summaryrefslogtreecommitdiff
path: root/windows-NT/filesubr.c
blob: 55d57de8981758261c98f5252c1437eccade3e71 (plain)
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
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
/* filesubr.c --- subroutines for dealing with files
   Jim Blandy <jimb@cyclic.com>

   This file is part of GNU CVS.

   GNU CVS is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 2, or (at your option) any
   later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.  */

/* These functions were moved out of subr.c because they need different
   definitions under operating systems (like, say, Windows NT) with different
   file system semantics.  */

#include <assert.h>
#include <io.h>
#include <sys/socket.h>  /* This does: #include <windows.h> */

#include "cvs.h"
#include "setenv.h"

#include "JmgStat.h"

#undef mkdir

static int deep_remove_dir( const char *path );

/* Copies "from" to "to".  Note that the functionality here is similar
   to the win32 function CopyFile, but (1) we copy LastAccessTime and
   CopyFile doesn't, (2) we set file attributes to the default set by
   the C library and CopyFile copies them.  Neither #1 nor #2 was intentional
   as far as I know, but changing them could be confusing, unless there
   is some reason they should be changed (this would need more
   investigation).  */
void
copy_file (from, to)
    const char *from;
    const char *to;
{
    struct stat sb;
    struct utimbuf t;
    int fdin, fdout;

    if (trace)
#ifdef SERVER_SUPPORT
	(void) fprintf (stderr, "%c-> copy(%s,%s)\n",
			(server_active) ? 'S' : ' ', from, to);
#else
	(void) fprintf (stderr, "-> copy(%s,%s)\n", from, to);
#endif
    if (noexec)
	return;

    if ((fdin = open (from, O_RDONLY | O_BINARY)) < 0)
	error (1, errno, "cannot open %s for copying", from);
    if (fstat (fdin, &sb) < 0)
	error (1, errno, "cannot fstat %s", from);
    if ((fdout = open (to, O_CREAT | O_TRUNC | O_RDWR | O_BINARY,
		       (int) sb.st_mode & 07777)) < 0)
	error (1, errno, "cannot create %s for copying", to);
    if (sb.st_size > 0)
    {
	char buf[BUFSIZ];
	int n;

	for (;;) 
	{
	    n = read (fdin, buf, sizeof(buf));
	    if (n == -1)
	    {
#ifdef EINTR
		if (errno == EINTR)
		    continue;
#endif
		error (1, errno, "cannot read file %s for copying", from);
	    }
            else if (n == 0) 
		break;
  
	    if (write(fdout, buf, n) != n) {
		error (1, errno, "cannot write file %s for copying", to);
	    }
	}

#ifdef HAVE_FSYNC
	if (fsync (fdout)) 
	    error (1, errno, "cannot fsync file %s after copying", to);
#endif
    }

    if (close (fdin) < 0) 
	error (0, errno, "cannot close %s", from);
    if (close (fdout) < 0)
	error (1, errno, "cannot close %s", to);

    /* now, set the times for the copied file to match those of the original */
    memset ((char *) &t, 0, sizeof (t));
    t.actime = sb.st_atime;
    t.modtime = sb.st_mtime;
    (void) utime (to, &t);
}


static char *tmpdir_env;
/*
 * Return seperator (\) terminated path to system temporary directory.
 */
const char *
get_system_temp_dir (void)
{
	if (! tmpdir_env)
	{
		DWORD dwBufferSize, dwReturn;

		dwReturn = 0;
		dwBufferSize = 64;
		do {
			if (dwReturn >= dwBufferSize)
			{
				dwBufferSize = dwReturn + 4;
			}

			tmpdir_env = xrealloc (tmpdir_env, dwBufferSize);
			if (tmpdir_env)
			{
				dwReturn = GetTempPath (dwBufferSize, tmpdir_env);
				if (dwReturn <= 0)
				{
					free (tmpdir_env);
					tmpdir_env = NULL;
				}
			}
		} while (tmpdir_env && dwReturn >= dwBufferSize);
	}

	return tmpdir_env;
}


void
push_env_temp_dir (void)
{
	const char *tmpdir = get_cvs_tmp_dir ();

	if (tmpdir_env && strcmp (tmpdir_env, tmpdir))
		setenv ("TMP", tmpdir, 1);
}


/* FIXME-krp: these functions would benefit from caching the char * &
   stat buf.  */

/*
 * Returns non-zero if the argument file is a directory, or is a symbolic
 * link which points to a directory.
 */
int
isdir (file)
    const char *file;
{
    struct stat sb;

    if (stat (file, &sb) < 0)
	return (0);
    return (S_ISDIR (sb.st_mode));
}

/*
 * Returns non-zero if the argument file is a symbolic link.
 */
int
islink (file)
    const char *file;
{
#ifdef S_ISLNK
    struct stat sb;

    if (lstat (file, &sb) < 0)
	return (0);
    return (S_ISLNK (sb.st_mode));
#else
    return (0);
#endif
}

/*
 * Returns non-zero if the argument file exists.
 */
int
isfile (file)
    const char *file;
{
    return isaccessible(file, F_OK);
}

/*
 * Returns non-zero if the argument file is readable.
 */
int
isreadable (file)
    const char *file;
{
    return isaccessible(file, R_OK);
}

/*
 * Returns non-zero if the argument file is writable.
 */
int
iswritable (file)
    const char *file;
{
    return isaccessible(file, W_OK);
}

/*
 * Returns non-zero if the argument file is accessable according to
 * mode.  If compiled with SETXID_SUPPORT also works if cvs has setxid
 * bits set.
 */
int
isaccessible (file, mode)
    const char *file;
    const int mode;
{
#ifdef SETXID_SUPPORT
    struct stat sb;
    int umask = 0;
    int gmask = 0;
    int omask = 0;
    int uid;
    
    if (stat(file, &sb) == -1)
	return 0;
    if (mode == F_OK)
	return 1;

    uid = geteuid();
    if (uid == 0)		/* superuser */
    {
	if (mode & X_OK)
	    return sb.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH);
	else
	    return 1;
    }
	
    if (mode & R_OK)
    {
	umask |= S_IRUSR;
	gmask |= S_IRGRP;
	omask |= S_IROTH;
    }
    if (mode & W_OK)
    {
	umask |= S_IWUSR;
	gmask |= S_IWGRP;
	omask |= S_IWOTH;
    }
    if (mode & X_OK)
    {
	umask |= S_IXUSR;
	gmask |= S_IXGRP;
	omask |= S_IXOTH;
    }

    if (sb.st_uid == uid)
	return (sb.st_mode & umask) == umask;
    else if (sb.st_gid == getegid())
	return (sb.st_mode & gmask) == gmask;
    else
	return (sb.st_mode & omask) == omask;
#else
    return access(file, mode) == 0;
#endif
}



/*
 * Make a directory and die if it fails
 */
void
make_directory (name)
    const char *name;
{
    struct stat sb;

    if (stat (name, &sb) == 0 && (!S_ISDIR (sb.st_mode)))
	    error (0, 0, "%s already exists but is not a directory", name);
    if (!noexec && mkdir (name) < 0)
	error (1, errno, "cannot make directory %s", name);
}

/*
 * Make a path to the argument directory, printing a message if something
 * goes wrong.
 */
void
make_directories (name)
    const char *name;
{
    char *cp;

    if (noexec)
	return;

    if (mkdir (name) == 0 || errno == EEXIST)
	return;
    if (errno != ENOENT)
    {
	error (0, errno, "cannot make path to %s", name);
	return;
    }
    if ((cp = strrchr (name, '/')) == NULL)
	return;
    *cp = '\0';
    make_directories (name);
    *cp++ = '/';
    if (*cp == '\0')
	return;
    (void) mkdir (name);
}

/* Create directory NAME if it does not already exist; fatal error for
   other errors.  Returns 0 if directory was created; 1 if it already
   existed.  */
int
mkdir_if_needed (name)
    const char *name;
{
    if (mkdir (name) < 0)
    {
	if (errno != EEXIST
#ifdef EACCESS
	    /* This was copied over from the OS/2 code; I would guess it
	       isn't needed here but that has not been verified.  */
	    && errno != EACCESS
#endif
#ifdef EACCES
	    /* This is said to be needed by NT on Alpha or PowerPC
	       (not sure what version) --August, 1996.  */
	    && errno != EACCES
#endif
	    )
	    error (1, errno, "cannot make directory %s", name);
	return 1;
    }
    return 0;
}

/*
 * Change the mode of a file, either adding write permissions, or removing
 * all write permissions.  Adding write permissions honors the current umask
 * setting.
 */
void
xchmod (fname, writable)
    const char *fname;
    int writable;
{
    struct stat sb;
    mode_t mode, oumask;

    if (stat (fname, &sb) < 0)
    {
	if (!noexec)
	    error (0, errno, "cannot stat %s", fname);
	return;
    }
    if (writable)
    {
	oumask = umask (0);
	(void) umask (oumask);
	mode = sb.st_mode | ~oumask & (((sb.st_mode & S_IRUSR) ? S_IWUSR : 0) |
				       ((sb.st_mode & S_IRGRP) ? S_IWGRP : 0) |
				       ((sb.st_mode & S_IROTH) ? S_IWOTH : 0));
    }
    else
    {
	mode = sb.st_mode & ~(S_IWRITE | S_IWGRP | S_IWOTH);
    }

    if (trace)
#ifdef SERVER_SUPPORT
	(void) fprintf (stderr, "%c-> chmod(%s,%o)\n",
			(server_active) ? 'S' : ' ', fname, mode);
#else
	(void) fprintf (stderr, "-> chmod(%s,%o)\n", fname, mode);
#endif
    if (noexec)
	return;

    if (chmod (fname, mode) < 0)
	error (0, errno, "cannot change mode of file %s", fname);
}


/* Rename for NT which works for read only files.  Apparently if we are
   accessing FROM and TO via a Novell network, this is an issue.  */
int
wnt_rename (from, to)
    const char *from;
    const char *to;
{
    int result, save_errno;
    int readonly = !iswritable (from);

    if (readonly)
    {
	if (chmod (from, S_IWRITE) < 0)
	    return -1;
    }
    result = rename (from, to);
    save_errno = errno;
    if (readonly)
    {
	if (result == 0)
	{
	    if (chmod (to, S_IREAD) < 0)
		return -1;
	}
	else
	{
	    /* We have a choice of which error to report, if there is
	       one here too; report the one from rename ().  */
	    chmod (from, S_IREAD);
	}
	errno = save_errno;
    }
    return result;
}

/*
 * Rename a file and die if it fails
 */
void
rename_file (from, to)
    const char *from;
    const char *to;
{
    if (trace)
#ifdef SERVER_SUPPORT
	(void) fprintf (stderr, "%c-> rename(%s,%s)\n",
			(server_active) ? 'S' : ' ', from, to);
#else
	(void) fprintf (stderr, "-> rename(%s,%s)\n", from, to);
#endif
    if (noexec)
	return;

    /* Win32 unlink is stupid --- it fails if the file is read-only  */
    chmod(to, S_IWRITE);
    unlink(to);
    if (CVS_RENAME (from, to) < 0)
	error (1, errno, "cannot rename file %s to %s", from, to);
}

/*
 * unlink a file, if possible.
 */
int
unlink_file (f)
    const char *f;
{
    if (trace)
#ifdef SERVER_SUPPORT
	(void) fprintf (stderr, "%c-> unlink(%s)\n",
			(server_active) ? 'S' : ' ', f);
#else
	(void) fprintf (stderr, "-> unlink(%s)\n", f);
#endif
    if (noexec)
	return (0);

    /* Win32 unlink is stupid - it fails if the file is read-only */
    chmod (f, _S_IWRITE);
    return (unlink (f));
}

/*
 * Unlink a file or dir, if possible.  If it is a directory do a deep
 * removal of all of the files in the directory.  Return -1 on error
 * (in which case errno is set).
 */
int
unlink_file_dir (f)
    const char *f;
{
    if (trace)
#ifdef SERVER_SUPPORT
	(void) fprintf (stderr, "%c-> unlink_file_dir(%s)\n",
			(server_active) ? 'S' : ' ', f);
#else
	(void) fprintf (stderr, "-> unlink_file_dir(%s)\n", f);
#endif
    if (noexec)
	return (0);

    /* Win32 unlink is stupid - it fails if the file is read-only */
    chmod (f, _S_IWRITE);
    if (unlink (f) != 0)
    {
	/* Under Windows NT, unlink returns EACCES if the path
           is a directory.  Under Windows 95, it returns ENOENT.
           Under Windows XP, it can return ENOTEMPTY. */
        if (errno == EISDIR || errno == EACCES || errno == ENOENT
            || errno == ENOTEMPTY)
                return deep_remove_dir (f);
        else
		/* The file wasn't a directory and some other
		 * error occured
		 */
                return -1;
    }
    /* We were able to remove the file from the disk */
    return 0;
}

/* Remove a directory and everything it contains.  Returns 0 for
 * success, -1 for failure (in which case errno is set).
 */

static int
deep_remove_dir (path)
    const char *path;
{
    DIR		  *dirp;
    struct dirent *dp;
    char	   buf[PATH_MAX];

    /* ENOTEMPTY for NT (obvious) but EACCES for Win95 (not obvious) */
    if (rmdir (path) != 0)
    {
	if (errno == ENOTEMPTY || errno == EACCES)
	{
	    if ((dirp = CVS_OPENDIR (path)) == NULL)
		/* If unable to open the directory return
		 * an error
		 */
		return -1;

	    while ((dp = CVS_READDIR (dirp)) != NULL)
	    {
		if (strcmp (dp->d_name, ".") == 0 ||
			    strcmp (dp->d_name, "..") == 0)
		    continue;

		sprintf (buf, "%s/%s", path, dp->d_name);

		/* Win32 unlink is stupid - it fails if the file is read-only */
		chmod (buf, _S_IWRITE);
		if (unlink (buf) != 0 )
		{
		    /* Under Windows NT, unlink returns EACCES if the path
		     * is a directory.  Under Windows 95, it returns ENOENT.
                     * Under Windows XP, it can return ENOTEMPTY.  It
		     * isn't really clear to me whether checking errno is
		     * better or worse than using _stat to check for a
                     * directory.
		     * We aren't really trying to prevent race conditions here
		     * (e.g. what if something changes between readdir and
		     * unlink?)
                     */
		    if (errno == EISDIR || errno == EACCES || errno == ENOENT
                        || errno == ENOTEMPTY)
		    {
			if (deep_remove_dir (buf))
			{
			    closedir (dirp);
			    return -1;
			}
		    }
		    else
		    {
			/* buf isn't a directory, or there are
			 * some sort of permision problems
			 */
			CVS_CLOSEDIR (dirp);
			return -1;
		    }
		}
	    }
	    CVS_CLOSEDIR (dirp);
	    return rmdir (path);
	}
	else
	    return -1;
    }
    /* Was able to remove the directory return 0 */
    return 0;
}

/* Read NCHARS bytes from descriptor FD into BUF.
   Return the number of characters successfully read.
   The number returned is always NCHARS unless end-of-file or error.  */
static size_t
block_read (fd, buf, nchars)
    int fd;
    char *buf;
    size_t nchars;
{
    char *bp = buf;
    size_t nread;

    do 
    {
	nread = read (fd, bp, nchars);
	if (nread == (size_t)-1)
	{
#ifdef EINTR
	    if (errno == EINTR)
		continue;
#endif
	    return (size_t)-1;
	}

	if (nread == 0)
	    break; 

	bp += nread;
	nchars -= nread;
    } while (nchars != 0);

    return bp - buf;
} 

    
/*
 * Compare "file1" to "file2". Return non-zero if they don't compare exactly.
 */
int
xcmp (file1, file2)
    const char *file1;
    const char *file2;
{
    char *buf1, *buf2;
    struct stat sb1, sb2;
    int fd1, fd2;
    int ret;

    if ((fd1 = open (file1, O_RDONLY | O_BINARY)) < 0)
	error (1, errno, "cannot open file %s for comparing", file1);
    if ((fd2 = open (file2, O_RDONLY | O_BINARY)) < 0)
	error (1, errno, "cannot open file %s for comparing", file2);
    if (fstat (fd1, &sb1) < 0)
	error (1, errno, "cannot fstat %s", file1);
    if (fstat (fd2, &sb2) < 0)
	error (1, errno, "cannot fstat %s", file2);

    /* A generic file compare routine might compare st_dev & st_ino here 
       to see if the two files being compared are actually the same file.
       But that won't happen in CVS, so we won't bother. */

    if (sb1.st_size != sb2.st_size)
	ret = 1;
    else if (sb1.st_size == 0)
	ret = 0;
    else
    {
	/* FIXME: compute the optimal buffer size by computing the least
	   common multiple of the files st_blocks field */
	size_t buf_size = 8 * 1024;
	size_t read1;
	size_t read2;

	buf1 = xmalloc (buf_size);
	buf2 = xmalloc (buf_size);

	do 
	{
	    read1 = block_read (fd1, buf1, buf_size);
	    if (read1 == (size_t)-1)
		error (1, errno, "cannot read file %s for comparing", file1);

	    read2 = block_read (fd2, buf2, buf_size);
	    if (read2 == (size_t)-1)
		error (1, errno, "cannot read file %s for comparing", file2);

	    /* assert (read1 == read2); */

	    ret = memcmp(buf1, buf2, read1);
	} while (ret == 0 && read1 == buf_size);

	free (buf1);
	free (buf2);
    }
	
    (void) close (fd1);
    (void) close (fd2);
    return (ret);
}

/* Generate a unique temporary filename.  Returns a pointer to a newly
 * malloc'd string containing the name.  Returns successfully or not at
 * all.
 *
 *     THIS FUNCTION IS DEPRECATED!!!  USE cvs_temp_file INSTEAD!!!
 *
 * and yes, I know about the way the rcs commands use temp files.  I think
 * they should be converted too but I don't have time to look into it right
 * now.
 */
char *
cvs_temp_name ()
{
    char *fn;
    FILE *fp;

    fp = cvs_temp_file (&fn);
    if (fp == NULL)
	error (1, errno, "Failed to create temporary file");
    if (fclose (fp) == EOF)
	error (0, errno, "Failed to close temporary file %s", fn);
    return fn;
}

/* Generate a unique temporary filename and return an open file stream
 * to the truncated file by that name
 *
 *  INPUTS
 *	filename	where to place the pointer to the newly allocated file
 *   			name string
 *
 *  OUTPUTS
 *	filename	dereferenced, will point to the newly allocated file
 *			name string.  This value is undefined if the function
 *			returns an error.
 *
 *  RETURNS
 *	An open file pointer to a read/write mode empty temporary file with the
 *	unique file name or NULL on failure.
 *
 *  ERRORS
 *	on error, errno will be set to some value either by CVS_FOPEN or
 *	whatever system function is called to generate the temporary file name
 */
/* FIXME: This should use the mkstemp() function from the lib/mkstemp.c file
 * from the GNULIB project.
 */
FILE *cvs_temp_file (char ** filename)
{
    char *fn;
    FILE *fp;

    /* FIXME - I'd like to be returning NULL here in noexec mode, but I think
     * some of the rcs & diff functions which rely on a temp file run in
     * noexec mode too.
     */

    /* assert (filename != NULL); */

    fn = _tempnam (getenv("TEMP"), "cvs");
    if (fn == NULL) fp = NULL;
    else
    if ((fp = CVS_FOPEN (fn, "w+")) == NULL)
    {
        free (fn);
        fn = NULL;
    }

    /* tempnam returns a pointer to a newly malloc'd string, so there's
     * no need for a xstrdup
     */

    *filename = fn;
    return fp;
}



/* Return a pointer into PATH's last component.  */
const char *
last_component (const char *path)
{
    const char *scan;
    const char *last = 0;

    for (scan = path; *scan; scan++)
        if (ISSLASH (*scan))
	    last = scan;

    if (last && (last != path))
        return last + 1;
    else
        return path;
}


/* NT has two evironment variables, HOMEPATH and HOMEDRIVE, which,
   when combined as ${HOMEDRIVE}${HOMEPATH}, give the unix equivalent
   of HOME.  Some NT users are just too unixy, though, and set the
   HOME variable themselves.  Therefore, we check for HOME first, and
   then try to combine the other two if that fails.

   Looking for HOME strikes me as bogus, particularly if the only reason
   is to cater to "unixy users".  On the other hand, if the reasoning is
   there should be a single variable, rather than requiring people to
   set both HOMEDRIVE and HOMEPATH, then it starts to make a little more
   sense.

   Win95: The system doesn't set HOME, HOMEDRIVE, or HOMEPATH (at
   least if you set it up as the "all users under one user ID" or
   whatever the name of that option is).  Based on thing overheard on
   the net, it seems that users of the pserver client have gotten in
   the habit of setting HOME (if you don't use pserver, you can
   probably get away without having a reasonable return from
   get_homedir.  Of course you lose .cvsrc and .cvsignore, but many
   users won't notice).  So it would seem that we should be somewhat
   careful if we try to change the current behavior.

   NT 3.51 or NT 4.0: I haven't checked this myself, but I am told
   that HOME gets set, but not to the user's home directory.  It is
   said to be set to c:\users\default by default.  */

char *
get_homedir (void)
{
    char *homedir;

    homedir = getenv ("HOME");

    if (homedir == NULL)
	homedir = woe32_home_dir ();

    return homedir;
}

/* Compose a path to a file in the home directory.  This is necessary because
 * of different behavior on UNIX, Windows, and VMS.  See more notes in
 * vms/filesubr.c.
 *
 * A more clean solution would be something more along the lines of a
 * "join a directory to a filename" kind of thing which was not specific to
 * the homedir.  This should aid portability between UNIX, Mac, Windows, VMS,
 * and possibly others.  This is already handled by Perl - it might be
 * interesting to see how much of the code was written in C since Perl is under
 * the GPL and the Artistic license - we might be able to use it.
 */
char *
strcat_filename_onto_homedir (dir, file)
    const char *dir;
    const char *file;
{
    char *path = xmalloc (strlen (dir) + 1 + strlen(file) + 1);
    sprintf (path, "%s\\%s", dir, file);
    return path;
}

/* See cvs.h for description.  */
void
expand_wild (argc, argv, pargc, pargv)
    int argc;
    char **argv;
    int *pargc;
    char ***pargv;
{
    int i;
    int new_argc;
    char **new_argv;
    /* Allocated size of new_argv.  We arrange it so there is always room for
	   one more element.  */
    int max_new_argc;

    new_argc = 0;
    /* Add one so this is never zero.  */
    max_new_argc = argc + 1;
    new_argv = (char **) xmalloc (max_new_argc * sizeof (char *));
    for (i = 0; i < argc; ++i)
    {
	HANDLE h;
	WIN32_FIND_DATA fdata;

	/* These variables help us extract the directory name from the
           given pathname. */

	char *last_forw_slash, *last_back_slash, *end_of_dirname;
	int dirname_length = 0;

	if ( strcmp( argv[i], "." ) == 0 )
	{
	    new_argv[new_argc] = (char *) xmalloc ( 2 );
	    strcpy( new_argv[ new_argc++ ], "." );
	    continue;
	}

	/* FindFirstFile doesn't return pathnames, so we have to do
	   this ourselves.  Luckily, it's no big deal, since globbing
	   characters under Win32s can only occur in the last segment
	   of the path.  For example,
                /a/path/q*.h                      valid
	        /w32/q*.dir/cant/do/this/q*.h     invalid */

	/* Win32 can handle both forward and backward slashes as
           filenames -- check for both. */
	     
	last_forw_slash = strrchr (argv[i], '/');
	last_back_slash = strrchr (argv[i], '\\');

#define cvs_max(x,y) ((x >= y) ? (x) : (y))

	/* FIXME: this comparing a NULL pointer to a non-NULL one is
	   extremely ugly, and I strongly suspect *NOT* sanctioned by
	   ANSI C.  The code should just use last_component instead.  */
	end_of_dirname = cvs_max (last_forw_slash, last_back_slash);

	if (end_of_dirname == NULL)
	  dirname_length = 0;	/* no directory name */
	else
	  dirname_length = end_of_dirname - argv[i] + 1; /* include slash */

	h = FindFirstFile (argv[i], &fdata);
	if (h == INVALID_HANDLE_VALUE)
	{
	    if (GetLastError () == ENOENT)
	    {
		/* No match.  The file specified didn't contain a wildcard (in which case
		   we clearly should return it unchanged), or it contained a wildcard which
		   didn't match (in which case it might be better for it to be an error,
		   but we don't try to do that).  */
		new_argv [new_argc++] = xstrdup (argv[i]);
		if (new_argc == max_new_argc)
		{
		    max_new_argc *= 2;
		    new_argv = xrealloc (new_argv, max_new_argc * sizeof (char *));
		}
	    }
	    else
	    {
		error (1, errno, "cannot find %s", argv[i]);
	    }
	}
	else
	{
	    while (1)
	    {
		new_argv[new_argc] =
		    (char *) xmalloc (strlen (fdata.cFileName) + 1
				      + dirname_length);

		/* Copy the directory name, if there is one. */

		if (dirname_length)
		{
		    strncpy (new_argv[new_argc], argv[i], dirname_length);
		    new_argv[new_argc][dirname_length] = '\0';
		}
		else
		    new_argv[new_argc][0] = '\0';

		/* Copy the file name. */
		
		if (fncmp (argv[i] + dirname_length, fdata.cFileName) == 0)
		    /* We didn't expand a wildcard; we just matched a filename.
		       Use the file name as specified rather than the filename
		       which exists in the directory (they may differ in case).
		       This is needed to make cvs add on a directory consistently
		       use the name specified on the command line, but it is
		       probably a good idea in other contexts too.  */
		    strcpy (new_argv[new_argc], argv[i]);
		else
		    strcat (new_argv[new_argc], fdata.cFileName);

		new_argc++;

		if (new_argc == max_new_argc)
		{
		    max_new_argc *= 2;
		    new_argv = xrealloc (new_argv, max_new_argc * sizeof (char *));
		}
		if (!FindNextFile (h, &fdata))
		{
		    if (GetLastError () == ERROR_NO_MORE_FILES)
			break;
		    else
			error (1, errno, "cannot find %s", argv[i]);
		}
	    }
	    if (!FindClose (h))
		error (1, GetLastError (), "cannot close %s", argv[i]);
	}
    }
    *pargc = new_argc;
    *pargv = new_argv;
}

/* undo config.h stat macro */
#undef stat
extern int stat (const char *file, struct wnt_stat *sb);

/* see config.h stat macro */
int
wnt_stat (const char *file, struct wnt_stat *sb)
{
    int retval;

    retval = stat (file, sb);
    if (retval < 0)
		return retval;

	/* Win32 processes file times in a 64 bit format
       (see Win32 functions SetFileTime and GetFileTime).
       If the file time on a file doesn't fit into the
       32 bit time_t format, then stat will set that time
       to -1.  This would be OK, except that functions
       like ctime() don't check for validity.  So what we
       do here is to give a error on -1.  A cleaner solution
       might be to change CVS's interfaces to return a time
       in RCS format (for example), and then implement it
       on Win32 via GetFileTime, but that would be a lot of
       hair and I'm not sure there is much payoff.  */
    if (sb->st_mtime == (time_t) -1)
		error (1, 0, "invalid modification time for %s", file);
    if (sb->st_ctime == (time_t) -1)
	/* I'm not sure what this means on windows.  It
	   might be a creation time (unlike unix)....  */
		error (1, 0, "invalid ctime for %s", file);
    if (sb->st_atime == (time_t) -1)
		error (1, 0, "invalid access time for %s", file);

    if (!GetUTCFileModTime (file, &sb->st_mtime))
		error (1, 0, "Failed to retrieve modification time for %s", file);

    return retval;
}