tools/nolibc: add more stat() variants

Add fstat(), fstatat() and lstat(). All of them use the existing implementation
based on statx().

Signed-off-by: Thomas Weißschuh <[e-mail]>
Acked-by: Willy Tarreau <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Thomas Weißschuh <[e-mail]>

tools/include/nolibc/sys/stat.h

···
 /*
  * int statx(int fd, const char *path, int flags, unsigned int mask, struct statx *buf);
  * int stat(const char *path, struct stat *buf);
+ * int fstatat(int fd, const char *path, struct stat *buf, int flag);
+ * int fstat(int fildes, struct stat *buf);
+ * int lstat(const char *path, struct stat *buf);
  */
 
 static __attribute__((unused))
···
 
 
 static __attribute__((unused))
-int stat(const char *path, struct stat *buf)
+int fstatat(int fd, const char *path, struct stat *buf, int flag)
 {
 	struct statx statx;
 	long ret;
 
-	ret = __sysret(sys_statx(AT_FDCWD, path, AT_NO_AUTOMOUNT, STATX_BASIC_STATS, &statx));
+	ret = __sysret(sys_statx(fd, path, flag | AT_NO_AUTOMOUNT, STATX_BASIC_STATS, &statx));
 	if (ret == -1)
 		return ret;
 
···
 	buf->st_ctim.tv_nsec = statx.stx_ctime.tv_nsec;
 
 	return 0;
+}
+
+static __attribute__((unused))
+int stat(const char *path, struct stat *buf)
+{
+	return fstatat(AT_FDCWD, path, buf, 0);
+}
+
+static __attribute__((unused))
+int fstat(int fildes, struct stat *buf)
+{
+	return fstatat(fildes, "", buf, AT_EMPTY_PATH);
+}
+
+static __attribute__((unused))
+int lstat(const char *path, struct stat *buf)
+{
+	return fstatat(AT_FDCWD, path, buf, AT_SYMLINK_NOFOLLOW);
 }
 
 #endif /* _NOLIBC_SYS_STAT_H */