File: cplfile.c

package info (click to toggle)
yuma123 2.11-1
  • links: PTS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 20,900 kB
  • sloc: ansic: 179,975; cpp: 10,968; python: 5,839; sh: 2,287; makefile: 1,021; xml: 621; exp: 592; perl: 70
file content (870 lines) | stat: -rw-r--r-- 28,855 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
 * 
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, and/or sell copies of the Software, and to permit persons
 * to whom the Software is furnished to do so, provided that the above
 * copyright notice(s) and this permission notice appear in all copies of
 * the Software and that both the above copyright notice(s) and this
 * permission notice appear in supporting documentation.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
 * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
 * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 * 
 * Except as contained in this notice, the name of a copyright holder
 * shall not be used in advertising or otherwise to promote the sale, use
 * or other dealings in this Software without prior written authorization
 * of the copyright holder.
 */

/*
 * If file-system access is to be excluded, this module has no function,
 * so all of its code should be excluded.
 */
#ifndef WITHOUT_FILE_SYSTEM

/*
 * Standard includes.
 */
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>

/*
 * Local includes.
 */
#include "libtecla.h"
#include "direader.h"
#include "homedir.h"
#include "pathutil.h"
#include "cplfile.h"
#include "errmsg.h"

/*
 * Set the maximum length allowed for usernames.
 * names.
 */
#define USR_LEN 100

/*
 * Set the maximum length allowed for environment variable names.
 */
#define ENV_LEN 100

/*
 * The resources needed to complete a filename are maintained in objects
 * of the following type.
 */
struct CompleteFile {
  ErrMsg *err;                 /* The error reporting buffer */
  DirReader *dr;               /* A directory reader */
  HomeDir *home;               /* A home directory expander */
  PathName *path;              /* The buffer in which to accumulate the path */
  PathName *buff;              /* A pathname work buffer */
  char usrnam[USR_LEN+1];      /* The buffer used when reading the names of */
                               /*  users. */
  char envnam[ENV_LEN+1];      /* The buffer used when reading the names of */
                               /*  environment variables. */
};

static int cf_expand_home_dir(CompleteFile *cf, const char *user);
static int cf_complete_username(CompleteFile *cf, WordCompletion *cpl,
				const char *prefix, const char *line,
				int word_start, int word_end, int escaped);
static HOME_DIR_FN(cf_homedir_callback);
static int cf_complete_entry(CompleteFile *cf, WordCompletion *cpl,
			     const char *line, int word_start, int word_end,
			     int escaped, CplCheckFn *check_fn,
			     void *check_data);
static char *cf_read_name(CompleteFile *cf, const char *type,
			  const char *string, int slen,
			  char *nambuf, int nammax);
static int cf_prepare_suffix(CompleteFile *cf, const char *suffix,
			     int add_escapes);

/*
 * A stack based object of the following type is used to pass data to the
 * cf_homedir_callback() function.
 */
typedef struct {
  CompleteFile *cf;    /* The file-completion resource object */
  WordCompletion *cpl; /* The string-completion rsource object */
  size_t prefix_len;   /* The length of the prefix being completed */
  const char *line;    /* The line from which the prefix was extracted */
  int word_start;      /* The index in line[] of the start of the username */
  int word_end;        /* The index in line[] following the end of the prefix */
  int escaped;         /* If true, add escapes to the completion suffixes */
} CfHomeArgs;

/*.......................................................................
 * Create a new file-completion object.
 *
 * Output:
 *  return  CompleteFile *  The new object, or NULL on error.
 */
CompleteFile *_new_CompleteFile(void)
{
  CompleteFile *cf;  /* The object to be returned */
/*
 * Allocate the container.
 */
  cf = (CompleteFile *) malloc(sizeof(CompleteFile));
  if(!cf) {
    errno = ENOMEM;
    return NULL;
  };
/*
 * Before attempting any operation that might fail, initialize the
 * container at least up to the point at which it can safely be passed
 * to _del_CompleteFile().
 */
  cf->err = NULL;
  cf->dr = NULL;
  cf->home = NULL;
  cf->path = NULL;
  cf->buff = NULL;
  cf->usrnam[0] = '\0';
  cf->envnam[0] = '\0';
/*
 * Allocate a place to record error messages.
 */
  cf->err = _new_ErrMsg();
  if(!cf->err)
    return _del_CompleteFile(cf);
/*
 * Create the object that is used for reading directories.
 */
  cf->dr = _new_DirReader();
  if(!cf->dr)
    return _del_CompleteFile(cf);
/*
 * Create the object that is used to lookup home directories.
 */
  cf->home = _new_HomeDir();
  if(!cf->home)
    return _del_CompleteFile(cf);
/*
 * Create the buffer in which the completed pathname is accumulated.
 */
  cf->path = _new_PathName();
  if(!cf->path)
    return _del_CompleteFile(cf);
/*
 * Create a pathname work buffer.
 */
  cf->buff = _new_PathName();
  if(!cf->buff)
    return _del_CompleteFile(cf);
  return cf;
}

/*.......................................................................
 * Delete a file-completion object.
 *
 * Input:
 *  cf     CompleteFile *  The object to be deleted.
 * Output:
 *  return CompleteFile *  The deleted object (always NULL).
 */
CompleteFile *_del_CompleteFile(CompleteFile *cf)
{
  if(cf) {
    cf->err = _del_ErrMsg(cf->err);
    cf->dr = _del_DirReader(cf->dr);
    cf->home = _del_HomeDir(cf->home);
    cf->path = _del_PathName(cf->path);
    cf->buff = _del_PathName(cf->buff);
    free(cf);
  };
  return NULL;
}

/*.......................................................................
 * Look up the possible completions of the incomplete filename that
 * lies between specified indexes of a given command-line string.
 *
 * Input:
 *  cpl   WordCompletion *  The object in which to record the completions.
 *  cf      CompleteFile *  The filename-completion resource object.
 *  line      const char *  The string containing the incomplete filename.
 *  word_start       int    The index of the first character in line[]
 *                          of the incomplete filename.
 *  word_end         int    The index of the character in line[] that
 *                          follows the last character of the incomplete
 *                          filename.
 *  escaped          int    If true, backslashes in line[] are
 *                          interpreted as escaping the characters
 *                          that follow them, and any spaces, tabs,
 *                          backslashes, or wildcard characters in the
 *                          returned suffixes will be similarly escaped.
 *                          If false, backslashes will be interpreted as
 *                          literal parts of the file name, and no
 *                          backslashes will be added to the returned
 *                          suffixes.
 *  check_fn  CplCheckFn *  If not zero, this argument specifies a
 *                          function to call to ask whether a given
 *                          file should be included in the list
 *                          of completions.
 *  check_data      void *  Anonymous data to be passed to check_fn().
 * Output:
 *  return           int    0 - OK.
 *                          1 - Error. A description of the error can be
 *                                     acquired by calling _cf_last_error(cf).
 */
int _cf_complete_file(WordCompletion *cpl, CompleteFile *cf,
		     const char *line, int word_start, int word_end,
		     int escaped, CplCheckFn *check_fn, void *check_data)
{
  const char *lptr; /* A pointer into line[] */
  int nleft;        /* The number of characters still to be processed */
                    /*  in line[]. */
/*
 * Check the arguments.
 */
  if(!cpl || !cf || !line || word_end < word_start) {
    if(cf) {
      _err_record_msg(cf->err, "_cf_complete_file: Invalid arguments",
		      END_ERR_MSG);
    };
    return 1;
  };
/*
 * Clear the buffer in which the filename will be constructed.
 */
  _pn_clear_path(cf->path);
/*
 * How many characters are to be processed?
 */
  nleft = word_end - word_start;
/*
 * Get a pointer to the start of the incomplete filename.
 */
  lptr = line + word_start;
/*
 * If the first character is a tilde, then perform home-directory
 * interpolation.
 */
  if(nleft > 0 && *lptr == '~') {
    int slen;
    if(!cf_read_name(cf, "User", ++lptr, --nleft, cf->usrnam, USR_LEN))
      return 1;
/*
 * Advance over the username in the input line.
 */
    slen = strlen(cf->usrnam);
    lptr += slen;
    nleft -= slen;
/*
 * If we haven't hit the end of the input string then we have a complete
 * username to translate to the corresponding home directory.
 */
    if(nleft > 0) {
      if(cf_expand_home_dir(cf, cf->usrnam))
	return 1;
/*
 * ~user and ~ are usually followed by a directory separator to
 * separate them from the file contained in the home directory.
 * If the home directory is the root directory, then we don't want
 * to follow the home directory by a directory separator, so we should
 * skip over it so that it doesn't get copied into the filename.
 */
      if(strcmp(cf->path->name, FS_ROOT_DIR) == 0 &&
	 strncmp(lptr, FS_DIR_SEP, FS_DIR_SEP_LEN) == 0) {
	lptr += FS_DIR_SEP_LEN;
	nleft -= FS_DIR_SEP_LEN;
      };
/*
 * If we have reached the end of the input string, then the username
 * may be incomplete, and we should attempt to complete it.
 */
    } else {
/*
 * Look up the possible completions of the username.
 */
      return cf_complete_username(cf, cpl, cf->usrnam, line, word_start+1,
				  word_end, escaped);
    };
  };
/*
 * Copy the rest of the path, stopping to expand $envvar expressions
 * where encountered.
 */
  while(nleft > 0) {
    int seglen;   /* The length of the next segment to be copied */
/*
 * Find the length of the next segment to be copied, stopping if an
 * unescaped '$' is seen, or the end of the path is reached.
 */
    for(seglen=0; seglen < nleft; seglen++) {
      int c = lptr[seglen];
      if(escaped && c == '\\')
	seglen++;
      else if(c == '$')
	break;
/*
 * We will be completing the last component of the file name,
 * so whenever a directory separator is seen, assume that it
 * might be the start of the last component, and mark the character
 * that follows it as the start of the name that is to be completed.
 */
      if(nleft >= FS_DIR_SEP_LEN &&
	 strncmp(lptr + seglen, FS_DIR_SEP, FS_DIR_SEP_LEN)==0) {
	word_start = (lptr + seglen) - line + FS_DIR_SEP_LEN;
      };
    };
/*
 * We have reached either the end of the filename or the start of
 * $environment_variable expression. Record the newly checked
 * segment of the filename in the output filename, removing
 * backslash-escapes where needed.
 */
    if(_pn_append_to_path(cf->path, lptr, seglen, escaped) == NULL) {
      _err_record_msg(cf->err, "Insufficient memory to complete filename",
		      END_ERR_MSG);
      return 1;
    };
    lptr += seglen;
    nleft -= seglen;
/*
 * If the above loop finished before we hit the end of the filename,
 * then this was because an unescaped $ was seen. In this case, interpolate
 * the value of the environment variable that follows it into the output
 * filename.
 */
    if(nleft > 0) {
      char *value;    /* The value of the environment variable */
      int vlen;       /* The length of the value string */
      int nlen;       /* The length of the environment variable name */
/*
 * Read the name of the environment variable.
 */
      if(!cf_read_name(cf, "Environment", ++lptr, --nleft, cf->envnam, ENV_LEN))
	return 1;
/*
 * Advance over the environment variable name in the input line.
 */
      nlen = strlen(cf->envnam);
      lptr += nlen;
      nleft -= nlen;
/*
 * Get the value of the environment variable.
 */
      value = getenv(cf->envnam);
      if(!value) {
	_err_record_msg(cf->err, "Unknown environment variable: ", cf->envnam,
			END_ERR_MSG);
	return 1;
      };
      vlen = strlen(value);
/*
 * If we are at the start of the filename and the first character of the
 * environment variable value is a '~', attempt home-directory
 * interpolation.
 */
      if(cf->path->name[0] == '\0' && value[0] == '~') {
	if(!cf_read_name(cf, "User", value+1, vlen-1, cf->usrnam, USR_LEN) ||
	   cf_expand_home_dir(cf, cf->usrnam))
	  return 1;
/*
 * If the home directory is the root directory, and the ~usrname expression
 * was followed by a directory separator, prevent the directory separator
 * from being appended to the root directory by skipping it in the
 * input line.
 */
	if(strcmp(cf->path->name, FS_ROOT_DIR) == 0 &&
	   strncmp(lptr, FS_DIR_SEP, FS_DIR_SEP_LEN) == 0) {
	  lptr += FS_DIR_SEP_LEN;
	  nleft -= FS_DIR_SEP_LEN;
	};
      } else {
/*
 * Append the value of the environment variable to the output path.
 */
	if(_pn_append_to_path(cf->path, value, strlen(value), escaped)==NULL) {
	  _err_record_msg(cf->err, "Insufficient memory to complete filename",
			  END_ERR_MSG);
	  return 1;
	};
/*
 * Prevent extra directory separators from being added.
 */
	if(nleft >= FS_DIR_SEP_LEN &&
	   strcmp(cf->path->name, FS_ROOT_DIR) == 0 &&
	   strncmp(lptr, FS_DIR_SEP, FS_DIR_SEP_LEN) == 0) {
	  lptr += FS_DIR_SEP_LEN;
	  nleft -= FS_DIR_SEP_LEN;
	} else if(vlen > FS_DIR_SEP_LEN &&
		  strcmp(value + vlen - FS_DIR_SEP_LEN, FS_DIR_SEP)==0) {
	  cf->path->name[vlen-FS_DIR_SEP_LEN] = '\0';
	};
      };
/*
 * If adding the environment variable didn't form a valid directory,
 * we can't complete the line, since there is no way to separate append
 * a partial filename to an environment variable reference without
 * that appended part of the name being seen later as part of the
 * environment variable name. Thus if the currently constructed path
 * isn't a directory, quite now with no completions having been
 * registered.
 */
      if(!_pu_path_is_dir(cf->path->name))
	return 0;
/*
 * For the reasons given above, if we have reached the end of the filename
 * with the expansion of an environment variable, the only allowed
 * completion involves the addition of a directory separator.
 */
      if(nleft == 0) {
	if(cpl_add_completion(cpl, line, lptr-line, word_end, FS_DIR_SEP,
			      "", "")) {
	  _err_record_msg(cf->err, cpl_last_error(cpl), END_ERR_MSG);
	  return 1;
	};
	return 0;
      };
    };
  };
/*
 * Complete the filename if possible.
 */
  return cf_complete_entry(cf, cpl, line, word_start, word_end, escaped,
			   check_fn, check_data);
}

/*.......................................................................
 * Return a description of the last path-completion error that occurred.
 *
 * Input:
 *  cf    CompleteFile *  The path-completion resource object.
 * Output:
 *  return  const char *  The description of the last error.
 */
const char *_cf_last_error(CompleteFile *cf)
{
  return cf ? _err_get_msg(cf->err) : "NULL CompleteFile argument";
}

/*.......................................................................
 * Lookup the home directory of the specified user, or the current user
 * if no name is specified, appending it to output pathname.
 *
 * Input:
 *  cf  CompleteFile *  The pathname completion resource object.
 *  user  const char *  The username to lookup, or "" to lookup the
 *                      current user.
 * Output:
 *  return        int    0 - OK.
 *                       1 - Error.
 */
static int cf_expand_home_dir(CompleteFile *cf, const char *user)
{
/*
 * Attempt to lookup the home directory.
 */
  const char *home_dir = _hd_lookup_home_dir(cf->home, user);
/*
 * Failed?
 */
  if(!home_dir) {
    _err_record_msg(cf->err, _hd_last_home_dir_error(cf->home), END_ERR_MSG);
    return 1;
  };
/*
 * Append the home directory to the pathname string.
 */
  if(_pn_append_to_path(cf->path, home_dir, -1, 0) == NULL) {
    _err_record_msg(cf->err, "Insufficient memory for home directory expansion",
		    END_ERR_MSG);
    return 1;
  };
  return 0;
}

/*.......................................................................
 * Lookup and report all completions of a given username prefix.
 *
 * Input:
 *  cf     CompleteFile *  The filename-completion resource object.
 *  cpl  WordCompletion *  The object in which to record the completions.
 *  prefix   const char *  The prefix of the usernames to lookup.
 *  line     const char *  The command-line in which the username appears.
 *  word_start      int    The index within line[] of the start of the
 *                         username that is being completed.
 *  word_end        int    The index within line[] of the character which
 *                         follows the incomplete username.
 *  escaped         int    True if the completions need to have special
 *                         characters escaped.
 * Output:
 *  return          int    0 - OK.
 *                         1 - Error.
 */
static int cf_complete_username(CompleteFile *cf, WordCompletion *cpl,
				const char *prefix, const char *line,
				int word_start, int word_end, int escaped)
{
/*
 * Set up a container of anonymous arguments to be sent to the
 * username-lookup iterator.
 */
  CfHomeArgs args;
  args.cf = cf;
  args.cpl = cpl;
  args.prefix_len = strlen(prefix);
  args.line = line;
  args.word_start = word_start;
  args.word_end = word_end;
  args.escaped = escaped;
/*
 * Iterate through the list of users, recording those which start
 * with the specified prefix.
 */
  if(_hd_scan_user_home_dirs(cf->home, prefix, &args, cf_homedir_callback)) {
    _err_record_msg(cf->err, _hd_last_home_dir_error(cf->home), END_ERR_MSG);
    return 1;
  };
  return 0;
}

/*.......................................................................
 * The user/home-directory scanner callback function (see homedir.h)
 * used by cf_complete_username().
 */
static HOME_DIR_FN(cf_homedir_callback)
{
/*
 * Get the file-completion resources from the anonymous data argument.
 */
  CfHomeArgs *args = (CfHomeArgs *) data;
  WordCompletion *cpl = args->cpl;
  CompleteFile *cf = args->cf;
/*
 * Copy the username into the pathname work buffer, adding backslash
 * escapes where needed.
 */
  if(cf_prepare_suffix(cf, usrnam+args->prefix_len, args->escaped)) {
    strncpy(errmsg, _err_get_msg(cf->err), maxerr);
    errmsg[maxerr] = '\0';
    return 1;
  };
/*
 * Report the completion suffix that was copied above.
 */
  if(cpl_add_completion(cpl, args->line, args->word_start, args->word_end,
			cf->buff->name, FS_DIR_SEP, FS_DIR_SEP)) {
    strncpy(errmsg, cpl_last_error(cpl), maxerr);
    errmsg[maxerr] = '\0';
    return 1;
  };
  return 0;
}

/*.......................................................................
 * Report possible completions of the filename in cf->path->name[].
 *
 * Input:
 *  cf      CompleteFile *  The file-completion resource object.
 *  cpl   WordCompletion *  The object in which to record the completions.
 *  line      const char *  The input line, as received by the callback
 *                          function.
 *  word_start       int    The index within line[] of the start of the
 *                          last component of the filename that is being
 *                          completed.
 *  word_end         int    The index within line[] of the character which
 *                          follows the incomplete filename.
 *  escaped          int    If true, escape special characters in the
 *                          completion suffixes.
 *  check_fn  CplCheckFn *  If not zero, this argument specifies a
 *                          function to call to ask whether a given
 *                          file should be included in the list
 *                          of completions.
 *  check_data      void *  Anonymous data to be passed to check_fn().
 * Output:
 *  return           int    0 - OK.
 *                          1 - Error.
 */
static int cf_complete_entry(CompleteFile *cf, WordCompletion *cpl,
			     const char *line, int word_start, int word_end,
			     int escaped, CplCheckFn *check_fn,
			     void *check_data)
{
  const char *dirpath;   /* The name of the parent directory */
  int start;             /* The index of the start of the last filename */
                         /*  component in the transcribed filename. */
  const char *prefix;    /* The filename prefix to be completed */
  int prefix_len;        /* The length of the filename prefix */
  const char *file_name; /* The lastest filename being compared */
  int waserr = 0;        /* True after errors */
  int terminated=0;      /* True if the directory part had to be terminated */
/*
 * Get the pathname string and its current length.
 */
  char *pathname = cf->path->name;
  int pathlen = strlen(pathname);
/*
 * Locate the start of the final component of the pathname.
 */
  for(start=pathlen - 1; start >= 0 &&
      strncmp(pathname + start, FS_DIR_SEP, FS_DIR_SEP_LEN) != 0; start--)
    ;
/*
 * Is the parent directory the root directory?
 */
  if(start==0 ||
     (start < 0 && strncmp(pathname, FS_ROOT_DIR, FS_ROOT_DIR_LEN) == 0)) {
    dirpath = FS_ROOT_DIR;
    start += FS_ROOT_DIR_LEN;
/*
 * If we found a directory separator then the part which precedes the
 * last component is the name of the directory to be opened.
 */
  } else if(start > 0) {
/*
 * The _dr_open_dir() function requires the directory name to be '\0'
 * terminated, so temporarily do this by overwriting the first character
 * of the directory separator.
 */
    pathname[start] = '\0';
    dirpath = pathname;
    terminated = 1;
/*
 * We reached the start of the pathname before finding a directory
 * separator, so arrange to open the current working directory.
 */
  } else {
    start = 0;
    dirpath = FS_PWD;
  };
/*
 * Attempt to open the directory.
 */
  if(_dr_open_dir(cf->dr, dirpath, NULL)) {
    _err_record_msg(cf->err, "Can't open directory: ", dirpath, END_ERR_MSG);
    return 1;
  };
/*
 * If removed above, restore the directory separator and skip over it
 * to the start of the filename.
 */
  if(terminated) {
    memcpy(pathname + start, FS_DIR_SEP, FS_DIR_SEP_LEN);
    start += FS_DIR_SEP_LEN;
  };
/*
 * Get the filename prefix and its length.
 */
  prefix = pathname + start;
  prefix_len = strlen(prefix);
/*
 * Traverse the directory, looking for files who's prefixes match the
 * last component of the pathname.
 */
  while((file_name = _dr_next_file(cf->dr)) != NULL && !waserr) {
    int name_len = strlen(file_name);
/*
 * Is the latest filename a possible completion of the filename prefix?
 */
    if(name_len >= prefix_len && strncmp(prefix, file_name, prefix_len)==0) {
/*
 * When listing all files in a directory, don't list files that start
 * with '.'. This is how hidden files are denoted in UNIX.
 */
      if(prefix_len > 0 || file_name[0] != '.') {
/*
 * Copy the completion suffix into the work pathname cf->buff->name,
 * adding backslash escapes if needed.
 */
	if(cf_prepare_suffix(cf, file_name + prefix_len, escaped)) {
	  waserr = 1;
	} else {
/*
 * We want directories to be displayed with directory suffixes,
 * and other fully completed filenames to be followed by spaces.
 * To check the type of the file, append the current suffix
 * to the path being completed, check the filetype, then restore
 * the path to its original form.
 */
	  const char *cont_suffix = "";  /* The suffix to add if fully */
                                         /*  completed. */
	  const char *type_suffix = "";  /* The suffix to add when listing */
	  if(_pn_append_to_path(cf->path, file_name + prefix_len,
				-1, escaped) == NULL) {
	    _err_record_msg(cf->err,
			    "Insufficient memory to complete filename.",
			    END_ERR_MSG);
	    return 1;
	  };
/*
 * Specify suffixes according to the file type.
 */
	  if(_pu_path_is_dir(cf->path->name)) {
	    cont_suffix = FS_DIR_SEP;
	    type_suffix = FS_DIR_SEP;
	  } else if(!check_fn || check_fn(check_data, cf->path->name)) {
	    cont_suffix = " ";
	  } else {
	    cf->path->name[pathlen] = '\0';
	    continue;
	  };
/*
 * Remove the temporarily added suffix.
 */
	  cf->path->name[pathlen] = '\0';
/*
 * Record the latest completion.
 */
	  if(cpl_add_completion(cpl, line, word_start, word_end, cf->buff->name,
				type_suffix, cont_suffix))
	    waserr = 1;
	};
      };
    };
  };
/*
 * Close the directory.
 */
  _dr_close_dir(cf->dr);
  return waserr;
}

/*.......................................................................
 * Read a username or environment variable name, stopping when a directory
 * separator is seen, when the end of the string is reached, or the
 * output buffer overflows.
 *
 * Input:
 *  cf   CompleteFile *  The file-completion resource object.
 *  type         char *  The capitalized name of the type of name being read.
 *  string       char *  The string who's prefix contains the name.
 *  slen          int    The number of characters in string[].
 *  nambuf       char *  The output name buffer.
 *  nammax        int    The longest string that will fit in nambuf[], excluding
 *                       the '\0' terminator.
 * Output:
 *  return       char *  A pointer to nambuf on success. On error NULL is
 *                       returned and a description of the error is recorded
 *                       in cf->err.
 */
static char *cf_read_name(CompleteFile *cf, const char *type,
			  const char *string, int slen,
			  char *nambuf, int nammax)
{
  int namlen;         /* The number of characters in nambuf[] */
  const char *sptr;   /* A pointer into string[] */
/*
 * Work out the max number of characters that should be copied.
 */
  int nmax = nammax < slen ? nammax : slen;
/*
 * Get the environment variable name that follows the dollar.
 */
  for(sptr=string,namlen=0;
      namlen < nmax && (slen-namlen < FS_DIR_SEP_LEN ||
			strncmp(sptr, FS_DIR_SEP, FS_DIR_SEP_LEN) != 0);
      namlen++) {
    nambuf[namlen] = *sptr++;
  };
/*
 * Did the name overflow the buffer?
 */
  if(namlen >= nammax) {
    _err_record_msg(cf->err, type, " name too long", END_ERR_MSG);
    return NULL;
  };
/*
 * Terminate the string.
 */
  nambuf[namlen] = '\0';
  return nambuf;
}

/*.......................................................................
 * Using the work buffer cf->buff, make a suitably escaped copy of a
 * given completion suffix, ready to be passed to cpl_add_completion().
 *
 * Input:
 *  cf   CompleteFile *  The file-completion resource object.
 *  suffix       char *  The suffix to be copied.
 *  add_escapes   int    If true, escape special characters.
 * Output:
 *  return        int    0 - OK.
 *                       1 - Error.
 */
static int cf_prepare_suffix(CompleteFile *cf, const char *suffix,
			     int add_escapes)
{
  const char *sptr; /* A pointer into suffix[] */
  int nbsl;         /* The number of backslashes to add to the suffix */
  int i;
/*
 * How long is the suffix?
 */
  int suffix_len = strlen(suffix);
/*
 * Clear the work buffer.
 */
  _pn_clear_path(cf->buff);
/*
 * Count the number of backslashes that will have to be added to
 * escape spaces, tabs, backslashes and wildcard characters.
 */
  nbsl = 0;
  if(add_escapes) {
    for(sptr = suffix; *sptr; sptr++) {
      switch(*sptr) {
      case ' ': case '\t': case '\\': case '*': case '?': case '[':
	nbsl++;
	break;
      };
    };
  };
/*
 * Arrange for the output path buffer to have sufficient room for the
 * both the suffix and any backslashes that have to be inserted.
 */
  if(_pn_resize_path(cf->buff, suffix_len + nbsl) == NULL) {
    _err_record_msg(cf->err, "Insufficient memory to complete filename",
		    END_ERR_MSG);
    return 1;
  };
/*
 * If the suffix doesn't need any escapes, copy it directly into the
 * work buffer.
 */
  if(nbsl==0) {
    strcpy(cf->buff->name, suffix);
  } else {
/*
 * Make a copy with special characters escaped?
 */
    if(nbsl > 0) {
      const char *src = suffix;
      char *dst = cf->buff->name;
      for(i=0; i<suffix_len; i++) {
	switch(*src) {
	case ' ': case '\t': case '\\': case '*': case '?': case '[':
	  *dst++ = '\\';
	};
	*dst++ = *src++;
      };
      *dst = '\0';
    };
  };
  return 0;
}

#endif  /* ifndef WITHOUT_FILE_SYSTEM */