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, 11 insertions, 13 deletions

diff --git a/sysdeps/generic/siglist.h b/sysdeps/generic/siglist.h
index dd72929ed5..022be56059 100644
--- a/sysdeps/generic/siglist.h
+++ b/sysdeps/generic/siglist.h
@@ -24,7 +24,8 @@
 
 /* This file is included multiple times.  */
 
-/* Standard signals  */
+/* Standard signals, in the numerical order defined in
+   bits/signum-generic.h.  */
   init_sig (SIGHUP, "HUP", N_("Hangup"))
   init_sig (SIGINT, "INT", N_("Interrupt"))
   init_sig (SIGQUIT, "QUIT", N_("Quit"))
@@ -34,6 +35,7 @@
   init_sig (SIGFPE, "FPE", N_("Floating point exception"))
   init_sig (SIGKILL, "KILL", N_("Killed"))
   init_sig (SIGBUS, "BUS", N_("Bus error"))
+  init_sig (SIGSYS, "SYS", N_("Bad system call"))
   init_sig (SIGSEGV, "SEGV", N_("Segmentation fault"))
   init_sig (SIGPIPE, "PIPE", N_("Broken pipe"))
   init_sig (SIGALRM, "ALRM", N_("Alarm clock"))
@@ -45,32 +47,28 @@
   init_sig (SIGCHLD, "CHLD", N_("Child exited"))
   init_sig (SIGTTIN, "TTIN", N_("Stopped (tty input)"))
   init_sig (SIGTTOU, "TTOU", N_("Stopped (tty output)"))
-  init_sig (SIGIO, "IO", N_("I/O possible"))
+  init_sig (SIGPOLL, "POLL", N_("I/O possible"))
   init_sig (SIGXCPU, "XCPU", N_("CPU time limit exceeded"))
   init_sig (SIGXFSZ, "XFSZ", N_("File size limit exceeded"))
   init_sig (SIGVTALRM, "VTALRM", N_("Virtual timer expired"))
   init_sig (SIGPROF, "PROF", N_("Profiling timer expired"))
   init_sig (SIGUSR1, "USR1", N_("User defined signal 1"))
   init_sig (SIGUSR2, "USR2", N_("User defined signal 2"))
+  init_sig (SIGWINCH, "WINCH", N_("Window changed"))
 
-/* Variations  */
+/* Signals that are not present on all supported platforms.  */
 #ifdef SIGEMT
   init_sig (SIGEMT, "EMT", N_("EMT trap"))
 #endif
-#ifdef SIGSYS
-  init_sig (SIGSYS, "SYS", N_("Bad system call"))
-#endif
 #ifdef SIGSTKFLT
   init_sig (SIGSTKFLT, "STKFLT", N_("Stack fault"))
 #endif
-#ifdef SIGINFO
-  init_sig (SIGINFO, "INFO", N_("Information request"))
-#elif defined(SIGPWR) && (!defined(SIGLOST) || (SIGPWR != SIGLOST))
+#ifdef SIGPWR
   init_sig (SIGPWR, "PWR", N_("Power failure"))
 #endif
-#ifdef SIGLOST
-  init_sig (SIGLOST, "LOST", N_("Resource lost"))
+#if defined SIGINFO && (!defined SIGPWR || SIGPWR != SIGINFO)
+  init_sig (SIGINFO, "INFO", N_("Information request"))
 #endif
-#ifdef SIGWINCH
-  init_sig (SIGWINCH, "WINCH", N_("Window changed"))
+#if defined SIGLOST && (!defined SIGPWR || SIGPWR != SIGLOST)
+  init_sig (SIGLOST, "LOST", N_("Resource lost"))
 #endif