test: add libkvm read test

This test checks if value received from kvm_read is sane, based on
value returned by sysctl interface.

This should catch regression on bug fixed by r359160

Reviewed by:	jhb
Approved by:	jhibbits (mentor)
MFC after:	1 week
Sponsored by:	Eldorado Research Institute (eldorado.org.br)
Differential Revision:	https://reviews.freebsd.org/D23783

lib/libkvm/tests/Makefile

@@ -6,8 +6,10 @@ ATF_TESTS_C+=	kvm_close_test
 ATF_TESTS_C+=	kvm_geterr_test
 ATF_TESTS_C+=	kvm_open_test
 ATF_TESTS_C+=	kvm_open2_test
+ATF_TESTS_C+=	kvm_read_test
 
 CFLAGS.kvm_geterr_test+=	-I${.CURDIR:H}
+CFLAGS.kvm_read_test+=		-I${.CURDIR:H}
 
 LIBADD+=	kvm
 
@@ -15,7 +17,7 @@ WARNS?=		6
 
 BINDIR=		${TESTSDIR}
 
-.for t in kvm_geterr_test kvm_open_test kvm_open2_test
+.for t in kvm_geterr_test kvm_open_test kvm_open2_test kvm_read_test
 SRCS.$t=	$t.c kvm_test_common.c
 .endfor
 

lib/libkvm/tests/kvm_read_test.c

@@ -0,0 +1,98 @@
+/*-
+ * Copyright (c) 2020 Alfredo Dal'Ava Junior <alfredo@freebsd.org>
+ * Copyright (c) 2017 Enji Cooper <ngie@freebsd.org>
+ *
+ * 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.
+ *
+ * From: FreeBSD: src/lib/libkvm/tests/kvm_geterr_test.c
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <kvm.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <atf-c.h>
+
+#include "kvm_test_common.h"
+
+ATF_TC(kvm_read_positive_test_no_error);
+ATF_TC_HEAD(kvm_read_positive_test_no_error, tc)
+{
+
+	atf_tc_set_md_var(tc, "descr",
+	    "test that kvm_read returns a sane value");
+	atf_tc_set_md_var(tc, "require.user", "root");
+}
+
+ATF_TC_BODY(kvm_read_positive_test_no_error, tc)
+{
+	kvm_t *kd;
+	struct nlist nl[] = {
+#define	SYMNAME	"_mp_maxcpus"
+#define	X_MAXCPUS	0
+		{ SYMNAME, 0, 0, 0, 0 },
+		{ NULL, 0, 0, 0, 0 },
+	};
+	ssize_t rc;
+	int sysctl_maxcpus, mp_maxcpus, retcode;
+	size_t len = sizeof(sysctl_maxcpus);
+
+	errbuf_clear();
+	kd = kvm_open(NULL, NULL, NULL, O_RDONLY, errbuf);
+	ATF_CHECK(!errbuf_has_error(errbuf));
+	ATF_REQUIRE_MSG(kd != NULL, "kvm_open failed: %s", errbuf);
+	retcode = kvm_nlist(kd, nl);
+	ATF_REQUIRE_MSG(retcode != -1,
+	    "kvm_nlist failed (returned %d): %s", retcode, kvm_geterr(kd));
+	if (nl[X_MAXCPUS].n_type == 0)
+		atf_tc_skip("symbol (\"%s\") couldn't be found", SYMNAME);
+
+	rc = kvm_read(kd, nl[X_MAXCPUS].n_value, &mp_maxcpus,
+	    sizeof(mp_maxcpus));
+
+	ATF_REQUIRE_MSG(rc != -1, "kvm_read failed: %s", kvm_geterr(kd));
+	ATF_REQUIRE_MSG(kvm_close(kd) == 0, "kvm_close failed: %s",
+	    strerror(errno));
+
+	/* Check if value read from kvm_read is sane */
+        retcode = sysctlbyname("kern.smp.maxcpus", &sysctl_maxcpus, &len, NULL, 0);
+	ATF_REQUIRE_MSG(retcode == 0, "sysctl read failed : %d", retcode);
+	ATF_REQUIRE_EQ_MSG(mp_maxcpus, sysctl_maxcpus,
+	    "failed: kvm_read of mp_maxcpus returned %d but sysctl maxcpus returned %d",
+	    mp_maxcpus, sysctl_maxcpus);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, kvm_read_positive_test_no_error);
+	return (atf_no_error());
+}