Linux: Require properly configured /dev/pts for PTYs

Current systems do not have BSD terminals, so the fallback code in
posix_openpt/getpt does not do anything.  Also remove the file system
check for /dev/pts.  Current systems always have a devpts file system
mounted there if /dev/ptmx exists.

grantpt is now essentially a no-op.  It only verifies that the
argument is a ptmx-descriptor.  Therefore, this change indirectly
addresses bug 24941.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

1 files changed, 3 insertions, 8 deletions

diff --git a/INSTALL b/INSTALL
index 41f5d6b708..2b00f80df5 100644
--- a/INSTALL
+++ b/INSTALL
@@ -188,14 +188,9 @@ if 'CFLAGS' is specified it must enable optimization.  For example:
 '--enable-pt_chown'
      The file 'pt_chown' is a helper binary for 'grantpt' (*note
      Pseudo-Terminals: Allocation.) that is installed setuid root to fix
-     up pseudo-terminal ownership.  It is not built by default because
-     systems using the Linux kernel are commonly built with the 'devpts'
-     filesystem enabled and mounted at '/dev/pts', which manages
-     pseudo-terminal ownership automatically.  By using
-     '--enable-pt_chown', you may build 'pt_chown' and install it setuid
-     and owned by 'root'.  The use of 'pt_chown' introduces additional
-     security risks to the system and you should enable it only if you
-     understand and accept those risks.
+     up pseudo-terminal ownership on GNU/Hurd.  It is not required on
+     GNU/Linux, and the GNU C Library will not use the installed
+     'pt_chown' program when configured with '--enable-pt_chown'.
 
 '--disable-werror'
      By default, the GNU C Library is built with '-Werror'.  If you wish