fileio.c 177 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 35
#include <ctype.h>
#include <errno.h>

Karel Klíc's avatar
Karel Klíc committed
36 37 38 39 40
#ifdef HAVE_LIBSELINUX
#include <selinux/selinux.h>
#include <selinux/context.h>
#endif

Jim Blandy's avatar
Jim Blandy committed
41
#include "lisp.h"
42
#include "intervals.h"
Jim Blandy's avatar
Jim Blandy committed
43
#include "buffer.h"
44
#include "character.h"
Karl Heuer's avatar
Karl Heuer committed
45
#include "coding.h"
Jim Blandy's avatar
Jim Blandy committed
46
#include "window.h"
YAMAMOTO Mitsuharu's avatar
YAMAMOTO Mitsuharu committed
47
#include "blockinput.h"
Karoly Lorentey's avatar
Karoly Lorentey committed
48 49
#include "frame.h"
#include "dispextern.h"
Jim Blandy's avatar
Jim Blandy committed
50

51 52 53 54 55 56
#ifdef WINDOWSNT
#define NOMINMAX 1
#include <windows.h>
#include <fcntl.h>
#endif /* not WINDOWSNT */

Eli Zaretskii's avatar
Eli Zaretskii committed
57 58 59 60 61 62
#ifdef MSDOS
#include "msdos.h"
#include <sys/param.h>
#include <fcntl.h>
#endif

63 64
#ifdef DOS_NT
/* On Windows, drive letters must be alphabetic - on DOS, the Netware
65
   redirector allows the six letters between 'Z' and 'a' as well.  */
66 67 68 69
#ifdef MSDOS
#define IS_DRIVE(x) ((x) >= 'A' && (x) <= 'z')
#endif
#ifdef WINDOWSNT
70
#define IS_DRIVE(x) isalpha ((unsigned char) (x))
71
#endif
72
/* Need to lower-case the drive letter, or else expanded
Paul Eggert's avatar
Paul Eggert committed
73
   filenames will sometimes compare unequal, because
74
   `expand-file-name' doesn't always down-case the drive letter.  */
75
#define DRIVE_LETTER(x) (tolower ((unsigned char) (x)))
76 77
#endif

Jim Blandy's avatar
Jim Blandy committed
78
#include "systime.h"
Jim Blandy's avatar
Jim Blandy committed
79 80 81

#ifdef HPUX
#include <netio.h>
82
#endif
Jim Blandy's avatar
Jim Blandy committed
83

84 85
#include "commands.h"

86 87 88 89
#ifndef FILE_SYSTEM_CASE
#define FILE_SYSTEM_CASE(filename)  (filename)
#endif

Jim Blandy's avatar
Jim Blandy committed
90
/* Nonzero during writing of auto-save files */
91
static int auto_saving;
Jim Blandy's avatar
Jim Blandy committed
92

93 94 95
/* Nonzero umask during creation of auto-save directories */
static int auto_saving_dir_umask;

Jim Blandy's avatar
Jim Blandy committed
96 97
/* Set by auto_save_1 to mode of original file so Fwrite_region will create
   a new file with the same mode as the original */
98
static int auto_save_mode_bits;
Jim Blandy's avatar
Jim Blandy committed
99

100
/* Set by auto_save_1 if an error occurred during the last auto-save. */
101
static int auto_save_error_occurred;
102

103 104 105 106 107
/* 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.  */
108
static Lisp_Object Qauto_save_coding;
109

110 111
/* Property name of a file name handler,
   which gives a list of operations it handles..  */
112
static Lisp_Object Qoperations;
113

114
/* Lisp functions for translating file formats */
115
static Lisp_Object Qformat_decode, Qformat_annotate_function;
116

117
/* Lisp function for setting buffer-file-coding-system and the
118
   multibyteness of the current buffer after inserting a file.  */
119
static Lisp_Object Qafter_insert_file_set_coding;
120

121
static Lisp_Object Qwrite_region_annotate_functions;
122 123
/* Each time an annotation function changes the buffer, the new buffer
   is added here.  */
124
static Lisp_Object Vwrite_region_annotation_buffers;
125

126 127 128
#ifdef HAVE_FSYNC
#endif

129
static Lisp_Object Qdelete_by_moving_to_trash;
130

131
/* Lisp function for moving files to trash.  */
132
static Lisp_Object Qmove_file_to_trash;
133

134
/* Lisp function for recursively copying directories.  */
135
static Lisp_Object Qcopy_directory;
136 137

/* Lisp function for recursively deleting directories.  */
138
static Lisp_Object Qdelete_directory;
139

140 141 142
#ifdef WINDOWSNT
#endif

143 144 145
Lisp_Object Qfile_error;
static Lisp_Object Qfile_already_exists, Qfile_date_error;
static Lisp_Object Qexcl;
146 147
Lisp_Object Qfile_name_history;

148
static Lisp_Object Qcar_less_than_car;
149

150
static Lisp_Object Fmake_symbolic_link (Lisp_Object, Lisp_Object, Lisp_Object);
151
static int a_write (int, Lisp_Object, EMACS_INT, EMACS_INT,
152
                    Lisp_Object *, struct coding_system *);
Paul Eggert's avatar
Paul Eggert committed
153
static int e_write (int, Lisp_Object, EMACS_INT, EMACS_INT,
154
		    struct coding_system *);
155

156

157
void
158
report_file_error (const char *string, Lisp_Object data)
Jim Blandy's avatar
Jim Blandy committed
159 160
{
  Lisp_Object errstring;
Richard M. Stallman's avatar
Richard M. Stallman committed
161
  int errorno = errno;
162
  char *str;
Jim Blandy's avatar
Jim Blandy committed
163

164
  synchronize_system_messages_locale ();
165 166 167
  str = strerror (errorno);
  errstring = code_convert_string_norecord (make_unibyte_string (str,
								 strlen (str)),
168 169
					    Vlocale_coding_system, 0);

Jim Blandy's avatar
Jim Blandy committed
170
  while (1)
Richard M. Stallman's avatar
Richard M. Stallman committed
171 172 173
    switch (errorno)
      {
      case EEXIST:
174
	xsignal (Qfile_already_exists, Fcons (errstring, data));
Richard M. Stallman's avatar
Richard M. Stallman committed
175 176 177
	break;
      default:
	/* System error messages are capitalized.  Downcase the initial
178 179
	   unless it is followed by a slash.  (The slash case caters to
	   error messages that begin with "I/O" or, in German, "E/A".)  */
180 181
	if (STRING_MULTIBYTE (errstring)
	    && ! EQ (Faref (errstring, make_number (1)), make_number ('/')))
182 183 184
	  {
	    int c;

185
	    str = SSDATA (errstring);
186
	    c = STRING_CHAR ((unsigned char *) str);
187
	    Faset (errstring, make_number (0), make_number (downcase (c)));
188
	  }
Richard M. Stallman's avatar
Richard M. Stallman committed
189

190
	xsignal (Qfile_error,
Richard M. Stallman's avatar
Richard M. Stallman committed
191 192
		 Fcons (build_string (string), Fcons (errstring, data)));
      }
Jim Blandy's avatar
Jim Blandy committed
193
}
194

195
Lisp_Object
196
close_file_unwind (Lisp_Object fd)
197
{
198
  emacs_close (XFASTINT (fd));
199
  return Qnil;
200
}
201 202 203

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

Andreas Schwab's avatar
Andreas Schwab committed
204
Lisp_Object
205
restore_point_unwind (Lisp_Object location)
206
{
207
  Fgoto_char (location);
208
  Fset_marker (location, Qnil, Qnil);
209
  return Qnil;
210
}
211

Jim Blandy's avatar
Jim Blandy committed
212

213 214 215 216 217 218 219 220 221 222 223
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;
224
Lisp_Object Qdelete_file;
225 226 227
static Lisp_Object Qrename_file;
static Lisp_Object Qadd_name_to_file;
static Lisp_Object Qmake_symbolic_link;
228
Lisp_Object Qfile_exists_p;
229 230 231 232 233
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;
234
Lisp_Object Qfile_directory_p;
235 236 237 238 239 240 241 242
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;
243 244
Lisp_Object Qinsert_file_contents;
Lisp_Object Qwrite_region;
245 246
static Lisp_Object Qverify_visited_file_modtime;
static Lisp_Object Qset_visited_file_modtime;
247

Paul Eggert's avatar
Paul Eggert committed
248
DEFUN ("find-file-name-handler", Ffind_file_name_handler,
249
       Sfind_file_name_handler, 2, 2, 0,
250 251 252 253 254 255 256 257 258
       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
259
  (Lisp_Object filename, Lisp_Object operation)
260
{
261
  /* This function must not munge the match data.  */
262
  Lisp_Object chain, inhibited_handlers, result;
263
  int pos = -1;
264

265
  result = Qnil;
266
  CHECK_STRING (filename);
267

268 269 270 271
  if (EQ (operation, Vinhibit_file_name_operation))
    inhibited_handlers = Vinhibit_file_name_handlers;
  else
    inhibited_handlers = Qnil;
272

273
  for (chain = Vfile_name_handler_alist; CONSP (chain);
274
       chain = XCDR (chain))
275 276
    {
      Lisp_Object elt;
277
      elt = XCAR (chain);
278
      if (CONSP (elt))
279
	{
280
	  Lisp_Object string = XCAR (elt);
281
	  EMACS_INT match_pos;
282
	  Lisp_Object handler = XCDR (elt);
283 284 285 286
	  Lisp_Object operations = Qnil;

	  if (SYMBOLP (handler))
	    operations = Fget (handler, Qoperations);
287

288
	  if (STRINGP (string)
289 290
	      && (match_pos = fast_string_match (string, filename)) > pos
	      && (NILP (operations) || ! NILP (Fmemq (operation, operations))))
291
	    {
292
	      Lisp_Object tem;
293

294
	      handler = XCDR (elt);
295 296
	      tem = Fmemq (handler, inhibited_handlers);
	      if (NILP (tem))
297 298 299 300
		{
		  result = handler;
		  pos = match_pos;
		}
301
	    }
302
	}
303 304

      QUIT;
305
    }
306
  return result;
307 308
}

Paul Eggert's avatar
Paul Eggert committed
309
DEFUN ("file-name-directory", Ffile_name_directory, Sfile_name_directory,
310 311 312
       1, 1, 0,
       doc: /* Return the directory component in file name FILENAME.
Return nil if FILENAME does not include a directory.
313
Otherwise return a directory name.
Dan Nicolaescu's avatar
Dan Nicolaescu committed
314
Given a Unix syntax file name, returns a string ending in slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
315
  (Lisp_Object filename)
Jim Blandy's avatar
Jim Blandy committed
316
{
317
#ifndef DOS_NT
318
  register const char *beg;
319
#else
320
  register char *beg;
321
#endif
322
  register const char *p;
323
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
324

325
  CHECK_STRING (filename);
Jim Blandy's avatar
Jim Blandy committed
326

327 328
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
329
  handler = Ffind_file_name_handler (filename, Qfile_name_directory);
330
  if (!NILP (handler))
331 332 333 334 335
    {
      Lisp_Object handled_name = call2 (handler, Qfile_name_directory,
					filename);
      return STRINGP (handled_name) ? handled_name : Qnil;
    }
336

337
  filename = FILE_SYSTEM_CASE (filename);
338
#ifdef DOS_NT
339 340
  beg = (char *) alloca (SBYTES (filename) + 1);
  memcpy (beg, SSDATA (filename), SBYTES (filename) + 1);
341
#else
342
  beg = SSDATA (filename);
343
#endif
344
  p = beg + SBYTES (filename);
Jim Blandy's avatar
Jim Blandy committed
345

346 347
  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
#ifdef DOS_NT
Paul Eggert's avatar
Paul Eggert committed
348
	 /* only recognize drive specifier at the beginning */
349 350 351 352
	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" and "/:foo" cases correctly  */
	      && ((p == beg + 2 && !IS_DIRECTORY_SEP (*beg))
		  || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
353
#endif
Jim Blandy's avatar
Jim Blandy committed
354 355 356 357
	 ) p--;

  if (p == beg)
    return Qnil;
358
#ifdef DOS_NT
359
  /* Expansion of "c:" to drive and default directory.  */
360
  if (p[-1] == ':')
361 362
    {
      /* MAXPATHLEN+1 is guaranteed to be enough space for getdefdir.  */
363 364
      char *res = alloca (MAXPATHLEN + 1);
      char *r = res;
365 366 367 368 369 370 371 372

      if (p == beg + 4 && IS_DIRECTORY_SEP (*beg) && beg[1] == ':')
	{
	  strncpy (res, beg, 2);
	  beg += 2;
	  r += 2;
	}

373
      if (getdefdir (toupper ((unsigned char) *beg) - 'A' + 1, r))
374
	{
375
	  if (!IS_DIRECTORY_SEP (res[strlen (res) - 1]))
376 377 378 379 380
	    strcat (res, "/");
	  beg = res;
	  p = beg + strlen (beg);
	}
    }
381
  dostounix_filename (beg);
382
#endif /* DOS_NT */
383

384
  return make_specified_string (beg, -1, p - beg, STRING_MULTIBYTE (filename));
Jim Blandy's avatar
Jim Blandy committed
385 386
}

Paul Eggert's avatar
Paul Eggert committed
387
DEFUN ("file-name-nondirectory", Ffile_name_nondirectory,
388
       Sfile_name_nondirectory, 1, 1, 0,
389 390 391 392
       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
393
  (Lisp_Object filename)
Jim Blandy's avatar
Jim Blandy committed
394
{
395
  register const char *beg, *p, *end;
396
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
397

398
  CHECK_STRING (filename);
Jim Blandy's avatar
Jim Blandy committed
399

400 401
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
402
  handler = Ffind_file_name_handler (filename, Qfile_name_nondirectory);
403
  if (!NILP (handler))
404 405 406 407 408 409 410
    {
      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'");
    }
411

412
  beg = SSDATA (filename);
413
  end = p = beg + SBYTES (filename);
Jim Blandy's avatar
Jim Blandy committed
414

415 416
  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
#ifdef DOS_NT
Paul Eggert's avatar
Paul Eggert committed
417
	 /* only recognize drive specifier at beginning */
418 419 420
	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" case correctly  */
	      && (p == beg + 2 || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
421
#endif
422 423
	 )
    p--;
Jim Blandy's avatar
Jim Blandy committed
424

425
  return make_specified_string (p, -1, end - p, STRING_MULTIBYTE (filename));
Jim Blandy's avatar
Jim Blandy committed
426
}
427

Paul Eggert's avatar
Paul Eggert committed
428
DEFUN ("unhandled-file-name-directory", Funhandled_file_name_directory,
429
       Sunhandled_file_name_directory, 1, 1, 0,
430 431 432 433 434
       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
435 436
If FILENAME refers to a file which is not accessible from a local process,
then this should return nil.
437 438
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
439
  (Lisp_Object filename)
440 441 442 443 444
{
  Lisp_Object handler;

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
445
  handler = Ffind_file_name_handler (filename, Qunhandled_file_name_directory);
446
  if (!NILP (handler))
447 448 449 450 451
    {
      Lisp_Object handled_name = call2 (handler, Qunhandled_file_name_directory,
					filename);
      return STRINGP (handled_name) ? handled_name : Qnil;
    }
452 453 454 455

  return Ffile_name_directory (filename);
}

Jim Blandy's avatar
Jim Blandy committed
456

457
static char *
458
file_name_as_directory (char *out, const char *in)
Jim Blandy's avatar
Jim Blandy committed
459
{
460
  ptrdiff_t len = strlen (in);
Jim Blandy's avatar
Jim Blandy committed
461

462
  if (len == 0)
463
    {
464 465 466
      out[0] = '.';
      out[1] = '/';
      out[2] = 0;
467 468 469
      return out;
    }

470 471
  strcpy (out, in);

Jim Blandy's avatar
Jim Blandy committed
472
  /* For Unix syntax, Append a slash if necessary */
473
  if (!IS_DIRECTORY_SEP (out[len - 1]))
474
    {
475 476
      out[len] = DIRECTORY_SEP;
      out[len + 1] = '\0';
477
    }
478
#ifdef DOS_NT
479
  dostounix_filename (out);
480
#endif
Jim Blandy's avatar
Jim Blandy committed
481 482 483
  return out;
}

Paul Eggert's avatar
Paul Eggert committed
484
DEFUN ("file-name-as-directory", Ffile_name_as_directory,
Jim Blandy's avatar
Jim Blandy committed
485
       Sfile_name_as_directory, 1, 1, 0,
486
       doc: /* Return a string representing the file name FILE interpreted as a directory.
487 488 489 490
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
491
For a Unix-syntax file name, just appends a slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
492
  (Lisp_Object file)
Jim Blandy's avatar
Jim Blandy committed
493 494
{
  char *buf;
495
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
496

497
  CHECK_STRING (file);
Jim Blandy's avatar
Jim Blandy committed
498
  if (NILP (file))
Jim Blandy's avatar
Jim Blandy committed
499
    return Qnil;
500 501 502

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
503
  handler = Ffind_file_name_handler (file, Qfile_name_as_directory);
504
  if (!NILP (handler))
505 506 507 508 509 510 511
    {
      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'");
    }
512

513
  buf = (char *) alloca (SBYTES (file) + 10);
514
  file_name_as_directory (buf, SSDATA (file));
515 516
  return make_specified_string (buf, -1, strlen (buf),
				STRING_MULTIBYTE (file));
Jim Blandy's avatar
Jim Blandy committed
517 518 519 520
}

/*
 * Convert from directory name to filename.
521
 * On UNIX, it's simple: just make sure there isn't a terminating /
Jim Blandy's avatar
Jim Blandy committed
522 523 524 525

 * Value is nonzero if the string output is different from the input.
 */

526
static int
527
directory_file_name (char *src, char *dst)
Jim Blandy's avatar
Jim Blandy committed
528
{
529
  ptrdiff_t slen;
Jim Blandy's avatar
Jim Blandy committed
530 531

  slen = strlen (src);
Dan Nicolaescu's avatar
Dan Nicolaescu committed
532

Jim Blandy's avatar
Jim Blandy committed
533 534 535
  /* Process as Unix format: just remove any final slash.
     But leave "/" unchanged; do not change it to "".  */
  strcpy (dst, src);
536
  if (slen > 1
537
      && IS_DIRECTORY_SEP (dst[slen - 1])
538 539 540 541
#ifdef DOS_NT
      && !IS_ANY_SEP (dst[slen - 2])
#endif
      )
Jim Blandy's avatar
Jim Blandy committed
542
    dst[slen - 1] = 0;
543
#ifdef DOS_NT
544
  dostounix_filename (dst);
545
#endif
Jim Blandy's avatar
Jim Blandy committed
546 547 548
  return 1;
}

Paul Eggert's avatar
Paul Eggert committed
549
DEFUN ("directory-file-name", Fdirectory_file_name, Sdirectory_file_name,
550 551 552 553 554
       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
555
In Unix-syntax, this function just removes the final slash.  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
556
  (Lisp_Object directory)
Jim Blandy's avatar
Jim Blandy committed
557 558
{
  char *buf;
559
  Lisp_Object handler;
Jim Blandy's avatar
Jim Blandy committed
560

561
  CHECK_STRING (directory);
Jim Blandy's avatar
Jim Blandy committed
562

Jim Blandy's avatar
Jim Blandy committed
563
  if (NILP (directory))
Jim Blandy's avatar
Jim Blandy committed
564
    return Qnil;
565 566 567

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
568
  handler = Ffind_file_name_handler (directory, Qdirectory_file_name);
569
  if (!NILP (handler))
570 571 572 573 574 575 576
    {
      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'");
    }
577

578
  buf = (char *) alloca (SBYTES (directory) + 20);
579
  directory_file_name (SSDATA (directory), buf);
580 581
  return make_specified_string (buf, -1, strlen (buf),
				STRING_MULTIBYTE (directory));
Jim Blandy's avatar
Jim Blandy committed
582 583
}

584
static const char make_temp_name_tbl[64] =
585 586 587 588 589 590 591 592 593 594
{
  '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','-','_'
};
595

596 597
static unsigned make_temp_name_count, make_temp_name_count_initialized_p;

598
/* Value is a temporary file name starting with PREFIX, a string.
599

600 601 602 603 604
   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.
605

606 607 608 609 610 611 612 613 614
   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
615
make_temp_name (Lisp_Object prefix, int base64_p)
Jim Blandy's avatar
Jim Blandy committed
616 617
{
  Lisp_Object val;
618
  int len, clen;
619
  printmax_t pid;
620
  char *p, *data;
621
  char pidbuf[INT_BUFSIZE_BOUND (printmax_t)];
622
  int pidlen;
623

624
  CHECK_STRING (prefix);
625 626 627 628 629 630

  /* 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.  */

631
  pid = getpid ();
632

633 634 635 636 637 638 639 640 641
  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
    {
642
#ifdef HAVE_LONG_FILE_NAMES
643
      pidlen = sprintf (pidbuf, "%"pMd, pid);
644
#else
645 646 647 648
      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;
649
#endif
650
    }
651

652 653 654 655
  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);
656 657
  data = SSDATA (val);
  memcpy (data, SSDATA (prefix), len);
658 659
  p = data + len;

660
  memcpy (p, pidbuf, pidlen);
661 662 663 664 665
  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
666 667 668 669 670 671
     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.  */

672 673
  if (!make_temp_name_count_initialized_p)
    {
674
      make_temp_name_count = time (NULL);
675 676 677 678 679 680
      make_temp_name_count_initialized_p = 1;
    }

  while (1)
    {
      struct stat ignored;
681
      unsigned num = make_temp_name_count;
682 683 684 685 686

      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;

687 688 689 690 691
      /* Poor man's congruential RN generator.  Replace with
         ++make_temp_name_count for debugging.  */
      make_temp_name_count += 25229;
      make_temp_name_count %= 225307;

692 693 694 695 696 697 698 699 700 701
      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
702
	       in looping through 225307 stat's, which is not only
703 704
	       dog-slow, but also useless since eventually nil would
	       have to be returned anyway.  */
705
	    report_file_error ("Cannot create temporary name for prefix",
706 707 708 709
			       Fcons (prefix, Qnil));
	  /* not reached */
	}
    }
Jim Blandy's avatar
Jim Blandy committed
710
}
711

712 713

DEFUN ("make-temp-name", Fmake_temp_name, Smake_temp_name, 1, 1, 0,
714 715 716 717 718 719 720 721 722 723
       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
724 725 726 727 728
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
729
  (Lisp_Object prefix)
730 731 732 733 734
{
  return make_temp_name (prefix, 0);
}


Jim Blandy's avatar
Jim Blandy committed
735

Paul Eggert's avatar
Paul Eggert committed
736
DEFUN ("expand-file-name", Fexpand_file_name, Sexpand_file_name, 1, 2, 0,
737 738
       doc: /* Convert filename NAME to absolute, and canonicalize it.
Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
739
\(does not start with slash or tilde); if DEFAULT-DIRECTORY is nil or missing,
740
the current buffer's value of `default-directory' is used.
741 742
NAME should be a string that is a valid file name for the underlying
filesystem.
743 744 745 746
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.
747 748 749
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.)
750 751
An initial `~/' expands to your home directory.
An initial `~USER/' expands to USER's home directory.
Chong Yidong's avatar
Chong Yidong committed
752 753 754 755 756
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
757
\(directory-file-name (file-name-directory dirname)) to traverse a
Chong Yidong's avatar
Chong Yidong committed
758
filesystem tree, not (expand-file-name ".."  dirname).  */)
Dan Nicolaescu's avatar
Dan Nicolaescu committed
759
  (Lisp_Object name, Lisp_Object default_directory)
Jim Blandy's avatar
Jim Blandy committed
760
{
761 762
  /* These point to SDATA and need to be careful with string-relocation
     during GC (via DECODE_FILE).  */
763 764
  char *nm;
  const char *newdir;
765
  /* This should only point to alloca'd data.  */
766
  char *target;
767

768
  ptrdiff_t tlen;
Jim Blandy's avatar
Jim Blandy committed
769
  struct passwd *pw;
770
#ifdef DOS_NT
771
  int drive = 0;
772
  int collapse_newdir = 1;
773
  int is_escaped = 0;
774
#endif /* DOS_NT */
775
  ptrdiff_t length;
776
  Lisp_Object handler, result, handled_name;
777
  int multibyte;
778
  Lisp_Object hdir;
779

780
  CHECK_STRING (name);
Jim Blandy's avatar
Jim Blandy committed
781

782 783
  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
784
  handler = Ffind_file_name_handler (name, Qexpand_file_name);
785
  if (!NILP (handler))
786 787 788 789 790 791 792 793
    {
      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'");
    }

794

795 796
  /* Use the buffer's default-directory if DEFAULT_DIRECTORY is omitted.  */
  if (NILP (default_directory))
Tom Tromey's avatar
Tom Tromey committed
797
    default_directory = BVAR (current_buffer, directory);
798
  if (! STRINGP (default_directory))
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813
    {
#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
    }
814

815
  if (!NILP (default_directory))
816
    {
817
      handler = Ffind_file_name_handler (default_directory, Qexpand_file_name);
818
      if (!NILP (handler))
819 820 821 822 823 824 825
	{
	  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'");
	}
826
    }
827

828
  {
829
    char *o = SSDATA (default_directory);
830 831 832 833 834 835 836 837 838 839 840 841 842 843 844

    /* 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.  */