Add sigsetop extensions commonly found in musl libc and glibc

These functions (sigandset, sigisemptyset, sigorset) are commonly available
in at least musl libc and glibc; sigorset, at least, has proven quite useful
in qemu-bsd-user work for tracking the current process signal mask in a more
self-documenting/aesthetically pleasing manner.

Reviewed by:	bapt, jilles, pfg
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D22187

include/signal.h

@@ -122,7 +122,10 @@ void	psignal(int, const char *);
 #endif
 
 #if __BSD_VISIBLE
+int	sigandset(sigset_t *dest, const sigset_t *left, const sigset_t *right);
 int	sigblock(int);
+int	sigisemptyset(const sigset_t *set);
+int	sigorset(sigset_t *dest, const sigset_t *left, const sigset_t *right);
 int	sigreturn(const struct __ucontext *);
 int	sigsetmask(int);
 int	sigstack(const struct sigstack *, struct sigstack *);

lib/libc/gen/Makefile.inc

@@ -497,10 +497,13 @@ MLINKS+=setjmp.3 _longjmp.3 \
 MLINKS+=setmode.3 getmode.3
 MLINKS+=setproctitle.3 setproctitle_fast.3
 MLINKS+=sigsetops.3 sigaddset.3 \
+	sigsetops.3 sigandset.3 \
 	sigsetops.3 sigdelset.3 \
 	sigsetops.3 sigemptyset.3 \
 	sigsetops.3 sigfillset.3 \
-	sigsetops.3 sigismember.3
+	sigsetops.3 sigisemptyset.3 \
+	sigsetops.3 sigismember.3 \
+	sigsetops.3 sigorset.3
 MLINKS+=statvfs.3 fstatvfs.3
 MLINKS+=stringlist.3 sl_add.3 \
 	stringlist.3 sl_find.3 \

lib/libc/gen/Symbol.map

@@ -422,6 +422,12 @@ FBSD_1.5 {
 	timespec_get;
 };
 
+FBSD_1.6 {
+	sigandset;
+	sigisemptyset;
+	sigorset;
+};
+
 FBSDprivate_1.0 {
 	/* needed by thread libraries */
 	__thr_jtable;

lib/libc/gen/sigsetops.3

@@ -28,15 +28,18 @@
 .\"     @(#)sigsetops.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd December 16, 2004
+.Dd October 29, 2019
 .Dt SIGSETOPS 3
 .Os
 .Sh NAME
 .Nm sigemptyset ,
 .Nm sigfillset ,
 .Nm sigaddset ,
+.Nm sigandset ,
 .Nm sigdelset ,
-.Nm sigismember
+.Nm sigisemptyset ,
+.Nm sigismember ,
+.Nm sigorset
 .Nd manipulate signal sets
 .Sh LIBRARY
 .Lb libc
@@ -49,9 +52,15 @@
 .Ft int
 .Fn sigaddset "sigset_t *set" "int signo"
 .Ft int
+.Fn sigandset "sigset_t *set" "const sigset_t *left" "const sigset_t *right"
+.Ft int
 .Fn sigdelset "sigset_t *set" "int signo"
 .Ft int
+.Fn sigisemptyset "const sigset_t *set"
+.Ft int
 .Fn sigismember "const sigset_t *set" "int signo"
+.Ft int
+.Fn sigorset "sigset_t *set" "const sigset_t *left" "const sigset_t *right"
 .Sh DESCRIPTION
 These functions manipulate signal sets stored in a
 .Fa sigset_t .
@@ -78,22 +87,54 @@ function adds the specified signal
 to the signal set.
 .Pp
 The
+.Fn sigandset
+function sets the specified
+.Fa set
+to the logical AND of all signals from the
+.Fa left
+and
+.Fa right
+signal sets.
+.Pp
+The
 .Fn sigdelset
 function deletes the specified signal
 .Fa signo
 from the signal set.
 .Pp
 The
+.Fn sigisemptyset
+function returns whether the specified
+.Fa set
+is empty or not.
+.Pp
+The
 .Fn sigismember
 function returns whether a specified signal
 .Fa signo
 is contained in the signal set.
+.Pp
+The
+.Fn sigorset
+function sets the specified
+.Fa set
+to the logical OR of all signals from the
+.Fa left
+and
+.Fa right
+signal sets.
 .Sh RETURN VALUES
 The
+.Fn sigisemptyset
+function returns 1
+if the set is empty, 0 otherwise.
+.Pp
+The
 .Fn sigismember
 function returns 1
 if the signal is a member of the set,
 0 otherwise.
+.Pp
 The other functions return 0 upon success.
 A \-1 return value
 indicates an error occurred and the global variable
@@ -113,5 +154,13 @@ has an invalid value.
 .Xr sigprocmask 2 ,
 .Xr sigsuspend 2
 .Sh STANDARDS
-These functions are defined by
+The
+.Fn sigandset ,
+.Fn sigisemptyset ,
+and
+.Fn sigorset
+functions are FreeBSD extensions, compatible with functions of the same name
+provided by both musl libc and GNU libc.
+.Pp
+The rest of these functions are defined by
 .St -p1003.1-88 .

lib/libc/gen/sigsetops.c

@@ -80,6 +80,37 @@ sigfillset(sigset_t *set)
 	return (0);
 }
 
+int
+sigorset(sigset_t *dest, const sigset_t *left, const sigset_t *right)
+{
+	int i;
+
+	for (i = 0; i < _SIG_WORDS; i++)
+		dest->__bits[i] = left->__bits[i] | right->__bits[i];
+	return (0);
+}
+
+int
+sigandset(sigset_t *dest, const sigset_t *left, const sigset_t *right)
+{
+	int i;
+
+	for (i = 0; i < _SIG_WORDS; i++)
+		dest->__bits[i] = left->__bits[i] & right->__bits[i];
+	return (0);
+}
+
+int
+sigisemptyset(const sigset_t *set)
+{
+	int i;
+
+	for (i = 0; i < _SIG_WORDS; i++)
+		if (set->__bits[i] != 0)
+			return (0);
+	return (1);
+}
+
 int
 sigismember(const sigset_t *set, int signo)
 {

lib/libc/tests/gen/Makefile

@@ -17,6 +17,7 @@ ATF_TESTS_C+=		makecontext_test
 ATF_TESTS_C+=		popen_test
 ATF_TESTS_C+=		posix_spawn_test
 ATF_TESTS_C+=		realpath2_test
+ATF_TESTS_C+=		sigsetops_test
 ATF_TESTS_C+=		wordexp_test
 
 # TODO: t_closefrom, t_cpuset, t_fmtcheck, t_randomid,

lib/libc/tests/gen/sigsetops_test.c

@@ -0,0 +1,191 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <errno.h>
+#include <signal.h>
+#include <stdbool.h>
+
+#include <atf-c.h>
+
+/* Return the status of the specified sig's bit. */
+static bool
+sigbitstatus(const sigset_t *set, int sig)
+{
+
+	return (set->__bits[_SIG_WORD(sig)] & _SIG_BIT(sig)) != 0;
+}
+
+/* Verify that sig is the lone bit set in the sigset. */
+static void
+siglonebit(const sigset_t *set, int sig)
+{
+	int i;
+
+	for (i = 0; i < _SIG_WORDS; ++i) {
+		if (i != _SIG_WORD(sig))
+			ATF_REQUIRE_MSG(set->__bits[i] == 0,
+			    "word %d altered to %x", i, set->__bits[i]);
+		else
+			ATF_REQUIRE_MSG((set->__bits[i] & ~_SIG_BIT(sig)) == 0,
+			    "word %d has other bits set: %x", i,
+			    set->__bits[i] & ~_SIG_BIT(sig));
+	}
+}
+
+static void
+sigcompare(const sigset_t *left, const sigset_t *right)
+{
+	int i;
+
+	for (i = 0; i < _SIG_WORDS; ++i) {
+		ATF_REQUIRE_MSG(left->__bits[i] == right->__bits[i],
+		    "sig comparison failed at %d; left=%x, right=%x",
+		    i, left->__bits[i], right->__bits[i]);
+	}
+}
+
+/*
+ * Test implementation details of our sigsetops... make sure the correct bits
+ * are getting set, for the most part, and that duplicate operations don't
+ * error out.
+ */
+ATF_TC_WITHOUT_HEAD(posix_sigsetop_test);
+ATF_TC_BODY(posix_sigsetop_test, tc)
+{
+	sigset_t set;
+	int i;
+
+	ATF_REQUIRE(sigfillset(&set) == 0);
+	for (i = 0; i < _SIG_WORDS; ++i) {
+		ATF_REQUIRE_MSG(set.__bits[i] == ~0U, "sigfillset failed @ %d",
+		    i);
+	}
+	ATF_REQUIRE(sigemptyset(&set) == 0);
+	for (i = 0; i < _SIG_WORDS; ++i) {
+		ATF_REQUIRE_MSG(set.__bits[i] == 0, "sigemptyset failed @ %d",
+		    i);
+	}
+	/* Ensure that sigismember reflects the empty set status. */
+	for (i = 1; i < NSIG; ++i) {
+		ATF_REQUIRE(sigismember(&set, i) == 0);
+	}
+
+	ATF_REQUIRE(sigaddset(&set, -1) == -1 && errno == EINVAL);
+	ATF_REQUIRE(sigaddset(&set, _SIG_MAXSIG + 1) == -1 && errno == EINVAL);
+	ATF_REQUIRE(sigdelset(&set, -1) == -1 && errno == EINVAL);
+	ATF_REQUIRE(sigdelset(&set, _SIG_MAXSIG + 1) == -1 && errno == EINVAL);
+
+	ATF_REQUIRE(sigaddset(&set, SIGSEGV) == 0);
+	ATF_REQUIRE(sigismember(&set, SIGSEGV) != 0);
+	ATF_REQUIRE_MSG(sigbitstatus(&set, SIGSEGV), "sigaddset failure");
+	siglonebit(&set, SIGSEGV);
+
+	/*
+	 * A second addition should succeed without altering the state.  This
+	 * should be trivially true.
+	 */
+	ATF_REQUIRE(sigaddset(&set, SIGSEGV) == 0);
+	ATF_REQUIRE_MSG(sigbitstatus(&set, SIGSEGV),
+	    "sigaddset twice changed bit");
+
+	ATF_REQUIRE(sigdelset(&set, SIGSEGV) == 0);
+	ATF_REQUIRE_MSG(!sigbitstatus(&set, SIGSEGV), "sigdelset failure");
+	ATF_REQUIRE(sigismember(&set, SIGSEGV) == 0);
+	ATF_REQUIRE(sigdelset(&set, SIGSEGV) == 0);
+	ATF_REQUIRE_MSG(!sigbitstatus(&set, SIGSEGV),
+	    "sigdelset twice changed bit");
+	for (i = 0; i < _SIG_WORDS; ++i) {
+		ATF_REQUIRE_MSG(set.__bits[i] == 0, "set not empty @ %d",
+		    i);
+	}
+	for (i = 1; i < NSIG; ++i) {
+		ATF_REQUIRE(sigismember(&set, i) == 0);
+	}
+}
+
+/*
+ * Test extended sigset ops for union/intersection and testing of empty set.
+ */
+ATF_TC_WITHOUT_HEAD(extended_sigsetop_test);
+ATF_TC_BODY(extended_sigsetop_test, tc)
+{
+	sigset_t chkset, set1, set2, set3;
+
+	sigemptyset(&chkset);
+	sigemptyset(&set1);
+	sigemptyset(&set2);
+	ATF_REQUIRE(sigisemptyset(&chkset) != 0);
+	sigaddset(&set1, SIGSEGV);
+	sigaddset(&set2, SIGKILL);
+	sigaddset(&chkset, SIGSEGV);
+	ATF_REQUIRE(sigisemptyset(&chkset) == 0);
+	sigaddset(&chkset, SIGKILL);
+	ATF_REQUIRE(sigorset(&set3, &set1, &set2) == 0);
+	ATF_REQUIRE(sigbitstatus(&set3, SIGSEGV));
+	ATF_REQUIRE(sigbitstatus(&set3, SIGKILL));
+
+	/*
+	 * chkset was built with our POSIX-specified set operations that we've
+	 * already tested, so it's a good comparison.
+	 */
+	sigcompare(&chkset, &set3);
+	/*
+	 * Clear chkset; make sure sigisemptyset() still looks ok.  sigaddset
+	 * and sigdelset have already been tested to make sure that they're not
+	 * touching other bits.
+	 */
+	sigdelset(&chkset, SIGSEGV);
+	sigdelset(&chkset, SIGKILL);
+	ATF_REQUIRE(sigisemptyset(&chkset) != 0);
+	ATF_REQUIRE(sigandset(&set3, &set1, &set2) == 0);
+	/* Make sure we clobbered these. */
+	ATF_REQUIRE(!sigbitstatus(&set3, SIGSEGV));
+	ATF_REQUIRE(!sigbitstatus(&set3, SIGKILL));
+	ATF_REQUIRE(sigisemptyset(&set3) != 0);
+	/* Rebuild for sigandset test */
+	sigemptyset(&set1);
+	sigemptyset(&set2);
+	sigaddset(&set1, SIGSEGV);
+	sigaddset(&set1, SIGKILL);
+	sigaddset(&set2, SIGSEGV);
+	ATF_REQUIRE(sigandset(&set3, &set1, &set2) == 0);
+	ATF_REQUIRE(sigbitstatus(&set3, SIGSEGV));
+	ATF_REQUIRE(!sigbitstatus(&set3, SIGKILL));
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, posix_sigsetop_test);
+	ATF_TP_ADD_TC(tp, extended_sigsetop_test);
+
+	return (atf_no_error());
+}