[newlib-cygwin] Don't generate Windows native symlinks targeting Cygwin-only targets

[Corinna Vinschen <corinna at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=8cdd7bad219ba2657e381bd0d716594c50a6ef62

commit 8cdd7bad219ba2657e381bd0d716594c50a6ef62
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Wed Nov 18 19:12:37 2015 +0100

    Don't generate Windows native symlinks targeting Cygwin-only targets
    
    	* path.cc (symlink_native): Don't generate native symlink targeting
    	Cygwin special file.  Inform the caller.
    	(symlink_worker): Don;t bail out in WSYM_nativestrict case if the
    	target is a Cygwin special file.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/ChangeLog |  7 +++++++
 winsup/cygwin/path.cc   | 10 ++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 37d2934..b562969 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,5 +1,12 @@
 2015-11-18  Corinna Vinschen  <corinna@vinschen.de>
 
+	* path.cc (symlink_native): Don't generate native symlink targeting
+	Cygwin special file.  Inform the caller.
+	(symlink_worker): Don;t bail out in WSYM_nativestrict case if the
+	target is a Cygwin special file.
+
+2015-11-18  Corinna Vinschen  <corinna@vinschen.de>
+
 	* lc_msg.h: Regenerate.
 
 2015-11-17  Yaakov Selkowitz  <yselkowi@redhat.com>
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 035872d..88080e1 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -1700,6 +1700,11 @@ symlink_native (const char *oldpath, path_conv &win32_newpath)
       SetLastError (ERROR_FILE_NOT_FOUND);
       return -1;
     }
+  /* Don't allow native symlinks to Cygwin special files.  However, the
+     caller shoud know because this case shouldn't be covered by the
+     default "nativestrict" behaviour, so we use a special return code. */
+  if (win32_oldpath.isspecial ())
+    return -2;
   /* Convert native paths to Win32 UNC paths. */
   final_newpath = win32_newpath.get_nt_native_path ();
   final_newpath->Buffer[1] = L'\\';
@@ -1843,8 +1848,9 @@ symlink_worker (const char *oldpath, const char *newpath, bool isdevice)
 	  res = symlink_native (oldpath, win32_newpath);
 	  if (!res)
 	    __leave;
-	  /* Strictly native?  Too bad. */
-	  if (wsym_type == WSYM_nativestrict)
+	  /* Strictly native?  Too bad, unless the target is a Cygwin
+	     special file. */
+	  if (res == -1 && wsym_type == WSYM_nativestrict)
 	    {
 	      __seterrno ();
 	      __leave;