+#ifndef MAXPATHLEN
+# ifdef PATH_MAX
+# define MAXPATHLEN PATH_MAX
+# else /* PATH_MAX */
+# define MAXPATHLEN 64 /* Should be safe */
+# endif /* PATH_MAX */
+#endif /* MAXPATHLEN */
+
+#ifndef STDIN_FILENO
+# define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+# define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+
+#ifndef NGROUPS_MAX /* Disable groupaccess if NGROUP_MAX is not set */
+#define NGROUPS_MAX 0
+#endif
+
+#ifndef O_NONBLOCK /* Non Blocking Open */
+# define O_NONBLOCK 00004
+#endif
+
+#ifndef S_ISREG
+# define S_ISDIR(mode) (((mode) & (_S_IFMT)) == (_S_IFDIR))
+# define S_ISREG(mode) (((mode) & (_S_IFMT)) == (_S_IFREG))
+#endif /* S_ISREG */
+
+#ifndef S_IXUSR
+# define S_IXUSR 0000100 /* execute/search permission, */
+# define S_IXGRP 0000010 /* execute/search permission, */
+# define S_IXOTH 0000001 /* execute/search permission, */
+# define _S_IWUSR 0000200 /* write permission, */
+# define S_IWUSR _S_IWUSR /* write permission, owner */
+# define S_IWGRP 0000020 /* write permission, group */
+# define S_IWOTH 0000002 /* write permission, other */
+# define S_IRUSR 0000400 /* read permission, owner */
+# define S_IRGRP 0000040 /* read permission, group */
+# define S_IROTH 0000004 /* read permission, other */
+# define S_IRWXU 0000700 /* read, write, execute */
+# define S_IRWXG 0000070 /* read, write, execute */
+# define S_IRWXO 0000007 /* read, write, execute */
+#endif /* S_IXUSR */
+