[WIP] BZ #14361: POSIX vs. BSD and the `ioctl' interface.

[Carlos O'Donell <carlos_odonell at mentor dot com>]

Roland,

In 1993 you changed ioctl's second argument to be `unsigned long int' to
match BSD 4.4. Here is the excerpt from ChangeLog.2:
...
Fri Dec 17 15:05:58 1993  Roland McGrath  (roland@churchy.gnu.ai.mit.edu)

        * misc/sys/ioctl.h (__ioctl, ioctl): Make second arg `unsigned
        long int' instead of `int' (4.4 uses unsigned long).
...

In BZ #14362 Linus Torvalds points out that `unsigned long int' as a
second argument doesn't match SuS. I verified that is still the case in 
POSIX 2008/SUSv4.

Worse it doesn't even match our own documentation in manual/llio.texi:
...
@comment sys/ioctl.h
@comment BSD
@deftypefun int ioctl (int @var{filedes}, int @var{command}, @dots{})
...
which also uses `int' for the second argument (written by Ulrich in 1998).

My worries are:

(a) POSIX conformance.

and

(b) Backwards compatibility with an interface that has been around
    since 1993.

Can we somehow juggle (a) and (b)?

Comments?

Just to frame the discussion I wrote up a WIP patch and included some 
FIXME's for Tilera and MIPS which expect certain behaviour from our 
ioctl interface:

2012-07-23  Carlos O'Donell  <carlos_odonell@mentor.com>

	[BZ #14362]
	* include/sys/ioctl.h: Use `int' for __request argument
	of function __ioctl.
	* misc/ioctl.c (__ioctl): Likewise.
	* misc/sys/ioctl.h: Likewise.
	* sysdeps/mach/hurd/ioctl.c (__ioctl): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/ioctl.c (__ioctl): Likewise.
	* ports/sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S:
	Add FIXME.
	* ports/sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S:
	Add FIXME.

diff --git a/include/sys/ioctl.h b/include/sys/ioctl.h
index ebadd52..883c12e 100644
--- a/include/sys/ioctl.h
+++ b/include/sys/ioctl.h
@@ -2,5 +2,5 @@
 #include <misc/sys/ioctl.h>
 
 /* Now define the internal interfaces.  */
-extern int __ioctl (int __fd, unsigned long int __request, ...);
+extern int __ioctl (int __fd, int __request, ...);
 #endif
diff --git a/misc/ioctl.c b/misc/ioctl.c
index 616ee2d..a5d4a81 100644
--- a/misc/ioctl.c
+++ b/misc/ioctl.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991, 93, 94, 95, 96, 97 Free Software Foundation, Inc.
+/* Copyright (C) 1991-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -23,7 +23,7 @@
 int
 __ioctl (fd, request)
      int fd;
-     unsigned long int request;
+     int request;
 {
   __set_errno (ENOSYS);
   return -1;
diff --git a/misc/sys/ioctl.h b/misc/sys/ioctl.h
index c49c4ab..8340a0a 100644
--- a/misc/sys/ioctl.h
+++ b/misc/sys/ioctl.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991, 92, 93, 94, 96, 98, 99 Free Software Foundation, Inc.
+/* Copyright (C) 1991-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -38,7 +38,7 @@ __BEGIN_DECLS
 /* Perform the I/O control operation specified by REQUEST on FD.
    One argument may follow; its presence and type depend on REQUEST.
    Return value depends on REQUEST.  Usually -1 indicates error.  */
-extern int ioctl (int __fd, unsigned long int __request, ...) __THROW;
+extern int ioctl (int __fd, int __request, ...) __THROW;
 
 __END_DECLS
 
diff --git a/ports/sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S b/ports/sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S
index 3ff0d0e..1cb3541 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S
+++ b/ports/sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S
@@ -1,4 +1,4 @@
-/* Copyright 2003, 2005 Free Software Foundation, Inc.
+/* Copyright 2003-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -19,6 +19,9 @@
 
 #include <sys/asm.h>
 
+/* FIXME: Now that the userspace API claims that the argument
+          if of type `int' does this code need updating?  */
+
 /* Sign-extend the ioctl number, since the kernel wants it as a
    sign-extended 32-bit value, but our prototype is that of a long.  */
 
diff --git a/ports/sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S b/ports/sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S
index e966c4d..b61592c 100644
--- a/ports/sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S
+++ b/ports/sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S
@@ -1,4 +1,4 @@
-/* Copyright (C) 2011 Free Software Foundation, Inc.
+/* Copyright (C) 2011-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
 
@@ -16,6 +16,8 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
+/* FIXME: Now that the userspace API claims that the argument
+          if of type `int' does this code need updating?  */
 
 /* TILE-Gx specifies that "unsigned int" is sign extended in the high
    32 bits.  But since the userspace API claims to be "unsigned long",
diff --git a/sysdeps/mach/hurd/ioctl.c b/sysdeps/mach/hurd/ioctl.c
index 543d437..6aeeca4 100644
--- a/sysdeps/mach/hurd/ioctl.c
+++ b/sysdeps/mach/hurd/ioctl.c
@@ -36,7 +36,7 @@
 /* Perform the I/O control operation specified by REQUEST on FD.
    The actual type and use of ARG and the return value depend on REQUEST.  */
 int
-__ioctl (int fd, unsigned long int request, ...)
+__ioctl (int fd, int request, ...)
 {
 #ifdef MACH_MSG_TYPE_CHAR
   /* Map individual type fields to Mach IPC types.  */
diff --git a/sysdeps/unix/sysv/linux/powerpc/ioctl.c b/sysdeps/unix/sysv/linux/powerpc/ioctl.c
index e8f5d16..b470ae8 100644
--- a/sysdeps/unix/sysv/linux/powerpc/ioctl.c
+++ b/sysdeps/unix/sysv/linux/powerpc/ioctl.c
@@ -25,7 +25,7 @@
    using the new-style struct termios, and translate them to old-style.  */
 
 int
-__ioctl (int fd, unsigned long int request, ...)
+__ioctl (int fd, int request, ...)
 {
   void *arg;
   va_list ap;
---

Cheers,
Carlos.
-- 
Carlos O'Donell
Mentor Graphics / CodeSourcery
carlos_odonell@mentor.com
carlos@codesourcery.com
+1 (613) 963 1026