arch/um/drivers/null.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdlib.h>
   7 #include <errno.h>
   8 #include "chan_user.h"
   9 #include "os.h"
  10
  11 /* This address is used only as a unique identifer */
  12 static int null_chan;
  13
  14 static void *null_init(char *str, int device, const struct chan_opts *opts)
  15 {
  16         return(&null_chan);
  17 }
  18
  19 static int null_open(int input, int output, int primary, void *d,
  20                      char **dev_out)
  21 {
  22         *dev_out = NULL;
  23         return(os_open_file(DEV_NULL, of_rdwr(OPENFLAGS()), 0));
  24 }
  25
  26 static int null_read(int fd, char *c_out, void *unused)
  27 {
  28         return(-ENODEV);
  29 }
  30
  31 static void null_free(void *data)
  32 {
  33 }
  34
  35 const struct chan_ops null_ops = {
  36         .type           = "null",
  37         .init           = null_init,
  38         .open           = null_open,
  39         .close          = generic_close,
  40         .read           = null_read,
  41         .write          = generic_write,
  42         .console_write  = generic_console_write,
  43         .window_size    = generic_window_size,
  44         .free           = null_free,
  45         .winch          = 0,
  46 };
  47
  48 /*
  49  * Overrides for Emacs so that we follow Linus's tabbing style.
  50  * Emacs will notice this stuff at the end of the file and automatically
  51  * adjust the settings for this buffer only.  This must remain at the end
  52  * of the file.
  53  * ---------------------------------------------------------------------------
  54  * Local variables:
  55  * c-file-style: "linux"
  56  * End:
  57  */