir, atom_to_list(?MODULE) ++ "_nonexistent"),
+    {error,enoent} = ?FILE_MODULE:read_file_info(FileName),
+    {error,enoent} = ?FILE_MODULE:read_file_info(FileName, [raw]),
     ?line {error, enoent} = ?FILE_MODULE:read_file_info(""),
+    {error, enoent} = ?FILE_MODULE:read_file_info("", [raw]),
     ?line [] = flush(),
     ?line test_server:timetrap_cancel(Dog),
     ok.
@@ -1346,8 +1348,9 @@ file_info_int(Config) ->
     ?line io:put_chars(Fd1,"foo"),
 
     %% check that the file got a modify date max a few seconds away from now
-    ?line {ok,#file_info{type=regular,atime=AccTime1,mtime=ModTime1}} =
-	?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo1} = ?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo1} = ?FILE_MODULE:read_file_info(Name, [raw]),
+    #file_info{type=regular,atime=AccTime1,mtime=ModTime1} = FileInfo1,
     ?line Now = erlang:localtime(), %???
     ?line io:format("Now ~p",[Now]),
     ?line io:format("Open file Acc ~p Mod ~p",[AccTime1,ModTime1]),
@@ -1363,9 +1366,10 @@ file_info_int(Config) ->
 
     %% close the file, and watch the modify date change
     ?line ok = ?FILE_MODULE:close(Fd1),
-    ?line {ok,#file_info{size=Size,type=regular,access=Access,
-			 atime=AccTime2,mtime=ModTime2}} =
-	?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo2} = ?FILE_MODULE:read_file_info(Name),
+    {ok,FileInfo2} = ?FILE_MODULE:read_file_info(Name, [raw]),
+    #file_info{size=Size,type=regular,access=Access,
+               atime=AccTime2,mtime=ModTime2} = FileInfo2,
     ?line io:format("Closed file Acc ~p Mod ~p",[AccTime2,ModTime2]),
     ?line true = time_dist(ModTime1,ModTime2) >= 0,
 
@@ -1374,9 +1378,10 @@ file_info_int(Config) ->
     ?line Access = read_write,
 
     %% Do some directory checking
-    ?line {ok,#file_info{size=DSize,type=directory,access=DAccess,
-			 atime=AccTime3,mtime=ModTime3}} =
-	?FILE_MODULE:read_file_info(RootDir),
+    {ok,FileInfo3} = ?FILE_MODULE:read_file_info(RootDir),
+    {ok,FileInfo3} = ?FILE_MODULE:read_file_info(RootDir, [raw]),
+    #file_info{size=DSize,type=directory,access=DAccess,
+               atime=AccTime3,mtime=ModTime3} = FileInfo3,
     %% this dir was modified only a few secs ago
     ?line io:format("Dir Acc ~p; Mod ~p; Now ~p", [AccTime3, ModTime3, Now]),
     ?line true = abs(time_dist(Now,ModTime3)) < 5,
@@ -1449,6 +1454,12 @@ file_write_file_info(Config) when is_list(Config) ->
     ?line ?FILE_MODULE:write_file_info(Name1, #file_info{mode=8#400}),
     ?line {error, eacces} = ?FILE_MODULE:write_file(Name1, "hello again"),
 
+    %% Same with raw.
+    ?FILE_MODULE:write_file_info(Name1, #file_info{mode=8#600}, [raw]),
+    ok = ?FILE_MODULE:write_file(Name1, "hello again"),
+    ?FILE_MODULE:write_file_info(Name1, #file_info{mode=8#400}, [raw]),
+    {error,eacces} = ?FILE_MODULE:write_file(Name1, "hello again"),
+
     %% Write the times again.
     %% Note: Seconds must be even; see note in file_info_times/1.
 
@@ -2650,7 +2661,9 @@ make_link(Config) when is_list(Config) ->
 		%% since they are not used on symbolic links.
 		
 		?line {ok, Info} = ?FILE_MODULE:read_link_info(Name),
+                {ok,Info} = ?FILE_MODULE:read_link_info(Name, [raw]),
 		?line {ok, Info} = ?FILE_MODULE:read_link_info(Alias),
+                {ok,Info} = ?FILE_MODULE:read_link_info(Alias, [raw]),
 		?line #file_info{links = 2, type = regular} = Info,
 		?line {error, eexist} = 
 		    ?FILE_MODULE:make_link(Name, Alias),
@@ -2670,6 +2683,7 @@ read_link_info_for_non_link(Config) when is_list(Config) ->
 
     ?line {ok, #file_info{type=directory}} = 
 	?FILE_MODULE:read_link_info("."),
+    {ok, #file_info{type=directory}} = ?FILE_MODULE:read_link_info(".", [raw]),
 		  
     ?line [] = flush(),
     ?line test_server:timetrap_cancel(Dog),
@@ -2700,11 +2714,15 @@ symlinks(Config) when is_list(Config) ->
 		{skipped, "Windows user not privileged to create symlinks"};
 	    ok ->
 		?line {ok, Info1} = ?FILE_MODULE:read_file_info(Name),
+                {ok,Info1} = ?FILE_MODULE:read_file_info(Name, [raw]),
 		?line {ok, Info1} = ?FILE_MODULE:read_file_info(Alias),
+                {ok,Info1} = ?FILE_MODULE:read_file_info(Alias, [raw]),
 		?line {ok, Info1} = ?FILE_MODULE:read_link_info(Name),
+                {ok,Info1} = ?FILE_MODULE:read_link_info(Name, [raw]),
 		?line #file_info{links = 1, type = regular} = Info1,
 		
 		?line {ok, Info2} = ?FILE_MODULE:read_link_info(Alias),
+                {ok,Info2} = ?FILE_MODULE:read_link_info(Alias, [raw]),
 		?line #file_info{links=1, type=symlink} = Info2,
 		?line {ok, Name} = ?FILE_MODULE:read_link(Alias),
 		{ok, Name} = ?FILE_MODULE:read_link_all(Alias),