[newlib-cygwin] Cygwin: path_conv: add PATH_RESOLVE_PROCFD path_types flag

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=ba12614f79347e6d67af79b7369869890aa5c741

commit ba12614f79347e6d67af79b7369869890aa5c741
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Sun Jan 6 20:13:52 2019 +0100

    Cygwin: path_conv: add PATH_RESOLVE_PROCFD path_types flag
    
    path_conv now sets the PATH_RESOLVE_PROCFD flag in path_flags if
    the PC_SYM_NOFOLLOW_PROCFD pathconv_arg flag has been set on input
    *and* the file is actually a proc fd symlink.
    
    Add matching path_conv::follow_fd_symlink method for checking and
    use it in open(2).
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/path.cc     | 5 ++++-
 winsup/cygwin/path.h      | 2 ++
 winsup/cygwin/syscalls.cc | 8 ++++----
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 0a68671..158f1e5 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -850,7 +850,10 @@ path_conv::check (const char *src, unsigned opt,
 		      case virt_fdsymlink:
 			/* Allow open/linkat to do the right thing. */
 			if (opt & PC_SYM_NOFOLLOW_PROCFD)
-			  opt &= ~PC_SYM_FOLLOW;
+			  {
+			    opt &= ~PC_SYM_FOLLOW;
+			    sym.path_flags |= PATH_RESOLVE_PROCFD;
+			  }
 			/*FALLTHRU*/
 		      case virt_symlink:
 			goto is_virtual_symlink;
diff --git a/winsup/cygwin/path.h b/winsup/cygwin/path.h
index 69da8fd..af10321 100644
--- a/winsup/cygwin/path.h
+++ b/winsup/cygwin/path.h
@@ -69,6 +69,7 @@ enum path_types
   PATH_REP		= _BIT ( 3),
   PATH_SYMLINK		= _BIT ( 4),
   PATH_SOCKET		= _BIT ( 5),
+  PATH_RESOLVE_PROCFD	= _BIT ( 6),
   PATH_DONT_USE		= _BIT (31)	/* conversion to signed happens. */
 };
 
@@ -192,6 +193,7 @@ class path_conv
   int iscygexec () const {return mount_flags & MOUNT_CYGWIN_EXEC;}
   int isopen () const {return path_flags & PATH_OPEN;}
   int isctty_capable () const {return path_flags & PATH_CTTY;}
+  int follow_fd_symlink () const {return path_flags & PATH_RESOLVE_PROCFD;}
   void set_cygexec (bool isset)
   {
     if (isset)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 9f43512..60f66a6 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1398,13 +1398,13 @@ open (const char *unix_path, int flags, ...)
       if (fd < 0)
 	__leave;		/* errno already set */
 
+      int opt = PC_OPEN | PC_SYM_NOFOLLOW_PROCFD;
+      opt |= (flags & (O_NOFOLLOW | O_EXCL)) ? PC_SYM_NOFOLLOW
+					     : PC_SYM_FOLLOW;
       /* This is a temporary kludge until all utilities can catch up
 	 with a change in behavior that implements linux functionality:
 	 opening a tty should not automatically cause it to become the
 	 controlling tty for the process.  */
-      int opt = PC_OPEN | PC_SYM_NOFOLLOW_PROCFD;
-      opt |= (flags & (O_NOFOLLOW | O_EXCL)) ? PC_SYM_NOFOLLOW
-					     : PC_SYM_FOLLOW;
       if (!(flags & O_NOCTTY) && fd > 2 && myself->ctty != -2)
 	{
 	  flags |= O_NOCTTY;
@@ -1472,7 +1472,7 @@ open (const char *unix_path, int flags, ...)
 	  fh = fh_file;
 	}
 
-      if (fh->dev () == FH_PROCESSFD)
+      if (fh->dev () == FH_PROCESSFD && fh->pc.follow_fd_symlink ())
 	{
 	  /* Reopen file by descriptor */
 	  fh_file = fh->fd_reopen (flags);