source: trunk/essentials/sys-apps/findutils/find/find.c@ 3175

/* find -- search for files in a directory hierarchy
   Copyright (C) 1990, 91, 92, 93, 94, 2000, 
                 2003, 2004, 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
   USA.*/

/* GNU find was written by Eric Decker <[email protected]>,
   with enhancements by David MacKenzie <[email protected]>,
   Jay Plett <[email protected]>,
   and Tim Wood <[email protected]>.
   The idea for -print0 and xargs -0 came from
   Dan Bernstein <[email protected]>.  
   Improvements have been made by James Youngman <[email protected]>.
*/


#include "defs.h"

#define USE_SAFE_CHDIR 1
#undef  STAT_MOUNTPOINTS


#include <errno.h>
#include <assert.h>


#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#else
#include <sys/file.h>
#endif

#include "../gnulib/lib/xalloc.h"
#include "../gnulib/lib/human.h"
#include "../gnulib/lib/canonicalize.h"
#include "closeout.h"
#include <modetype.h>
#include "savedirinfo.h"
#include "buildcmd.h"
#include "dirname.h"
#include "quote.h"
#include "quotearg.h"

#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif

#if ENABLE_NLS
# include <libintl.h>
# define _(Text) gettext (Text)
#else
# define _(Text) Text
#define textdomain(Domain)
#define bindtextdomain(Package, Directory)
#endif
#ifdef gettext_noop
# define N_(String) gettext_noop (String)
#else
/* See locate.c for explanation as to why not use (String) */
# define N_(String) String
#endif

#define apply_predicate(pathname, stat_buf_ptr, node)   \
  (*(node)->pred_func)((pathname), (stat_buf_ptr), (node))

#ifdef STAT_MOUNTPOINTS
static void init_mounted_dev_list(int mandatory);
#endif

static void process_top_path PARAMS((char *pathname, mode_t mode));
static int process_path PARAMS((char *pathname, char *name, boolean leaf, char *parent, mode_t type));
static void process_dir PARAMS((char *pathname, char *name, int pathlen, struct stat *statp, char *parent));



/* Name this program was run with. */
char *program_name;

/* A file descriptor open to the initial working directory.
   Doing it this way allows us to work when the i.w.d. has
   unreadable parents.  */
int starting_desc;

/* The stat buffer of the initial working directory. */
static struct stat starting_stat_buf;

enum ChdirSymlinkHandling
  {
    SymlinkHandleDefault,       /* Normally the right choice */
    SymlinkFollowOk             /* see comment in process_top_path() */
  };


enum TraversalDirection
  {
    TraversingUp,
    TraversingDown
  };

enum WdSanityCheckFatality
  {
    FATAL_IF_SANITY_CHECK_FAILS,
    RETRY_IF_SANITY_CHECK_FAILS,
    NON_FATAL_IF_SANITY_CHECK_FAILS
  };



int
main (int argc, char **argv)
{
  int i;
  int end_of_leading_options = 0; /* First arg after any -H/-L etc. */
  struct predicate *eval_tree;

  program_name = argv[0];
  state.exit_status = 0;

  /* Set the option defaults before we do the the locale
   * initialisation as check_nofollow() needs to be executed in the
   * POSIX locale.
   */
  set_option_defaults(&options);

#ifdef HAVE_SETLOCALE
  setlocale (LC_ALL, "");
#endif
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);
  atexit (close_stdout);

  /* Check for -P, -H or -L options. */
  end_of_leading_options = process_leading_options(argc, argv);

  if (options.debug_options & DebugStat)
    options.xstat = debug_stat;

#ifdef DEBUG
/*  fprintf (stderr, "cur_day_start = %s", ctime (&p->cur_day_start)); - what's "p"? */
#endif /* DEBUG */

  /* We are now processing the part of the "find" command line 
   * after the -H/-L options (if any).
   */
  eval_tree = build_expression_tree(argc, argv, end_of_leading_options);

  
  /* safely_chdir() needs to check that it has ended up in the right place. 
   * To avoid bailing out when something gets automounted, it checks if 
   * the target directory appears to have had a directory mounted on it as
   * we chdir()ed.  The problem with this is that in order to notice that 
   * a filesystem was mounted, we would need to lstat() all the mount points.
   * That strategy loses if our machine is a client of a dead NFS server.
   *
   * Hence if safely_chdir() and wd_sanity_check() can manage without needing 
   * to know the mounted device list, we do that.  
   */
  if (!options.open_nofollow_available)
    {
#ifdef STAT_MOUNTPOINTS
      init_mounted_dev_list(0);
#endif
    }
  

  starting_desc = open (".", O_RDONLY);
  if (0 <= starting_desc && fchdir (starting_desc) != 0)
    {
      close (starting_desc);
      starting_desc = -1;
    }
  if (starting_desc < 0)
    {
      starting_dir = xgetcwd ();
      if (! starting_dir)
        error (1, errno, _("cannot get current directory"));
    }
  if ((*options.xstat) (".", &starting_stat_buf) != 0)
    error (1, errno, _("cannot get current directory"));

  /* If no paths are given, default to ".".  */
  for (i = end_of_leading_options; i < argc && !looks_like_expression(argv[i], true); i++)
    {
      process_top_path (argv[i], 0);
    }

  /* If there were no path arguments, default to ".". */
  if (i == end_of_leading_options)
    {
      /* 
       * We use a temporary variable here because some actions modify 
       * the path temporarily.  Hence if we use a string constant, 
       * we get a coredump.  The best example of this is if we say 
       * "find -printf %H" (note, not "find . -printf %H").
       */
      char defaultpath[2] = ".";
      process_top_path (defaultpath, 0);
    }

  /* If "-exec ... {} +" has been used, there may be some 
   * partially-full command lines which have been built, 
   * but which are not yet complete.   Execute those now.
   */
  cleanup();
  return state.exit_status;
}


boolean is_fts_enabled()
{
  /* this version of find (i.e. this main()) does not use fts. */
  return false;
}



static char *
specific_dirname(const char *dir)
{
  char dirbuf[1024];

  if (0 == strcmp(".", dir))
    {
      /* OK, what's '.'? */
      if (NULL != getcwd(dirbuf, sizeof(dirbuf)))
        {
          return strdup(dirbuf);
        }
      else
        {
          return strdup(dir);
        }
    }
  else
    {
      char *result = canonicalize_filename_mode(dir, CAN_EXISTING);
      if (NULL == result)
        return strdup(dir);
      else
        return result;
    }
}




/* Return non-zero if FS is the name of a filesystem that is likely to
 * be automounted
 */
static int
fs_likely_to_be_automounted(const char *fs)
{
  return ( (0==strcmp(fs, "nfs")) || (0==strcmp(fs, "autofs")) || (0==strcmp(fs, "subfs")));
}



#ifdef STAT_MOUNTPOINTS
static dev_t *mounted_devices = NULL;
static size_t num_mounted_devices = 0u;


static void
init_mounted_dev_list(int mandatory)
{
  assert(NULL == mounted_devices);
  assert(0 == num_mounted_devices);
  mounted_devices = get_mounted_devices(&num_mounted_devices);
  if (mandatory && (NULL == mounted_devices))
    {
      error(1, 0, "Cannot read list of mounted devices.");
    }
}

static void
refresh_mounted_dev_list(void)
{
  if (mounted_devices)
    {
      free(mounted_devices);
      mounted_devices = 0;
    }
  num_mounted_devices = 0u;
  init_mounted_dev_list(1);
}


/* Search for device DEV in the array LIST, which is of size N. */
static int
dev_present(dev_t dev, const dev_t *list, size_t n)
{
  if (list)
    {
      while (n-- > 0u)
        {
          if ( (*list++) == dev )
            return 1;
        }
    }
  return 0;
}

enum MountPointStateChange
  {
    MountPointRecentlyMounted,
    MountPointRecentlyUnmounted,
    MountPointStateUnchanged
  };



static enum MountPointStateChange
get_mount_state(dev_t newdev)
{
  int new_is_present, new_was_present;
  
  new_was_present = dev_present(newdev, mounted_devices, num_mounted_devices);
  refresh_mounted_dev_list();
  new_is_present  = dev_present(newdev, mounted_devices, num_mounted_devices);
  
  if (new_was_present == new_is_present)
    return MountPointStateUnchanged;
  else if (new_is_present)
    return MountPointRecentlyMounted;
  else
    return MountPointRecentlyUnmounted;
}



/* We stat()ed a directory, chdir()ed into it (we know this 
 * since direction is TraversingDown), stat()ed it again,
 * and noticed that the device numbers are different.  Check
 * if the filesystem was recently mounted. 
 * 
 * If it was, it looks like chdir()ing into the directory
 * caused a filesystem to be mounted.  Maybe automount is
 * running.  Anyway, that's probably OK - but it happens
 * only when we are moving downward.
 *
 * We also allow for the possibility that a similar thing
 * has happened with the unmounting of a filesystem.  This
 * is much rarer, as it relies on an automounter timeout
 * occurring at exactly the wrong moment.
 */
static enum WdSanityCheckFatality
dirchange_is_fatal(const char *specific_what,
                   enum WdSanityCheckFatality isfatal,
                   int silent,
                   struct stat *newinfo)
{
  enum MountPointStateChange transition = get_mount_state(newinfo->st_dev);
  switch (transition)
    {
    case MountPointRecentlyUnmounted:
      isfatal = NON_FATAL_IF_SANITY_CHECK_FAILS;
      if (!silent)
        {
          error (0, 0,
                 _("Warning: filesystem %s has recently been unmounted."),
                 specific_what);
        }
      break;
              
    case MountPointRecentlyMounted:
      isfatal = NON_FATAL_IF_SANITY_CHECK_FAILS;
      if (!silent)
        {
          error (0, 0,
                 _("Warning: filesystem %s has recently been mounted."),
                 specific_what);
        }
      break;

    case MountPointStateUnchanged:
      /* leave isfatal as it is */
      break;
    }
  
  return isfatal;
}


#endif



/* Examine the results of the stat() of a directory from before we
 * entered or left it, with the results of stat()ing it afterward.  If
 * these are different, the filesystem tree has been modified while we
 * were traversing it.  That might be an attempt to use a race
 * condition to persuade find to do something it didn't intend
 * (e.g. an attempt by an ordinary user to exploit the fact that root
 * sometimes runs find on the whole filesystem).  However, this can
 * also happen if automount is running (certainly on Solaris).  With 
 * automount, moving into a directory can cause a filesystem to be 
 * mounted there.
 *
 * To cope sensibly with this, we will raise an error if we see the
 * device number change unless we are chdir()ing into a subdirectory,
 * and the directory we moved into has been mounted or unmounted "recently".  
 * Here "recently" means since we started "find" or we last re-read 
 * the /etc/mnttab file. 
 *
 * If the device number does not change but the inode does, that is a
 * problem.
 *
 * If the device number and inode are both the same, we are happy.
 *
 * If a filesystem is (un)mounted as we chdir() into the directory, that 
 * may mean that we're now examining a section of the filesystem that might 
 * have been excluded from consideration (via -prune or -quit for example).
 * Hence we print a warning message to indicate that the output of find 
 * might be inconsistent due to the change in the filesystem.
 */
static boolean
wd_sanity_check(const char *thing_to_stat,
                const char *progname,
                const char *what,
                dev_t old_dev,
                ino_t old_ino,
                struct stat *newinfo,
                int parent,
                int line_no,
                enum TraversalDirection direction,
                enum WdSanityCheckFatality isfatal,
                boolean *changed) /* output parameter */
{
  const char *fstype;
  char *specific_what = NULL;
  int silent = 0;
  const char *current_dir = ".";
  
  *changed = false;
  
  if ((*options.xstat) (current_dir, newinfo) != 0)
    error (1, errno, "%s", thing_to_stat);
  
  if (old_dev != newinfo->st_dev)
    {
      *changed = true;
      specific_what = specific_dirname(what);
      fstype = filesystem_type(newinfo, current_dir);
      silent = fs_likely_to_be_automounted(fstype);

      /* This condition is rare, so once we are here it is 
       * reasonable to perform an expensive computation to 
       * determine if we should continue or fail. 
       */
      if (TraversingDown == direction)
        {
#ifdef STAT_MOUNTPOINTS
          isfatal = dirchange_is_fatal(specific_what,isfatal,silent,newinfo);
#else
          isfatal = RETRY_IF_SANITY_CHECK_FAILS;
#endif
        }

      switch (isfatal)
        {
        case FATAL_IF_SANITY_CHECK_FAILS:
          {
            fstype = filesystem_type(newinfo, current_dir);
            error (1, 0,
                   _("%s%s changed during execution of %s (old device number %ld, new device number %ld, filesystem type is %s) [ref %ld]"),
                   specific_what,
                   parent ? "/.." : "",
                   progname,
                   (long) old_dev,
                   (long) newinfo->st_dev,
                   fstype,
                   line_no);
            /*NOTREACHED*/
            return false;
          }
          
        case NON_FATAL_IF_SANITY_CHECK_FAILS:
          {
            /* Since the device has changed under us, the inode number 
             * will almost certainly also be different. However, we have 
             * already decided that this is not a problem.  Hence we return
             * without checking the inode number.
             */
            free(specific_what);
            return true;
          }

        case RETRY_IF_SANITY_CHECK_FAILS:
          return false;
        }
    }

  /* Device number was the same, check if the inode has changed. */
  if (old_ino != newinfo->st_ino)
    {
      *changed = true;
      specific_what = specific_dirname(what);
      fstype = filesystem_type(newinfo, current_dir);
      
      error ((isfatal == FATAL_IF_SANITY_CHECK_FAILS) ? 1 : 0,
             0,                 /* no relevant errno value */
             _("%s%s changed during execution of %s (old inode number %ld, new inode number %ld, filesystem type is %s) [ref %ld]"),
             specific_what, 
             parent ? "/.." : "",
             progname,
             (long) old_ino,
             (long) newinfo->st_ino,
             fstype,
             line_no);
      free(specific_what);
      return false;
    }
  
  return true;
}


enum SafeChdirStatus
  {
    SafeChdirOK,
    SafeChdirFailSymlink,
    SafeChdirFailNotDir,
    SafeChdirFailStat,
    SafeChdirFailWouldBeUnableToReturn,
    SafeChdirFailChdirFailed,
    SafeChdirFailNonexistent
  };

/* Safely perform a change in directory.  We do this by calling
 * lstat() on the subdirectory, using chdir() to move into it, and
 * then lstat()ing ".".  We compare the results of the two stat calls
 * to see if they are consistent.  If not, we sound the alarm.
 *
 * If following_links() is true, we do follow symbolic links.
 */
static enum SafeChdirStatus
safely_chdir_lstat(const char *dest,
                   enum TraversalDirection direction,
                   struct stat *statbuf_dest,
                   enum ChdirSymlinkHandling symlink_follow_option,
                   boolean *did_stat)
{
  struct stat statbuf_arrived;
  int rv, dotfd=-1;
  int saved_errno;              /* specific_dirname() changes errno. */
  boolean rv_set = false;
  boolean statflag = false;
  int tries = 0;
  enum WdSanityCheckFatality isfatal = RETRY_IF_SANITY_CHECK_FAILS;
  
  saved_errno = errno = 0;

  dotfd = open(".", O_RDONLY);

  /* We jump back to here if wd_sanity_check()
   * recoverably triggers an alert.
   */
 retry:
  ++tries;
  
  if (dotfd >= 0)
    {
      /* Stat the directory we're going to. */
      if (0 == options.xstat(dest, statbuf_dest))
        {
          statflag = true;
          
#ifdef S_ISLNK
          /* symlink_follow_option might be set to SymlinkFollowOk, which
           * would allow us to chdir() into a symbolic link.  This is
           * only useful for the case where the directory we're
           * chdir()ing into is the basename of a command line
           * argument, for example where "foo/bar/baz" is specified on
           * the command line.  When -P is in effect (the default),
           * baz will not be followed if it is a symlink, but if bar
           * is a symlink, it _should_ be followed.  Hence we need the
           * ability to override the policy set by following_links().
           */
          if (!following_links() && S_ISLNK(statbuf_dest->st_mode))
            {
              /* We're not supposed to be following links, but this is 
               * a link.  Check symlink_follow_option to see if we should 
               * make a special exception.
               */
              if (symlink_follow_option == SymlinkFollowOk)
                {
                  /* We need to re-stat() the file so that the 
                   * sanity check can pass. 
                   */
                  if (0 != stat(dest, statbuf_dest))
                    {
                      rv = SafeChdirFailNonexistent;
                      rv_set = true;
                      saved_errno = errno;
                      goto fail;
                    }
                  statflag = true;
                }
              else
                {
                  /* Not following symlinks, so the attempt to
                   * chdir() into a symlink should be prevented.
                   */
                  rv = SafeChdirFailSymlink;
                  rv_set = true;
                  saved_errno = 0;      /* silence the error message */
                  goto fail;
                }
            }
#endif    
#ifdef S_ISDIR
          /* Although the immediately following chdir() would detect
           * the fact that this is not a directory for us, this would
           * result in an extra system call that fails.  Anybody
           * examining the system-call trace should ideally not be
           * concerned that something is actually failing.
           */
          if (!S_ISDIR(statbuf_dest->st_mode))
            {
              rv = SafeChdirFailNotDir;
              rv_set = true;
              saved_errno = 0;  /* silence the error message */
              goto fail;
            }
#endif
          
          if (options.debug_options & DebugSearch)
            fprintf(stderr, "safely_chdir(): chdir(\"%s\")\n", dest);

          if (0 == chdir(dest))
            {
              /* check we ended up where we wanted to go */
              boolean changed = false;
              if (!wd_sanity_check(".", program_name, ".",
                                   statbuf_dest->st_dev,
                                   statbuf_dest->st_ino,
                                   &statbuf_arrived, 
                                   0, __LINE__, direction,
                                   isfatal,
                                   &changed))
                {
                  /* Only allow one failure. */
                  if (RETRY_IF_SANITY_CHECK_FAILS == isfatal)
                    {
                      if (0 == fchdir(dotfd))
                        {
                          isfatal = FATAL_IF_SANITY_CHECK_FAILS;
                          goto retry;
                        }
                      else
                        {
                          /* Failed to return to original directory,
                           * but we know that the current working
                           * directory is not the one that we intend
                           * to be in.  Since fchdir() failed, we
                           * can't recover from this and so this error
                           * is fatal.
                           */
                          error(1, errno,
                                "failed to return to parent directory");
                        }
                    }
                  else
                    {
                      /* XXX: not sure what to use as an excuse here. */
                      rv = SafeChdirFailNonexistent;
                      rv_set = true;
                      saved_errno = 0;
                      goto fail;
                    }
                }
              
              close(dotfd);
              return SafeChdirOK;
            }
          else
            {
              saved_errno = errno;
              if (ENOENT == saved_errno)
                {
                  rv = SafeChdirFailNonexistent;
                  rv_set = true;
                  if (options.ignore_readdir_race)
                    errno = 0;  /* don't issue err msg */
                }