[PATCH 1/3] tools/nolibc: verify that a directory is opened

[Thomas Weißschuh]

If a non-directory is opened, ENODIR should be returned from
opendir()/fdopendir() right away and not only during readdir_r().

Validate the type of opened file during open.

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
 tools/include/nolibc/dirent.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/include/nolibc/dirent.h b/tools/include/nolibc/dirent.h
index 4e02ef25e72d..25fbff208998 100644
--- a/tools/include/nolibc/dirent.h
+++ b/tools/include/nolibc/dirent.h
@@ -30,10 +30,23 @@ typedef struct {
 static __attribute__((unused))
 DIR *fdopendir(int fd)
 {
+	struct stat buf;
+	int ret;
+
 	if (fd < 0) {
 		SET_ERRNO(EBADF);
 		return NULL;
 	}
+
+	ret = fstat(fd, &buf);
+	if (ret < 0)
+		return NULL;
+
+	if (!S_ISDIR(buf.st_mode)) {
+		SET_ERRNO(ENOTDIR);
+		return NULL;
+	}
+
 	return (DIR *)(intptr_t)~fd;
 }
 

-- 
2.55.0