[PATCH v10 3/3] fstat: add test for multiple file types using fstat

Following review feedback, create a dedicated fstat test that verifies
that fstat() correctly identifies regular files, directories, FIFOs,
character devices, and block devices.

Signed-off-by: Jinseok Kim <[email protected]>
---
Changes in v10:
- Document why root privileges are required.
- Replace the S_IS*() switch with a single S_IFMT comparison.
- Link to v9: https://lore.kernel.org/ltp/20260621090403.2236-2-always.starving0-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Changes in v9:
- Open test files with O_PATH to avoid unnecessary device access
- Link to v8: https://lore.kernel.org/ltp/20260604142029.2077-2-always.starving0-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Changes in v8:
- Link to the man page
- Remove desc from tcase and TST_EXP_EXPR
- Link to v7: https://lore.kernel.org/ltp/20260327152751.3637-1-always.starving0-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
---
 runtest/syscalls                           |  2 +
 testcases/kernel/syscalls/fstat/.gitignore |  2 +
 testcases/kernel/syscalls/fstat/fstat04.c  | 94 ++++++++++++++++++++++
 3 files changed, 98 insertions(+)
 create mode 100644 testcases/kernel/syscalls/fstat/fstat04.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 43951df2a..a38743ded 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -436,6 +436,8 @@ fstat02 fstat02
 fstat02_64 fstat02_64
 fstat03 fstat03
 fstat03_64 fstat03_64
+fstat04 fstat04
+fstat04_64 fstat04_64

 #fstatat64/newfstatat test cases
 fstatat01 fstatat01
diff --git a/testcases/kernel/syscalls/fstat/.gitignore b/testcases/kernel/syscalls/fstat/.gitignore
index 9b1089438..a1f538f7e 100644
--- a/testcases/kernel/syscalls/fstat/.gitignore
+++ b/testcases/kernel/syscalls/fstat/.gitignore
@@ -2,3 +2,5 @@
 /fstat02_64
 /fstat03
 /fstat03_64
+/fstat04
+/fstat04_64
diff --git a/testcases/kernel/syscalls/fstat/fstat04.c b/testcases/kernel/syscalls/fstat/fstat04.c
new file mode 100644
index 000000000..c9a83989b
--- /dev/null
+++ b/testcases/kernel/syscalls/fstat/fstat04.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Jinseok Kim <[email protected]>
+ */
+/*\
+ * Verify that :manpage:`fstat(2)` correctly identifies various
+ * file types.
+ *
+ * Root privileges are required to create character and block device nodes.
+ */
+#define _GNU_SOURCE
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <fcntl.h>
+
+#include "tst_test.h"
+
+#define MOUNT_PATH	"test_mnt"
+#define REG_FILE	"regfile"
+#define DIR_FILE	"dirfile"
+#define FIFO_FILE	"fifofile"
+#define CHR_DEV	MOUNT_PATH "/chrdev"
+#define BLK_DEV	MOUNT_PATH "/blkdev"
+
+static struct tcase {
+	const char *path;
+	mode_t exp_type;
+} tcases[] = {
+	{ REG_FILE,	S_IFREG },
+	{ DIR_FILE,	S_IFDIR },
+	{ FIFO_FILE,	S_IFIFO },
+	{ CHR_DEV,	S_IFCHR },
+	{ BLK_DEV,	S_IFBLK },
+};
+
+static void verify_fstat(unsigned int i)
+{
+	struct tcase *tc = &tcases[i];
+	struct stat buf;
+
+	int flags = O_PATH;
+	int fd;
+
+	if (tc->exp_type == S_IFDIR)
+		flags |= O_DIRECTORY;
+
+	fd = SAFE_OPEN(tc->path, flags);
+
+	SAFE_FSTAT(fd, &buf);
+	SAFE_CLOSE(fd);
+
+	TST_EXP_EXPR((buf.st_mode & S_IFMT) == tc->exp_type, "checking %s", tc->path);
+}
+
+static void setup(void)
+{
+	SAFE_TOUCH(REG_FILE, 0644, NULL);
+	SAFE_MKDIR(DIR_FILE, 0755);
+
+	SAFE_MKNOD(FIFO_FILE, S_IFIFO | 0777, 0);
+	SAFE_MKNOD(CHR_DEV, S_IFCHR | 0777, makedev(1, 3));
+	SAFE_MKNOD(BLK_DEV, S_IFBLK | 0777, makedev(7, 3));
+}
+
+static void cleanup(void)
+{
+	if (!access(REG_FILE, F_OK))
+		SAFE_UNLINK(REG_FILE);
+
+	if (!access(DIR_FILE,  F_OK))
+		SAFE_RMDIR(DIR_FILE);
+
+	if (!access(FIFO_FILE, F_OK))
+		SAFE_UNLINK(FIFO_FILE);
+
+	if (!access(CHR_DEV, F_OK))
+		SAFE_UNLINK(CHR_DEV);
+
+	if (!access(BLK_DEV, F_OK))
+		SAFE_UNLINK(BLK_DEV);
+}
+
+static struct tst_test test = {
+	.tcnt = ARRAY_SIZE(tcases),
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = verify_fstat,
+	.mntpoint = MOUNT_PATH,
+	.needs_devfs = 1,
+	.needs_tmpdir = 1,
+	.needs_root = 1,
+};
--
2.43.0

-- 
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