bash/builtins/cd.def

This file is cd.def, from which is created cd.c.  It implements the
builtins "cd" and "pwd" in Bash.

Copyright (C) 1987-2005 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

Bash 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, or (at your option) any later
version.

Bash 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 Bash; see the file COPYING.  If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.

$PRODUCES cd.c
#include <config.h>

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include "../bashtypes.h"
#include "posixdir.h"
#include "posixstat.h"
#ifndef _MINIX
#include <sys/param.h>
#endif

#include <stdio.h>

#include "../bashansi.h"
#include "../bashintl.h"

#include <errno.h>
#include <tilde/tilde.h>

#include "../shell.h"
#include "../flags.h"
#include "maxpath.h"
#include "common.h"
#include "bashgetopt.h"

#if !defined (errno)
extern int errno;
#endif /* !errno */

extern int posixly_correct;
extern int array_needs_making;
extern char *bash_getcwd_errstr;

static int bindpwd __P((int));
static void setpwd __P((char *));
static char *resetpwd __P((char *));
static int change_to_directory __P((char *, int));

static char *cdspell __P((char *));

/* Change this to 1 to get cd spelling correction by default. */
int cdspelling = 0;

int cdable_vars;

$BUILTIN cd
$FUNCTION cd_builtin
$SHORT_DOC cd [-L|-P] [dir]
Change the current directory to DIR.  The default for DIR is the value
of the HOME shell variable.  The variable CDPATH defines the search
path for the directory containing DIR.  Alternative directory names in
CDPATH are separated by a colon (:).  A null directory name is the same
as the current directory, i.e., `.'.  If DIR begins with a slash (/),
then CDPATH is not used.  If the directory is not found, and the
shell option `cdable_vars' is set, then try the word as a variable
name.  If that variable has a value, then cd to the value of that
variable.  The -P option says to use the physical directory structure
instead of following symbolic links; the -L option forces symbolic links
to be followed.
$END

/* Just set $PWD, don't change OLDPWD.  Used by `pwd -P' in posix mode. */
static void
setpwd (dirname)
     char *dirname;
{
  int old_anm;
  SHELL_VAR *tvar;

  old_anm = array_needs_making;
  tvar = bind_variable ("PWD", dirname ? dirname : "", 0);
  if (old_anm == 0 && array_needs_making && exported_p (tvar))
    {
      update_export_env_inplace ("PWD=", 4, dirname ? dirname : "");
      array_needs_making = 0;
    }
}

static int
bindpwd (no_symlinks)
     int no_symlinks;
{
  char *dirname, *pwdvar;
  int old_anm;
  SHELL_VAR *tvar;

#define tcwd the_current_working_directory
  dirname = tcwd ? (no_symlinks ? sh_physpath (tcwd, 0) : tcwd)
  		 : get_working_directory ("cd");
#undef tcwd

  old_anm = array_needs_making;
  pwdvar = get_string_value ("PWD");

  tvar = bind_variable ("OLDPWD", pwdvar, 0);
  if (old_anm == 0 && array_needs_making && exported_p (tvar))
    {
      update_export_env_inplace ("OLDPWD=", 7, pwdvar);
      array_needs_making = 0;
    }

  setpwd (dirname);

  if (dirname && dirname != the_current_working_directory)
    free (dirname);

  return (EXECUTION_SUCCESS);
}

/* Call get_working_directory to reset the value of
   the_current_working_directory () */
static char *
resetpwd (caller)
     char *caller;
{
  char *tdir;
      
  FREE (the_current_working_directory);
  the_current_working_directory = (char *)NULL;
  tdir = get_working_directory (caller);
  return (tdir);
}

#define LCD_DOVARS	0x001
#define LCD_DOSPELL	0x002
#define LCD_PRINTPATH	0x004
#define LCD_FREEDIRNAME	0x010

/* This builtin is ultimately the way that all user-visible commands should
   change the current working directory.  It is called by cd_to_string (),
   so the programming interface is simple, and it handles errors and
   restrictions properly. */
int
cd_builtin (list)
     WORD_LIST *list;
{
  char *dirname, *cdpath, *path, *temp;
  int path_index, no_symlinks, opt, lflag;

#if defined (RESTRICTED_SHELL)
  if (restricted)
    {
      sh_restricted ((char *)NULL);
      return (EXECUTION_FAILURE);
    }
#endif /* RESTRICTED_SHELL */

  no_symlinks = no_symbolic_links;
  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "LP")) != -1)
    {
      switch (opt)
	{
	case 'P':
	  no_symlinks = 1;
	  break;
	case 'L':
	  no_symlinks = 0;
	  break;
	default:
	  builtin_usage ();
	  return (EXECUTION_FAILURE);
	}
    }
  list = loptend;

  lflag = (cdable_vars ? LCD_DOVARS : 0) |
	  ((interactive && cdspelling) ? LCD_DOSPELL : 0);

  if (list == 0)
    {
      /* `cd' without arguments is equivalent to `cd $HOME' */
      dirname = get_string_value ("HOME");

      if (dirname == 0)
	{
	  builtin_error (_("HOME not set"));
	  return (EXECUTION_FAILURE);
	}
      lflag = 0;
    }
  else if (list->word->word[0] == '-' && list->word->word[1] == '\0')
    {
      /* This is `cd -', equivalent to `cd $OLDPWD' */
      dirname = get_string_value ("OLDPWD");

      if (dirname == 0)
	{
	  builtin_error (_("OLDPWD not set"));
	  return (EXECUTION_FAILURE);
	}
#if 0
      lflag = interactive ? LCD_PRINTPATH : 0;
#else
      lflag = LCD_PRINTPATH;		/* According to SUSv3 */
#endif
    }
  else if (absolute_pathname (list->word->word))
    dirname = list->word->word;
  else if (cdpath = get_string_value ("CDPATH"))
    {
      dirname = list->word->word;

      /* Find directory in $CDPATH. */
      path_index = 0;
      while (path = extract_colon_unit (cdpath, &path_index))
	{
	  /* OPT is 1 if the path element is non-empty */
	  opt = path[0] != '\0';
	  temp = sh_makepath (path, dirname, MP_DOTILDE);
	  free (path);

	  if (change_to_directory (temp, no_symlinks))
	    {
	      /* POSIX.2 says that if a nonempty directory from CDPATH
		 is used to find the directory to change to, the new
		 directory name is echoed to stdout, whether or not
		 the shell is interactive. */
	      if (opt && (path = no_symlinks ? temp : the_current_working_directory))
		printf ("%s\n", path);

	      free (temp);
#if 0
	      /* Posix.2 says that after using CDPATH, the resultant
		 value of $PWD will not contain `.' or `..'. */
	      return (bindpwd (posixly_correct || no_symlinks));
#else
	      return (bindpwd (no_symlinks));
#endif
	    }
	  else
	    free (temp);
	}

      /* POSIX.2 says that if `.' does not appear in $CDPATH, we don't
	 try the current directory, so we just punt now with an error
	 message if POSIXLY_CORRECT is non-zero.  The check for cdpath[0]
	 is so we don't mistakenly treat a CDPATH value of "" as not
	 specifying the current directory. */
      if (posixly_correct && cdpath[0])
	{
	  builtin_error ("%s: %s", dirname, strerror (ENOENT));
	  return (EXECUTION_FAILURE);
	}
    }
  else
    dirname = list->word->word;

  /* When we get here, DIRNAME is the directory to change to.  If we
     chdir successfully, just return. */
  if (change_to_directory (dirname, no_symlinks))
    {
      if (lflag & LCD_PRINTPATH)
	printf ("%s\n", dirname);
      return (bindpwd (no_symlinks));
    }

  /* If the user requests it, then perhaps this is the name of
     a shell variable, whose value contains the directory to
     change to. */
  if (lflag & LCD_DOVARS)
    {
      temp = get_string_value (dirname);
      if (temp && change_to_directory (temp, no_symlinks))
	{
	  printf ("%s\n", temp);
	  return (bindpwd (no_symlinks));
	}
    }

  /* If the user requests it, try to find a directory name similar in
     spelling to the one requested, in case the user made a simple
     typo.  This is similar to the UNIX 8th and 9th Edition shells. */
  if (lflag & LCD_DOSPELL)
    {
      temp = cdspell (dirname);
      if (temp && change_to_directory (temp, no_symlinks))
	{
	  printf ("%s\n", temp);
	  return (bindpwd (no_symlinks));
	}
      else
	FREE (temp);
    }

  builtin_error ("%s: %s", dirname, strerror (errno));
  return (EXECUTION_FAILURE);
}

$BUILTIN pwd
$FUNCTION pwd_builtin
$SHORT_DOC pwd [-LP]
Print the current working directory.  With the -P option, pwd prints
the physical directory, without any symbolic links; the -L option
makes pwd follow symbolic links.
$END

/* Non-zero means that pwd always prints the physical directory, without
   symbolic links. */
static int verbatim_pwd;

/* Print the name of the current working directory. */
int
pwd_builtin (list)
     WORD_LIST *list;
{
  char *directory;
  int opt, pflag;

  verbatim_pwd = no_symbolic_links;
  pflag = 0;
  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "LP")) != -1)
    {
      switch (opt)
	{
	case 'P':
	  verbatim_pwd = pflag = 1;
	  break;
	case 'L':
	  verbatim_pwd = 0;
	  break;
	default:
	  builtin_usage ();
	  return (EXECUTION_FAILURE);
	}
    }
  list = loptend;

#define tcwd the_current_working_directory

  directory = tcwd ? (verbatim_pwd ? sh_physpath (tcwd, 0) : tcwd)
		   : get_working_directory ("pwd");

  /* Try again using getcwd() if canonicalization fails (for instance, if
     the file system has changed state underneath bash). */
  if ((tcwd && directory == 0) ||
      (posixly_correct && same_file (".", tcwd, (struct stat *)0, (struct stat *)0) == 0))
    directory = resetpwd ("pwd");

#undef tcwd

  if (directory)
    {
      printf ("%s\n", directory);
      /* This is dumb but posix-mandated. */
      if (posixly_correct && pflag)
	setpwd (directory);
      if (directory != the_current_working_directory)
	free (directory);
      fflush (stdout);
      if (ferror (stdout))
	{
	  sh_wrerror ();
	  clearerr (stdout);
	  return (EXECUTION_FAILURE);
	}

      return (EXECUTION_SUCCESS);
    }
  else
    return (EXECUTION_FAILURE);
}

/* Do the work of changing to the directory NEWDIR.  Handle symbolic
   link following, etc.  This function *must* return with
   the_current_working_directory either set to NULL (in which case
   getcwd() will eventually be called), or set to a string corresponding
   to the working directory.  Return 1 on success, 0 on failure. */

static int
change_to_directory (newdir, nolinks)
     char *newdir;
     int nolinks;
{
  char *t, *tdir;
  int err, canon_failed, r, ndlen, dlen;

  tdir = (char *)NULL;

  if (the_current_working_directory == 0)
    {
      t = get_working_directory ("chdir");
      FREE (t);
    }

  t = make_absolute (newdir, the_current_working_directory);

  /* TDIR is either the canonicalized absolute pathname of NEWDIR
     (nolinks == 0) or the absolute physical pathname of NEWDIR
     (nolinks != 0). */
  tdir = nolinks ? sh_physpath (t, 0)
		 : sh_canonpath (t, PATH_CHECKDOTDOT|PATH_CHECKEXISTS);

  ndlen = strlen (newdir);
  dlen = strlen (t);

  /* Use the canonicalized version of NEWDIR, or, if canonicalization
     failed, use the non-canonical form. */
  canon_failed = 0;
  if (tdir && *tdir)
    free (t);
  else
    {
      FREE (tdir);
      tdir = t;
      canon_failed = 1;
    }

  /* In POSIX mode, if we're resolving symlinks logically and sh_canonpath
     returns NULL (because it checks the path, it will return NULL if the
     resolved path doesn't exist), fail immediately. */
  if (posixly_correct && nolinks == 0 && canon_failed && (errno != ENAMETOOLONG || ndlen > PATH_MAX))
    {
#if defined ENAMETOOLONG
      if (errno != ENOENT && errno != ENAMETOOLONG)
#else
      if (errno != ENOENT)
#endif
	errno = ENOTDIR;
      free (tdir);
      return (0);
    }

  /* If the chdir succeeds, update the_current_working_directory. */
  if (chdir (nolinks ? newdir : tdir) == 0)
    {
      /* If canonicalization failed, but the chdir succeeded, reset the
	 shell's idea of the_current_working_directory. */
      if (canon_failed)
	{
	  t = resetpwd ("cd");
	  if (t == 0)
	    set_working_directory (tdir);
	}
      else
	set_working_directory (tdir);

      free (tdir);
      return (1);
    }

  /* We failed to change to the appropriate directory name.  If we tried
     what the user passed (nolinks != 0), punt now. */
  if (nolinks)
    {
      free (tdir);
      return (0);
    }

  err = errno;

  /* We're not in physical mode (nolinks == 0), but we failed to change to
     the canonicalized directory name (TDIR).  Try what the user passed
     verbatim. If we succeed, reinitialize the_current_working_directory. */
  if (chdir (newdir) == 0)
    {
      t = resetpwd ("cd");
      if (t == 0)
	set_working_directory (tdir);
      else
	free (t);

      r = 1;
    }
  else
    {
      errno = err;
      r = 0;
    }

  free (tdir);
  return r;
}

/* Code for cd spelling correction.  Original patch submitted by
   Neil Russel (caret@c-side.com). */

static char *
cdspell (dirname)
     char *dirname;
{
  int n;
  char *guess;

  n = (strlen (dirname) * 3 + 1) / 2 + 1;
  guess = (char *)xmalloc (n);

  switch (spname (dirname, guess))
    {
    case -1:
    default:
      free (guess);
      return (char *)NULL;
    case 0:
    case 1:
      return guess;
    }
}