From eae496a72e270fd7af411714738e99a7fadfd19b Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Wed, 6 Sep 2017 17:00:14 +0200
Subject: Don't allow null in filenames

---
 lib/kernel/doc/src/file.xml | 38 ++++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

(limited to 'lib/kernel/doc/src')

diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index b674b3ca93..593bee74fe 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -59,7 +59,7 @@
     terminal supports UTF-8, otherwise <c>latin1</c>. The default can
     be overridden using <c>+fnl</c> (to force <c>latin1</c> mode)
     or <c>+fnu</c> (to force <c>utf8</c> mode) when starting
-    <seealso marker="erts:erl"><c>erts:erl</c></seealso>.</p>
+    <seealso marker="erts:erl"><c>erl</c></seealso>.</p>
 
     <p>On operating systems with transparent naming, files can be
     inconsistently named, for example, some files are encoded in UTF-8 while
@@ -81,6 +81,22 @@
 
     <p>See also section <seealso marker="stdlib:unicode_usage#notes-about-raw-filenames">Notes About Raw Filenames</seealso> in the STDLIB User's Guide.</p>
 
+    <note><p>
+      File operations used to accept filenames containing
+      null characters (integer value zero). This caused
+      the name to be truncated at the first null character.
+      Filenames containing null characters inside the filename
+      are now <em>rejected</em> and will cause primitive
+      file operations fail.
+    </p></note>
+    <warning><p>
+      Currently null characters at the end of the filename
+      will be accepted by primitive file operations. Such
+      filenames are however still documented as invalid. The
+      implementation will also change in the future and
+      reject such filenames.
+    </p></warning>
+
   </description>
 
   <datatypes>
@@ -96,9 +112,21 @@
     </datatype>
     <datatype>
       <name name="filename"/>
+      <desc>
+        <p>
+	  See also the documentation of the
+	  <seealso marker="#type-name_all"><c>name_all()</c></seealso> type.
+	</p>
+      </desc>
     </datatype>
     <datatype>
       <name name="filename_all"/>
+      <desc>
+        <p>
+	  See also the documentation of the
+	  <seealso marker="#type-name_all"><c>name_all()</c></seealso> type.
+	</p>
+      </desc>
     </datatype>
     <datatype>
       <name name="io_device"/>
@@ -112,21 +140,23 @@
       <name name="name"/>
       <desc>
         <p>If VM is in Unicode filename mode, <c>string()</c> and <c>char()</c>
-          are allowed to be &gt; 255.
+          are allowed to be &gt; 255. See also the documentation of the
+	  <seealso marker="#type-name_all"><c>name_all()</c></seealso> type.
         </p>
       </desc>
     </datatype>
     <datatype>
       <name name="name_all"/>
       <desc>
-        <p>If VM is in Unicode filename mode, <c>string()</c> and <c>char()</c>
+        <p>If VM is in Unicode filename mode, characters
           are allowed to be &gt; 255.
           <c><anno>RawFilename</anno></c> is a filename not subject to
           Unicode translation,
           meaning that it can contain characters not conforming to
           the Unicode encoding expected from the file system
           (that is, non-UTF-8 characters although the VM is started
-          in Unicode filename mode).
+          in Unicode filename mode). Null characters (integer value zero)
+	  are <em>not</em> allowed in filenames (not even at the end).
         </p>
       </desc>
     </datatype>
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