libspl: Provide platform-specific zone implementations

FreeBSD has the concept of jails, a precursor to Solaris's zones, which
can be mapped to the required zones interface with relative ease.  The
previous ZFS implementation in FreeBSD did so, and we should continue
to provide an appropriate implementation in OpenZFS as well.

Move lib/libspl/zone.c into platform code and adopt the correct
implementation for FreeBSD.

While here, prune unused code.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #10851

lib/libspl/Makefile.am

@@ -27,7 +27,6 @@ USER_C = \
 	strlcat.c \
 	strlcpy.c \
 	timestamp.c \
-	zone.c \
 	include/sys/list.h \
 	include/sys/list_impl.h
 
@@ -35,7 +34,8 @@ if BUILD_LINUX
 USER_C += \
 	os/linux/getexecname.c \
 	os/linux/gethostid.c \
-	os/linux/getmntany.c
+	os/linux/getmntany.c \
+	os/linux/zone.c
 endif
 
 if BUILD_FREEBSD
@@ -43,7 +43,8 @@ USER_C += \
 	os/freebsd/getexecname.c \
 	os/freebsd/gethostid.c \
 	os/freebsd/getmntany.c \
-	os/freebsd/mnttab.c
+	os/freebsd/mnttab.c \
+	os/freebsd/zone.c
 endif
 
 libspl_la_SOURCES = \

lib/libspl/include/zone.h

@@ -26,25 +26,16 @@
 #ifndef _LIBSPL_ZONE_H
 #define	_LIBSPL_ZONE_H
 
-
-
 #include <sys/types.h>
 #include <sys/zone.h>
-#include <sys/priv.h>
 
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
 #define	GLOBAL_ZONEID		0
-#define	GLOBAL_ZONEID_NAME	"global"
 
-/*
- * Functions for mapping between id and name for active zones.
- */
 extern zoneid_t		getzoneid(void);
-extern zoneid_t		getzoneidbyname(const char *);
-extern ssize_t		getzonenamebyid(zoneid_t, char *, size_t);
 
 #ifdef	__cplusplus
 }

lib/libspl/os/freebsd/zone.c

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@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 AUTHORS 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 AUTHORS 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <zone.h>
+
+zoneid_t
+getzoneid(void)
+{
+	size_t size;
+	int jailid;
+
+	/* Information that we are in jail or not is enough for our needs. */
+	size = sizeof (jailid);
+	if (sysctlbyname("security.jail.jailed", &jailid, &size, NULL, 0) == -1)
+		assert(!"No security.jail.jailed sysctl!");
+	return ((zoneid_t)jailid);
+}

lib/libspl/os/linux/zone.c

@@ -24,40 +24,9 @@
  */
 
 #include <zone.h>
-#include <string.h>
-#include <errno.h>
 
 zoneid_t
 getzoneid()
 {
 	return (GLOBAL_ZONEID);
 }
-
-zoneid_t
-getzoneidbyname(const char *name)
-{
-	if (name == NULL)
-		return (GLOBAL_ZONEID);
-
-	if (strcmp(name, GLOBAL_ZONEID_NAME) == 0)
-		return (GLOBAL_ZONEID);
-
-	return (EINVAL);
-}
-
-ssize_t
-getzonenamebyid(zoneid_t id, char *buf, size_t buflen)
-{
-	if (id != GLOBAL_ZONEID)
-		return (EINVAL);
-
-	ssize_t ret = strlen(GLOBAL_ZONEID_NAME) + 1;
-
-	if (buf == NULL || buflen == 0)
-		return (ret);
-
-	strncpy(buf, GLOBAL_ZONEID_NAME, buflen);
-	buf[buflen - 1] = '\0';
-
-	return (ret);
-}