Factor out shared definitions from bits/signum.h.

Many of the things defined by bits/signum.h are invariant across all
supported operating systems.  This patch factors out all of them to a
new header bits/signum-generic.h, which each bits/signum.h will include
and then override whichever things need adjustment.  Normally that will
mean, at most, adding or changing a few signal numbers.

A user-visible side effect is that the obsolete signal constant SIGUNUSED
(which is an alias for SIGSYS on all platforms that define it) is no
longer exposed by any version of bits/signum.h.

A side effect only relevant to glibc hackers is that _NSIG is now defined
in terms of __SIGRTMAX, instead of the other way around.  This is because
__SIGRTMAX varies from platform to platform, but _NSIG==__SIGRTMAX+1 is
true universally.  If your platform doesn't support realtime signals,
leave __SIGRTMAX equal to __SIGRTMIN.

I also added a Linux-specific test to make sure that our signal constants
match the ones in <asm/signal.h>, since we can't use that header (it's
not even vaguely namespace-clean).

	* bits/signum-generic.h: Renamed from bits/signum.h.
	Add proper multiple include guard and misuse check.
	Define __SIGRTMIN = __SIGRTMAX = 32, and define _NSIG = __SIGRTMAX+1.
	Move definition of SIGIO to "archaic names for compatibility" section.
	* bits/signum.h: New file which just includes bits/signum-generic.h.
	* sysdeps/unix/bsd/bits/signum.h
	* sysdeps/unix/sysv/linux/bits/signum.h
	* sysdeps/unix/sysv/linux/alpha/bits/signum.h
	* sysdeps/unix/sysv/linux/hppa/bits/signum.h
	* sysdeps/unix/sysv/linux/mips/bits/signum.h
	* sysdeps/unix/sysv/linux/sparc/bits/signum.h
	Just include <bits/signum-generic.h> and then add or adjust
	signal constants.  Do not define SIGUNUSED, SIGRTMIN, or SIGRTMAX.

	* signal/Makefile: Install bits/signum-generic.h.
	* signal/signal.h: Define SIGRTMIN and SIGRTMAX here.

	* sysdeps/generic/siglist.h: SIGSYS and SIGWINCH are
	universal.  Prefer SIGPOLL to SIGIO. Simplify #ifdeffage.

	* sysdeps/unix/sysv/linux/tst-signal-numbers.sh: New test.
	* sysdeps/unix/sysv/linux/Makefile: Run it.

1 files changed, 42 insertions, 52 deletions

diff --git a/sysdeps/unix/sysv/linux/mips/bits/signum.h b/sysdeps/unix/sysv/linux/mips/bits/signum.h
index 6c31e01cd7..1672847212 100644
--- a/sysdeps/unix/sysv/linux/mips/bits/signum.h
+++ b/sysdeps/unix/sysv/linux/mips/bits/signum.h
@@ -1,4 +1,4 @@
-/* Signal number definitions.  Linux version.
+/* Signal number definitions.  Linux/MIPS version.
    Copyright (C) 1995-2017 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,63 +16,53 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifdef	_SIGNAL_H
+#ifndef _BITS_SIGNUM_H
+#define _BITS_SIGNUM_H 1
 
-/* Fake signal functions.  */
-#define SIG_ERR ((__sighandler_t) -1)		/* Error return.  */
-#define SIG_DFL ((__sighandler_t) 0)		/* Default action.  */
-#define SIG_IGN ((__sighandler_t) 1)		/* Ignore signal.  */
-
-#ifdef __USE_XOPEN
-# define SIG_HOLD	((__sighandler_t) 2)	/* Add signal to hold mask.  */
+#ifndef _SIGNAL_H
+#error "Never include <bits/signum.h> directly; use <signal.h> instead."
 #endif
 
+#include <bits/signum-generic.h>
 
-#define SIGHUP		 1	/* Hangup (POSIX).  */
-#define SIGINT		 2	/* Interrupt (ANSI).  */
-#define SIGQUIT		 3	/* Quit (POSIX).  */
-#define SIGILL		 4	/* Illegal instruction (ANSI).  */
-#define SIGTRAP		 5	/* Trace trap (POSIX).  */
-#define SIGIOT		 6	/* IOT trap (4.2 BSD).  */
-#define SIGABRT		 SIGIOT	/* Abort (ANSI).  */
-#define SIGEMT		 7
-#define SIGFPE		 8	/* Floating-point exception (ANSI).  */
-#define SIGKILL		 9	/* Kill, unblockable (POSIX).  */
-#define SIGBUS		10	/* BUS error (4.2 BSD).  */
-#define SIGSEGV		11	/* Segmentation violation (ANSI).  */
-#define SIGSYS		12
-#define SIGPIPE		13	/* Broken pipe (POSIX).  */
-#define SIGALRM		14	/* Alarm clock (POSIX).  */
-#define SIGTERM		15	/* Termination (ANSI).  */
-#define SIGUSR1		16	/* User-defined signal 1 (POSIX).  */
-#define SIGUSR2		17	/* User-defined signal 2 (POSIX).  */
-#define SIGCHLD		18	/* Child status has changed (POSIX).  */
-#define SIGCLD		SIGCHLD	/* Same as SIGCHLD (System V).  */
-#define SIGPWR		19	/* Power failure restart (System V).  */
-#define SIGWINCH	20	/* Window size change (4.3 BSD, Sun).  */
-#define SIGURG		21	/* Urgent condition on socket (4.2 BSD).  */
-#define SIGIO		22	/* I/O now possible (4.2 BSD).  */
-#define SIGPOLL		SIGIO	/* Pollable event occurred (System V).  */
-#define SIGSTOP		23	/* Stop, unblockable (POSIX).  */
-#define SIGTSTP		24	/* Keyboard stop (POSIX).  */
-#define SIGCONT		25	/* Continue (POSIX).  */
-#define SIGTTIN		26	/* Background read from tty (POSIX).  */
-#define SIGTTOU		27	/* Background write to tty (POSIX).  */
-#define SIGVTALRM	28	/* Virtual alarm clock (4.2 BSD).  */
-#define SIGPROF		29	/* Profiling alarm clock (4.2 BSD).  */
-#define SIGXCPU		30	/* CPU limit exceeded (4.2 BSD).  */
-#define SIGXFSZ		31	/* File size limit exceeded (4.2 BSD).  */
-
+/* Adjustments and additions to the signal number constants for
+   Linux/MIPS.  */
 
-#define _NSIG		128	/* Biggest signal number + 1
-				   (including real-time signals).  */
+#define SIGEMT		 7	/* Emulator trap.  */
+#define SIGPWR		19	/* Power failure imminent.  */
 
-#define SIGRTMIN	(__libc_current_sigrtmin ())
-#define SIGRTMAX	(__libc_current_sigrtmax ())
+#undef	SIGUSR1
+#define SIGUSR1		16
+#undef	SIGUSR2
+#define SIGUSR2		17
+#undef	SIGCHLD
+#define SIGCHLD		18
+#undef	SIGWINCH
+#define SIGWINCH	20
+#undef	SIGURG
+#define SIGURG		21
+#undef	SIGPOLL
+#define SIGPOLL		22
+#undef	SIGSTOP
+#define SIGSTOP		23
+#undef	SIGTSTP
+#define SIGTSTP		24
+#undef	SIGCONT
+#define SIGCONT		25
+#undef	SIGTTIN
+#define SIGTTIN		26
+#undef	SIGTTOU
+#define SIGTTOU		27
+#undef	SIGVTALRM
+#define SIGVTALRM	28
+#undef	SIGPROF
+#define SIGPROF		29
+#undef	SIGXCPU
+#define SIGXCPU		30
+#undef	SIGXFSZ
+#define SIGXFSZ		31
 
-/* These are the hard limits of the kernel.  These values should not be
-   used directly at user level.  */
-#define __SIGRTMIN	32
-#define __SIGRTMAX	(_NSIG - 1)
+#undef	__SIGRTMAX
+#define __SIGRTMAX	127
 
 #endif	/* <signal.h> included.  */