From bd3f4f05bb6dafdedbae5671ee50c769a3560021 Mon Sep 17 00:00:00 2001
From: Andre Nathan <andre@digirati.com.br>
Date: Thu, 18 Apr 2019 17:45:04 -0300
Subject: file: allow open/2 to work on directories

This is useful mainly to ensure that a new file has been persisted
to disk by calling file:sync/1 or file:datasync/1 on file's parent
directory.
---
 lib/kernel/doc/src/file.xml    | 10 ++++++++--
 lib/kernel/src/file.erl        |  4 ++--
 lib/kernel/test/file_SUITE.erl | 11 +++++++++++
 3 files changed, 21 insertions(+), 4 deletions(-)

(limited to 'lib')

diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index fc25e83d40..b3e8149cc2 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -939,6 +939,10 @@ f.txt:  {person, "kalle", 25}.
             support for POSIX <c>O_SYNC</c> or equivalent, use of the <c>sync</c>
 	    flag causes <c>open</c> to return <c>{error, enotsup}</c>.</p>
           </item>
+          <tag><c>directory</c></tag>
+          <item>
+            <p>Allows <c>open</c> to work on directories.</p>
+          </item>
         </taglist>
         <p>Returns:</p>
         <taglist>
@@ -985,8 +989,10 @@ f.txt:  {person, "kalle", 25}.
           </item>
           <tag><c>enotdir</c></tag>
           <item>
-            <p>A component of the filename is not a directory. On some
-              platforms, <c>enoent</c> is returned instead.</p>
+            <p>A component of the filename is not a directory, or the
+              filename itself is not a directory if <c>directory</c>
+              mode was specified. On some platforms, <c>enoent</c> is
+              returned instead.</p>
           </item>
           <tag><c>enospc</c></tag>
           <item>
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 1d4e37196c..a0616da670 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -460,7 +460,7 @@ raw_write_file_info(Name, #file_info{} = Info) ->
 -spec open(File, Modes) -> {ok, IoDevice} | {error, Reason} when
       File :: Filename | iodata(),
       Filename :: name_all(),
-      Modes :: [mode() | ram],
+      Modes :: [mode() | ram | directory],
       IoDevice :: io_device(),
       Reason :: posix() | badarg | system_limit.
 
@@ -1143,7 +1143,7 @@ path_script(Path, File, Bs) ->
              {ok, IoDevice, FullName} | {error, Reason} when
       Path :: [Dir :: name_all()],
       Filename :: name_all(),
-      Modes :: [mode()],
+      Modes :: [mode() | directory],
       IoDevice :: io_device(),
       FullName :: filename_all(),
       Reason :: posix() | badarg | system_limit.
diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl
index 3bc8e6e828..21aaefa654 100644
--- a/lib/kernel/test/file_SUITE.erl
+++ b/lib/kernel/test/file_SUITE.erl
@@ -987,6 +987,14 @@ new_modes(Config) when is_list(Config) ->
 	     ok
      end,
 
+     % open directory
+     {ok, Fd9} = ?FILE_MODULE:open(NewDir, [directory]),
+     ok = ?FILE_MODULE:close(Fd9),
+
+     % open raw directory
+     {ok, Fd10} = ?FILE_MODULE:open(NewDir, [raw, directory]),
+     ok = ?FILE_MODULE:close(Fd10),
+
      [] = flush(),
      ok.
 
@@ -1236,6 +1244,9 @@ open_errors(Config) when is_list(Config) ->
     {error, E4} = ?FILE_MODULE:open(DataDirSlash, [write]),
     {eisdir,eisdir,eisdir,eisdir} = {E1,E2,E3,E4},
 
+    Real = filename:join(DataDir, "realmen.html"),
+    {error, enotdir} = ?FILE_MODULE:open(Real, [directory]),
+
     [] = flush(),
     ok.
 
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