zdtm: netns check ipv4 device config preserve while c/r

check it for default/lo, test values for config options are randomly
generated and restricted by rand_limit

changes:
v2: make for all config options, avoid use of "system".
v3: err->fail, run in own set of namespaces, add random,
check not all options.
v4: use all options because test is run in net-namespace,
use ARRAY_SIZE macro
v5: check fscanf and snprintf return values properly

Signed-off-by: Pavel Tikhomirov <ptikhomirov@parallels.com>
Acked-by:  Andrew Vagin <avagin@odin.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -191,6 +191,7 @@ generate_test_list()
 		transition/ipc
 		static/netns-nf
 		static/netns
+		ns/static/netns-dev
 		static/cgroup00
 		static/cgroup01
 		static/cgroup02
@@ -324,6 +325,7 @@ mntns_shared_bind
 mntns_shared_bind02
 mntns_root_bind
 mntns_rw_ro_rw
+netns-dev
 sockets00
 cow01
 "

test/zdtm/live/static/Makefile

@@ -95,6 +95,7 @@ TST_NOFILE	=				\
 		poll				\
 		mountpoints			\
 		netns				\
+		netns-dev			\
 		session01			\
 		session02			\
 		session03			\

test/zdtm/live/static/netns-dev.c

@@ -0,0 +1,208 @@
+#include <unistd.h>
+#include <stdlib.h>
+#include <dirent.h>
+
+#include "zdtmtst.h"
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+#define LO_CONF_DIR_PATH "/proc/sys/net/ipv4/conf/lo"
+#define DEF_CONF_DIR_PATH "/proc/sys/net/ipv4/conf/default"
+
+char *devconfs[] = {
+	"accept_local",
+	"accept_redirects",
+	"accept_source_route",
+	"arp_accept",
+	"arp_announce",
+	"arp_filter",
+	"arp_ignore",
+	"arp_notify",
+	"bootp_relay",
+	"disable_policy",
+	"disable_xfrm",
+	"force_igmp_version",
+	"forwarding",
+	"igmpv2_unsolicited_report_interval",
+	"igmpv3_unsolicited_report_interval",
+	"log_martians",
+	"mc_forwarding",
+	"medium_id",
+	"promote_secondaries",
+	"proxy_arp",
+	"proxy_arp_pvlan",
+	"route_localnet",
+	"rp_filter",
+	"secure_redirects",
+	"send_redirects",
+	"shared_media",
+	"src_valid_mark",
+	"tag",
+	NULL,
+};
+
+int rand_limit[] = {
+	2,	/* accept_local */
+	2,	/* accept_redirects */
+	2,	/* accept_source_route */
+	2,	/* arp_accept */
+	3,	/* arp_announce */
+	2,	/* arp_filter */
+	9,	/* arp_ignore */
+	2,	/* arp_notify */
+	2,	/* bootp_relay */
+	2,	/* disable_policy */
+	2,	/* disable_xfrm */
+	0,	/* force_igmp_version */
+	2,	/* forwarding */
+	0,	/* igmpv2_unsolicited_report_interval */
+	0,	/* igmpv3_unsolicited_report_interval */
+	2,	/* log_martians */
+	2,	/* mc_forwarding */
+	0,	/* medium_id */
+	2,	/* promote_secondaries */
+	2,	/* proxy_arp */
+	2,	/* proxy_arp_pvlan */
+	2,	/* route_localnet */
+	3,	/* rp_filter */
+	2,	/* secure_redirects */
+	2,	/* send_redirects */
+	2,	/* shared_media */
+	0,	/* src_valid_mark */
+	0,	/* tag */
+};
+
+struct test_conf {
+	int ipv4_conf[ARRAY_SIZE(devconfs)];
+	int ipv4_conf_rand[ARRAY_SIZE(devconfs)];
+	char *dir;
+} lo, def;
+
+static int save_and_set(int opt, FILE *fp, struct test_conf *tc) {
+	int ret;
+	int val;
+
+	/*
+	 * Save
+	 */
+	ret = fscanf(fp, "%d", &tc->ipv4_conf[opt]);
+	if (ret != 1) {
+		err("fscanf");
+		return -1;
+	}
+
+	/*
+	 * Set random value
+	 */
+	val = (int)lrand48();
+
+	if (rand_limit[opt] != 0)
+		tc->ipv4_conf_rand[opt] = val % rand_limit[opt];
+	else
+		tc->ipv4_conf_rand[opt] = val;
+
+	ret = fprintf(fp, "%d", tc->ipv4_conf_rand[opt]);
+	if (ret < 0) {
+		err("fprintf");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int check_and_restore(int opt, FILE *fp, struct test_conf *tc) {
+	int ret;
+	int val;
+
+	/*
+	 * Check opt
+	 */
+	ret = fscanf(fp, "%d", &val);
+	if (ret != 1) {
+		err("fscanf");
+		return -1;
+	}
+
+	if (val != tc->ipv4_conf_rand[opt]) {
+		fail("Option \"%s/%s\" changed from %d to %d",
+		     tc->dir, devconfs[opt], tc->ipv4_conf_rand[opt], val);
+		return -1;
+	}
+
+	/*
+	 * Restore opt
+	 */
+	ret = fprintf(fp, "%d", tc->ipv4_conf[opt]);
+	if (ret < 0) {
+		err("fprintf");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int for_each_option_do(int (*f)(int opt, FILE *fp, struct test_conf *tc), struct test_conf *tc) {
+	int ret;
+	int i;
+
+	for (i = 0; devconfs[i]; i++) {
+		FILE *fp;
+		char path[PATH_MAX];
+
+		ret = snprintf(path, sizeof(path), "%s/%s", tc->dir, devconfs[i]);
+		if (ret < 0) {
+			err("snprintf");
+			return -1;
+		}
+
+		ret = access(path, W_OK);
+		if (ret < 0)
+			continue;
+
+		fp = fopen(path, "r+");
+		if (fp == NULL) {
+			err("fopen");
+			return -1;
+		}
+
+		ret = (*f)(i, fp, tc);
+		if (ret < 0)
+			return -1;
+
+		fclose(fp);
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int ret;
+
+	lo.dir = LO_CONF_DIR_PATH;
+	def.dir = DEF_CONF_DIR_PATH;
+
+	test_init(argc, argv);
+
+	ret = for_each_option_do(save_and_set, &lo);
+	if (ret < 0)
+		return -1;
+
+	ret = for_each_option_do(save_and_set, &def);
+	if (ret < 0)
+		return -1;
+
+	test_daemon();
+	test_waitsig();
+
+	ret = for_each_option_do(check_and_restore, &lo);
+	if (ret < 0)
+		return -1;
+
+	ret = for_each_option_do(check_and_restore, &def);
+	if (ret < 0)
+		return -1;
+
+	pass();
+	return 0;
+}