+#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 */
+#ifdef NGROUPS
+#define NGROUPS_MAX NGROUPS
+#else
+#define NGROUPS_MAX 0
+#endif
+#endif
+
+#ifndef O_NONBLOCK /* Non Blocking Open */
+# define O_NONBLOCK 00004
+#endif
+
+#ifndef S_ISDIR
+# define S_ISDIR(mode) (((mode) & (_S_IFMT)) == (_S_IFDIR))
+#endif /* S_ISDIR */
+
+#ifndef S_ISREG
+# define S_ISREG(mode) (((mode) & (_S_IFMT)) == (_S_IFREG))
+#endif /* S_ISREG */
+
+#ifndef S_ISLNK
+# define S_ISLNK(mode) (((mode) & S_IFMT) == S_IFLNK)
+#endif /* S_ISLNK */
+
+#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 */
+
+#if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
+#define MAP_ANON MAP_ANONYMOUS
+#endif
+
+#ifndef MAP_FAILED
+# define MAP_FAILED ((void *)-1)
+#endif
+
+/* *-*-nto-qnx doesn't define this constant in the system headers */
+#ifdef MISSING_NFDBITS
+# define NFDBITS (8 * sizeof(unsigned long))
+#endif
+
+/*
+SCO Open Server 3 has INADDR_LOOPBACK defined in rpc/rpc.h but
+including rpc/rpc.h breaks Solaris 6
+*/
+#ifndef INADDR_LOOPBACK
+#define INADDR_LOOPBACK ((u_long)0x7f000001)
+#endif
+
+#ifndef __unused
+#define __unused
+#endif
+