extern pid_t setsid (void);
extern pid_t tcgetpgrp (int);
+extern int faccessat (int, char const *, int, int);
+
+/* These are normally on fcntl.h, but we don't override that header. */
+/* Use values compatible with gnulib, as there's no reason to differ. */
+#define AT_FDCWD (-3041965)
+#define AT_EACCESS 4
+#define AT_SYMLINK_NOFOLLOW 4096
+
+#define O_NOCTTY 0
+#define O_IGNORE_CTTY 0
+
+/* This is normally on stdlib.h, but we don't override that header. */
+extern int unsetenv (const char *);
+
#endif /* _UNISTD_H */