Implement sighold, sigignore, sigpause, sigrelse, sigset functions

from SUSv4 XSI. Note that the functions are obsoleted, and only
provided to ease porting from System V-like systems. Since sigpause
already exists in compat with different interface, XSI sigpause is
named xsi_sigpause.

Reviewed by:	davidxu
MFC after:	3 weeks

include/signal.h

@@ -99,7 +99,12 @@ int	sigwaitinfo(const sigset_t * __restrict, siginfo_t * __restrict);
 #if __XSI_VISIBLE
 int	killpg(__pid_t, int);
 int	sigaltstack(const stack_t * __restrict, stack_t * __restrict); 
-int	sigpause(int);
+int	sighold(int sig);
+int	sigignore(int sig);
+int	sigpause(int sigmask);
+int	sigrelse(int sig);
+void	(*sigset(int sig, void (*disp)(int)))(int);
+int	xsi_sigpause(int sig);
 #endif
 
 #if __XSI_VISIBLE >= 600

lib/libc/compat-43/Makefile.inc

@@ -13,6 +13,11 @@ MAN+=	creat.2 killpg.2 sigpause.2 sigsetmask.2 sigvec.2
 MAN+=	gethostid.3 setruid.3
 
 MLINKS+=gethostid.3 sethostid.3
+MLINKS+=sigpause.2 sighold.2
+MLINKS+=sigpause.2 sigignore.2
+MLINKS+=sigpause.2 sigrelse.2
+MLINKS+=sigpause.2 sigset.2
+MLINKS+=sigpause.2 xsi_sigpause.2
 MLINKS+=setruid.3 setrgid.3
 
 MLINKS+=sigsetmask.2 sigblock.2

lib/libc/compat-43/Symbol.map

@@ -17,6 +17,14 @@ FBSD_1.0 {
 	sigvec;
 };
 
+FBSD_1.2 {
+	sighold;
+	sigignore;
+	sigrelse;
+	sigset;
+	xsi_sigpause;
+};
+
 FBSDprivate_1.0 {
 	__creat;
 	_creat;

lib/libc/compat-43/sigcompat.c

@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include "namespace.h"
 #include <sys/param.h>
 #include <signal.h>
+#include <string.h>
 #include "un-namespace.h"
 #include "libc_private.h"
 
@@ -97,8 +98,7 @@ sigblock(mask)
 }
 
 int
-sigpause(mask)
-	int mask;
+sigpause(int mask)
 {
 	sigset_t set;
 
@@ -106,3 +106,84 @@ sigpause(mask)
 	set.__bits[0] = mask;
 	return (_sigsuspend(&set));
 }
+
+int
+xsi_sigpause(int sig)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	return (_sigsuspend(&set));
+}
+
+int
+sighold(int sig)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	return (_sigprocmask(SIG_BLOCK, &set, NULL));
+}
+
+int
+sigignore(int sig)
+{
+	struct sigaction sa;
+
+	bzero(&sa, sizeof(sa));
+	sa.sa_handler = SIG_IGN;
+	return (_sigaction(sig, &sa, NULL));
+}
+
+int
+sigrelse(int sig)
+{
+	sigset_t set;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	return (_sigprocmask(SIG_UNBLOCK, &set, NULL));
+}
+
+void
+(*sigset(int sig, void (*disp)(int)))(int)
+{
+	sigset_t set, pset;
+	struct sigaction sa, psa;
+	int error;
+
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	error = _sigprocmask(SIG_BLOCK, NULL, &pset);
+	if (error == -1)
+		return (SIG_ERR);
+	if ((__sighandler_t *)disp == SIG_HOLD) {
+		error = _sigprocmask(SIG_BLOCK, &set, &pset);
+		if (error == -1)
+			return (SIG_ERR);
+		if (sigismember(&pset, sig))
+			return (SIG_HOLD);
+		else {
+			error = _sigaction(sig, NULL, &psa);
+			if (error == -1)
+				return (SIG_ERR);
+			return (psa.sa_handler);
+		}
+	} else {
+		error = _sigprocmask(SIG_UNBLOCK, &set, &pset);
+		if (error == -1)
+			return (SIG_ERR);
+	}
+
+	bzero(&sa, sizeof(sa));
+	sa.sa_handler = disp;
+	error = _sigaction(sig, &sa, &psa);
+	if (error == -1)
+		return (SIG_ERR);
+	if (sigismember(&pset, sig))
+		return (SIG_HOLD);
+	else
+		return (psa.sa_handler);
+}

lib/libc/compat-43/sigpause.2

@@ -28,21 +28,118 @@
 .\"     @(#)sigpause.2	8.1 (Berkeley) 6/2/93
 .\" $FreeBSD$
 .\"
+.\" Part of the content of the man page was derived from
+.\" The Open Group Base Specifications Issue 7
+.\" IEEE Std 1003.1-2008
+.\"
 .Dd June 2, 1993
 .Dt SIGPAUSE 2
 .Os
 .Sh NAME
-.Nm sigpause
-.Nd atomically release blocked signals and wait for interrupt
+.Nm sighold ,
+.Nm sigignore ,
+.Nm sigpause ,
+.Nm sigrelse ,
+.Nm sigset
+.Nd legacy interface for signal management
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In signal.h
 .Ft int
+.Fn sighold "int sig"
+.Ft int
+.Fn sigignore "int sig"
+.Ft int
+.Fn xsi_sigpause "int sigmask"
+.Ft int
+.Fn sigrelse "int sig"
+.Ft void (*)(int)
+.Fn sigset "int" "void (*disp)(int)"
+.Ft int
 .Fn sigpause "int sigmask"
 .Sh DESCRIPTION
 .Sy This interface is made obsolete by
-.Xr sigsuspend 2 .
+.Xr sigsuspend 2
+.Sy and
+.Xr sigaction 2
+.Pp
+The
+.Fn sigset
+function modifies signal dispositions.
+The
+.Fa sig
+argument specifies the signal, which may be any signal except
+.Dv SIGKILL
+and
+.Dv SIGSTOP .
+The
+.Fa disp
+argument specifies the signal's disposition,
+which may be
+.Dv SIG_DFL ,
+.Dv SIG_IGN ,
+or the address of a signal handler.
+If
+.Fn sigset
+is used, and
+.Fa disp
+is the address of a signal handler, the
+system adds
+.Fa sig
+to the signal mask of the calling process before executing the signal
+handler; when the signal handler returns, the system restores the
+signal mask of the calling process to its state prior to the delivery
+of the signal.
+In addition, if
+.Fn sigset
+is used, and
+.Fa disp
+is equal to
+.Dv SIG_HOLD ,
+.Fa sig
+is added to the signal
+mask of the calling process and
+.Fa sig 's
+disposition remains unchanged.
+If
+.Fn sigset
+is used, and
+.Fa disp
+is not equal to
+.Dv SIG_HOLD ,
+.Fa sig
+is removed from the signal mask of the calling process.
+.Pp
+The
+.Fn sighold
+function adds
+.Fa sig
+to the signal mask of the calling process.
+.Pp
+The
+.Fn sigrelse
+function removes
+.Fa sig
+from the signal mask of the calling process.
+.Pp
+The
+.Fn sigignore
+function sets the disposition of
+.Fa sig
+to
+.Dv SIG_IGN .
+.Pp
+The
+.Fn xsi_sigpause
+function removes
+.Fa sig
+from the signal mask of the calling process and suspend the calling process
+until a signal is received.
+The
+.Fn xsi_sigpause
+function restores the signal mask of the process to its original state before
+returning.
 .Pp
 The
 .Fn sigpause
@@ -57,13 +154,47 @@ The
 argument
 is usually 0 to indicate that no
 signals are to be blocked.
+.Sh RETURN VALUES
 The
 .Fn sigpause
-function
-always terminates by being interrupted, returning -1 with
+and
+.Fn xsi_sigpause
+functions
+always terminate by being interrupted, returning -1 with
 .Va errno
 set to
-.Er EINTR
+.Er EINTR .
+.Pp
+Upon successful completion,
+.Fn sigset
+returns
+.Dv SIG_HOLD
+if the signal had been blocked and the signal's previous disposition if
+it had not been blocked.
+Otherwise,
+.Dv SIG_ERR is returned and
+.Va errno
+set to indicate the error.
+.Pp
+For all other functions, upon successful completion, 0 is returned.
+Otherwise, -1 is returned and
+.Va errno
+is set to indicate the error:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The
+.Fa sig
+argument
+is not a valid signal number.
+.It Bq Er EINVAL
+For
+.Fn sigset
+and
+.Fn sigignore
+functions, an attempt was made to catch or ignore
+.Dv SIGKILL
+or
+.Dv SIGSTOP .
 .Sh SEE ALSO
 .Xr kill 2 ,
 .Xr sigaction 2 ,
@@ -85,9 +216,26 @@ and was copied from there into the
 .Pq Tn XSI
 option of
 .St -p1003.1-2001 .
+.Fx
+implements it under the name
+.Fn xsi_sigpause .
+The
+.Fn sighold ,
+.Fn sigignore ,
+.Fn sigrelse
+and
+.Fn sigset
+functions are implemented for compatibility with
+.Sy System V
+and
+.Sy XSI
+interfaces.
 .Sh HISTORY
 The
 .Fn sigpause
 function appeared in
 .Bx 4.2
 and has been deprecated.
+All other functions appeared in
+.Fx 9.0
+and were deprecated before being implemented.

sys/sys/signal.h

@@ -119,9 +119,8 @@
 #define	SIG_DFL		((__sighandler_t *)0)
 #define	SIG_IGN		((__sighandler_t *)1)
 #define	SIG_ERR		((__sighandler_t *)-1)
-/*
- * XXX missing SIG_HOLD.
- */
+/* #define	SIG_CATCH	((__sighandler_t *)2) See signalvar.h */
+#define SIG_HOLD        ((__sighandler_t *)3)
 
 /*-
  * Type of a signal handling function.

sys/sys/signalvar.h

@@ -97,7 +97,7 @@ typedef void __osiginfohandler_t(int, osiginfo_t *, void *);
 
 /* additional signal action values, used only temporarily/internally */
 #define	SIG_CATCH	((__sighandler_t *)2)
-#define SIG_HOLD        ((__sighandler_t *)3)
+/* #define SIG_HOLD        ((__sighandler_t *)3) See signal.h */
 
 /*
  * get signal action for process and signal; currently only for current process