arch/um/drivers/fd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <termios.h>
  11 #include "chan_user.h"
  12 #include <os.h>
  13 #include <um_malloc.h>
  14
  15 struct fd_chan {
  16         int fd;
  17         int raw;
  18         struct termios tt;
  19         char str[sizeof("1234567890\0")];
  20 };
  21
  22 static void *fd_init(char *str, int device, const struct chan_opts *opts)
  23 {
  24         struct fd_chan *data;
  25         char *end;
  26         int n;
  27
  28         if (*str != ':') {
  29                 printk(UM_KERN_ERR "fd_init : channel type 'fd' must specify a "
  30                        "file descriptor\n");
  31                 return NULL;
  32         }
  33         str++;
  34         n = strtoul(str, &end, 0);
  35         if ((*end != '\0') || (end == str)) {
  36                 printk(UM_KERN_ERR "fd_init : couldn't parse file descriptor "
  37                        "'%s'\n", str);
  38                 return NULL;
  39         }
  40
  41         data = uml_kmalloc(sizeof(*data), UM_GFP_KERNEL);
  42         if (data == NULL)
  43                 return NULL;
  44
  45         *data = ((struct fd_chan) { .fd         = n,
  46                                     .raw        = opts->raw });
  47         return data;
  48 }
  49
  50 static int fd_open(int input, int output, int primary, void *d, char **dev_out)
  51 {
  52         struct fd_chan *data = d;
  53         int err;
  54
  55         if (data->raw && isatty(data->fd)) {
  56                 CATCH_EINTR(err = tcgetattr(data->fd, &data->tt));
  57                 if (err)
  58                         return err;
  59
  60                 err = raw(data->fd);
  61                 if (err)
  62                         return err;
  63         }
  64         sprintf(data->str, "%d", data->fd);
  65         *dev_out = data->str;
  66         return data->fd;
  67 }
  68
  69 static void fd_close(int fd, void *d)
  70 {
  71         struct fd_chan *data = d;
  72         int err;
  73
  74         if (!data->raw || !isatty(fd))
  75                 return;
  76
  77         CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &data->tt));
  78         if (err)
  79                 printk(UM_KERN_ERR "Failed to restore terminal state - "
  80                        "errno = %d\n", -err);
  81         data->raw = 0;
  82 }
  83
  84 const struct chan_ops fd_ops = {
  85         .type           = "fd",
  86         .init           = fd_init,
  87         .open           = fd_open,
  88         .close          = fd_close,
  89         .read           = generic_read,
  90         .write          = generic_write,
  91         .console_write  = generic_console_write,
  92         .window_size    = generic_window_size,
  93         .free           = generic_free,
  94         .winch          = 1,
  95 };