summaryrefslogtreecommitdiffstats
path: root/dbus/dbus-sysdeps.c
blob: bcb81f7d8156d852fae3ad799f5b105dee93947f (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
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
/* -*- mode: C; c-file-style: "gnu" -*- */
/* dbus-sysdeps.c Wrappers around system/libc features (internal to D-BUS implementation)
 * 
 * Copyright (C) 2002  Red Hat, Inc.
 *
 * Licensed under the Academic Free License version 1.2
 * 
 * This program 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 of the License, 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.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include "dbus-internals.h"
#include "dbus-sysdeps.h"
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <dirent.h>
#include <sys/un.h>
#include <pwd.h>
#include <time.h>
#include <sys/time.h>
#include <sys/stat.h>

#ifdef HAVE_WRITEV
#include <sys/uio.h>
#endif
#ifdef HAVE_POLL
#include <sys/poll.h>
#endif

#ifndef O_BINARY
#define O_BINARY 0
#endif

/**
 * @addtogroup DBusInternalsUtils
 * @{
 */
/**
 * Aborts the program with SIGABRT (dumping core).
 */
void
_dbus_abort (void)
{
  abort ();
  _exit (1); /* in case someone manages to ignore SIGABRT */
}

/**
 * Wrapper for getenv().
 *
 * @param varname name of environment variable
 * @returns value of environment variable or #NULL if unset
 */
const char*
_dbus_getenv (const char *varname)
{  
  return getenv (varname);
}

/**
 * Thin wrapper around the read() system call that appends
 * the data it reads to the DBusString buffer. It appends
 * up to the given count, and returns the same value
 * and same errno as read(). The only exception is that
 * _dbus_read() handles EINTR for you.
 *
 * @param fd the file descriptor to read from
 * @param buffer the buffer to append data to
 * @param count the amount of data to read
 * @returns the number of bytes read or -1
 */
int
_dbus_read (int               fd,
            DBusString       *buffer,
            int               count)
{
  int bytes_read;
  int start;
  char *data;

  _dbus_assert (count >= 0);
  
  start = _dbus_string_get_length (buffer);

  if (!_dbus_string_lengthen (buffer, count))
    {
      errno = ENOMEM;
      return -1;
    }

  _dbus_string_get_data_len (buffer, &data, start, count);

 again:
  
  bytes_read = read (fd, data, count);

  if (bytes_read < 0)
    {
      if (errno == EINTR)
        goto again;
      else
        {
          /* put length back (note that this doesn't actually realloc anything) */
          _dbus_string_set_length (buffer, start);
          return -1;
        }
    }
  else
    {
      /* put length back (doesn't actually realloc) */
      _dbus_string_set_length (buffer, start + bytes_read);

#if 0
      if (bytes_read > 0)
        _dbus_verbose_bytes_of_string (buffer, start, bytes_read);
#endif
      
      return bytes_read;
    }
}

/**
 * Thin wrapper around the write() system call that writes a part of a
 * DBusString and handles EINTR for you.
 * 
 * @param fd the file descriptor to write
 * @param buffer the buffer to write data from
 * @param start the first byte in the buffer to write
 * @param len the number of bytes to try to write
 * @returns the number of bytes written or -1 on error
 */
int
_dbus_write (int               fd,
             const DBusString *buffer,
             int               start,
             int               len)
{
  const char *data;
  int bytes_written;
  
  _dbus_string_get_const_data_len (buffer, &data, start, len);
  
 again:

  bytes_written = write (fd, data, len);

  if (bytes_written < 0 && errno == EINTR)
    goto again;

#if 0
  if (bytes_written > 0)
    _dbus_verbose_bytes_of_string (buffer, start, bytes_written);
#endif
  
  return bytes_written;
}

/**
 * Like _dbus_write() but will use writev() if possible
 * to write both buffers in sequence. The return value
 * is the number of bytes written in the first buffer,
 * plus the number written in the second. If the first
 * buffer is written successfully and an error occurs
 * writing the second, the number of bytes in the first
 * is returned (i.e. the error is ignored), on systems that
 * don't have writev. Handles EINTR for you.
 * The second buffer may be #NULL.
 *
 * @param fd the file descriptor
 * @param buffer1 first buffer
 * @param start1 first byte to write in first buffer
 * @param len1 number of bytes to write from first buffer
 * @param buffer2 second buffer, or #NULL
 * @param start2 first byte to write in second buffer
 * @param len2 number of bytes to write in second buffer
 * @returns total bytes written from both buffers, or -1 on error
 */
int
_dbus_write_two (int               fd,
                 const DBusString *buffer1,
                 int               start1,
                 int               len1,
                 const DBusString *buffer2,
                 int               start2,
                 int               len2)
{
  _dbus_assert (buffer1 != NULL);
  _dbus_assert (start1 >= 0);
  _dbus_assert (start2 >= 0);
  _dbus_assert (len1 >= 0);
  _dbus_assert (len2 >= 0);
  
#ifdef HAVE_WRITEV
  {
    struct iovec vectors[2];
    const char *data1;
    const char *data2;
    int bytes_written;

    _dbus_string_get_const_data_len (buffer1, &data1, start1, len1);

    if (buffer2 != NULL)
      _dbus_string_get_const_data_len (buffer2, &data2, start2, len2);
    else
      {
        data2 = NULL;
        start2 = 0;
        len2 = 0;
      }
   
    vectors[0].iov_base = (char*) data1;
    vectors[0].iov_len = len1;
    vectors[1].iov_base = (char*) data2;
    vectors[1].iov_len = len2;

  again:
   
    bytes_written = writev (fd,
                            vectors,
                            data2 ? 2 : 1);

    if (bytes_written < 0 && errno == EINTR)
      goto again;
   
    return bytes_written;
  }
#else /* HAVE_WRITEV */
  {
    int ret1;
    
    ret1 = _dbus_write (fd, buffer1, start1, len1);
    if (ret1 == len1 && buffer2 != NULL)
      {
        ret2 = _dbus_write (fd, buffer2, start2, len2);
        if (ret2 < 0)
          ret2 = 0; /* we can't report an error as the first write was OK */
       
        return ret1 + ret2;
      }
    else
      return ret1;
  }
#endif /* !HAVE_WRITEV */   
}

/**
 * Creates a socket and connects it to the UNIX domain socket at the
 * given path.  The connection fd is returned, and is set up as
 * nonblocking.
 *
 * @param path the path to UNIX domain socket
 * @param result return location for error code
 * @returns connection file descriptor or -1 on error
 */
int
_dbus_connect_unix_socket (const char     *path,
                           DBusResultCode *result)
{
  int fd;
  struct sockaddr_un addr;  
  
  fd = socket (AF_LOCAL, SOCK_STREAM, 0);

  if (fd < 0)
    {
      dbus_set_result (result,
                       _dbus_result_from_errno (errno));
      
      _dbus_verbose ("Failed to create socket: %s\n",
                     _dbus_strerror (errno)); 
      
      return -1;
    }

  _DBUS_ZERO (addr);
  addr.sun_family = AF_LOCAL;
  strncpy (addr.sun_path, path, _DBUS_MAX_SUN_PATH_LENGTH);
  addr.sun_path[_DBUS_MAX_SUN_PATH_LENGTH] = '\0';
  
  if (connect (fd, (struct sockaddr*) &addr, sizeof (addr)) < 0)
    {      
      dbus_set_result (result,
                       _dbus_result_from_errno (errno));

      _dbus_verbose ("Failed to connect to socket %s: %s\n",
                     path, _dbus_strerror (errno));

      close (fd);
      fd = -1;
      
      return -1;
    }

  if (!_dbus_set_fd_nonblocking (fd, result))
    {
      close (fd);
      fd = -1;

      return -1;
    }

  return fd;
}

/**
 * Creates a socket and binds it to the given path,
 * then listens on the socket. The socket is
 * set to be nonblocking. 
 *
 * @param path the socket name
 * @param result return location for errors
 * @returns the listening file descriptor or -1 on error
 */
int
_dbus_listen_unix_socket (const char     *path,
                          DBusResultCode *result)
{
  int listen_fd;
  struct sockaddr_un addr;

  listen_fd = socket (AF_LOCAL, SOCK_STREAM, 0);

  if (listen_fd < 0)
    {
      dbus_set_result (result, _dbus_result_from_errno (errno));
      _dbus_verbose ("Failed to create socket \"%s\": %s\n",
                     path, _dbus_strerror (errno));
      return -1;
    }

  _DBUS_ZERO (addr);
  addr.sun_family = AF_LOCAL;
  strncpy (addr.sun_path, path, _DBUS_MAX_SUN_PATH_LENGTH);
  addr.sun_path[_DBUS_MAX_SUN_PATH_LENGTH] = '\0';
  
  if (bind (listen_fd, (struct sockaddr*) &addr, SUN_LEN (&addr)) < 0)
    {
      dbus_set_result (result, _dbus_result_from_errno (errno));
      _dbus_verbose ("Failed to bind socket \"%s\": %s\n",
                     path, _dbus_strerror (errno));
      close (listen_fd);
      return -1;
    }

  if (listen (listen_fd, 30 /* backlog */) < 0)
    {
      dbus_set_result (result, _dbus_result_from_errno (errno));      
      _dbus_verbose ("Failed to listen on socket \"%s\": %s\n",
                     path, _dbus_strerror (errno));
      close (listen_fd);
      return -1;
    }

  if (!_dbus_set_fd_nonblocking (listen_fd, result))
    {
      close (listen_fd);
      return -1;
    }
  
  return listen_fd;
}

/* try to read a single byte and return #TRUE if we read it
 * and it's equal to nul.
 */
static dbus_bool_t
read_credentials_byte (int             client_fd,
                       DBusResultCode *result)
{
  char buf[1];
  int bytes_read;

 again:
  bytes_read = read (client_fd, buf, 1);
  if (bytes_read < 0)
    {
      if (errno == EINTR)
        goto again;
      else
        {
          dbus_set_result (result, _dbus_result_from_errno (errno));      
          _dbus_verbose ("Failed to read credentials byte: %s\n",
                         _dbus_strerror (errno));
          return FALSE;
        }
    }
  else if (bytes_read == 0)
    {
      dbus_set_result (result, DBUS_RESULT_IO_ERROR);
      _dbus_verbose ("EOF reading credentials byte\n");
      return FALSE;
    }
  else
    {
      _dbus_assert (bytes_read == 1);

      if (buf[0] != '\0')
        {
          dbus_set_result (result, DBUS_RESULT_FAILED);
          _dbus_verbose ("Credentials byte was not nul\n");
          return FALSE;
        }

      _dbus_verbose ("read credentials byte\n");
      
      return TRUE;
    }
}

static dbus_bool_t
write_credentials_byte (int             server_fd,
                        DBusResultCode *result)
{
  int bytes_written;
  char buf[1] = { '\0' };
  
 again:

  bytes_written = write (server_fd, buf, 1);

  if (bytes_written < 0 && errno == EINTR)
    goto again;

  if (bytes_written < 0)
    {
      dbus_set_result (result, _dbus_result_from_errno (errno));      
      _dbus_verbose ("Failed to write credentials byte: %s\n",
                     _dbus_strerror (errno));
      return FALSE;
    }
  else if (bytes_written == 0)
    {
      dbus_set_result (result, DBUS_RESULT_IO_ERROR);
      _dbus_verbose ("wrote zero bytes writing credentials byte\n");
      return FALSE;
    }
  else
    {
      _dbus_assert (bytes_written == 1);
      _dbus_verbose ("wrote credentials byte\n");
      return TRUE;
    }
}

/**
 * Reads a single byte which must be nul (an error occurs otherwise),
 * and reads unix credentials if available. Fills in pid/uid/gid with
 * -1 if no credentials are available. Return value indicates whether
 * a byte was read, not whether we got valid credentials. On some
 * systems, such as Linux, reading/writing the byte isn't actually
 * required, but we do it anyway just to avoid multiple codepaths.
 * 
 * Fails if no byte is available, so you must select() first.
 *
 * The point of the byte is that on some systems we have to
 * use sendmsg()/recvmsg() to transmit credentials.
 *
 * @param client_fd the client file descriptor
 * @param credentials struct to fill with credentials of client
 * @param result location to store result code
 * @returns #TRUE on success
 */
dbus_bool_t
_dbus_read_credentials_unix_socket  (int              client_fd,
                                     DBusCredentials *credentials,
                                     DBusResultCode  *result)
{
  credentials->pid = -1;
  credentials->uid = -1;
  credentials->gid = -1;
  
#ifdef SO_PEERCRED
  if (read_credentials_byte (client_fd, result))
    {
      struct ucred cr;   
      int cr_len = sizeof (cr);
   
      if (getsockopt (client_fd, SOL_SOCKET, SO_PEERCRED, &cr, &cr_len) == 0 &&
          cr_len == sizeof (cr))
        {
          credentials->pid = cr.pid;
          credentials->uid = cr.uid;
          credentials->gid = cr.gid;
          _dbus_verbose ("Got credentials pid %d uid %d gid %d\n",
                         credentials->pid,
                         credentials->uid,
                         credentials->gid);
        }
      else
        {
          _dbus_verbose ("Failed to getsockopt() credentials, returned len %d/%d: %s\n",
                         cr_len, (int) sizeof (cr), _dbus_strerror (errno));
        }

      return TRUE;
    }
  else
    return FALSE;
#else /* !SO_PEERCRED */
  _dbus_verbose ("Socket credentials not supported on this OS\n");
  return TRUE;
#endif
}

/**
 * Sends a single nul byte with our UNIX credentials as ancillary
 * data.  Returns #TRUE if the data was successfully written.  On
 * systems that don't support sending credentials, just writes a byte,
 * doesn't send any credentials.  On some systems, such as Linux,
 * reading/writing the byte isn't actually required, but we do it
 * anyway just to avoid multiple codepaths.
 *
 * Fails if no byte can be written, so you must select() first.
 *
 * The point of the byte is that on some systems we have to
 * use sendmsg()/recvmsg() to transmit credentials.
 *
 * @param server_fd file descriptor for connection to server
 * @param result return location for error code
 * @returns #TRUE if the byte was sent
 */
dbus_bool_t
_dbus_send_credentials_unix_socket  (int              server_fd,
                                     DBusResultCode  *result)
{
  if (write_credentials_byte (server_fd, result))
    return TRUE;
  else
    return FALSE;
}

/**
 * Accepts a connection on a listening socket.
 * Handles EINTR for you.
 *
 * @param listen_fd the listen file descriptor
 * @returns the connection fd of the client, or -1 on error
 */
int
_dbus_accept  (int listen_fd)
{
  int client_fd;
  
 retry:
  client_fd = accept (listen_fd, NULL, NULL);
  
  if (client_fd < 0)
    {
      if (errno == EINTR)
        goto retry;
    }
  
  return client_fd;
}

/** @} */

/**
 * @addtogroup DBusString
 *
 * @{
 */
/**
 * Appends an integer to a DBusString.
 * 
 * @param str the string
 * @param value the integer value
 * @returns #FALSE if not enough memory or other failure.
 */
dbus_bool_t
_dbus_string_append_int (DBusString *str,
                         long        value)
{
  /* this calculation is from comp.lang.c faq */
#define MAX_LONG_LEN ((sizeof (long) * 8 + 2) / 3 + 1)  /* +1 for '-' */
  int orig_len;
  int i;
  char *buf;
  
  orig_len = _dbus_string_get_length (str);

  if (!_dbus_string_lengthen (str, MAX_LONG_LEN))
    return FALSE;

  _dbus_string_get_data_len (str, &buf, orig_len, MAX_LONG_LEN);

  snprintf (buf, MAX_LONG_LEN, "%ld", value);

  i = 0;
  while (*buf)
    {
      ++buf;
      ++i;
    }
  
  _dbus_string_shorten (str, MAX_LONG_LEN - i);
  
  return TRUE;
}

/**
 * Appends a double to a DBusString.
 * 
 * @param str the string
 * @param value the floating point value
 * @returns #FALSE if not enough memory or other failure.
 */
dbus_bool_t
_dbus_string_append_double (DBusString *str,
                            double      value)
{
#define MAX_DOUBLE_LEN 64 /* this is completely made up :-/ */
  int orig_len;
  char *buf;
  int i;
  
  orig_len = _dbus_string_get_length (str);

  if (!_dbus_string_lengthen (str, MAX_DOUBLE_LEN))
    return FALSE;

  _dbus_string_get_data_len (str, &buf, orig_len, MAX_DOUBLE_LEN);

  snprintf (buf, MAX_LONG_LEN, "%g", value);

  i = 0;
  while (*buf)
    {
      ++buf;
      ++i;
    }
  
  _dbus_string_shorten (str, MAX_DOUBLE_LEN - i);
  
  return TRUE;
}

/**
 * Parses an integer contained in a DBusString. Either return parameter
 * may be #NULL if you aren't interested in it. The integer is parsed
 * and stored in value_return. Return parameters are not initialized
 * if the function returns #FALSE.
 *
 * @param str the string
 * @param start the byte index of the start of the integer
 * @param value_return return location of the integer value or #NULL
 * @param end_return return location of the end of the integer, or #NULL
 * @returns #TRUE on success
 */
dbus_bool_t
_dbus_string_parse_int (const DBusString *str,
                        int               start,
                        long             *value_return,
                        int              *end_return)
{
  long v;
  const char *p;
  char *end;

  _dbus_string_get_const_data_len (str, &p, start,
                                   _dbus_string_get_length (str) - start);

  end = NULL;
  errno = 0;
  v = strtol (p, &end, 0);
  if (end == NULL || end == p || errno != 0)
    return FALSE;

  if (value_return)
    *value_return = v;
  if (end_return)
    *end_return = (end - p);

  return TRUE;
}

/**
 * Parses a floating point number contained in a DBusString. Either
 * return parameter may be #NULL if you aren't interested in it. The
 * integer is parsed and stored in value_return. Return parameters are
 * not initialized if the function returns #FALSE.
 *
 * @todo this function is currently locale-dependent. Should
 * ask alexl to relicense g_ascii_strtod() code and put that in
 * here instead, so it's locale-independent.
 *
 * @param str the string
 * @param start the byte index of the start of the float
 * @param value_return return location of the float value or #NULL
 * @param end_return return location of the end of the float, or #NULL
 * @returns #TRUE on success
 */
dbus_bool_t
_dbus_string_parse_double (const DBusString *str,
                           int               start,
                           double           *value_return,
                           int              *end_return)
{
  double v;
  const char *p;
  char *end;

  _dbus_warn ("_dbus_string_parse_double() needs to be made locale-independent\n");
  
  _dbus_string_get_const_data_len (str, &p, start,
                                   _dbus_string_get_length (str) - start);

  end = NULL;
  errno = 0;
  v = strtod (p, &end);
  if (end == NULL || end == p || errno != 0)
    return FALSE;

  if (value_return)
    *value_return = v;
  if (end_return)
    *end_return = (end - p);

  return TRUE;
}

/**
 * Gets the credentials corresponding to the given username.
 *
 * @param username the username
 * @param credentials credentials to fill in
 * @returns #TRUE if the username existed and we got some credentials
 */
dbus_bool_t
_dbus_credentials_from_username (const DBusString *username,
                                 DBusCredentials  *credentials)
{
  const char *username_c_str;
  
  credentials->pid = -1;
  credentials->uid = -1;
  credentials->gid = -1;

  _dbus_string_get_const_data (username, &username_c_str);
  
#ifdef HAVE_GETPWNAM_R
  {
    struct passwd *p;
    int result;
    char buf[1024];
    struct passwd p_str;

    p = NULL;
    result = getpwnam_r (username_c_str, &p_str, buf, sizeof (buf),
                         &p);

    if (result == 0 && p == &p_str)
      {
        credentials->uid = p->pw_uid;
        credentials->gid = p->pw_gid;

        _dbus_verbose ("Username %s has uid %d gid %d\n",
                       username_c_str, credentials->uid, credentials->gid);
        return TRUE;
      }
    else
      {
        _dbus_verbose ("User %s unknown\n", username_c_str);
        return FALSE;
      }
  }
#else /* ! HAVE_GETPWNAM_R */
  {
    /* I guess we're screwed on thread safety here */
    struct passwd *p;

    p = getpwnam (username_c_str);

    if (p != NULL)
      {
        credentials->uid = p->pw_uid;
        credentials->gid = p->pw_gid;

        _dbus_verbose ("Username %s has uid %d gid %d\n",
                       username_c_str, credentials->uid, credentials->gid);
        return TRUE;
      }
    else
      {
        _dbus_verbose ("User %s unknown\n", username_c_str);
        return FALSE;
      }
  }
#endif  
}

/**
 * Gets credentials from a UID string. (Parses a string to a UID
 * and converts to a DBusCredentials.)
 *
 * @param uid_str the UID in string form
 * @param credentials credentials to fill in
 * @returns #TRUE if successfully filled in some credentials
 */
dbus_bool_t
_dbus_credentials_from_uid_string (const DBusString      *uid_str,
                                   DBusCredentials       *credentials)
{
  int end;
  long uid;

  credentials->pid = -1;
  credentials->uid = -1;
  credentials->gid = -1;
  
  if (_dbus_string_get_length (uid_str) == 0)
    {
      _dbus_verbose ("UID string was zero length\n");
      return FALSE;
    }

  uid = -1;
  end = 0;
  if (!_dbus_string_parse_int (uid_str, 0, &uid,
                               &end))
    {
      _dbus_verbose ("could not parse string as a UID\n");
      return FALSE;
    }
  
  if (end != _dbus_string_get_length (uid_str))
    {
      _dbus_verbose ("string contained trailing stuff after UID\n");
      return FALSE;
    }

  credentials->uid = uid;

  return TRUE;
}

/**
 * Gets the credentials of the current process.
 *
 * @param credentials credentials to fill in.
 */
void
_dbus_credentials_from_current_process (DBusCredentials *credentials)
{
  credentials->pid = getpid ();
  credentials->uid = getuid ();
  credentials->gid = getgid ();
}

/**
 * Checks whether the provided_credentials are allowed to log in
 * as the expected_credentials.
 *
 * @param expected_credentials credentials we're trying to log in as
 * @param provided_credentials credentials we have
 * @returns #TRUE if we can log in
 */
dbus_bool_t
_dbus_credentials_match (const DBusCredentials *expected_credentials,
                         const DBusCredentials *provided_credentials)
{
  if (provided_credentials->uid < 0)
    return FALSE;
  else if (expected_credentials->uid < 0)
    return FALSE;
  else if (provided_credentials->uid == 0)
    return TRUE;
  else if (provided_credentials->uid == expected_credentials->uid)
    return TRUE;
  else
    return FALSE;
}

/**
 * Appends the uid of the current process to the given string.
 *
 * @param str the string to append to
 * @returns #TRUE on success
 */
dbus_bool_t
_dbus_string_append_our_uid (DBusString *str)
{
  return _dbus_string_append_int (str, getuid ());
}


/**
 * Wrapper for poll().
 *
 * @todo need a fallback implementation using select()
 *
 * @param fds the file descriptors to poll
 * @param n_fds number of descriptors in the array
 * @param timeout_milliseconds timeout or -1 for infinite
 * @returns numbers of fds with revents, or <0 on error
 */
int
_dbus_poll (DBusPollFD *fds,
            int         n_fds,
            int         timeout_milliseconds)
{
#ifdef HAVE_POLL
  /* This big thing is a constant expression and should get optimized
   * out of existence. So it's more robust than a configure check at
   * no cost.
   */
  if (_DBUS_POLLIN == POLLIN &&
      _DBUS_POLLPRI == POLLPRI &&
      _DBUS_POLLOUT == POLLOUT &&
      _DBUS_POLLERR == POLLERR &&
      _DBUS_POLLHUP == POLLHUP &&
      _DBUS_POLLNVAL == POLLNVAL &&
      sizeof (DBusPollFD) == sizeof (struct pollfd) &&
      _DBUS_STRUCT_OFFSET (DBusPollFD, fd) ==
      _DBUS_STRUCT_OFFSET (struct pollfd, fd) &&
      _DBUS_STRUCT_OFFSET (DBusPollFD, events) ==
      _DBUS_STRUCT_OFFSET (struct pollfd, events) &&
      _DBUS_STRUCT_OFFSET (DBusPollFD, revents) ==
      _DBUS_STRUCT_OFFSET (struct pollfd, revents))
    {
      return poll ((struct pollfd*) fds,
                   n_fds, 
                   timeout_milliseconds);
    }
  else
    {
      /* We have to convert the DBusPollFD to an array of
       * struct pollfd, poll, and convert back.
       */
      _dbus_warn ("didn't implement poll() properly for this system yet\n");
      return -1;
    }
#else /* ! HAVE_POLL */
  _dbus_warn ("need to implement select() fallback for systems with no poll()\n");
  return -1;
#endif
}

/** nanoseconds in a second */
#define NANOSECONDS_PER_SECOND       1000000000
/** microseconds in a second */
#define MICROSECONDS_PER_SECOND      1000000
/** milliseconds in a second */
#define MILLISECONDS_PER_SECOND      1000
/** nanoseconds in a millisecond */
#define NANOSECONDS_PER_MILLISECOND  1000000
/** microseconds in a millisecond */
#define MICROSECONDS_PER_MILLISECOND 1000

/**
 * Sleeps the given number of milliseconds.
 * @param milliseconds number of milliseconds
 */
void
_dbus_sleep_milliseconds (int milliseconds)
{
#ifdef HAVE_NANOSLEEP
  struct timespec req;
  struct timespec rem;

  req.tv_sec = milliseconds / MILLISECONDS_PER_SECOND;
  req.tv_nsec = (milliseconds % MILLISECONDS_PER_SECOND) * NANOSECONDS_PER_MILLISECOND;
  rem.tv_sec = 0;
  rem.tv_nsec = 0;

  while (nanosleep (&req, &rem) < 0 && errno == EINTR)
    req = rem;
#elif defined (HAVE_USLEEP)
  usleep (milliseconds * MICROSECONDS_PER_MILLISECOND);
#else /* ! HAVE_USLEEP */
  sleep (MAX (milliseconds / 1000, 1));
#endif
}

/**
 * Get current time, as in gettimeofday().
 *
 * @param tv_sec return location for number of seconds
 * @param tv_usec return location for number of microseconds (thousandths)
 */
void
_dbus_get_current_time (long *tv_sec,
                        long *tv_usec)
{
  struct timeval t;

  gettimeofday (&t, NULL);

  if (tv_sec)
    *tv_sec = t.tv_sec;
  if (tv_usec)
    *tv_usec = t.tv_usec;
}

/**
 * Appends the contents of the given file to the string,
 * returning result code. At the moment, won't open a file
 * more than a megabyte in size.
 *
 * @param str the string to append to
 * @param filename filename to load
 * @returns result
 */
DBusResultCode
_dbus_file_get_contents (DBusString       *str,
                         const DBusString *filename)
{
  int fd;
  struct stat sb;
  int orig_len;
  int total;
  const char *filename_c;

  _dbus_string_get_const_data (filename, &filename_c);
  
  /* O_BINARY useful on Cygwin */
  fd = open (filename_c, O_RDONLY | O_BINARY);
  if (fd < 0)
    return _dbus_result_from_errno (errno);

  if (fstat (fd, &sb) < 0)
    {
      DBusResultCode result;      

      result = _dbus_result_from_errno (errno); /* prior to close() */

      _dbus_verbose ("fstat() failed: %s",
                     _dbus_strerror (errno));
      
      close (fd);
      
      return result;
    }

  if (sb.st_size > _DBUS_ONE_MEGABYTE)
    {
      _dbus_verbose ("File size %lu is too large.\n",
                     (unsigned long) sb.st_size);
      close (fd);
      return DBUS_RESULT_FAILED;
    }
  
  total = 0;
  orig_len = _dbus_string_get_length (str);
  if (sb.st_size > 0 && S_ISREG (sb.st_mode))
    {
      int bytes_read;

      while (total < (int) sb.st_size)
        {
          bytes_read = _dbus_read (fd, str,
                                   sb.st_size - total);
          if (bytes_read <= 0)
            {
              DBusResultCode result;
              
              result = _dbus_result_from_errno (errno); /* prior to close() */

              _dbus_verbose ("read() failed: %s",
                             _dbus_strerror (errno));
              
              close (fd);
              _dbus_string_set_length (str, orig_len);
              return result;
            }
          else
            total += bytes_read;
        }

      close (fd);
      return DBUS_RESULT_SUCCESS;
    }
  else if (sb.st_size != 0)
    {
      _dbus_verbose ("Can only open regular files at the moment.\n");
      close (fd);
      return DBUS_RESULT_FAILED;
    }
  else
    {
      close (fd);
      return DBUS_RESULT_SUCCESS;
    }
}

/**
 * Appends the given filename to the given directory.
 *
 * @param dir the directory name
 * @param next_component the filename
 * @returns #TRUE on success
 */
dbus_bool_t
_dbus_concat_dir_and_file (DBusString       *dir,
                           const DBusString *next_component)
{
  dbus_bool_t dir_ends_in_slash;
  dbus_bool_t file_starts_with_slash;

  if (_dbus_string_get_length (dir) == 0 ||
      _dbus_string_get_length (next_component) == 0)
    return TRUE;
  
  dir_ends_in_slash = '/' == _dbus_string_get_byte (dir,
                                                    _dbus_string_get_length (dir) - 1);

  file_starts_with_slash = '/' == _dbus_string_get_byte (next_component, 0);

  if (dir_ends_in_slash && file_starts_with_slash)
    {
      _dbus_string_shorten (dir, 1);
    }
  else if (!(dir_ends_in_slash || file_starts_with_slash))
    {
      if (!_dbus_string_append_byte (dir, '/'))
        return FALSE;
    }

  return _dbus_string_copy (next_component, 0, dir,
                            _dbus_string_get_length (dir));
}

struct DBusDirIter
{
  DIR *d;
  
};

/**
 * Open a directory to iterate over.
 *
 * @param filename the directory name
 * @param result return location for error code if #NULL returned
 * @returns new iterator, or #NULL on error
 */
DBusDirIter*
_dbus_directory_open (const DBusString *filename,
                      DBusResultCode   *result)
{
  DIR *d;
  DBusDirIter *iter;
  const char *filename_c;

  _dbus_string_get_const_data (filename, &filename_c);

  d = opendir (filename_c);
  if (d == NULL)
    {
      dbus_set_result (result, _dbus_result_from_errno (errno));
      return NULL;
    }
  
  iter = dbus_new0 (DBusDirIter, 1);
  if (iter == NULL)
    {
      closedir (d);
      dbus_set_result (result, DBUS_RESULT_NO_MEMORY);
      return NULL;
    }

  iter->d = d;

  return iter;
}

/**
 * Get next file in the directory. Will not return "." or ".."
 * on UNIX. If an error occurs, the contents of "filename"
 * are undefined. #DBUS_RESULT_SUCCESS is always returned
 * in result if no error occurs.
 *
 * @todo for thread safety, I think we have to use
 * readdir_r(). (GLib has the same issue, should file a bug.)
 *
 * @param iter the iterator
 * @param filename string to be set to the next file in the dir
 * @param result return location for error, or #DBUS_RESULT_SUCCESS
 * @returns #TRUE if filename was filled in with a new filename
 */
dbus_bool_t
_dbus_directory_get_next_file (DBusDirIter      *iter,
                               DBusString       *filename,
                               DBusResultCode   *result)
{
  /* we always have to put something in result, since return
   * value means whether there's a filename and doesn't
   * reliably indicate whether an error was set.
   */
  struct dirent *ent;
  
  dbus_set_result (result, DBUS_RESULT_SUCCESS);

 again:
  errno = 0;
  ent = readdir (iter->d);
  if (ent == NULL)
    {
      dbus_set_result (result,
                       _dbus_result_from_errno (errno));
      return FALSE;
    }
  else if (ent->d_name[0] == '.' &&
           (ent->d_name[1] == '\0' ||
            (ent->d_name[1] == '.' && ent->d_name[2] == '\0')))
    goto again;
  else
    {
      _dbus_string_set_length (filename, 0);
      if (!_dbus_string_append (filename, ent->d_name))
        {
          dbus_set_result (result, DBUS_RESULT_NO_MEMORY);
          return FALSE;
        }
      else
        return TRUE;
    }
}

/**
 * Closes a directory iteration.
 */
void
_dbus_directory_close (DBusDirIter *iter)
{
  closedir (iter->d);
  dbus_free (iter);
}


/** @} end of sysdeps */