zdtm: check a ghost file in a read-only directory

=[log]=> dump/zdtm/static/unlink_fstat00/39/1/restore.log
------------------------ grep Error ------------------------
(00.097701)      4: Error (files-reg.c:1231): Can't link zdtm/static/unlink_fstat00.test/test\file'
(00.097707)      4: Error (files-reg.c:1431): Can't link zdtm/static/unlink_fstat00.test/test\file'
(00.097952)      1: Error (cr-restore.c:1404): 4 exited, status=1
(00.108085) Error (cr-restore.c:1407): 64 killed by signal 9: Killed
(00.114341) Error (cr-restore.c:2246): Restoring FAILED.
------------------------ ERROR OVER ------------------------

v2: add a new test instead of changing the existing one.
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/.gitignore

@@ -185,6 +185,7 @@
 /static/unlink_fstat01+
 /static/unlink_fstat02
 /static/unlink_fstat03
+/static/unlink_fstat04
 /static/unlink_largefile
 /static/unlink_mmap00
 /static/unlink_mmap01

test/zdtm/static/Makefile

@@ -219,6 +219,7 @@ TST_DIR		=				\
 		cgroup02			\
 		cgroup03			\
 		cgroup_stray		\
+		unlink_fstat04			\
 		mntns_open			\
 		mntns_link_remap		\
 		mntns_link_ghost		\
@@ -376,6 +377,7 @@ maps02:		get_smaps_bits.o
 mlock_setuid:		get_smaps_bits.o
 inotify01:		override CFLAGS += -DINOTIFY01
 unlink_fstat01+:	override CFLAGS += -DUNLINK_OVER
+unlink_fstat04:		override CFLAGS += -DUNLINK_FSTAT04
 sk-freebind-false:	override CFLAGS += -DZDTM_FREEBIND_FALSE
 stopped01:	override CFLAGS += -DZDTM_STOPPED_KILL
 stopped02:	override CFLAGS += -DZDTM_STOPPED_TKILL

test/zdtm/static/unlink_fstat00.c

@@ -5,13 +5,19 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <string.h>
+#include <linux/limits.h>
 
 #include "zdtmtst.h"
 
 const char *test_doc	= "Open, unlink, change size, seek, migrate, check size";
 
+#ifdef UNLINK_FSTAT04
+char *dirname;
+TEST_OPTION(dirname, string, "directory name", 1);
+#else
 char *filename;
 TEST_OPTION(filename, string, "file name", 1);
+#endif
 
 int main(int argc, char ** argv)
 {
@@ -23,15 +29,30 @@ int main(int argc, char ** argv)
 	uint8_t buf[fsize];
 	struct stat fst;
 	uint32_t crc;
+#ifdef UNLINK_FSTAT04
+	char filename[PATH_MAX];
+#endif
 
 	test_init(argc, argv);
 
+#ifdef UNLINK_FSTAT04
+	snprintf(filename, sizeof(filename), "%s/test\\file'\n\"un%%linkfstat00", dirname);
+
+	mkdir(dirname, 0700);
+#endif
 	fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0644);
 	if (fd < 0) {
 		pr_perror("can't open %s", filename);
 		exit(1);
 	}
 
+#ifdef UNLINK_FSTAT04
+	if (chmod(dirname, 0500)) {
+		pr_perror("chmod");
+		exit(1);
+	}
+#endif
+
 	if (fstat(fd, &fst) < 0) {
 		pr_perror("can't get file info %s before", filename);
 		goto failed;

test/zdtm/static/unlink_fstat04.c

+unlink_fstat00.c
\ No newline at end of file

test/zdtm/static/unlink_fstat04.desc

+{ "flags" : "suid" }