new module 'tcgetsid'

[Bruno Haible]

Here comes the module 'tcgetsid'. Its main use is that on OpenBSD and
MacOS X 10.3 the functionality is available through an ioctl() but
the function is not present in libc.

Note that tcgetsid(fd) is sometimes, but not always, the same as tcgetpgrp(fd).


2010-09-16  Bruno Haible  <address@hidden>

        New module 'tcgetsid'.
        * lib/tcgetsid.c: New file.
        * m4/tcgetsid.m4: New file.
        * modules/tcgetsid: New file.
        * modules/termios (Depends-on): Add c++defs, warn-on-use.
        (Makefile.am): Ensure c++defs.h, warn-on-use.h get included. Substitute
        GNULIB_TCGETSID, HAVE_TCGETSID.
        * lib/termios.in.h: Include <sys/types.h>.
        (tcgetsid): New declaration.
        * m4/termios_h.m4 (gl_TERMIOS_H): Check whether tcgetsid is declared.
        (gl_TERMIOS_H_DEFAULTS): Initialize GNULIB_TCGETSID, HAVE_TCGETSID.
        * doc/posix-functions/tcgetsid.texi: Mention the new module.
        * tests/test-termios-c++.cc: Check GNULIB_NAMESPACE::tcgetsid.

=============================== lib/tcgetsid.c ===============================
/* Determine the session ID of the controlling terminal of the current process.
   Copyright (C) 2010 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

#define USE_OLD_TTY /* needed on OpenBSD 4.5, so that TIOCGSID gets defined */

/* Specification.  */
#include <termios.h>

#include <errno.h>
#include <sys/ioctl.h>

pid_t
tcgetsid (int fd)
{
#ifdef TIOCGSID /* MacOS X, OpenBSD */
  int sid;

  if (ioctl (fd, TIOCGSID, &sid) < 0)
    return -1; /* errno is set here */

  return sid;
#else /* FreeBSD, Cygwin, mingw */
  errno = ENOSYS;
  return -1;
#endif
}
=============================== m4/tcgetsid.m4 ===============================
# tcgetsid.m4 serial 1
dnl Copyright (C) 2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_TCGETSID],
[
  AC_REQUIRE([gl_TERMIOS_H_DEFAULTS])

  dnl Persuade glibc <termios.h> to declare tcgetsid().
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_CHECK_FUNCS([tcgetsid])
  if test $ac_cv_func_tcgetsid = no; then
    HAVE_TCGETSID=0
    AC_LIBOBJ([tcgetsid])
    gl_PREREQ_TCGETSID
  fi
])

# Prerequisites of lib/tcgetsid.c.
AC_DEFUN([gl_PREREQ_TCGETSID], [
  :
])
============================== modules/tcgetsid ==============================
Description:
tcgetsid() function: Determine the session ID of the controlling terminal of
the current process.

Files:
lib/tcgetsid.c
m4/tcgetsid.m4

Depends-on:
termios
extensions
sys_ioctl

configure.ac:
gl_FUNC_TCGETSID
gl_TERMIOS_MODULE_INDICATOR([tcgetsid])

Makefile.am:

Include:
<termios.h>

License:
LGPL

Maintainer:
Bruno Haible
==============================================================================
--- doc/posix-functions/tcgetsid.texi.orig      Fri Sep 17 03:11:00 2010
+++ doc/posix-functions/tcgetsid.texi   Fri Sep 17 02:59:46 2010
@@ -4,15 +4,17 @@
 
 POSIX specification:@* 
@url{http://www.opengroup.org/onlinepubs/9699919799/functions/tcgetsid.html}
 
-Gnulib module: ---
+Gnulib module: tcgetsid
 
 Portability problems fixed by Gnulib:
 @itemize
+This function is missing on some platforms:
+MacOS X 10.3, FreeBSD 6.0, OpenBSD 4.5, Cygwin, mingw, Interix 3.5, BeOS.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on some platforms:
-MacOS X 10.3, FreeBSD 6.0, OpenBSD 3.8, Cygwin, mingw, Interix 3.5, BeOS.
+This function always fails on some platforms:
+FreeBSD 6.0, Cygwin, mingw, Interix 3.5, BeOS.
 @end itemize
--- lib/termios.in.h.orig       Fri Sep 17 03:11:00 2010
+++ lib/termios.in.h    Fri Sep 17 02:57:44 2010
@@ -27,8 +27,36 @@
 #ifndef _GL_TERMIOS_H
 #define _GL_TERMIOS_H
 
+#if @GNULIB_TCGETSID@
+/* Get pid_t.  */
+# include <sys/types.h>
+#endif
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
 
 /* Declare overridden functions.  */
 
+#if @GNULIB_TCGETSID@
+/* Return the session ID of the controlling terminal of the current process.
+   The argument is a descriptor if this controlling terminal.
+   Return -1, with errno set, upon failure.  errno = ENOSYS means that the
+   function is unsupported.  */
+# if address@hidden@
+_GL_FUNCDECL_SYS (tcgetsid, pid_t, (int fd));
+# endif
+_GL_CXXALIAS_SYS (tcgetsid, pid_t, (int fd));
+_GL_CXXALIASWARN (tcgetsid);
+#elif defined GNULIB_POSIXCHECK
+# undef tcgetsid
+# if HAVE_RAW_DECL_TCGETSID
+_GL_WARN_ON_USE (tcgetsid, "tcgetsid is not portable - "
+                 "use gnulib module tcgetsid for portability");
+# endif
+#endif
+
+
 #endif /* _GL_TERMIOS_H */
 #endif /* _GL_TERMIOS_H */
--- m4/termios_h.m4.orig        Fri Sep 17 03:11:00 2010
+++ m4/termios_h.m4     Fri Sep 17 02:43:50 2010
@@ -11,6 +11,12 @@
   AC_REQUIRE([gl_TERMIOS_H_DEFAULTS])
 
   gl_CHECK_NEXT_HEADERS([termios.h])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, and which is not
+  dnl guaranteed by C89.
+  gl_WARN_ON_USE_PREPARE([[#include <termios.h>]],
+    [tcgetsid])
 ])
 
 AC_DEFUN([gl_TERMIOS_MODULE_INDICATOR],
@@ -24,4 +30,7 @@
 
 AC_DEFUN([gl_TERMIOS_H_DEFAULTS],
 [
+  GNULIB_TCGETSID=0;      AC_SUBST([GNULIB_TCGETSID])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_TCGETSID=1;        AC_SUBST([HAVE_TCGETSID])
 ])
--- modules/termios.orig        Fri Sep 17 03:11:00 2010
+++ modules/termios     Fri Sep 17 02:38:39 2010
@@ -7,6 +7,8 @@
 
 Depends-on:
 include_next
+c++defs
+warn-on-use
 
 configure.ac:
 gl_TERMIOS_H
@@ -16,12 +18,16 @@
 
 # We need the following in order to create <termios.h> when the system
 # version does not have all declarations.
-termios.h: termios.in.h
+termios.h: termios.in.h $(CXXDEFS_H) $(WARN_ON_USE_H)
        $(AM_V_GEN)rm -f address@hidden $@ && \
        { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
          sed -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
              -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
              -e 's|@''NEXT_TERMIOS_H''@|$(NEXT_TERMIOS_H)|g' \
+             -e 's|@''GNULIB_TCGETSID''@|$(GNULIB_TCGETSID)|g' \
+             -e 's|@''HAVE_TCGETSID''@|$(HAVE_TCGETSID)|g' \
+             -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
+             -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
            < $(srcdir)/termios.in.h; \
        } > address@hidden && \
        mv address@hidden $@
--- tests/test-termios-c++.cc.orig      Fri Sep 17 03:11:00 2010
+++ tests/test-termios-c++.cc   Fri Sep 17 02:45:39 2010
@@ -24,6 +24,11 @@
 #include "signature.h"
 
 
+#if GNULIB_TEST_TCGETSID
+SIGNATURE_CHECK (GNULIB_NAMESPACE::tcgetsid, pid_t, (int));
+#endif
+
+
 int
 main ()
 {