Bug#339855: [g-i] Small patch to run a shell from the GTK frontend

[Attilio Fiandrotti <fiandro@tiscali.it>]

As it seems that creating a GTK terminal widget usable with DFB is not 
something is going to be done in short time ( and removing "Execute a 
shell" form main-menu is not the optimal solution, as proposed in the 
plan for tomorrow's d-i meeting ) i propose this patch to 
d-i-utils-shell.postinst from debian-installer-utils package

Index: debian/di-utils-shell.postinst
===================================================================
--- debian/di-utils-shell.postinst      (revisione 35117)
+++ debian/di-utils-shell.postinst      (copia locale)
@@ -4,6 +4,10 @@

 db_capb backup
 db_input high di-utils-shell/do-shell
-db_go || exit 10
-
-debconf-disconnect /bin/sh || true
+if [ "$DEBIAN_FRONTEND" = gtk ] ; then
+       db_go || true
+       chvt 2
+else
+    db_go || exit
+    debconf-disconnect /bin/sh || true
+elif

when the user presses "Execute a shell", the "chvt 2" command is run and 
the console is switched to VT2.
As the original chvt tool from console-tools depends from a couple of 
libraries, i've rewritten it (source code attached below) taking source 
code from the original console-tools package.
I've tested this solution and it works well; we should also provide a 
way for the user to get back to the VT where the g-i runs, as actually 
he's told to press run "exit" to get back to the instalation even if the 
GTK frontend i used.
If the patch is accepted, someone should also choose where to place the 
chvt.c sourcecode.

friendly

Attilio


/**
 * @chvt.c Command-line terminal switcher
 *
 * Copyright (C) 2006 Attilio Fiandrotti <fiandro@tiscali.it>
 *
 * This program is 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 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * This application is a patchwork of source code from package "console-tools"
 * (for more informations about the original package see author's page
 * http://www.multimania.com/ydirson/en/lct/) and it's meant to be used 
 * in the debian-installer while not relying on  external libraries.
 *
**/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <linux/vt.h>
#include <linux/kd.h>

int get_console_fd(char* tty_name);
int is_a_console(int fd);
static int open_a_console(char *fnam);


int main(int argc, char *argv[]) 
{
  int fd, num ;
  char console_name[16];

  if  ( argc < 2 ) {
    printf ("Usage %s [vt_number]\n", argv[0]);
    exit(0);
  }

  num = atoi(argv[1]);
  sprintf(console_name,"/dev/tty%d",num);

  if (-1 == (fd = get_console_fd(console_name))) exit (1);
  
  if (ioctl(fd,VT_ACTIVATE,num)) 
    {
      perror("chvt: VT_ACTIVATE");
      exit(1);
    }
  if (ioctl(fd,VT_WAITACTIVE,num)) 
    {
      perror("VT_WAITACTIVE");
      exit(1);
    }
  exit(0);
}

int is_a_console(int fd) 
{
  char arg;
  
  arg = 0;
  return (ioctl(fd, KDGKBTYPE, &arg) == 0
	  && ((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;
}

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;
  
  fprintf(stderr,
	  "Couldnt get a file descriptor referring to the console\n");
  return -1;		/* total failure */
}