- /* On reasonable systems, binary I/O is the default. */
-# undef O_BINARY
-# define O_BINARY 0
-# define SET_BINARY(fd) /* do nothing */ ((void) 0)
+ /* On reasonable systems, binary I/O is the only choice. */
+ /* Use a function rather than a macro, to avoid gcc warnings
+ "warning: statement with no effect". */
+BINARY_IO_INLINE int
+set_binary_mode (int fd, int mode)
+{
+ (void) fd;
+ (void) mode;
+ return O_BINARY;
+}
+#endif
+
+/* SET_BINARY (fd);
+ changes the file descriptor fd to perform binary I/O. */
+#ifdef __DJGPP__
+# include <unistd.h> /* declares isatty() */
+ /* Avoid putting stdin/stdout in binary mode if it is connected to
+ the console, because that would make it impossible for the user
+ to interrupt the program through Ctrl-C or Ctrl-Break. */
+# define SET_BINARY(fd) ((void) (!isatty (fd) ? (set_binary_mode (fd, O_BINARY), 0) : 0))
+#else
+# define SET_BINARY(fd) ((void) set_binary_mode (fd, O_BINARY))