[LTP] [PATCH 2/2] Add test for multiple file types using fstat

[Jinseok Kim]

Following review feedback, create a dedicated fstat test that verifies
S_ISREG(), S_ISDIR(), S_ISFIFO(), S_ISLNK(), S_ISCHR(), S_ISBLK()
on different file types.

Signed-off-by: Jinseok Kim <always.starving0@gmail.com>
---
 testcases/kernel/syscalls/fstat/fstat04.c | 103 ++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 testcases/kernel/syscalls/fstat/fstat04.c

diff --git a/testcases/kernel/syscalls/fstat/fstat04.c b/testcases/kernel/syscalls/fstat/fstat04.c
new file mode 100644
index 000000000..6aa9a8e79
--- /dev/null
+++ b/testcases/kernel/syscalls/fstat/fstat04.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Jinseok Kim <always.starving0@gmail.com>
+ */
+/*\
+ * Verify that fstat correctly identifies various file types
+ */
+
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include "tst_test.h"
+
+#define REG_FILE    "regfile"
+#define DIR_FILE    "dirfile"
+#define FIFO_FILE   "fifofile"
+#define SYMLINK     "symlink"
+#define CHR_DEV     "chrdev"
+#define BLK_DEV     "blkdev"
+
+static int fd = -1;
+
+static struct tcase {
+    const char *desc;
+    const char *path;
+    const char *macro_name;
+    mode_t exp_type;
+} tcases[] = {
+    { "regular file",   REG_FILE,  "S_IFREG", S_IFREG },
+    { "directory",      DIR_FILE,  "S_IFDIR", S_IFDIR },
+    { "FIFO (pipe)",    FIFO_FILE, "S_IFIFO", S_IFIFO },
+    { "symbolic link",  SYMLINK,   "S_IFLNK", S_IFLNK },
+    { "character dev",  CHR_DEV,   "S_IFCHR", S_IFCHR },
+    { "block dev",      BLK_DEV,   "S_IFBLK", S_IFBLK },
+};
+
+static void verify_fstat(unsigned int i)
+{
+    struct tcase *tc = &tcases[i];
+    struct stat buf;
+
+    int flags = O_RDONLY | O_NONBLOCK;
+
+    if (tc->exp_type == S_IFDIR)
+        flags |= O_DIRECTORY;
+
+    fd = SAFE_OPEN(tc->path, flags);
+
+    SAFE_FSTAT(fd, &buf);
+    SAFE_CLOSE(fd);
+
+    int is_correct = 0;
+    switch (tc->exp_type) {
+    case S_IFREG: is_correct = S_ISREG(buf.st_mode); break;
+    case S_IFDIR: is_correct = S_ISDIR(buf.st_mode); break;
+    case S_IFIFO: is_correct = S_ISFIFO(buf.st_mode); break;
+    case S_IFLNK: is_correct = S_ISLNK(buf.st_mode); break;
+    case S_IFCHR: is_correct = S_ISCHR(buf.st_mode); break;
+    case S_IFBLK: is_correct = S_ISBLK(buf.st_mode); break;
+    }
+
+    if (is_correct)
+        tst_res(TPASS, "%s: %s() macro matches", tc->desc, tc->macro_name);
+    else
+        tst_res(TFAIL, "%s: %s() macro does NOT match", tc->desc, tc->macro_name);
+}
+
+static void setup(void)
+{
+    fd = SAFE_OPEN(REG_FILE, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+    SAFE_CLOSE(fd);
+
+    SAFE_MKDIR(DIR_FILE, 0755);
+    SAFE_SYMLINK(REG_FILE, SYMLINK);
+
+    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)
+{
+    SAFE_UNLINK(SYMLINK);
+    SAFE_UNLINK(REG_FILE);
+    SAFE_RMDIR(DIR_FILE);
+
+    SAFE_UNLINK(FIFO_FILE);
+    SAFE_UNLINK(CHR_DEV);
+    SAFE_UNLINK(BLK_DEV);
+}
+
+static struct tst_test test = {
+    .tcnt = ARRAY_SIZE(tcases),
+    .setup = setup,
+    .cleanup = cleanup,
+    .test = verify_fstat,
+    .needs_tmpdir = 1,
+    .needs_root = 1,
+};
--
2.43.0