coreutils/lib/makepath.c

/* makepath.c -- Ensure that a directory path exists.

   Copyright (C) 1990, 1997, 1998, 1999, 2000, 2002, 2003, 2004 Free
   Software Foundation, Inc.

   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, 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.  */

/* Written by David MacKenzie <djm@gnu.ai.mit.edu> and Jim Meyering.  */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include "makepath.h"

#include <alloca.h>

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#endif

#include <stdlib.h>
#include <errno.h>
#include <string.h>

#include "gettext.h"
#define _(msgid) gettext (msgid)

#include "save-cwd.h"
#include "dirname.h"
#include "error.h"
#include "quote.h"
#include "stat-macros.h"

#define WX_USR (S_IWUSR | S_IXUSR)

#define CLEANUP_CWD					\
  do							\
    {							\
      /* We're done operating on basename_dir.		\
	 Restore working directory.  */			\
      if (do_chdir)					\
	{						\
	  if (restore_cwd (&cwd) != 0)			\
	    {						\
	      int _saved_errno = errno;			\
	      error (0, errno,				\
		_("failed to return to initial working directory")); \
	      free_cwd (&cwd);				\
	      errno = _saved_errno;			\
	      return 1;					\
	    }						\
	  free_cwd (&cwd);				\
	}						\
    }							\
  while (0)

#define CLEANUP						\
  do							\
    {							\
      umask (oldmask);					\
      CLEANUP_CWD;					\
    }							\
  while (0)

/* Attempt to create directory DIR (aka DIRPATH) with the specified MODE.
   If CREATED_DIR_P is non-NULL, set *CREATED_DIR_P if this
   function creates DIR and clear it otherwise.  Give a diagnostic and
   return false if DIR cannot be created or cannot be determined to
   exist already.  Use DIRPATH in any diagnostic, not DIR.
   Note that if DIR already exists, this function returns true
   (indicating success) and clears *CREATED_DIR_P.  */

bool
make_dir (const char *dir, const char *dirpath, mode_t mode,
	  bool *created_dir_p)
{
  bool ok = true;
  bool created_dir;

  created_dir = (mkdir (dir, mode) == 0);

  if (!created_dir)
    {
      struct stat stats;
      int saved_errno = errno;

      /* The mkdir and stat calls below may appear to be reversed.
	 They are not.  It is important to call mkdir first and then to
	 call stat (to distinguish the three cases) only if mkdir fails.
	 The alternative to this approach is to `stat' each directory,
	 then to call mkdir if it doesn't exist.  But if some other process
	 were to create the directory between the stat & mkdir, the mkdir
	 would fail with EEXIST.  */

      if (stat (dir, &stats))
	{
	  error (0, saved_errno, _("cannot create directory %s"),
		 quote (dirpath));
	  ok = false;
	}
      else if (!S_ISDIR (stats.st_mode))
	{
	  error (0, 0, _("%s exists but is not a directory"), quote (dirpath));
	  ok = false;
	}
      else
	{
	  /* DIR (aka DIRPATH) already exists and is a directory. */
	}
    }

  if (created_dir_p)
    *created_dir_p = created_dir;

  return ok;
}

/* Ensure that the directory ARGPATH exists.

   Create any leading directories that don't already exist, with
   permissions PARENT_MODE.
   If the last element of ARGPATH does not exist, create it as
   a new directory with permissions MODE.
   If OWNER and GROUP are non-negative, use them to set the UID and GID of
   any created directories.
   If VERBOSE_FMT_STRING is nonzero, use it as a printf format
   string for printing a message after successfully making a directory,
   with the name of the directory that was just made as an argument.
   If PRESERVE_EXISTING is true and ARGPATH is an existing directory,
   then do not attempt to set its permissions and ownership.

   Return true iff ARGPATH exists as a directory with the proper
   ownership and permissions when done.  */

bool
make_path (const char *argpath,
	   mode_t mode,
	   mode_t parent_mode,
	   uid_t owner,
	   gid_t group,
	   bool preserve_existing,
	   const char *verbose_fmt_string)
{
  struct stat stats;
  bool retval = true;

  if (stat (argpath, &stats))
    {
      char *slash;
      mode_t tmp_mode;		/* Initial perms for leading dirs.  */
      bool re_protect;		/* Should leading dirs be unwritable? */
      struct ptr_list
      {
	char *dirname_end;
	struct ptr_list *next;
      };
      struct ptr_list *p, *leading_dirs = NULL;
      bool do_chdir;		/* Whether to chdir before each mkdir.  */
      struct saved_cwd cwd;
      char *basename_dir;
      char *dirpath;

      /* Temporarily relax umask in case it's overly restrictive.  */
      mode_t oldmask = umask (0);

      /* Make a copy of ARGPATH that we can scribble NULs on.  */
      dirpath = (char *) alloca (strlen (argpath) + 1);
      strcpy (dirpath, argpath);
      strip_trailing_slashes (dirpath);

      /* If leading directories shouldn't be writable or executable,
	 or should have set[ug]id or sticky bits set and we are setting
	 their owners, we need to fix their permissions after making them.  */
      if (((parent_mode & WX_USR) != WX_USR)
	  || ((owner != (uid_t) -1 || group != (gid_t) -1)
	      && (parent_mode & (S_ISUID | S_ISGID | S_ISVTX)) != 0))
	{
	  tmp_mode = S_IRWXU;
	  re_protect = true;
	}
      else
	{
	  tmp_mode = parent_mode;
	  re_protect = false;
	}

      /* If we can record the current working directory, we may be able
	 to do the chdir optimization.  */
      do_chdir = (save_cwd (&cwd) == 0);

      /* If we've saved the cwd and DIRPATH is an absolute pathname,
	 we must chdir to `/' in order to enable the chdir optimization.
         So if chdir ("/") fails, turn off the optimization.  */
      if (do_chdir && *dirpath == '/' && chdir ("/") < 0)
	do_chdir = false;

      slash = dirpath;

      /* Skip over leading slashes.  */
      while (*slash == '/')
	slash++;

      while (1)
	{
	  bool newly_created_dir;

	  /* slash points to the leftmost unprocessed component of dirpath.  */
	  basename_dir = slash;

	  slash = strchr (slash, '/');
	  if (slash == NULL)
	    break;

	  /* If we're *not* doing chdir before each mkdir, then we have to refer
	     to the target using the full (multi-component) directory name.  */
	  if (!do_chdir)
	    basename_dir = dirpath;

	  *slash = '\0';
	  if (! make_dir (basename_dir, dirpath, tmp_mode, &newly_created_dir))
	    {
	      CLEANUP;
	      return false;
	    }

	  if (newly_created_dir)
	    {
	      if (verbose_fmt_string)
		error (0, 0, verbose_fmt_string, quote (dirpath));

	      if ((owner != (uid_t) -1 || group != (gid_t) -1)
		  && chown (basename_dir, owner, group)
#if defined AFS && defined EPERM
		  && errno != EPERM
#endif
		  )
		{
		  error (0, errno, _("cannot change owner and/or group of %s"),
			 quote (dirpath));
		  CLEANUP;
		  return false;
		}

	      if (re_protect)
		{
		  struct ptr_list *new = (struct ptr_list *)
		    alloca (sizeof (struct ptr_list));
		  new->dirname_end = slash;
		  new->next = leading_dirs;
		  leading_dirs = new;
		}
	    }

	  /* If we were able to save the initial working directory,
	     then we can use chdir to change into each directory before
	     creating an entry in that directory.  This avoids making
	     stat and mkdir process O(n^2) file name components.  */
	  if (do_chdir && chdir (basename_dir) < 0)
	    {
	      error (0, errno, _("cannot chdir to directory %s"),
		     quote (dirpath));
	      CLEANUP;
	      return false;
	    }

	  *slash++ = '/';

	  /* Avoid unnecessary calls to `stat' when given
	     pathnames containing multiple adjacent slashes.  */
	  while (*slash == '/')
	    slash++;
	}

      if (!do_chdir)
	basename_dir = dirpath;

      /* Done creating leading directories.  Restore original umask.  */
      umask (oldmask);

      /* We're done making leading directories.
	 Create the final component of the path.  */

      if (! make_dir (basename_dir, dirpath, mode, NULL))
	{
	  CLEANUP;
	  return false;
	}

      if (verbose_fmt_string != NULL)
	error (0, 0, verbose_fmt_string, quote (dirpath));

      if (owner != (uid_t) -1 || group != (gid_t) -1)
	{
	  if (chown (basename_dir, owner, group)
#ifdef AFS
	      && errno != EPERM
#endif
	      )
	    {
	      error (0, errno, _("cannot change owner and/or group of %s"),
		     quote (dirpath));
	      retval = false;
	    }
	}

      /* The above chown may have turned off some permission bits in MODE.
	 Another reason we may have to use chmod here is that mkdir(2) is
	 required to honor only the file permission bits.  In particular,
	 it need not honor the `special' bits, so if MODE includes any
	 special bits, set them here.  */
      if ((mode & ~S_IRWXUGO)
	  && chmod (basename_dir, mode))
	{
	  error (0, errno, _("cannot change permissions of %s"),
		 quote (dirpath));
	  retval = false;
	}

      CLEANUP_CWD;

      /* If the mode for leading directories didn't include owner "wx"
	 privileges, we have to reset their protections to the correct
	 value.  */
      for (p = leading_dirs; p != NULL; p = p->next)
	{
	  *(p->dirname_end) = '\0';
	  if (chmod (dirpath, parent_mode))
	    {
	      error (0, errno, _("cannot change permissions of %s"),
		     quote (dirpath));
	      retval = false;
	    }
	}
    }
  else
    {
      /* We get here if the entire path already exists.  */

      const char *dirpath = argpath;

      if (!S_ISDIR (stats.st_mode))
	{
	  error (0, 0, _("%s exists but is not a directory"), quote (dirpath));
	  return false;
	}

      if (!preserve_existing)
	{
	  /* chown must precede chmod because on some systems,
	     chown clears the set[ug]id bits for non-superusers,
	     resulting in incorrect permissions.
	     On System V, users can give away files with chown and then not
	     be able to chmod them.  So don't give files away.  */

	  if ((owner != (uid_t) -1 || group != (gid_t) -1)
	      && chown (dirpath, owner, group)
#ifdef AFS
	      && errno != EPERM
#endif
	      )
	    {
	      error (0, errno, _("cannot change owner and/or group of %s"),
		     quote (dirpath));
	      retval = false;
	    }
	  if (chmod (dirpath, mode))
	    {
	      error (0, errno, _("cannot change permissions of %s"),
				 quote (dirpath));
	      retval = false;
	    }
	}
    }

  return retval;
}