Terry Lambert's loadable kernel module support - example modules.

7 files changed, 592 insertions, 0 deletions

diff --git a/share/examples/lkm/misc/Makefile b/share/examples/lkm/misc/Makefile
new file mode 100644
index 0000000..b793cca
--- /dev/null
+++ b/share/examples/lkm/misc/Makefile
@@ -0,0 +1,48 @@
+# 25 May 93
+#
+# Makefile for sample loadable system call
+#
+# 25 May 93	Terry Lambert		Original
+#
+# Copyright (c) 1993 Terrence R. Lambert.
+# 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.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#      This product includes software developed by Terrence R. Lambert.
+# 4. The name Terrence R. Lambert may not be used to endorse or promote
+#    products derived from this software without specific prior written
+#    permission.
+#
+# THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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.
+#
+
+SUBDIR=	module test
+
+load: _SUBDIRUSE
+
+unload: _SUBDIRUSE
+
+.include <bsd.subdir.mk>
+
+#
+# EOF -- This file has not been truncated.
+#
diff --git a/share/examples/lkm/misc/README b/share/examples/lkm/misc/README
new file mode 100644
index 0000000..e3099f1
--- /dev/null
+++ b/share/examples/lkm/misc/README
@@ -0,0 +1,85 @@
+# Copyright (c) 1993 Terrence R. Lambert.
+# 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.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#      This product includes software developed by Terrence R. Lambert.
+# 4. The name Terrence R. Lambert may not be used to endorse or promote
+#    products derived from this software without specific prior written
+#    permission.
+#
+# THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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.
+
+1.0	Overview
+
+	This is the README file for the sample miscellaneous module
+	that mimics the loaded system call.
+
+	A miscellaneous module may be used to load any data or
+	program into the kernel that can be made available by
+	modifying a table, pointer, or other kernel data to inform
+	the kernel that the module should be used instead of the
+	previous code/data path.
+
+	Generally, it is assumed that a loadable module is one of
+	a set of similar modules (such as a file system or console
+	terminal emulation), and that the reference is through a
+	table (such as vfssw[]), and that a "special" value is
+	assigned to the slots which are allowed to be replaced.
+	This is not enforced, so you may use the "miscellaneous"
+	module any way you see fit.
+
+	As with the loadable system calls, it may be desirable to
+	allow the module loader to replace an *existing* entry to
+	try out changes to kernel code without rebuilding and
+	booting from the new kernel.
+
+
+2.0	Directions
+
+	To test the module, do the following:
+
+		cd module
+		make load
+
+	A load message (the copyright) will be printed on the console.
+
+		cd ../test
+		make load
+
+	The system call prints a message on the console when called.
+	This message will be printed when running "make load" in
+	the "test" subdirectory.
+
+
+3.0	Recovering resources
+
+	The miscellaneous module consumes 8 pages of memory when
+	loaded; it can be freed up by unloading it.  To unload it,
+	type the following from the directory this file is in:
+
+		cd module
+		make unload
+
+	The miscellaneous module will be unloaded by name.
+
+
+4.0	END OF DOCUMENT
diff --git a/share/examples/lkm/misc/module/Makefile b/share/examples/lkm/misc/module/Makefile
new file mode 100644
index 0000000..562a75d
--- /dev/null
+++ b/share/examples/lkm/misc/module/Makefile
@@ -0,0 +1,65 @@
+# 05 Jun 93
+#
+# Makefile for miscmod
+#
+# 05 Jun 93	Terry Lambert		Original
+#
+# Copyright (c) 1993 Terrence R. Lambert.
+# 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.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#      This product includes software developed by Terrence R. Lambert.
+# 4. The name Terrence R. Lambert may not be used to endorse or promote
+#    products derived from this software without specific prior written
+#    permission.
+#
+# THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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.
+#
+
+SRCS=miscmod.c
+OBJS=$(SRCS:.c=.o)
+
+KSRCS=misccall.c
+KOBJS=misccall.o
+
+MODOBJ=combined.o
+
+KMOD=miscmod
+CFLAGS= -DKERNEL -I/sys/sys -I/sys
+
+all:	$(MODOBJ)
+
+clean:
+	rm -f $(OBJS) $(KOBJS) $(MODOBJ) $(KMOD)
+
+load:
+	/sbin/modload -o $(KMOD) -e$(KMOD) $(MODOBJ)
+
+unload:
+	/sbin/modunload -n $(KMOD)
+
+$(MODOBJ): $(OBJS) $(KOBJS)
+	$(LD) -r -o $(MODOBJ) $(OBJS) $(KOBJS)
+
+#
+# EOF -- This file has not been truncated
+#
diff --git a/share/examples/lkm/misc/module/misccall.c b/share/examples/lkm/misc/module/misccall.c
new file mode 100644
index 0000000..86741c4
--- /dev/null
+++ b/share/examples/lkm/misc/module/misccall.c
@@ -0,0 +1,77 @@
+/* 05 Jun 93*/
+/*
+ * misccall.c
+ *
+ * 05 Jun 93	Terry Lambert		Split out of newsyscall.c
+ *
+ * Copyright (c) 1993 Terrence R. Lambert.
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Terrence R. Lambert.
+ * 4. The name Terrence R. Lambert may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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/param.h>
+#include <sys/ioctl.h>
+#include <sys/systm.h>
+
+
+/*
+ * This is the actual code for system call...  it can be static because
+ * we've externed it up above... the only plae it needs to be referenced
+ * is the sysent we are interested in.
+ *
+ * To write your own system call using this as a template, you could strip
+ * out this code and use the rest as a prototype module, changing only the
+ * function names and the number of arguments to the call in the module
+ * specific "sysent".
+ *
+ * You would have to use the "-R" option of "ld" to ensure a linkable file
+ * if you were to do this, since you would need to combine multiple ".o"
+ * files into a single ".o" file for use by "modload".
+ */
+int
+misccall( p, uap, retval)
+struct proc	*p;
+void		*uap;
+int		retval[];
+{
+	/*
+	 * Our new system call simply prints a message; it takes no
+	 * arguments.
+	 */
+
+	printf( "\nI am a loaded system call using the miscellaneous\n");
+	printf( "module loader interface and a kernel printf!\n");
+	printf( "I will print this message each time I am called!\n");
+
+	return( 0);	/* success (or error code from errno.h)*/
+}
+
+/*
+ * EOF -- This file has not been truncated.
+ */
diff --git a/share/examples/lkm/misc/module/miscmod.c b/share/examples/lkm/misc/module/miscmod.c
new file mode 100644
index 0000000..04aa07c
--- /dev/null
+++ b/share/examples/lkm/misc/module/miscmod.c
@@ -0,0 +1,189 @@
+/* 25 May 93*/
+/*
+ * Makefile for miscmod
+ *
+ * 05 Jun 93	Terry Lambert		Split mycall.c out
+ * 25 May 93	Terry Lambert		Original
+ *
+ * Copyright (c) 1993 Terrence R. Lambert.
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Terrence R. Lambert.
+ * 4. The name Terrence R. Lambert may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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/param.h>
+#include <sys/ioctl.h>
+#include <sys/systm.h>
+#include <sys/conf.h>
+#include <sys/mount.h>
+#include <sys/exec.h>
+#include <sys/lkm.h>
+#include <a.out.h>
+#include <sys/file.h>
+#include <sys/errno.h>
+
+
+extern int	misccall();
+
+/*
+ * These two entries define our system call and module information.  We
+ * have 0 arguments to our system call.
+ */
+static struct sysent newent = {
+	0,	misccall		/* # of args, function pointer*/
+};
+
+/*
+ * Miscellaneous modules must have their own save areas...
+ */
+static struct sysent	oldent;		/* save are for old callslot entry*/
+
+MOD_MISC( "miscmod")
+
+
+/*
+ * This function is called each time the module is loaded or unloaded.
+ * Since we are a miscellaneous module, we have to provide whatever
+ * code is necessary to patch ourselves into the area we are being
+ * loaded to change.
+ *
+ * For the system call table, we duplicate the code in the kern_lkm.c
+ * file for patching into the system call table.  We can tell what
+ * has been allocated, etc. by virtue of the fact that we know the
+ * criteria used by the system call loader interface.  We still
+ * kick out the copyright to the console here (to give an example).
+ *
+ * The stat information is basically common to all modules, so there
+ * is no real issue involved with stat; we will leave it nosys(),
+ * cince we don't have to do anything about it.
+ */
+static int
+miscmod_handle( lkmtp, cmd)
+struct lkm_table	*lkmtp;
+int			cmd;
+{
+	int			i;
+	struct lkm_misc		*args = lkmtp->private.lkm_misc;
+	int			err = 0;	/* default = success*/
+	extern int		nsysent;	/* init_sysent.c*/
+	extern int		lkmnosys();	/* allocable slot*/
+
+	switch( cmd) {
+	case LKM_E_LOAD:
+
+		/*
+		 * Don't load twice! (lkmexists() is exported by kern_lkm.c)
+		 */
+		if( lkmexists( lkmtp))
+			return( EEXIST);
+
+		/*
+		 * This is where we would express a slot preference if
+		 * we had one; since we don't, we will simply duplicate
+		 * the "auto" code and forget the other.
+		 */
+
+		/*
+		 * Search the table looking for a slot...
+		 */
+		for( i = 0; i < nsysent; i++)
+			if( sysent[ i].sy_call == lkmnosys)
+				break;		/* found it!*/
+		/* out of allocable slots?*/
+		if( i == nsysent) {
+			err = ENFILE;
+			break;
+		}
+
+		/* save old -- we must provide our own data area*/
+		bcopy( &sysent[ i], &oldent, sizeof( struct sysent));
+
+		/* replace with new*/
+		bcopy( &newent, &sysent[ i], sizeof( struct sysent));
+
+		/* done!*/
+		args->lkm_offset = i;	/* slot in sysent[]*/
+
+
+		/* if we make it to here, print copyright on console*/
+		printf( "\nSample Loaded miscellaneous module (system call)\n");
+		printf( "Copyright (c) 1993\n");
+		printf( "Terrence R. Lambert\n");
+		printf( "All rights reserved\n");
+
+		break;		/* Success*/
+
+	case LKM_E_UNLOAD:
+		/* current slot...*/
+		i = args->lkm_offset;
+
+		/* replace current slot contents with old contents*/
+		bcopy( &oldent, &sysent[ i], sizeof( struct sysent));
+
+		break;		/* Success*/
+
+	default:	/* we only understand load/unload*/
+		err = EINVAL;
+		break;
+	}
+
+	return( err);
+}
+
+
+/*
+ * External entry point; should generally match name of .o file.  The
+ * arguments are always the same for all loaded modules.  The "load",
+ * "unload", and "stat" functions in "DISPATCH" will be called under
+ * their respective circumstances unless their value is "nosys".  If
+ * called, they are called with the same arguments (cmd is included to
+ * allow the use of a single function, ver is included for version
+ * matching between modules and the kernel loader for the modules).
+ *
+ * Since we expect to link in the kernel and add external symbols to
+ * the kernel symbol name space in a future version, generally all
+ * functions used in the implementation of a particular module should
+ * be static unless they are expected to be seen in other modules or
+ * to resolve unresolved symbols alread existing in the kernel (the
+ * second case is not likely to ever occur).
+ *
+ * The entry point should return 0 unless it is refusing load (in which
+ * case it should return an errno from errno.h).
+ */
+miscmod( lkmtp, cmd, ver)
+struct lkm_table	*lkmtp;	
+int			cmd;
+int			ver;
+{
+	DISPATCH(lkmtp,cmd,ver,miscmod_handle,miscmod_handle,nosys)
+}
+
+
+/*
+ * EOF -- This file has not been truncated.
+ */
diff --git a/share/examples/lkm/misc/test/Makefile b/share/examples/lkm/misc/test/Makefile
new file mode 100644
index 0000000..466e4ac
--- /dev/null
+++ b/share/examples/lkm/misc/test/Makefile
@@ -0,0 +1,66 @@
+# 05 Jun 93
+#
+# Makefile for testmisc
+#
+# 05 Jun 93	Terry Lambert		Original
+#
+# Copyright (c) 1993 Terrence R. Lambert.
+# 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.
+# 3. All advertising materials mentioning features or use of this software
+#    must display the following acknowledgement:
+#      This product includes software developed by Terrence R. Lambert.
+# 4. The name Terrence R. Lambert may not be used to endorse or promote
+#    products derived from this software without specific prior written
+#    permission.
+#
+# THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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.
+#
+
+PROG=	testmisc
+NOMAN=
+
+load:
+	@echo "This test program will call the sample system call;"
+	@echo "the "offset requested will be shown as 'Off' in the"
+	@echo "status display below.  If no modules are loaded, an"
+	@echo "error '3' will be reported."
+	@echo
+	@echo "The sample system call will display a message on the"
+	@echo "system console each time it is run."
+	@echo
+	@echo
+	/sbin/modstat -n miscmod
+	@echo
+	@./testmisc
+
+unload:
+	@echo "This test program will cause an error '3' if the call"
+	@echo "has been successfully unloaded by building 'unload' in"
+	@echo "the 'module' subdirectory."
+	@echo
+	/sbin/modstat -n miscmod
+
+.include <bsd.prog.mk>
+
+#
+# EOF -- This file has not been truncated.
+#
diff --git a/share/examples/lkm/misc/test/testmisc.c b/share/examples/lkm/misc/test/testmisc.c
new file mode 100644
index 0000000..622857d
--- /dev/null
+++ b/share/examples/lkm/misc/test/testmisc.c
@@ -0,0 +1,62 @@
+/* 05 Jun 93*/
+/*
+ * testmisc.c
+ *
+ * Test program to call the sample loaded miscellaneous system call.
+ *
+ * 05 Jun 93	Terry Lambert		Original
+ *
+ *
+ * Copyright (c) 1993 Terrence R. Lambert.
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Terrence R. Lambert.
+ * 4. The name Terrence R. Lambert may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``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 TERRENCE R. LAMBERT 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 <stdio.h>
+
+main()
+{
+	char	buf[ 80];
+	int	err = 0;
+
+	printf( "Table offset as reported by modstat: ");
+	if( gets( buf) == NULL) {
+		printf( "[ABORT]\n");
+		exit( 1);
+	}
+
+	if( err = syscall( atoi( buf) /* no arguments*/))
+		perror( "syscall");
+
+	exit( err);
+}
+
+/*
+ * EOF -- This file has not been truncated
+ */