Attachment 579914 Details for Bug 815790 – c code

c code

clear_console.c (text/plain), 5.28 KB, created by Account closed by user on 2012-04-24 16:39:57 UTC

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Creator: Account closed by user

Created: 2012-04-24 16:39:57 UTC

Size: 5.28 KB

patch

obsolete

>/*
>Copyright (C) 2006-2008 Canonical Ltd.
>
>clear_console and it's man page are free software; you can redistribute it
>and/or modify it under the terms of the GNU General Public License as
>published by the Free Software Foundation; either version 2, or (at your
>option) any later version.
>*/
>
>#include <stdlib.h>
>#include <stdio.h>
>#include <fcntl.h>
>#include <string.h>
>#include <getopt.h>
>#include <errno.h>
>#include <unistd.h>
>#include <sys/ioctl.h>
>#if defined(__linux)
>#include <linux/kd.h>
>#include <linux/vt.h>
>#elif defined(__FreeBSD_kernel__)
>#include <sys/consio.h>
>#include <sys/kbio.h>
>#endif
>
>#include <curses.h>
>#include <term.h>
>
>#define VERSION "0.1"
>
>char* progname;
>int quiet = 0;
>
>void usage()
>{
>  fprintf(stderr, "Usage: %s [option]\n", progname);
>  fprintf(stderr, "valid options are:\n");
>  fprintf(stderr, "\t-q  --quiet    don't print error messages\n");
>  fprintf(stderr, "\t-h --help      display this help text and exit\n");
>  fprintf(stderr, "\t-V --version   display version information and exit\n");
>}
>
>const struct option opts[] =
>{
>  /* operations */
>    {"help", no_argument, 0, 'h'},
>    {"version", no_argument, 0, 'V'},
>    {"quiet", no_argument, 0, 'q'},
>    {0, 0, 0, 0}
>};
>
>static int putch(int c)
>{
>        return putchar(c);
>}
>
>
>/* taken from console-utils, lib/misc-console-utils.c */
>
>int is_a_console(int fd)
>{
>#if defined(__linux__)
>  char arg;
>#elif defined(__FreeBSD_kernel__)
>  int arg;
>#endif
>
>  arg = 0;
>  return (ioctl(fd, KDGKBTYPE, &arg) == 0
>          && ((arg == KB_OTHER) || (arg == KB_101) || (arg == KB_84)));
>}
>
>static int open_a_console(char *fnam)
>{
>  int fd;
>
>  /* try read-only */
>  fd = open(fnam, O_RDWR);
>
>  /* if failed, try read-only */
>  if (fd < 0 && errno == EACCES)
>      fd = open(fnam, O_RDONLY);
>
>  /* if failed, try write-only */
>  if (fd < 0 && errno == EACCES)
>      fd = open(fnam, O_WRONLY);
>
>  /* if failed, fail */
>  if (fd < 0)
>      return -1;
>
>  /* if not a console, fail */
>  if (! is_a_console(fd))
>    {
>      close(fd);
>      return -1;
>    }
>
>  /* success */
>  return fd;
>}
>
>/*
> * Get an fd for use with kbd/console ioctls.
> * We try several things because opening /dev/console will fail
> * if someone else used X (which does a chown on /dev/console).
> *
> * if tty_name is non-NULL, try this one instead.
> */
>
>int get_console_fd(char* tty_name)
>{
>  int fd;
>
>  if (tty_name)
>    {
>      if (-1 == (fd = open_a_console(tty_name)))
>        return -1;
>      else
>        return fd;
>    }
>
>  fd = open_a_console("/dev/tty");
>  if (fd >= 0)
>    return fd;
>
>  fd = open_a_console("/dev/tty0");
>  if (fd >= 0)
>    return fd;
>
>  fd = open_a_console("/dev/console");
>  if (fd >= 0)
>    return fd;
>
>  for (fd = 0; fd < 3; fd++)
>    if (is_a_console(fd))
>      return fd;
>
>#if 0
>  fprintf(stderr,
>          _("Couldnt get a file descriptor referring to the console\n"));
>#endif
>  return -1;            /* total failure */
>}
>
>
>int is_pseudo_tty(int fd)
>{
>  char *tty = ttyname(fd);
>
>  if (!tty)
>    {
>      if (!quiet)
>	perror("ttyname");
>      return 0;
>    }
>
>  if (strlen(tty) >= 9 && !strncmp(tty, "/dev/pts/", 9))
>    return 1;
>
>  if (strlen(tty) >= 8 && !strncmp(tty, "/dev/tty", 8)
>      && tty[8] >= 'a' && tty[8] <= 'z')
>    return 1;
>
>  return 0;
>}
>
>int clear_console(int fd)
>{
>  int num, tmp_num;
>#if defined(__linux__)
>  struct vt_stat vtstat;
>#endif
>
>  /* clear screen */
>  setupterm((char *) 0, 1, (int *) 0);
>  if (tputs(clear_screen, lines > 0 ? lines : 1, putch) == ERR)
>    {
>      exit(1);
>    }
>
>  if (is_pseudo_tty(STDIN_FILENO))
>    return 0;
>
>  if (!strcmp(getenv("TERM"), "screen"))
>      return 0;
>
>  /* get current vt */
>#if defined(__linux__)
>  if (ioctl(fd, VT_GETSTATE, &vtstat) < 0)
>#elif defined(__FreeBSD_kernel__)
>  if (ioctl(fd, VT_ACTIVATE, &num) < 0)
>#endif
>    {
>      if (!quiet)
>	fprintf(stderr, "%s: cannot get VTstate\n", progname);
>      exit(1);
>    }
>#if defined(__linux__)
>  num = vtstat.v_active;
>#endif
>  tmp_num = (num == 1 ? 2 : 1);
>
>  /* switch vt to clear the scrollback buffer */
>  if (ioctl(fd, VT_ACTIVATE, tmp_num))
>    {
>      if (!quiet)
>	perror("chvt: VT_ACTIVATE");
>      exit(1);
>    }
>
>  if (ioctl(fd, VT_WAITACTIVE, tmp_num))
>    {
>      if (!quiet)
>	perror("VT_WAITACTIVE");
>      exit(1);
>    }
>
>  /* switch back */
>  if (ioctl(fd, VT_ACTIVATE, num))
>    {
>      if (!quiet)
>	perror("chvt: VT_ACTIVATE");
>      exit(1);
>    }
>
>  if (ioctl(fd, VT_WAITACTIVE, num))
>    {
>      if (!quiet)
>	perror("VT_WAITACTIVE");
>      exit(1);
>    }
>  return 0;
>}
>
>int main (int argc, char* argv[])
>{
>  int fd;
>  int result;                          /* option handling */
>  int an_option;
>
>  if ((progname = strrchr(argv[0], '/')) == NULL)
>    progname = argv[0];
>  else
>    progname++;
>
>  while (1)
>    {
>      result = getopt_long(argc, argv, "Vhq", opts, &an_option);
>      
>      if (result == EOF)
>	break;
>
>      switch (result)
>        {
>        case 'V':
>	  fprintf(stdout, "%s: Version %s\n", progname, VERSION);
>          exit (0);
>        case 'h':
>          usage();
>          exit (0);
>	  
>        case 'q':
>          quiet = 1;
>        }
>    }
>
>  if (optind < argc)
>    {
>      if (!quiet)
>	fprintf(stderr, "%s: no non-option arguments are valid", progname);
>      exit(1);
>    }
>
>  if ((fd = get_console_fd(NULL)) == -1)
>    {
>      if (!quiet)
>	fprintf(stderr, "%s: terminal is not a console\n", progname);
>      exit(1);
>    }
>
>  clear_console(fd);
>
>  return 0;
>}

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Attachments on bug 815790: 579914 | 579915 | 579920