fileio.c 178 KB
Newer Older
Jim Blandy's avatar
Jim Blandy committed
1
/* File IO for GNU Emacs.
Glenn Morris's avatar
Glenn Morris committed
2

Glenn Morris's avatar
Glenn Morris committed
3
Copyright (C) 1985-1988, 1993-2012 Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
4 5 6

This file is part of GNU Emacs.

7
GNU Emacs is free software: you can redistribute it and/or modify
Jim Blandy's avatar
Jim Blandy committed
8
it under the terms of the GNU General Public License as published by
9 10
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Jim Blandy's avatar
Jim Blandy committed
11 12 13 14 15 16 17

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
18
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
Jim Blandy's avatar
Jim Blandy committed
19

20
#include <config.h>
21
#include <limits.h>
22
#include <fcntl.h>
23
#include <stdio.h>
Jim Blandy's avatar
Jim Blandy committed
24 25
#include <sys/types.h>
#include <sys/stat.h>
26
#include <setjmp.h>
27 28
#include <unistd.h>

29
#ifdef HAVE_PWD_H
Jim Blandy's avatar
Jim Blandy committed
30
#include <pwd.h>
Jim Blandy's avatar
Jim Blandy committed
31 32
#endif

Jim Blandy's avatar
Jim Blandy committed
33 34
#include <errno.h>

Karel Klíc's avatar
Karel Klíc committed
35 36 37 38 39
#ifdef HAVE_LIBSELINUX
#include <selinux/selinux.h>
#include <selinux/context.h>
#endif

40 41
#include <c-ctype.h>

Jim Blandy's avatar
Jim Blandy committed
42
#include "lisp.h"
43
#include "intervals.h"
44
#include "character.h"
45
#include "buffer.h"
Karl Heuer's avatar
Karl Heuer committed
46
#include "coding.h"
Jim Blandy's avatar
Jim Blandy committed
47
#include "window.h"
YAMAMOTO Mitsuharu's avatar
YAMAMOTO Mitsuharu committed
48
#include "blockinput.h"
Karoly Lorentey's avatar
Karoly Lorentey committed
49 50
#include "frame.h"
#include "dispextern.h"
Jim Blandy's avatar
Jim Blandy committed
51

52 53 54 55 56 57
#ifdef WINDOWSNT
#define NOMINMAX 1
#include <windows.h>
#include <fcntl.h>
#endif /* not WINDOWSNT */

Eli Zaretskii's avatar
Eli Zaretskii committed
58 59 60 61 62 63
#ifdef MSDOS
#include "msdos.h"
#include <sys/param.h>
#include <fcntl.h>
#endif

64 65
#ifdef DOS_NT
/* On Windows, drive letters must be alphabetic - on DOS, the Netware
66
   redirector allows the six letters between 'Z' and 'a' as well.  */
67 68 69 70
#ifdef MSDOS
#define IS_DRIVE(x) ((x) >= 'A' && (x) <= 'z')
#endif
#ifdef WINDOWSNT
71
#define IS_DRIVE(x) c_isalpha (x)
72
#endif
73
/* Need to lower-case the drive letter, or else expanded
Paul Eggert's avatar
Paul Eggert committed
74
   filenames will sometimes compare unequal, because
75
   `expand-file-name' doesn't always down-case the drive letter.  */
76
#define DRIVE_LETTER(x) c_tolower (x)
77 78
#endif

Jim Blandy's avatar
Jim Blandy committed
79
#include "systime.h"
80
#include <stat-time.h>
Jim Blandy's avatar
Jim Blandy committed
81 82 83

#ifdef HPUX
#include <netio.h>
84
#endif
Jim Blandy's avatar
Jim Blandy committed
85

86 87
#include "commands.h"

88
/* Nonzero during writing of auto-save files.  */
89
static int auto_saving;
Jim Blandy's avatar
Jim Blandy committed
90

91
/* Nonzero umask during creation of auto-save directories.  */
92 93
static int auto_saving_dir_umask;

Jim Blandy's avatar
Jim Blandy committed
94
/* Set by auto_save_1 to mode of original file so Fwrite_region will create
95
   a new file with the same mode as the original.  */
96
static int auto_save_mode_bits;
Jim Blandy's avatar
Jim Blandy committed
97

98
/* Set by auto_save_1 if an error occurred during the last auto-save.  */
99
static int auto_save_error_occurred;
100

101 102 103 104 105
/* The symbol bound to coding-system-for-read when
   insert-file-contents is called for recovering a file.  This is not
   an actual coding system name, but just an indicator to tell
   insert-file-contents to use `emacs-mule' with a special flag for
   auto saving and recovering a file.  */
106
static Lisp_Object Qauto_save_coding;
107

108 109
/* Property name of a file name handler,
   which gives a list of operations it handles..  */
110
static Lisp_Object Qoperations;
111

112
/* Lisp functions for translating file formats.  */
113
static Lisp_Object Qformat_decode, Qformat_annotate_function;
114

115
/* Lisp function for setting buffer-file-coding-system and the
116
   multibyteness of the current buffer after inserting a file.  */
117
static Lisp_Object Qafter_insert_file_set_coding;
118

119
static Lisp_Object Qwrite_region_annotate_functions;
120 121
/* Each time an annotation function changes the buffer, the new buffer
   is added here.  */
122
static Lisp_Object Vwrite_region_annotation_buffers;
123

124 125 126
#ifdef HAVE_FSYNC
#endif

127
static Lisp_Object Qdelete_by_moving_to_trash;
128

129
/* Lisp function for moving files to trash.  */
130
static Lisp_Object Qmove_file_to_trash;
131

132
/* Lisp function for recursively copying directories.  */
133
static Lisp_Object Qcopy_directory;
134 135

/* Lisp function for recursively deleting directories.  */
136
static Lisp_Object Qdelete_directory;
137

138 139 140
#ifdef WINDOWSNT
#endif

141 142 143
Lisp_Object Qfile_error;
static Lisp_Object Qfile_already_exists, Qfile_date_error;
static Lisp_Object Qexcl;
144 145
Lisp_Object Qfile_name_history;

146
static Lisp_Object Qcar_less_than_car;
147

148
static int a_write (int, Lisp_Object, ptrdiff_t, ptrdiff_t,
149
                    Lisp_Object *, struct coding_system *);
150
static int e_write (int, Lisp_Object, ptrdiff_t, ptrdiff_t,
151
		    struct coding_system *);
152

153

154
void
155
report_file_error (const char *string, Lisp_Object data)
Jim Blandy's avatar
Jim Blandy committed
156 157
{
  Lisp_Object errstring;
Richard M. Stallman's avatar
Richard M. Stallman committed
158
  int errorno = errno;
159
  char *str;
Jim Blandy's avatar
Jim Blandy committed
160

161
  synchronize_system_messages_locale ();
162
  str = strerror (errorno);
163
  errstring = code_convert_string_norecord (build_unibyte_string (str),
164 165
					    Vlocale_coding_system, 0);

Jim Blandy's avatar
Jim Blandy committed
166
  while (1)
Richard M. Stallman's avatar
Richard M. Stallman committed
167 168 169
    switch (errorno)
      {
      case EEXIST:
170
	xsignal (Qfile_already_exists, Fcons (errstring, data));
Richard M. Stallman's avatar
Richard M. Stallman committed
171 172 173
	break;
      default:
	/* System error messages are capitalized.  Downcase the initial
174 175
	   unless it is followed by a slash.  (The slash case caters to
	   error messages that begin with "I/O" or, in German, "E/A".)  */
176 177
	if (STRING_MULTIBYTE (errstring)
	    && ! EQ (Faref (errstring, make_number (1)), make_number ('/')))
178 179 180
	  {
	    int c;

181
	    str = SSDATA (errstring);
182
	    c = STRING_CHAR ((unsigned char *) str);
183
	    Faset (errstring, make_number (0), make_number (downcase (c)));
184
	  }
Richard M. Stallman's avatar
Richard M. Stallman committed
185

186
	xsignal (Qfile_error,
Richard M. Stallman's avatar
Richard M. Stallman committed
187 188
		 Fcons (build_string (string), Fcons (errstring, data)));
      }
Jim Blandy's avatar
Jim Blandy committed
189
}
190

191
Lisp_Object
192
close_file_unwind (Lisp_Object fd)
193
{
194
  emacs_close (XFASTINT (fd));
195
  return Qnil;
196
}
197 198 199

/* Restore point, having saved it as a marker.  */

Andreas Schwab's avatar
Andreas Schwab committed
200
Lisp_Object
201
restore_point_unwind (Lisp_Object location)
202
{
203
  Fgoto_char (location);
204
  Fset_marker (location, Qnil, Qnil);
205
  return Qnil;
206
}
207

Jim Blandy's avatar
Jim Blandy committed
208

209 210 211 212 213 214 215 216 217 218 219
static Lisp_Object Qexpand_file_name;
static Lisp_Object Qsubstitute_in_file_name;
static Lisp_Object Qdirectory_file_name;
static Lisp_Object Qfile_name_directory;
static Lisp_Object Qfile_name_nondirectory;
static Lisp_Object Qunhandled_file_name_directory;
static Lisp_Object Qfile_name_as_directory;
static Lisp_Object Qcopy_file;
static Lisp_Object Qmake_directory_internal;
static Lisp_Object Qmake_directory;
static Lisp_Object Qdelete_directory_internal;
220
Lisp_Object Qdelete_file;
221 222 223
static Lisp_Object Qrename_file;
static Lisp_Object Qadd_name_to_file;
static Lisp_Object Qmake_symbolic_link;
224
Lisp_Object Qfile_exists_p;
225 226 227 228 229
static Lisp_Object Qfile_executable_p;
static Lisp_Object Qfile_readable_p;
static Lisp_Object Qfile_writable_p;
static Lisp_Object Qfile_symlink_p;
static Lisp_Object Qaccess_file;
230
Lisp_Object Qfile_directory_p;
231 232 233 234 235 236 237 238
static Lisp_Object Qfile_regular_p;
static Lisp_Object Qfile_accessible_directory_p;
static Lisp_Object Qfile_modes;
static Lisp_Object Qset_file_modes;
static Lisp_Object Qset_file_times;
static Lisp_Object Qfile_selinux_context;
static Lisp_Object Qset_file_selinux_context;
static Lisp_Object Qfile_newer_than_file_p;
239 240
Lisp_Object Qinsert_file_contents;
Lisp_Object Qwrite_region;
241 242
static Lisp_Object Qverify_visited_file_modtime;
static Lisp_Object Qset_visited_file_modtime;
243

Paul Eggert's avatar
Paul Eggert committed
244
DEFUN ("find-file-name-handler", Ffind_file_name_handler,
245
       Sfind_file_name_handler, 2, 2, 0,
246 247 248 249 250 251 252 253 254
       doc: /* Return FILENAME's handler function for OPERATION, if it has one.
Otherwise, return nil.
A file name is handled if one of the regular expressions in
`file-name-handler-alist' matches it.

If OPERATION equals `inhibit-file-name-operation', then we ignore
any handlers that are members of `inhibit-file-name-handlers',
but we still do run any other handlers.  This lets handlers
use the standard functions without calling themselves recursively.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
255
  (Lisp_Object filename, Lisp_Object operation)
256
{
257
  /* This function must not munge the match data.  */
258
  Lisp_Object chain, inhibited_handlers, result;
259
  ptrdiff_t pos = -1;
260

261
  result = Qnil;
262
  CHECK_STRING (filename);
263

264 265 266 267
  if (EQ (operation, Vinhibit_file_name_operation))
    inhibited_handlers = Vinhibit_file_name_handlers;
  else
    inhibited_handlers = Qnil;
268

269
  for (chain = Vfile_name_handler_alist; CONSP (chain);
270
       chain = XCDR (chain))
271 272
    {
      Lisp_Object elt;
273
      elt = XCAR (chain);
274
      if (CONSP (elt))
275
	{
276
	  Lisp_Object string = XCAR (elt);
277
	  ptrdiff_t match_pos;
278
	  Lisp_Object handler = XCDR (elt);
279 280 281 282
	  Lisp_Object operations = Qnil;

	  if (SYMBOLP (handler))
	    operations = Fget (handler, Qoperations);
283

284
	  if (STRINGP (string)
285 286
	      && (match_pos = fast_string_match (string, filename)) > pos
	      && (NILP (operations) || ! NILP (Fmemq (operation, operations))))
287
	    {
288
	      Lisp_Object tem;
289

290
	      handler = XCDR (elt);
291 292
	      tem = Fmemq (handler, inhibited_handlers);
	      if (NILP (tem))
293 294 295 296
		{
		  result = handler;
		  pos = match_pos;
		}
297
	    }
298
	}
299 300

      QUIT;
301
    }
302
  return result;
303 304
}

Paul Eggert's avatar
Paul Eggert committed
305
DEFUN ("file-name-directory", Ffile_name_directory, Sfile_name_directory,
306 307 308
       1, 1, 0,
       doc: /* Return the directory component in file name FILENAME.
Return nil if FILENAME does not include a directory.
309
Otherwise return a directory name.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
310
Given a Unix syntax file name, returns a string ending in slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
311
  (Lisp_Object filename)
Jim Blandy's avatar
Jim Blandy committed
312
{
313
#ifndef DOS_NT
314
  register const char *beg;
315
#else
316
  register char *beg;
317
#endif
318
  register const char *p;
319
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
320

321
  CHECK_STRING (filename);
Jim Blandy's avatar
Jim Blandy committed
322

323 324
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
325
  handler = Ffind_file_name_handler (filename, Qfile_name_directory);
326
  if (!NILP (handler))
327 328 329 330 331
    {
      Lisp_Object handled_name = call2 (handler, Qfile_name_directory,
					filename);
      return STRINGP (handled_name) ? handled_name : Qnil;
    }
332

333
#ifdef DOS_NT
334
  beg = alloca (SBYTES (filename) + 1);
335
  memcpy (beg, SSDATA (filename), SBYTES (filename) + 1);
336
#else
337
  beg = SSDATA (filename);
338
#endif
339
  p = beg + SBYTES (filename);
Jim Blandy's avatar
Jim Blandy committed
340

341 342
  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
#ifdef DOS_NT
Paul Eggert's avatar
Paul Eggert committed
343
	 /* only recognize drive specifier at the beginning */
344 345 346 347
	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" and "/:foo" cases correctly  */
	      && ((p == beg + 2 && !IS_DIRECTORY_SEP (*beg))
		  || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
348
#endif
Jim Blandy's avatar
Jim Blandy committed
349 350 351 352
	 ) p--;

  if (p == beg)
    return Qnil;
353
#ifdef DOS_NT
354
  /* Expansion of "c:" to drive and default directory.  */
355
  if (p[-1] == ':')
356 357
    {
      /* MAXPATHLEN+1 is guaranteed to be enough space for getdefdir.  */
358 359
      char *res = alloca (MAXPATHLEN + 1);
      char *r = res;
360 361 362

      if (p == beg + 4 && IS_DIRECTORY_SEP (*beg) && beg[1] == ':')
	{
363
	  memcpy (res, beg, 2);
364 365 366 367
	  beg += 2;
	  r += 2;
	}

368
      if (getdefdir (c_toupper (*beg) - 'A' + 1, r))
369
	{
370
	  if (!IS_DIRECTORY_SEP (res[strlen (res) - 1]))
371 372 373 374 375
	    strcat (res, "/");
	  beg = res;
	  p = beg + strlen (beg);
	}
    }
376
  dostounix_filename (beg);
377
#endif /* DOS_NT */
378

379
  return make_specified_string (beg, -1, p - beg, STRING_MULTIBYTE (filename));
Jim Blandy's avatar
Jim Blandy committed
380 381
}

Paul Eggert's avatar
Paul Eggert committed
382
DEFUN ("file-name-nondirectory", Ffile_name_nondirectory,
383
       Sfile_name_nondirectory, 1, 1, 0,
384 385 386 387
       doc: /* Return file name FILENAME sans its directory.
For example, in a Unix-syntax file name,
this is everything after the last slash,
or the entire name if it contains no slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
388
  (Lisp_Object filename)
Jim Blandy's avatar
Jim Blandy committed
389
{
390
  register const char *beg, *p, *end;
391
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
392

393
  CHECK_STRING (filename);
Jim Blandy's avatar
Jim Blandy committed
394

395 396
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
397
  handler = Ffind_file_name_handler (filename, Qfile_name_nondirectory);
398
  if (!NILP (handler))
399 400 401 402 403 404 405
    {
      Lisp_Object handled_name = call2 (handler, Qfile_name_nondirectory,
					filename);
      if (STRINGP (handled_name))
	return handled_name;
      error ("Invalid handler in `file-name-handler-alist'");
    }
406

407
  beg = SSDATA (filename);
408
  end = p = beg + SBYTES (filename);
Jim Blandy's avatar
Jim Blandy committed
409

410 411
  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
#ifdef DOS_NT
Paul Eggert's avatar
Paul Eggert committed
412
	 /* only recognize drive specifier at beginning */
413 414 415
	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" case correctly  */
	      && (p == beg + 2 || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
416
#endif
417 418
	 )
    p--;
Jim Blandy's avatar
Jim Blandy committed
419

420
  return make_specified_string (p, -1, end - p, STRING_MULTIBYTE (filename));
Jim Blandy's avatar
Jim Blandy committed
421
}
422

Paul Eggert's avatar
Paul Eggert committed
423
DEFUN ("unhandled-file-name-directory", Funhandled_file_name_directory,
424
       Sunhandled_file_name_directory, 1, 1, 0,
425 426 427 428 429
       doc: /* Return a directly usable directory name somehow associated with FILENAME.
A `directly usable' directory name is one that may be used without the
intervention of any file handler.
If FILENAME is a directly usable file itself, return
\(file-name-directory FILENAME).
Stefan Monnier's avatar
Stefan Monnier committed
430 431
If FILENAME refers to a file which is not accessible from a local process,
then this should return nil.
432 433
The `call-process' and `start-process' functions use this function to
get a current directory to run processes in.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
434
  (Lisp_Object filename)
435 436 437 438 439
{
  Lisp_Object handler;

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
440
  handler = Ffind_file_name_handler (filename, Qunhandled_file_name_directory);
441
  if (!NILP (handler))
442 443 444 445 446
    {
      Lisp_Object handled_name = call2 (handler, Qunhandled_file_name_directory,
					filename);
      return STRINGP (handled_name) ? handled_name : Qnil;
    }
447 448 449 450

  return Ffile_name_directory (filename);
}

451 452 453
/* Convert from file name SRC of length SRCLEN to directory name
   in DST.  On UNIX, just make sure there is a terminating /.
   Return the length of DST.  */
Jim Blandy's avatar
Jim Blandy committed
454

455 456 457 458
static ptrdiff_t
file_name_as_directory (char *dst, const char *src, ptrdiff_t srclen)
{
  if (srclen == 0)
459
    {
460 461 462 463
      dst[0] = '.';
      dst[1] = '/';
      dst[2] = '\0';
      return 2;
464 465
    }

466
  strcpy (dst, src);
467

468
  if (!IS_DIRECTORY_SEP (dst[srclen - 1]))
469
    {
470 471 472
      dst[srclen] = DIRECTORY_SEP;
      dst[srclen + 1] = '\0';
      srclen++;
473
    }
474
#ifdef DOS_NT
475
  dostounix_filename (dst);
476
#endif
477
  return srclen;
Jim Blandy's avatar
Jim Blandy committed
478 479
}

Paul Eggert's avatar
Paul Eggert committed
480
DEFUN ("file-name-as-directory", Ffile_name_as_directory,
Jim Blandy's avatar
Jim Blandy committed
481
       Sfile_name_as_directory, 1, 1, 0,
482
       doc: /* Return a string representing the file name FILE interpreted as a directory.
483 484 485 486
This operation exists because a directory is also a file, but its name as
a directory is different from its name as a file.
The result can be used as the value of `default-directory'
or passed as second argument to `expand-file-name'.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
487
For a Unix-syntax file name, just appends a slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
488
  (Lisp_Object file)
Jim Blandy's avatar
Jim Blandy committed
489 490
{
  char *buf;
491
  ptrdiff_t length;
492
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
493

494
  CHECK_STRING (file);
Jim Blandy's avatar
Jim Blandy committed
495
  if (NILP (file))
Jim Blandy's avatar
Jim Blandy committed
496
    return Qnil;
497 498 499

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
500
  handler = Ffind_file_name_handler (file, Qfile_name_as_directory);
501
  if (!NILP (handler))
502 503 504 505 506 507 508
    {
      Lisp_Object handled_name = call2 (handler, Qfile_name_as_directory,
					file);
      if (STRINGP (handled_name))
	return handled_name;
      error ("Invalid handler in `file-name-handler-alist'");
    }
509

510
  buf = alloca (SBYTES (file) + 10);
511 512
  length = file_name_as_directory (buf, SSDATA (file), SBYTES (file));
  return make_specified_string (buf, -1, length, STRING_MULTIBYTE (file));
Jim Blandy's avatar
Jim Blandy committed
513 514
}

515 516 517
/* Convert from directory name SRC of length SRCLEN to
   file name in DST.  On UNIX, just make sure there isn't
   a terminating /.  Return the length of DST.  */
Jim Blandy's avatar
Jim Blandy committed
518

519 520
static ptrdiff_t
directory_file_name (char *dst, char *src, ptrdiff_t srclen)
Jim Blandy's avatar
Jim Blandy committed
521 522 523 524
{
  /* Process as Unix format: just remove any final slash.
     But leave "/" unchanged; do not change it to "".  */
  strcpy (dst, src);
525 526
  if (srclen > 1
      && IS_DIRECTORY_SEP (dst[srclen - 1])
527
#ifdef DOS_NT
528
      && !IS_ANY_SEP (dst[srclen - 2])
529 530
#endif
      )
531 532 533 534
    {
      dst[srclen - 1] = 0;
      srclen--;
    }
535
#ifdef DOS_NT
536
  dostounix_filename (dst);
537
#endif
538
  return srclen;
Jim Blandy's avatar
Jim Blandy committed
539 540
}

Paul Eggert's avatar
Paul Eggert committed
541
DEFUN ("directory-file-name", Fdirectory_file_name, Sdirectory_file_name,
542 543 544 545 546
       1, 1, 0,
       doc: /* Returns the file name of the directory named DIRECTORY.
This is the name of the file that holds the data for the directory DIRECTORY.
This operation exists because a directory is also a file, but its name as
a directory is different from its name as a file.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
547
In Unix-syntax, this function just removes the final slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
548
  (Lisp_Object directory)
Jim Blandy's avatar
Jim Blandy committed
549 550
{
  char *buf;
551
  ptrdiff_t length;
552
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
553

554
  CHECK_STRING (directory);
Jim Blandy's avatar
Jim Blandy committed
555

Jim Blandy's avatar
Jim Blandy committed
556
  if (NILP (directory))
Jim Blandy's avatar
Jim Blandy committed
557
    return Qnil;
558 559 560

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
561
  handler = Ffind_file_name_handler (directory, Qdirectory_file_name);
562
  if (!NILP (handler))
563 564 565 566 567 568 569
    {
      Lisp_Object handled_name = call2 (handler, Qdirectory_file_name,
					directory);
      if (STRINGP (handled_name))
	return handled_name;
      error ("Invalid handler in `file-name-handler-alist'");
    }
570

571
  buf = alloca (SBYTES (directory) + 20);
572 573
  length = directory_file_name (buf, SSDATA (directory), SBYTES (directory));
  return make_specified_string (buf, -1, length, STRING_MULTIBYTE (directory));
Jim Blandy's avatar
Jim Blandy committed
574 575
}

576
static const char make_temp_name_tbl[64] =
577 578 579 580 581 582 583 584 585 586
{
  'A','B','C','D','E','F','G','H',
  'I','J','K','L','M','N','O','P',
  'Q','R','S','T','U','V','W','X',
  'Y','Z','a','b','c','d','e','f',
  'g','h','i','j','k','l','m','n',
  'o','p','q','r','s','t','u','v',
  'w','x','y','z','0','1','2','3',
  '4','5','6','7','8','9','-','_'
};
587

588 589
static unsigned make_temp_name_count, make_temp_name_count_initialized_p;

590
/* Value is a temporary file name starting with PREFIX, a string.
591

592 593 594 595 596
   The Emacs process number forms part of the result, so there is
   no danger of generating a name being used by another process.
   In addition, this function makes an attempt to choose a name
   which has no existing file.  To make this work, PREFIX should be
   an absolute file name.
597

598 599 600 601 602 603 604 605 606
   BASE64_P non-zero means add the pid as 3 characters in base64
   encoding.  In this case, 6 characters will be added to PREFIX to
   form the file name.  Otherwise, if Emacs is running on a system
   with long file names, add the pid as a decimal number.

   This function signals an error if no unique file name could be
   generated.  */

Lisp_Object
607
make_temp_name (Lisp_Object prefix, int base64_p)
Jim Blandy's avatar
Jim Blandy committed
608 609
{
  Lisp_Object val;
610
  int len, clen;
611
  printmax_t pid;
612
  char *p, *data;
613
  char pidbuf[INT_BUFSIZE_BOUND (printmax_t)];
614
  int pidlen;
615

616
  CHECK_STRING (prefix);
617 618 619 620 621 622

  /* VAL is created by adding 6 characters to PREFIX.  The first
     three are the PID of this process, in base 64, and the second
     three are incremented if the file already exists.  This ensures
     262144 unique file names per PID per PREFIX.  */

623
  pid = getpid ();
624

625 626 627 628 629 630 631 632 633
  if (base64_p)
    {
      pidbuf[0] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[1] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[2] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidlen = 3;
    }
  else
    {
634
#ifdef HAVE_LONG_FILE_NAMES
635
      pidlen = sprintf (pidbuf, "%"pMd, pid);
636
#else
637 638 639 640
      pidbuf[0] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[1] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[2] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidlen = 3;
641
#endif
642
    }
643

644 645 646 647
  len = SBYTES (prefix); clen = SCHARS (prefix);
  val = make_uninit_multibyte_string (clen + 3 + pidlen, len + 3 + pidlen);
  if (!STRING_MULTIBYTE (prefix))
    STRING_SET_UNIBYTE (val);
648 649
  data = SSDATA (val);
  memcpy (data, SSDATA (prefix), len);
650 651
  p = data + len;

652
  memcpy (p, pidbuf, pidlen);
653 654 655 656 657
  p += pidlen;

  /* Here we try to minimize useless stat'ing when this function is
     invoked many times successively with the same PREFIX.  We achieve
     this by initializing count to a random value, and incrementing it
Richard M. Stallman's avatar
Richard M. Stallman committed
658 659 660 661 662 663
     afterwards.

     We don't want make-temp-name to be called while dumping,
     because then make_temp_name_count_initialized_p would get set
     and then make_temp_name_count would not be set when Emacs starts.  */

664 665
  if (!make_temp_name_count_initialized_p)
    {
666
      make_temp_name_count = time (NULL);
667 668 669 670 671 672
      make_temp_name_count_initialized_p = 1;
    }

  while (1)
    {
      struct stat ignored;
673
      unsigned num = make_temp_name_count;
674 675 676 677 678

      p[0] = make_temp_name_tbl[num & 63], num >>= 6;
      p[1] = make_temp_name_tbl[num & 63], num >>= 6;
      p[2] = make_temp_name_tbl[num & 63], num >>= 6;

679 680 681 682 683
      /* Poor man's congruential RN generator.  Replace with
         ++make_temp_name_count for debugging.  */
      make_temp_name_count += 25229;
      make_temp_name_count %= 225307;

684 685 686 687 688 689 690 691 692 693
      if (stat (data, &ignored) < 0)
	{
	  /* We want to return only if errno is ENOENT.  */
	  if (errno == ENOENT)
	    return val;
	  else
	    /* The error here is dubious, but there is little else we
	       can do.  The alternatives are to return nil, which is
	       as bad as (and in many cases worse than) throwing the
	       error, or to ignore the error, which will likely result
694
	       in looping through 225307 stat's, which is not only
695 696
	       dog-slow, but also useless since eventually nil would
	       have to be returned anyway.  */
697
	    report_file_error ("Cannot create temporary name for prefix",
698 699 700 701
			       Fcons (prefix, Qnil));
	  /* not reached */
	}
    }
Jim Blandy's avatar
Jim Blandy committed
702
}
703

704 705

DEFUN ("make-temp-name", Fmake_temp_name, Smake_temp_name, 1, 1, 0,
706 707 708 709 710 711 712 713 714 715
       doc: /* Generate temporary file name (string) starting with PREFIX (a string).
The Emacs process number forms part of the result,
so there is no danger of generating a name being used by another process.

In addition, this function makes an attempt to choose a name
which has no existing file.  To make this work,
PREFIX should be an absolute file name.

There is a race condition between calling `make-temp-name' and creating the
file which opens all kinds of security holes.  For that reason, you should
716 717 718 719 720
probably use `make-temp-file' instead, except in three circumstances:

* If you are creating the file in the user's home directory.
* If you are creating a directory rather than an ordinary file.
* If you are taking special precautions as `make-temp-file' does.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
721
  (Lisp_Object prefix)
722 723 724 725 726
{
  return make_temp_name (prefix, 0);
}


Jim Blandy's avatar
Jim Blandy committed
727

Paul Eggert's avatar
Paul Eggert committed
728
DEFUN ("expand-file-name", Fexpand_file_name, Sexpand_file_name, 1, 2, 0,
729 730
       doc: /* Convert filename NAME to absolute, and canonicalize it.
Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
731
\(does not start with slash or tilde); if DEFAULT-DIRECTORY is nil or missing,
732
the current buffer's value of `default-directory' is used.
733 734
NAME should be a string that is a valid file name for the underlying
filesystem.
735 736 737 738
File name components that are `.' are removed, and
so are file name components followed by `..', along with the `..' itself;
note that these simplifications are done without checking the resulting
file names in the file system.
739 740 741
Multiple consecutive slashes are collapsed into a single slash,
except at the beginning of the file name when they are significant (e.g.,
UNC file names on MS-Windows.)
742 743
An initial `~/' expands to your home directory.
An initial `~USER/' expands to USER's home directory.
Chong Yidong's avatar
Chong Yidong committed
744 745 746 747 748
See also the function `substitute-in-file-name'.

For technical reasons, this function can return correct but
non-intuitive results for the root directory; for instance,
\(expand-file-name ".." "/") returns "/..".  For this reason, use
749
\(directory-file-name (file-name-directory dirname)) to traverse a
Chong Yidong's avatar
Chong Yidong committed
750
filesystem tree, not (expand-file-name ".."  dirname).  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
751
  (Lisp_Object name, Lisp_Object default_directory)
Jim Blandy's avatar
Jim Blandy committed
752
{
753 754
  /* These point to SDATA and need to be careful with string-relocation
     during GC (via DECODE_FILE).  */
755 756
  char *nm;
  const char *newdir;
757
  /* This should only point to alloca'd data.  */
758
  char *target;
759

760
  ptrdiff_t tlen;
Jim Blandy's avatar
Jim Blandy committed
761
  struct passwd *pw;
762
#ifdef DOS_NT
763
  int drive = 0;
764
  int collapse_newdir = 1;
765
  int is_escaped = 0;
766
#endif /* DOS_NT */
767
  ptrdiff_t length;
768
  Lisp_Object handler, result, handled_name;
769
  int multibyte;
770
  Lisp_Object hdir;
771

772
  CHECK_STRING (name);
Jim Blandy's avatar
Jim Blandy committed
773

774 775
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
776
  handler = Ffind_file_name_handler (name, Qexpand_file_name);
777
  if (!NILP (handler))
778 779 780 781 782 783 784 785
    {
      handled_name = call3 (handler, Qexpand_file_name,
			    name, default_directory);
      if (STRINGP (handled_name))
	return handled_name;
      error ("Invalid handler in `file-name-handler-alist'");
    }

786

787 788
  /* Use the buffer's default-directory if DEFAULT_DIRECTORY is omitted.  */
  if (NILP (default_directory))
Tom Tromey's avatar
Tom Tromey committed
789
    default_directory = BVAR (current_buffer, directory);
790
  if (! STRINGP (default_directory))
791 792 793 794 795 796 797 798 799 800 801 802 803 804 805
    {
#ifdef DOS_NT
      /* "/" is not considered a root directory on DOS_NT, so using "/"
	 here causes an infinite recursion in, e.g., the following:

            (let (default-directory)
	      (expand-file-name "a"))

	 To avoid this, we set default_directory to the root of the
	 current drive.  */
      default_directory = build_string (emacs_root_dir ());
#else
      default_directory = build_string ("/");
#endif
    }
806

807
  if (!NILP (default_directory))
808
    {
809
      handler = Ffind_file_name_handler (default_directory, Qexpand_file_name);
810
      if (!NILP (handler))
811 812 813 814 815 816 817
	{
	  handled_name = call3 (handler, Qexpand_file_name,
				name, default_directory);
	  if (STRINGP (handled_name))
	    return handled_name;
	  error ("Invalid handler in `file-name-handler-alist'");
	}
818
    }
819

820
  {
821
    char *o = SSDATA (default_directory);
822 823 824 825 826 827 828 829 830 831 832 833 834 835 836

    /* Make sure DEFAULT_DIRECTORY is properly expanded.
       It would be better to do this down below where we actually use
       default_directory.  Unfortunately, calling Fexpand_file_name recursively
       could invoke GC, and the strings might be relocated.  This would
       be annoying because we have pointers into strings lying around
       that would need adjusting, and people would add new pointers to
       the code and forget to adjust them, resulting in intermittent bugs.
       Putting this call here avoids all that crud.

       The EQ test avoids infinite recursion.  */
    if (! NILP (default_directory) && !EQ (default_directory, name)
	/* Save time in some common cases - as long as default_directory
	   is not relative, it can be canonicalized with name below (if it
	   is needed at all) without requiring it to be expanded now.  */
837
#ifdef DOS_NT
838 839 840
	/* Detect MSDOS file names with drive specifiers.  */
	&&