[PATCH 3/3] Add winsymlinks:wslstrict

[Jon Turney <jon.turney@dronecode.org.uk>]

Add winsymlinks:wslstrict, so we have a spanning set of values for
winsymlinks.
---
 winsup/cygwin/environ.cc |  3 +++
 winsup/cygwin/globals.cc |  1 +
 winsup/cygwin/path.cc    |  7 +++++++
 winsup/doc/cygwinenv.xml | 15 ++++++++++++++-
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index a7a52feeb..b53b018fd 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -88,6 +88,9 @@ set_winsymlinks (const char *buf)
   else if (ascii_strncasematch (buf, "native", 6))
     allow_winsymlinks = ascii_strcasematch (buf + 6, "strict")
 			? WSYM_nativestrict : WSYM_native;
+  else if (ascii_strncasematch (buf, "wsl", 3))
+    allow_winsymlinks = ascii_strcasematch (buf + 3, "strict")
+			? WSYM_wslstrict : WSYM_default;
 }
 
 /* The structure below is used to set up an array which is used to
diff --git a/winsup/cygwin/globals.cc b/winsup/cygwin/globals.cc
index b15980bb3..9459d8bcb 100644
--- a/winsup/cygwin/globals.cc
+++ b/winsup/cygwin/globals.cc
@@ -59,6 +59,7 @@ enum winsym_t
   WSYM_nativestrict,
   WSYM_nfs,
   WSYM_magic,
+  WSYM_wslstrict,
 };
 
 exit_states NO_COPY exit_state;
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index edb3b27ee..57ec8be72 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -2062,12 +2062,19 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 	  wsym_type = WSYM_default;
 	  fallthrough;
 	case WSYM_default:
+	case WSYM_wslstrict:
 	  if (win32_newpath.fs_flags () & FILE_SUPPORTS_REPARSE_POINTS)
 	    {
 	      res = symlink_wsl (oldpath, win32_newpath);
 	      if (!res)
 		__leave;
 	    }
+	  /* Strictly wsl? */
+	  if (wsym_type == WSYM_wslstrict)
+	    {
+	      __seterrno ();
+	      __leave;
+	    }
 	  /* On FSes not supporting reparse points, or in case of an error
 	     creating the WSL symlink, fall back to creating the plain old
 	     SYSTEM file symlink. */
diff --git a/winsup/doc/cygwinenv.xml b/winsup/doc/cygwinenv.xml
index 496088292..b98e27243 100644
--- a/winsup/doc/cygwinenv.xml
+++ b/winsup/doc/cygwinenv.xml
@@ -76,7 +76,7 @@ in addition to the normal UNIX argv list.  Defaults to not set.</para>
 </listitem>
 
 <listitem>
-<para><envar>winsymlinks:{lnk,magic,native,nativestrict}</envar></para>
+<para><envar>winsymlinks:{lnk,magic,native,nativestrict,wsl,wslstrict}</envar></para>
 
 <itemizedlist mark="square">
 <listitem>
@@ -105,6 +105,19 @@ with <literal>winsymlinks:native</literal>, while with
 <literal>winsymlinks:nativestrict</literal> the <literal>symlink(2)</literal>
 system call will immediately fail.</para>
 </listitem>
+
+<listitem>
+<para>If set to <literal>winsymlinks:wsl</literal> or
+<literal>winsymlinks:wslstrict</literal>, Cygwin creates symlinks as special
+reparse points, defined by WSL.</para>
+
+<para>With <literal>winsymlinks:wsl</literal>, if Cygwin fails to create a WSL
+symlink for some reason, it will fall back to creating a Cygwin magic cookie
+symlink, while with <literal>winsymlinks:wslstrict</literal> the
+<literal>symlink(2)</literal> system call will immediately fail.</para>
+
+<para><literal>winsymlinks:wsl</literal> is the default behaviour.</para>
+</listitem>
 </itemizedlist>
 
 <para>For more information on symbolic links, see
-- 
2.32.0