dired.c

/* Lisp functions for making directory listings.
   Copyright (C) 1985, 1986, 1993, 1994, 1999, 2000, 2001, 2002, 2003,
                 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs 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 3 of the License, or
(at your option) any later version.

GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */


#include <config.h>

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <setjmp.h>

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#include <grp.h>

#include <errno.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

/* The d_nameln member of a struct dirent includes the '\0' character
   on some systems, but not on others.  What's worse, you can't tell
   at compile-time which one it will be, since it really depends on
   the sort of system providing the filesystem you're reading from,
   not the system you are running on.  Paul Eggert
   <eggert@bi.twinsun.com> says this occurs when Emacs is running on a
   SunOS 4.1.2 host, reading a directory that is remote-mounted from a
   Solaris 2.1 host and is in a native Solaris 2.1 filesystem.

   Since applying strlen to the name always works, we'll just do that.  */
#define NAMLEN(p) strlen (p->d_name)

#ifdef SYSV_SYSTEM_DIR

#include <dirent.h>
#define DIRENTRY struct dirent

#else /* not SYSV_SYSTEM_DIR */

#ifdef MSDOS
#include <dirent.h>
#else
#include <sys/dir.h>
#endif

#include <sys/stat.h>

#ifndef MSDOS
#define DIRENTRY struct direct

extern DIR *opendir ();
extern struct direct *readdir ();

#endif /* not MSDOS */
#endif /* not SYSV_SYSTEM_DIR */

/* Some versions of Cygwin don't have d_ino in `struct dirent'.  */
#if defined(MSDOS) || defined(__CYGWIN__)
#define DIRENTRY_NONEMPTY(p) ((p)->d_name[0] != 0)
#else
#define DIRENTRY_NONEMPTY(p) ((p)->d_ino)
#endif

#include "lisp.h"
#include "systime.h"
#include "buffer.h"
#include "commands.h"
#include "character.h"
#include "charset.h"
#include "coding.h"
#include "regex.h"
#include "blockinput.h"

/* Returns a search buffer, with a fastmap allocated and ready to go.  */
extern struct re_pattern_buffer *compile_pattern ();

/* From filemode.c.  Can't go in Lisp.h because of `stat'.  */
extern void filemodestring P_ ((struct stat *, char *));

/* if system does not have symbolic links, it does not have lstat.
   In that case, use ordinary stat instead.  */

#ifndef S_IFLNK
#define lstat stat
#endif

extern int completion_ignore_case;
extern Lisp_Object Qcompletion_ignore_case;
extern Lisp_Object Vcompletion_regexp_list;
extern Lisp_Object Vw32_get_true_file_attributes;

Lisp_Object Vcompletion_ignored_extensions;
Lisp_Object Qdirectory_files;
Lisp_Object Qdirectory_files_and_attributes;
Lisp_Object Qfile_name_completion;
Lisp_Object Qfile_name_all_completions;
Lisp_Object Qfile_attributes;
Lisp_Object Qfile_attributes_lessp;

static int scmp P_ ((unsigned char *, unsigned char *, int));

#ifdef WINDOWSNT
Lisp_Object
directory_files_internal_w32_unwind (Lisp_Object arg)
{
  Vw32_get_true_file_attributes = arg;
  return Qnil;
}
#endif

Lisp_Object
directory_files_internal_unwind (dh)
     Lisp_Object dh;
{
  DIR *d = (DIR *) XSAVE_VALUE (dh)->pointer;
  BLOCK_INPUT;
  closedir (d);
  UNBLOCK_INPUT;
  return Qnil;
}

/* Function shared by Fdirectory_files and Fdirectory_files_and_attributes.
   When ATTRS is zero, return a list of directory filenames; when
   non-zero, return a list of directory filenames and their attributes.
   In the latter case, ID_FORMAT is passed to Ffile_attributes.  */

Lisp_Object
directory_files_internal (directory, full, match, nosort, attrs, id_format)
     Lisp_Object directory, full, match, nosort;
     int attrs;
     Lisp_Object id_format;
{
  DIR *d;
  int directory_nbytes;
  Lisp_Object list, dirfilename, encoded_directory;
  struct re_pattern_buffer *bufp = NULL;
  int needsep = 0;
  int count = SPECPDL_INDEX ();
  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
  DIRENTRY *dp;
#ifdef WINDOWSNT
  Lisp_Object w32_save = Qnil;
#endif

  /* Because of file name handlers, these functions might call
     Ffuncall, and cause a GC.  */
  list = encoded_directory = dirfilename = Qnil;
  GCPRO5 (match, directory, list, dirfilename, encoded_directory);
  dirfilename = Fdirectory_file_name (directory);

  if (!NILP (match))
    {
      CHECK_STRING (match);

      /* MATCH might be a flawed regular expression.  Rather than
	 catching and signaling our own errors, we just call
	 compile_pattern to do the work for us.  */
      /* Pass 1 for the MULTIBYTE arg
	 because we do make multibyte strings if the contents warrant.  */
# ifdef WINDOWSNT
      /* Windows users want case-insensitive wildcards.  */
      bufp = compile_pattern (match, 0,
			      buffer_defaults.case_canon_table, 0, 1);
# else	/* !WINDOWSNT */
      bufp = compile_pattern (match, 0, Qnil, 0, 1);
# endif	 /* !WINDOWSNT */
    }

  /* Note: ENCODE_FILE and DECODE_FILE can GC because they can run
     run_pre_post_conversion_on_str which calls Lisp directly and
     indirectly.  */
  if (STRING_MULTIBYTE (dirfilename))
    dirfilename = ENCODE_FILE (dirfilename);
  encoded_directory = (STRING_MULTIBYTE (directory)
		       ? ENCODE_FILE (directory) : directory);

  /* Now *bufp is the compiled form of MATCH; don't call anything
     which might compile a new regexp until we're done with the loop!  */

  BLOCK_INPUT;
  d = opendir (SDATA (dirfilename));
  UNBLOCK_INPUT;
  if (d == NULL)
    report_file_error ("Opening directory", Fcons (directory, Qnil));

  /* Unfortunately, we can now invoke expand-file-name and
     file-attributes on filenames, both of which can throw, so we must
     do a proper unwind-protect.  */
  record_unwind_protect (directory_files_internal_unwind,
			 make_save_value (d, 0));

#ifdef WINDOWSNT
  if (attrs)
    {
      extern Lisp_Object Qlocal;
      extern int is_slow_fs (const char *);

      /* Do this only once to avoid doing it (in w32.c:stat) for each
	 file in the directory, when we call Ffile_attributes below.  */
      record_unwind_protect (directory_files_internal_w32_unwind,
			     Vw32_get_true_file_attributes);
      w32_save = Vw32_get_true_file_attributes;
      if (EQ (Vw32_get_true_file_attributes, Qlocal))
	{
	  /* w32.c:stat will notice these bindings and avoid calling
	     GetDriveType for each file.  */
	  if (is_slow_fs (SDATA (dirfilename)))
	    Vw32_get_true_file_attributes = Qnil;
	  else
	    Vw32_get_true_file_attributes = Qt;
	}
    }
#endif

  directory_nbytes = SBYTES (directory);
  re_match_object = Qt;

  /* Decide whether we need to add a directory separator.  */
  if (directory_nbytes == 0
      || !IS_ANY_SEP (SREF (directory, directory_nbytes - 1)))
    needsep = 1;

  /* Loop reading blocks until EOF or error.  */
  for (;;)
    {
      errno = 0;
      dp = readdir (d);

      if (dp == NULL && (0
#ifdef EAGAIN
			 || errno == EAGAIN
#endif
#ifdef EINTR
			 || errno == EINTR
#endif
			 ))
	{ QUIT; continue; }

      if (dp == NULL)
	break;

      if (DIRENTRY_NONEMPTY (dp))
	{
	  int len;
	  int wanted = 0;
	  Lisp_Object name, finalname;
	  struct gcpro gcpro1, gcpro2;

	  len = NAMLEN (dp);
	  name = finalname = make_unibyte_string (dp->d_name, len);
	  GCPRO2 (finalname, name);

	  /* Note: DECODE_FILE can GC; it should protect its argument,
	     though.  */
	  name = DECODE_FILE (name);
	  len = SBYTES (name);

	  /* Now that we have unwind_protect in place, we might as well
             allow matching to be interrupted.  */
	  immediate_quit = 1;
	  QUIT;

	  if (NILP (match)
	      || (0 <= re_search (bufp, SDATA (name), len, 0, len, 0)))
	    wanted = 1;

	  immediate_quit = 0;

	  if (wanted)
	    {
	      if (!NILP (full))
		{
		  Lisp_Object fullname;
		  int nbytes = len + directory_nbytes + needsep;
		  int nchars;

		  fullname = make_uninit_multibyte_string (nbytes, nbytes);
		  bcopy (SDATA (directory), SDATA (fullname),
			 directory_nbytes);

		  if (needsep)
		    SSET (fullname, directory_nbytes, DIRECTORY_SEP);

		  bcopy (SDATA (name),
			 SDATA (fullname) + directory_nbytes + needsep,
			 len);

		  nchars = chars_in_text (SDATA (fullname), nbytes);

		  /* Some bug somewhere.  */
		  if (nchars > nbytes)
		    abort ();

		  STRING_SET_CHARS (fullname, nchars);
		  if (nchars == nbytes)
		    STRING_SET_UNIBYTE (fullname);

		  finalname = fullname;
		}
	      else
		finalname = name;

	      if (attrs)
		{
		  /* Construct an expanded filename for the directory entry.
		     Use the decoded names for input to Ffile_attributes.  */
		  Lisp_Object decoded_fullname, fileattrs;
		  struct gcpro gcpro1, gcpro2;

		  decoded_fullname = fileattrs = Qnil;
		  GCPRO2 (decoded_fullname, fileattrs);

		  /* Both Fexpand_file_name and Ffile_attributes can GC.  */
		  decoded_fullname = Fexpand_file_name (name, directory);
		  fileattrs = Ffile_attributes (decoded_fullname, id_format);

		  list = Fcons (Fcons (finalname, fileattrs), list);
		  UNGCPRO;
		}
	      else
		list = Fcons (finalname, list);
	    }

	  UNGCPRO;
	}
    }

  BLOCK_INPUT;
  closedir (d);
  UNBLOCK_INPUT;
#ifdef WINDOWSNT
  if (attrs)
    Vw32_get_true_file_attributes = w32_save;
#endif

  /* Discard the unwind protect.  */
  specpdl_ptr = specpdl + count;

  if (NILP (nosort))
    list = Fsort (Fnreverse (list),
		  attrs ? Qfile_attributes_lessp : Qstring_lessp);

  RETURN_UNGCPRO (list);
}


DEFUN ("directory-files", Fdirectory_files, Sdirectory_files, 1, 4, 0,
       doc: /* Return a list of names of files in DIRECTORY.
There are three optional arguments:
If FULL is non-nil, return absolute file names.  Otherwise return names
 that are relative to the specified directory.
If MATCH is non-nil, mention only file names that match the regexp MATCH.
If NOSORT is non-nil, the list is not sorted--its order is unpredictable.
 Otherwise, the list returned is sorted with `string-lessp'.
 NOSORT is useful if you plan to sort the result yourself.  */)
     (directory, full, match, nosort)
     Lisp_Object directory, full, match, nosort;
{
  Lisp_Object handler;
  directory = Fexpand_file_name (directory, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (directory, Qdirectory_files);
  if (!NILP (handler))
    return call5 (handler, Qdirectory_files, directory,
                  full, match, nosort);

  return directory_files_internal (directory, full, match, nosort, 0, Qnil);
}

DEFUN ("directory-files-and-attributes", Fdirectory_files_and_attributes,
       Sdirectory_files_and_attributes, 1, 5, 0,
       doc: /* Return a list of names of files and their attributes in DIRECTORY.
There are four optional arguments:
If FULL is non-nil, return absolute file names.  Otherwise return names
 that are relative to the specified directory.
If MATCH is non-nil, mention only file names that match the regexp MATCH.
If NOSORT is non-nil, the list is not sorted--its order is unpredictable.
 NOSORT is useful if you plan to sort the result yourself.
ID-FORMAT specifies the preferred format of attributes uid and gid, see
`file-attributes' for further documentation.
On MS-Windows, performance depends on `w32-get-true-file-attributes',
which see.  */)
     (directory, full, match, nosort, id_format)
     Lisp_Object directory, full, match, nosort, id_format;
{
  Lisp_Object handler;
  directory = Fexpand_file_name (directory, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (directory, Qdirectory_files_and_attributes);
  if (!NILP (handler))
    return call6 (handler, Qdirectory_files_and_attributes,
                  directory, full, match, nosort, id_format);

  return directory_files_internal (directory, full, match, nosort, 1, id_format);
}


Lisp_Object file_name_completion ();

DEFUN ("file-name-completion", Ffile_name_completion, Sfile_name_completion,
       2, 3, 0,
       doc: /* Complete file name FILE in directory DIRECTORY.
Returns the longest string
common to all file names in DIRECTORY that start with FILE.
If there is only one and FILE matches it exactly, returns t.
Returns nil if DIRECTORY contains no name starting with FILE.

If PREDICATE is non-nil, call PREDICATE with each possible
completion (in absolute form) and ignore it if PREDICATE returns nil.

This function ignores some of the possible completions as
determined by the variable `completion-ignored-extensions', which see.  */)
     (file, directory, predicate)
     Lisp_Object file, directory, predicate;
{
  Lisp_Object handler;

  /* If the directory name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (directory, Qfile_name_completion);
  if (!NILP (handler))
    return call4 (handler, Qfile_name_completion, file, directory, predicate);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (file, Qfile_name_completion);
  if (!NILP (handler))
    return call4 (handler, Qfile_name_completion, file, directory, predicate);

  return file_name_completion (file, directory, 0, 0, predicate);
}

DEFUN ("file-name-all-completions", Ffile_name_all_completions,
       Sfile_name_all_completions, 2, 2, 0,
       doc: /* Return a list of all completions of file name FILE in directory DIRECTORY.
These are all file names in directory DIRECTORY which begin with FILE.  */)
     (file, directory)
     Lisp_Object file, directory;
{
  Lisp_Object handler;

  /* If the directory name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (directory, Qfile_name_all_completions);
  if (!NILP (handler))
    return call3 (handler, Qfile_name_all_completions, file, directory);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (file, Qfile_name_all_completions);
  if (!NILP (handler))
    return call3 (handler, Qfile_name_all_completions, file, directory);

  return file_name_completion (file, directory, 1, 0, Qnil);
}

static int file_name_completion_stat ();
Lisp_Object Qdefault_directory;

Lisp_Object
file_name_completion (file, dirname, all_flag, ver_flag, predicate)
     Lisp_Object file, dirname;
     int all_flag, ver_flag;
     Lisp_Object predicate;
{
  DIR *d;
  int bestmatchsize = 0;
  int matchcount = 0;
  /* If ALL_FLAG is 1, BESTMATCH is the list of all matches, decoded.
     If ALL_FLAG is 0, BESTMATCH is either nil
     or the best match so far, not decoded.  */
  Lisp_Object bestmatch, tem, elt, name;
  Lisp_Object encoded_file;
  Lisp_Object encoded_dir;
  struct stat st;
  int directoryp;
  /* If includeall is zero, exclude files in completion-ignored-extensions as
     well as "." and "..".  Until shown otherwise, assume we can't exclude
     anything.  */
  int includeall = 1;
  int count = SPECPDL_INDEX ();
  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;

  elt = Qnil;

  CHECK_STRING (file);

#ifdef FILE_SYSTEM_CASE
  file = FILE_SYSTEM_CASE (file);
#endif
  bestmatch = Qnil;
  encoded_file = encoded_dir = Qnil;
  GCPRO5 (file, dirname, bestmatch, encoded_file, encoded_dir);
  dirname = Fexpand_file_name (dirname, Qnil);
  specbind (Qdefault_directory, dirname);

  /* Do completion on the encoded file name
     because the other names in the directory are (we presume)
     encoded likewise.  We decode the completed string at the end.  */
  /* Actually, this is not quite true any more: we do most of the completion
     work with decoded file names, but we still do some filtering based
     on the encoded file name.  */
  encoded_file = STRING_MULTIBYTE (file) ? ENCODE_FILE (file) : file;

  encoded_dir = ENCODE_FILE (dirname);

  BLOCK_INPUT;
  d = opendir (SDATA (Fdirectory_file_name (encoded_dir)));
  UNBLOCK_INPUT;
  if (!d)
    report_file_error ("Opening directory", Fcons (dirname, Qnil));

  record_unwind_protect (directory_files_internal_unwind,
			 make_save_value (d, 0));

  /* Loop reading blocks */
  /* (att3b compiler bug requires do a null comparison this way) */
  while (1)
    {
      DIRENTRY *dp;
      int len;
      int canexclude = 0;

      errno = 0;
      dp = readdir (d);
      if (dp == NULL && (0
# ifdef EAGAIN
			 || errno == EAGAIN
# endif
# ifdef EINTR
			 || errno == EINTR
# endif
			 ))
	{ QUIT; continue; }

      if (!dp) break;

      len = NAMLEN (dp);

      QUIT;
      if (! DIRENTRY_NONEMPTY (dp)
	  || len < SCHARS (encoded_file)
	  || 0 <= scmp (dp->d_name, SDATA (encoded_file),
			SCHARS (encoded_file)))
	continue;

      if (file_name_completion_stat (encoded_dir, dp, &st) < 0)
	continue;

      directoryp = ((st.st_mode & S_IFMT) == S_IFDIR);
      tem = Qnil;
      /* If all_flag is set, always include all.
	 It would not actually be helpful to the user to ignore any possible
	 completions when making a list of them.  */
      if (!all_flag)
	{
	  int skip;

#if 0 /* FIXME: The `scmp' call compares an encoded and a decoded string. */
	  /* If this entry matches the current bestmatch, the only
	     thing it can do is increase matchcount, so don't bother
	     investigating it any further.  */
	  if (!completion_ignore_case
	      /* The return result depends on whether it's the sole match.  */
	      && matchcount > 1
	      && !includeall /* This match may allow includeall to 0.  */
	      && len >= bestmatchsize
	      && 0 > scmp (dp->d_name, SDATA (bestmatch), bestmatchsize))
	    continue;
#endif

	  if (directoryp)
	    {
#ifndef TRIVIAL_DIRECTORY_ENTRY
#define TRIVIAL_DIRECTORY_ENTRY(n) (!strcmp (n, ".") || !strcmp (n, ".."))
#endif
	      /* "." and ".." are never interesting as completions, and are
		 actually in the way in a directory with only one file.  */
	      if (TRIVIAL_DIRECTORY_ENTRY (dp->d_name))
		canexclude = 1;
	      else if (len > SCHARS (encoded_file))
		/* Ignore directories if they match an element of
		   completion-ignored-extensions which ends in a slash.  */
		for (tem = Vcompletion_ignored_extensions;
		     CONSP (tem); tem = XCDR (tem))
		  {
		    int elt_len;
		    unsigned char *p1;

		    elt = XCAR (tem);
		    if (!STRINGP (elt))
		      continue;
		    /* Need to encode ELT, since scmp compares unibyte
		       strings only.  */
		    elt = ENCODE_FILE (elt);
		    elt_len = SCHARS (elt) - 1; /* -1 for trailing / */
		    if (elt_len <= 0)
		      continue;
		    p1 = SDATA (elt);
		    if (p1[elt_len] != '/')
		      continue;
		    skip = len - elt_len;
		    if (skip < 0)
		      continue;

		    if (0 <= scmp (dp->d_name + skip, p1, elt_len))
		      continue;
		    break;
		  }
	    }
	  else
	    {
	      /* Compare extensions-to-be-ignored against end of this file name */
	      /* if name is not an exact match against specified string */
	      if (len > SCHARS (encoded_file))
		/* and exit this for loop if a match is found */
		for (tem = Vcompletion_ignored_extensions;
		     CONSP (tem); tem = XCDR (tem))
		  {
		    elt = XCAR (tem);
		    if (!STRINGP (elt)) continue;
		    /* Need to encode ELT, since scmp compares unibyte
		       strings only.  */
		    elt = ENCODE_FILE (elt);
		    skip = len - SCHARS (elt);
		    if (skip < 0) continue;

		    if (0 <= scmp (dp->d_name + skip,
				   SDATA (elt),
				   SCHARS (elt)))
		      continue;
		    break;
		  }
	    }

	  /* If an ignored-extensions match was found,
	     don't process this name as a completion.  */
	  if (CONSP (tem))
	    canexclude = 1;

	  if (!includeall && canexclude)
	    /* We're not including all files and this file can be excluded.  */
	    continue;

	  if (includeall && !canexclude)
	    { /* If we have one non-excludable file, we want to exclude the
		 excudable files.  */
	      includeall = 0;
	      /* Throw away any previous excludable match found.  */
	      bestmatch = Qnil;
	      bestmatchsize = 0;
	      matchcount = 0;
	    }
	}
      /* FIXME: If we move this `decode' earlier we can eliminate
	 the repeated ENCODE_FILE on Vcompletion_ignored_extensions.  */
      name = make_unibyte_string (dp->d_name, len);
      name = DECODE_FILE (name);

      {
	Lisp_Object regexps;
	Lisp_Object zero;
	XSETFASTINT (zero, 0);

	/* Ignore this element if it fails to match all the regexps.  */
	if (completion_ignore_case)
	  {
	    for (regexps = Vcompletion_regexp_list; CONSP (regexps);
		 regexps = XCDR (regexps))
	      if (fast_string_match_ignore_case (XCAR (regexps), name) < 0)
		break;
	  }
	else
	  {
	    for (regexps = Vcompletion_regexp_list; CONSP (regexps);
		 regexps = XCDR (regexps))
	      if (fast_string_match (XCAR (regexps), name) < 0)
		break;
	  }

	if (CONSP (regexps))
	  continue;
      }

      /* This is a possible completion */
      if (directoryp)
	/* This completion is a directory; make it end with '/'.  */
	name = Ffile_name_as_directory (name);

      /* Test the predicate, if any.  */
      if (!NILP (predicate))
	{
	  Lisp_Object val;
	  struct gcpro gcpro1;

	  GCPRO1 (name);
	  val = call1 (predicate, name);
	  UNGCPRO;

	  if (NILP (val))
	    continue;
	}

      /* Suitably record this match.  */

      matchcount++;

      if (all_flag)
	bestmatch = Fcons (name, bestmatch);
      else if (NILP (bestmatch))
	{
	  bestmatch = name;
	  bestmatchsize = SCHARS (name);
	}
      else
	{
	  Lisp_Object zero = make_number (0);
	  /* FIXME: This is a copy of the code in Ftry_completion.  */
	  int compare = min (bestmatchsize, SCHARS (name));
	  Lisp_Object tem
	    = Fcompare_strings (bestmatch, zero,
				make_number (compare),
				name, zero,
				make_number (compare),
				completion_ignore_case ? Qt : Qnil);
	  int matchsize
	    = (EQ (tem, Qt)     ? compare
	       : XINT (tem) < 0 ? - XINT (tem) - 1
	       :                  XINT (tem) - 1);

	  if (completion_ignore_case)
	    {
	      /* If this is an exact match except for case,
		 use it as the best match rather than one that is not
		 an exact match.  This way, we get the case pattern
		 of the actual match.  */
	      /* This tests that the current file is an exact match
		 but BESTMATCH is not (it is too long).  */
	      if ((matchsize == SCHARS (name)
		   && matchsize + !!directoryp < SCHARS (bestmatch))
		  ||
		  /* If there is no exact match ignoring case,
		     prefer a match that does not change the case
		     of the input.  */
		  /* If there is more than one exact match aside from
		     case, and one of them is exact including case,
		     prefer that one.  */
		  /* This == checks that, of current file and BESTMATCH,
		     either both or neither are exact.  */
		  (((matchsize == SCHARS (name))
		    ==
		    (matchsize + !!directoryp == SCHARS (bestmatch)))
		   && (tem = Fcompare_strings (name, zero,
					       make_number (SCHARS (file)),
					       file, zero,
					       Qnil,
					       Qnil),
		       EQ (Qt, tem))
		   && (tem = Fcompare_strings (bestmatch, zero,
					       make_number (SCHARS (file)),
					       file, zero,
					       Qnil,
					       Qnil),
		       ! EQ (Qt, tem))))
		bestmatch = name;
	    }
	  bestmatchsize = matchsize;

	  /* If the best completion so far is reduced to the string
	     we're trying to complete, then we already know there's no
	     other completion, so there's no point looking any further.  */
	  if (matchsize <= SCHARS (file)
	      && !includeall /* A future match may allow includeall to 0.  */
	      /* If completion-ignore-case is non-nil, don't
		 short-circuit because we want to find the best
		 possible match *including* case differences.  */
	      && (!completion_ignore_case || matchsize == 0)
	      /* The return value depends on whether it's the sole match.  */
	      && matchcount > 1)
	    break;

	}
    }

  UNGCPRO;
  /* This closes the directory.  */
  bestmatch = unbind_to (count, bestmatch);

  if (all_flag || NILP (bestmatch))
    return bestmatch;
  /* Return t if the supplied string is an exact match (counting case);
     it does not require any change to be made.  */
  if (matchcount == 1 && !NILP (Fequal (bestmatch, file)))
    return Qt;
  bestmatch = Fsubstring (bestmatch, make_number (0),
			  make_number (bestmatchsize));
  return bestmatch;
}

/* Compare exactly LEN chars of strings at S1 and S2,
   ignoring case if appropriate.
   Return -1 if strings match,
   else number of chars that match at the beginning.  */

static int
scmp (s1, s2, len)
     register unsigned char *s1, *s2;
     int len;
{
  register int l = len;

  if (completion_ignore_case)
    {
      while (l && DOWNCASE (*s1++) == DOWNCASE (*s2++))
	l--;
    }
  else
    {
      while (l && *s1++ == *s2++)
	l--;
    }
  if (l == 0)
    return -1;
  else
    return len - l;
}

static int
file_name_completion_stat (dirname, dp, st_addr)
     Lisp_Object dirname;
     DIRENTRY *dp;
     struct stat *st_addr;
{
  int len = NAMLEN (dp);
  int pos = SCHARS (dirname);
  int value;
  char *fullname = (char *) alloca (len + pos + 2);

#ifdef MSDOS
#if __DJGPP__ > 1
  /* Some fields of struct stat are *very* expensive to compute on MS-DOS,
     but aren't required here.  Avoid computing the following fields:
     st_inode, st_size and st_nlink for directories, and the execute bits
     in st_mode for non-directory files with non-standard extensions.  */

  unsigned short save_djstat_flags = _djstat_flags;

  _djstat_flags = _STAT_INODE | _STAT_EXEC_MAGIC | _STAT_DIRSIZE;
#endif /* __DJGPP__ > 1 */
#endif /* MSDOS */

  bcopy (SDATA (dirname), fullname, pos);
  if (!IS_DIRECTORY_SEP (fullname[pos - 1]))
    fullname[pos++] = DIRECTORY_SEP;

  bcopy (dp->d_name, fullname + pos, len);
  fullname[pos + len] = 0;

#ifdef S_IFLNK
  /* We want to return success if a link points to a nonexistent file,
     but we want to return the status for what the link points to,
     in case it is a directory.  */
  value = lstat (fullname, st_addr);
  stat (fullname, st_addr);
  return value;