/* $Id$
 *
 * Talk to the Moira database to change a person's login shell.  The chosen
 * shell must exist.  A warning will be issued if the shell is not in
 * /etc/shells.
 *
 * chsh with no modifiers changes the shell of the user who is running
 * the program.
 *
 * If a commandline argument is given, it is taken to be the username
 * of the user whose shell is to be changed.
 *
 * Copyright (C) 1988-1998 by the Massachusetts Institute of Technology
 * For copying and distribution information, please see the file
 * <mit-copyright.h>.
 */

#include <mit-copyright.h>
#include <moira.h>
#include <moira_site.h>
#include <mrclient.h>

#include <stdio.h>
#include <string.h>
#include <unistd.h>

RCSID("$Header$");

void usage(void);
int chsh(char *uname);
int get_shell(int argc, char **argv, void *uname);
int get_fmodtime(int argc, char **argv, void *uname);
void check_shell(char *shell);
#ifndef HAVE_GETUSERSHELL
char *getusershell(void);
#endif

char *whoami;

int main(int argc, char *argv[])
{
  char *uname;

  if ((whoami = strrchr(argv[0], '/')) == NULL)
    whoami = argv[0];
  else
    whoami++;

  if (argc > 2)
    usage();

  if (argc == 2)
    uname = argv[1];
  else
    {
      uname = mrcl_krb_user();
      if (!uname)
	exit(1);
    }

  exit(chsh(uname));
}

int chsh(char *uname)
{
  int status;			/* general purpose exit status */
  int q_argc;			/* argc for mr_query */
  char *q_argv[U_END];		/* argv for mr_query */
  char *motd;			/* determine Moira server status */

  int got_one = 0;		/* have we got a new shell yet? */
  char shell[BUFSIZ];		/* the new shell */

  if (mrcl_connect(NULL, "chsh", 2, 1) != MRCL_SUCCESS)
    exit(1);

  /* First, do an access check */

  q_argv[USH_NAME] = uname;
  q_argv[USH_SHELL] = "junk";
  q_argc = USH_END;

  if ((status = mr_access("update_user_shell", q_argc, q_argv)))
    {
      com_err(whoami, status, "; shell not\nchanged.");
      exit(2);
    }

  printf("Changing login shell for %s.\n", uname);

  /* Display current information */

  q_argv[NAME] = uname;
  q_argc = NAME + 1;

  if ((status = mr_query("get_finger_by_login", q_argc, q_argv,
			 get_fmodtime, uname)))
    {
      com_err(whoami, status, "while getting user information.");
      exit(2);
    }

  if ((status = mr_query("get_user_account_by_login", q_argc, q_argv,
			 get_shell, uname)))
    {
      com_err(whoami, status, "while getting user information.");
      exit(2);
    }

  /* Ask for new shell */
  while (!got_one)
    {
      printf("New shell: ");
      if (!fgets(shell, sizeof(shell), stdin))
	exit(0);
      got_one = (strlen(shell) > 1);
    }

  shell[strlen(shell) - 1] = 0;	/* strip off newline */

  /* Make sure we have a valid shell.  This routine could exit */
  check_shell(shell);

  /* Change shell */

  printf("Changing shell to %s...\n", shell);

  q_argv[USH_NAME] = uname;
  q_argv[USH_SHELL] = shell;
  q_argc = USH_END;
  if ((status = mr_query("update_user_shell", q_argc, q_argv, NULL, NULL)))
    {
      com_err(whoami, status, "while changing shell.");
      exit(2);
    }

  printf("Shell successfully changed.\n");
  mr_disconnect();

  return 0;
}

int get_shell(int argc, char **argv, void *uname)
{
  /* We'll just take the first information we get since login names
     cannot be duplicated in the database. */

  if (argc < U_END || strcmp(argv[U_NAME], uname))
    {
      fprintf(stderr, "Some internal error has occurred.  Try again.\n");
      exit(3);
    }

  printf("Current shell for %s is %s.\n", (char *)uname, argv[U_SHELL]);

  return MR_ABORT;		/* Don't pay attention to other matches. */
}

int get_fmodtime(int argc, char **argv, void *uname)
{
  /* We'll just take the first information we get since login names
     cannot be duplicated in the database. */

  if (argc < F_END || strcmp(argv[F_NAME], uname))
    {
      fprintf(stderr, "Some internal error has occurred.  Try again.\n");
      exit(3);
    }

  printf("Finger information last changed on %s\n", argv[F_MODTIME]);
  printf("by user %s with %s.\n", argv[F_MODBY], argv[F_MODWITH]);

  return MR_ABORT;		/* Don't pay attention to other matches. */
}

void check_shell(char *shell)
{
  char *valid_shell;
  int ok = 0;

  while ((valid_shell = getusershell()))
    {
      if (!strcmp(shell, valid_shell))
	{
	  ok = 1;
	  break;
	}
      else if (!strcmp(shell, 1 + strrchr(valid_shell, '/')))
	{
	  ok = 1;
	  strcpy(shell, valid_shell);
	  break;
	}
    }

  if (!ok)
    {
      if (shell[0] != '/')
	{
	  fprintf(stderr, "%s is not a standard shell.  ", shell);
	  fprintf(stderr, "You may choose to use a nonstandard\n");
	  fprintf(stderr, "shell, but you must specify its complete ");
	  fprintf(stderr, "path name.\n");
	  exit(2);
	}
      else if (access(shell, X_OK))
	{
	  fprintf(stderr, "%s is not available.\n", shell);
	  exit(2);
	}
      else
	{
	  printf("%s exists but is an unusual choice.\n", shell);
	  printf("Try again if it is not what you wanted.\n");
	}
    }
}

void usage(void)
{
  fprintf(stderr, "Usage: %s [user]\n", whoami);
  exit(1);
}

#ifndef HAVE_GETUSERSHELL
#include <sys/param.h>

char *getusershell(void)
{
  static FILE *shells = NULL;

  /* In a sane universe, no shell will have a length longer than
   * MAXPATHLEN. If any line in /etc/shells does, we'll lose, but
   * not much. shrug.
   */
  static char buf[MAXPATHLEN];
  char *p;

  if (!shells)
    {
      shells = fopen("/etc/shells", "r");
      if (!shells)
	{
	  fprintf(stderr, "%s: Can't open /etc/shells. Unable to determine if "
		  "this is a normal shell.\n\n", whoami);
	  return NULL;
	}
    }

  while (1)
    {
      if (!fgets(buf, sizeof(buf), shells))
	{
	  fclose(shells);
	  shells = NULL;
	  return NULL;
	}

      if (buf[0] != '/')
	continue;

      p = strchr(buf, '\n');
      if (p)
	*p = '\0';

      return buf;
    }
}
#endif