summaryrefslogtreecommitdiffstats
path: root/Utilities/cmcurl/lib/strerror.c
blob: 74c3457795b448f620b5f0bb2a5ddcaab1a9aa86 (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
/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 2004 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

#include "setup.h"

#ifdef HAVE_STRERROR_R
#if !defined(HAVE_POSIX_STRERROR_R) && !defined(HAVE_GLIBC_STRERROR_R)
#error "you MUST have either POSIX or glibc strerror_r if strerror_r is found"
#endif /* !POSIX && !glibc */
#endif /* HAVE_STRERROR_R */

#include <curl/curl.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#ifdef USE_LIBIDN
#include <idna.h>
#endif

#include "strerror.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#if defined(HAVE_STRERROR_R) && defined(HAVE_NO_STRERROR_R_DECL)
#ifdef HAVE_POSIX_STRERROR_R
/* seen on AIX 5100-02 gcc 2.9 */
extern int strerror_r(int errnum, char *strerrbuf, size_t buflen);
#else
extern char *strerror_r(int errnum, char *buf, size_t buflen);
#endif
#endif

const char *
curl_easy_strerror(CURLcode error)
{
#ifndef CURL_DISABLE_VERBOSE_STRINGS
  switch (error) {
  case CURLE_OK:
    return "no error";

  case CURLE_UNSUPPORTED_PROTOCOL:
    return "unsupported protocol";

  case CURLE_FAILED_INIT:
    return "failed init";

  case CURLE_URL_MALFORMAT:
    return "URL using bad/illegal format or missing URL";

  case CURLE_NOT_BUILT_IN:
    return "A requested feature, protocol or option was not found built-in in"
      " this libcurl due to a build-time decision.";

  case CURLE_COULDNT_RESOLVE_PROXY:
    return "couldn't resolve proxy name";

  case CURLE_COULDNT_RESOLVE_HOST:
    return "couldn't resolve host name";

  case CURLE_COULDNT_CONNECT:
    return "couldn't connect to server";

  case CURLE_FTP_WEIRD_SERVER_REPLY:
    return "FTP: weird server reply";

  case CURLE_FTP_ACCESS_DENIED:
    return "FTP: access denied";

  case CURLE_FTP_WEIRD_PASS_REPLY:
    return "FTP: unknown PASS reply";

  case CURLE_FTP_WEIRD_USER_REPLY:
    return "FTP: unknown USER reply";

  case CURLE_FTP_WEIRD_PASV_REPLY:
    return "FTP: unknown PASV reply";

  case CURLE_FTP_WEIRD_227_FORMAT:
    return "FTP: unknown 227 response format";

  case CURLE_FTP_CANT_GET_HOST:
    return "FTP: can't figure out the host in the PASV response";

  case CURLE_FTP_CANT_RECONNECT:
    return "FTP: can't connect to server the response code is unknown";

  case CURLE_FTP_COULDNT_SET_BINARY:
    return "FTP: couldn't set binary mode";

  case CURLE_PARTIAL_FILE:
    return "Transferred a partial file";

  case CURLE_FTP_COULDNT_RETR_FILE:
    return "FTP: couldn't retrieve (RETR failed) the specified file";

  case CURLE_FTP_WRITE_ERROR:
    return "FTP: the post-transfer acknowledge response was not OK";

  case CURLE_FTP_QUOTE_ERROR:
    return "FTP: a quote command returned error";

  case CURLE_HTTP_RETURNED_ERROR:
    return "HTTP response code said error";

  case CURLE_WRITE_ERROR:
    return "failed writing received data to disk/application";

  case CURLE_FTP_COULDNT_STOR_FILE:
    return "failed FTP upload (the STOR command)";

  case CURLE_READ_ERROR:
    return "failed to open/read local data from file/application";

  case CURLE_OUT_OF_MEMORY:
#ifdef CURL_DOES_CONVERSIONS
    return "conversion failed -or- out of memory";
#else
    return "out of memory";
#endif /* CURL_DOES_CONVERSIONS */

  case CURLE_OPERATION_TIMEOUTED:
    return "a timeout was reached";

  case CURLE_FTP_COULDNT_SET_ASCII:
    return "FTP could not set ASCII mode (TYPE A)";

  case CURLE_FTP_PORT_FAILED:
    return "FTP command PORT failed";

  case CURLE_FTP_COULDNT_USE_REST:
    return "FTP command REST failed";

  case CURLE_FTP_COULDNT_GET_SIZE:
    return "FTP command SIZE failed";

  case CURLE_HTTP_RANGE_ERROR:
    return "a range was requested but the server did not deliver it";

  case CURLE_HTTP_POST_ERROR:
    return "internal problem setting up the POST";

  case CURLE_SSL_CONNECT_ERROR:
    return "SSL connect error";

  case CURLE_BAD_DOWNLOAD_RESUME:
    return "couldn't resume download";

  case CURLE_FILE_COULDNT_READ_FILE:
    return "couldn't read a file:// file";

  case CURLE_LDAP_CANNOT_BIND:
    return "LDAP: cannot bind";

  case CURLE_LDAP_SEARCH_FAILED:
    return "LDAP: search failed";

  case CURLE_LIBRARY_NOT_FOUND:
    return "a required shared library was not found";

  case CURLE_FUNCTION_NOT_FOUND:
    return "a required function in the shared library was not found";

  case CURLE_ABORTED_BY_CALLBACK:
    return "the operation was aborted by an application callback";

  case CURLE_BAD_FUNCTION_ARGUMENT:
    return "a libcurl function was given a bad argument";

  case CURLE_INTERFACE_FAILED:
    return "failed binding local connection end";

  case CURLE_TOO_MANY_REDIRECTS :
    return "number of redirects hit maximum amount";

  case CURLE_UNKNOWN_TELNET_OPTION:
    return "User specified an unknown option";

  case CURLE_TELNET_OPTION_SYNTAX :
    return "Malformed telnet option";

  case CURLE_SSL_PEER_CERTIFICATE:
    return "SSL peer certificate was not ok";

  case CURLE_GOT_NOTHING:
    return "server returned nothing (no headers, no data)";

  case CURLE_SSL_ENGINE_NOTFOUND:
    return "SSL crypto engine not found";

  case CURLE_SSL_ENGINE_SETFAILED:
    return "can not set SSL crypto engine as default";

  case CURLE_SSL_ENGINE_INITFAILED:
    return "failed to initialise SSL crypto engine";

  case CURLE_SEND_ERROR:
    return "failed sending data to the peer";

  case CURLE_RECV_ERROR:
    return "failure when receiving data from the peer";

  case CURLE_SHARE_IN_USE:
    return "share is already in use";

  case CURLE_SSL_CERTPROBLEM:
    return "problem with the local SSL certificate";

  case CURLE_SSL_CIPHER:
    return "couldn't use specified SSL cipher";

  case CURLE_SSL_CACERT:
    return "peer certificate cannot be authenticated with known CA certificates";

  case CURLE_SSL_CACERT_BADFILE:
    return "problem with the SSL CA cert (path? access rights?)";

  case CURLE_BAD_CONTENT_ENCODING:
    return "Unrecognized HTTP Content-Encoding";

  case CURLE_LDAP_INVALID_URL:
    return "Invalid LDAP URL";

  case CURLE_FILESIZE_EXCEEDED:
    return "Maximum file size exceeded";

  case CURLE_FTP_SSL_FAILED:
    return "Requested FTP SSL level failed";

  case CURLE_SSL_SHUTDOWN_FAILED:
    return "Failed to shut down the SSL connection";

  case CURLE_SEND_FAIL_REWIND:
    return "Send failed since rewinding of the data stream failed";

  case CURLE_LOGIN_DENIED:
    return "FTP: login denied";

  case CURLE_TFTP_NOTFOUND:
    return "TFTP: File Not Found";

  case CURLE_TFTP_PERM:
    return "TFTP: Access Violation";

  case CURLE_TFTP_DISKFULL:
    return "TFTP: Disk full or allocation exceeded";

  case CURLE_TFTP_ILLEGAL:
    return "TFTP: Illegal operation";

  case CURLE_TFTP_UNKNOWNID:
    return "TFTP: Unknown transfer ID";

  case CURLE_TFTP_EXISTS:
    return "TFTP: File already exists";

  case CURLE_TFTP_NOSUCHUSER:
    return "TFTP: No such user";

  case CURLE_CONV_FAILED:
    return "conversion failed";

  case CURLE_CONV_REQD:
    return "caller must register CURLOPT_CONV_ callback options";

  case CURLE_REMOTE_FILE_NOT_FOUND:
    return "Remote file not found";

  case CURLE_SSH:
    return "Error in the SSH layer";

    /* error codes not used by current libcurl */
  case CURLE_FTP_USER_PASSWORD_INCORRECT:
  case CURLE_MALFORMAT_USER:
  case CURLE_BAD_CALLING_ORDER:
  case CURLE_BAD_PASSWORD_ENTERED:
  case CURLE_OBSOLETE:
  case CURL_LAST:
    break;
  }
  /*
   * By using a switch, gcc -Wall will complain about enum values
   * which do not appear, helping keep this function up-to-date.
   * By using gcc -Wall -Werror, you can't forget.
   *
   * A table would not have the same benefit.  Most compilers will
   * generate code very similar to a table in any case, so there
   * is little performance gain from a table.  And something is broken
   * for the user's application, anyways, so does it matter how fast
   * it _doesn't_ work?
   *
   * The line number for the error will be near this comment, which
   * is why it is here, and not at the start of the switch.
   */
  return "unknown error";
#else
  if (error == CURLE_OK)
    return "no error";
  else
    return "error";
#endif
}

const char *
curl_multi_strerror(CURLMcode error)
{
#ifndef CURL_DISABLE_VERBOSE_STRINGS
  switch (error) {
  case CURLM_CALL_MULTI_PERFORM:
    return "please call curl_multi_perform() soon";

  case CURLM_OK:
    return "no error";

  case CURLM_BAD_HANDLE:
    return "invalid multi handle";

  case CURLM_BAD_EASY_HANDLE:
    return "invalid easy handle";

  case CURLM_OUT_OF_MEMORY:
    return "out of memory";

  case CURLM_INTERNAL_ERROR:
    return "internal error";

  case CURLM_BAD_SOCKET:
    return "invalid socket argument";

  case CURLM_UNKNOWN_OPTION:
    return "unknown option";

  case CURLM_LAST:
    break;
  }

  return "unknown error";
#else
  if (error == CURLM_OK)
    return "no error";
  else
    return "error";
#endif
}

const char *
curl_share_strerror(CURLSHcode error)
{
#ifndef CURL_DISABLE_VERBOSE_STRINGS
  switch (error) {
  case CURLSHE_OK:
    return "no error";

  case CURLSHE_BAD_OPTION:
    return "unknown share option";

  case CURLSHE_IN_USE:
    return "share currently in use";

  case CURLSHE_INVALID:
    return "invalid share handle";

  case CURLSHE_NOMEM:
    return "out of memory";

  case CURLSHE_LAST:
    break;
  }

  return "CURLSH unknown";
#else
  if (error == CURLSHE_OK)
    return "no error";
  else
    return "error";
#endif
}

#ifdef USE_WINSOCK

/* This function handles most / all (?) Winsock errors cURL is able to produce.
 */
static const char *
get_winsock_error (int err, char *buf, size_t len)
{
  const char *p;

#ifndef CURL_DISABLE_VERBOSE_STRINGS
  switch (err) {
  case WSAEINTR:
    p = "Call interrupted.";
    break;
  case WSAEBADF:
    p = "Bad file";
    break;
  case WSAEACCES:
    p = "Bad access";
    break;
  case WSAEFAULT:
    p = "Bad argument";
    break;
  case WSAEINVAL:
    p = "Invalid arguments";
    break;
  case WSAEMFILE:
    p = "Out of file descriptors";
    break;
  case WSAEWOULDBLOCK:
    p = "Call would block";
    break;
  case WSAEINPROGRESS:
  case WSAEALREADY:
    p = "Blocking call in progress";
    break;
  case WSAENOTSOCK:
    p = "Descriptor is not a socket.";
    break;
  case WSAEDESTADDRREQ:
    p = "Need destination address";
    break;
  case WSAEMSGSIZE:
    p = "Bad message size";
    break;
  case WSAEPROTOTYPE:
    p = "Bad protocol";
    break;
  case WSAENOPROTOOPT:
    p = "Protocol option is unsupported";
    break;
  case WSAEPROTONOSUPPORT:
    p = "Protocol is unsupported";
    break;
  case WSAESOCKTNOSUPPORT:
    p = "Socket is unsupported";
    break;
  case WSAEOPNOTSUPP:
    p = "Operation not supported";
    break;
  case WSAEAFNOSUPPORT:
    p = "Address family not supported";
    break;
  case WSAEPFNOSUPPORT:
    p = "Protocol family not supported";
    break;
  case WSAEADDRINUSE:
    p = "Address already in use";
    break;
  case WSAEADDRNOTAVAIL:
    p = "Address not available";
    break;
  case WSAENETDOWN:
    p = "Network down";
    break;
  case WSAENETUNREACH:
    p = "Network unreachable";
    break;
  case WSAENETRESET:
    p = "Network has been reset";
    break;
  case WSAECONNABORTED:
    p = "Connection was aborted";
    break;
  case WSAECONNRESET:
    p = "Connection was reset";
    break;
  case WSAENOBUFS:
    p = "No buffer space";
    break;
  case WSAEISCONN:
    p = "Socket is already connected";
    break;
  case WSAENOTCONN:
    p = "Socket is not connected";
    break;
  case WSAESHUTDOWN:
    p = "Socket has been shut down";
    break;
  case WSAETOOMANYREFS:
    p = "Too many references";
    break;
  case WSAETIMEDOUT:
    p = "Timed out";
    break;
  case WSAECONNREFUSED:
    p = "Connection refused";
    break;
  case WSAELOOP:
    p = "Loop??";
    break;
  case WSAENAMETOOLONG:
    p = "Name too long";
    break;
  case WSAEHOSTDOWN:
    p = "Host down";
    break;
  case WSAEHOSTUNREACH:
    p = "Host unreachable";
    break;
  case WSAENOTEMPTY:
    p = "Not empty";
    break;
  case WSAEPROCLIM:
    p = "Process limit reached";
    break;
  case WSAEUSERS:
    p = "Too many users";
    break;
  case WSAEDQUOT:
    p = "Bad quota";
    break;
  case WSAESTALE:
    p = "Something is stale";
    break;
  case WSAEREMOTE:
    p = "Remote error";
    break;
#ifdef WSAEDISCON  /* missing in SalfordC! */
  case WSAEDISCON:
    p = "Disconnected";
    break;
#endif
    /* Extended Winsock errors */
  case WSASYSNOTREADY:
    p = "Winsock library is not ready";
    break;
  case WSANOTINITIALISED:
    p = "Winsock library not initialised";
    break;
  case WSAVERNOTSUPPORTED:
    p = "Winsock version not supported.";
    break;

    /* getXbyY() errors (already handled in herrmsg):
     * Authoritative Answer: Host not found */
  case WSAHOST_NOT_FOUND:
    p = "Host not found";
    break;

    /* Non-Authoritative: Host not found, or SERVERFAIL */
  case WSATRY_AGAIN:
    p = "Host not found, try again";
    break;

    /* Non recoverable errors, FORMERR, REFUSED, NOTIMP */
  case WSANO_RECOVERY:
    p = "Unrecoverable error in call to nameserver";
    break;

    /* Valid name, no data record of requested type */
  case WSANO_DATA:
    p = "No data record of requested type";
    break;

  default:
    return NULL;
  }
#else
  if (error == CURLE_OK)
    return NULL;
  else
    p = "error";
#endif
  strncpy (buf, p, len);
  buf [len-1] = '\0';
  return buf;
}
#endif   /* USE_WINSOCK */

/*
 * Our thread-safe and smart strerror() replacement.
 *
 * The 'err' argument passed in to this function MUST be a true errno number
 * as reported on this system. We do no range checking on the number before
 * we pass it to the "number-to-message" convertion function and there might
 * be systems that don't do proper range checking in there themselves.
 *
 * We don't do range checking (on systems other than Windows) since there is
 * no good reliable and portable way to do it.
 */
const char *Curl_strerror(struct connectdata *conn, int err)
{
  char *buf, *p;
  size_t max;

  curlassert(conn);
  curlassert(err >= 0);

  buf = conn->syserr_buf;
  max = sizeof(conn->syserr_buf)-1;
  *buf = '\0';

#ifdef USE_WINSOCK

#ifdef _WIN32_WCE
  buf[0]=0;
  {
    wchar_t wbuf[256];

    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, err,
                  LANG_NEUTRAL, wbuf, sizeof(wbuf)/sizeof(wchar_t), NULL);
    wcstombs(buf,wbuf,max);
  }

#else

  /* 'sys_nerr' is the maximum errno number, it is not widely portable */
  if (err >= 0 && err < sys_nerr)
    strncpy(buf, strerror(err), max);
  else {
    if (!get_winsock_error(err, buf, max) &&
        !FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, err,
                       LANG_NEUTRAL, buf, (DWORD)max, NULL))
      snprintf(buf, max, "Unknown error %d (%#x)", err, err);
  }
#endif
#else /* not USE_WINSOCK coming up */

  /* These should be atomic and hopefully thread-safe */
#ifdef HAVE_STRERROR_R
  /* There are two different APIs for strerror_r(). The POSIX and the GLIBC
     versions. */
#ifdef HAVE_POSIX_STRERROR_R
  strerror_r(err, buf, max);
  /* this may set errno to ERANGE if insufficient storage was supplied via
     'strerrbuf' and 'buflen' to contain the generated message string, or
     EINVAL if the value of 'errnum' is not a valid error number.*/
#else
  {
    /* HAVE_GLIBC_STRERROR_R */
    char buffer[256];
    char *msg = strerror_r(err, buffer, sizeof(buffer));
    /* this version of strerror_r() only *might* use the buffer we pass to
       the function, but it always returns the error message as a pointer,
       so we must copy that string unconditionally (if non-NULL) */
    if(msg)
      strncpy(buf, msg, max);
    else
      snprintf(buf, max, "Unknown error %d", err);
  }
#endif /* end of HAVE_GLIBC_STRERROR_R */
#else /* HAVE_STRERROR_R */
  strncpy(buf, strerror(err), max);
#endif /* end of HAVE_STRERROR_R */
#endif /* end of ! USE_WINSOCK */

  buf[max] = '\0'; /* make sure the string is zero terminated */

  /* strip trailing '\r\n' or '\n'. */
  if ((p = strrchr(buf,'\n')) != NULL && (p - buf) >= 2)
     *p = '\0';
  if ((p = strrchr(buf,'\r')) != NULL && (p - buf) >= 1)
     *p = '\0';
  return buf;
}

#ifdef USE_LIBIDN
/*
 * Return error-string for libidn status as returned from idna_to_ascii_lz().
 */
const char *Curl_idn_strerror (struct connectdata *conn, int err)
{
#ifdef HAVE_IDNA_STRERROR
  (void)conn;
  return idna_strerror((Idna_rc) err);
#else
  const char *str;
  char *buf;
  size_t max;

  curlassert(conn);

  buf = conn->syserr_buf;
  max = sizeof(conn->syserr_buf)-1;

#ifndef CURL_DISABLE_VERBOSE_STRINGS
  switch ((Idna_rc)err) {
    case IDNA_SUCCESS:
      str = "No error";
      break;
    case IDNA_STRINGPREP_ERROR:
      str = "Error in string preparation";
      break;
    case IDNA_PUNYCODE_ERROR:
      str = "Error in Punycode operation";
      break;
    case IDNA_CONTAINS_NON_LDH:
      str = "Illegal ASCII characters";
      break;
    case IDNA_CONTAINS_MINUS:
      str = "Contains minus";
      break;
    case IDNA_INVALID_LENGTH:
      str = "Invalid output length";
      break;
    case IDNA_NO_ACE_PREFIX:
      str = "No ACE prefix (\"xn--\")";
      break;
    case IDNA_ROUNDTRIP_VERIFY_ERROR:
      str = "Roundtrip verify error";
      break;
    case IDNA_CONTAINS_ACE_PREFIX:
      str = "Already have ACE prefix (\"xn--\")";
      break;
    case IDNA_ICONV_ERROR:
      str = "Locale conversion failed";
      break;
    case IDNA_MALLOC_ERROR:
      str = "Allocation failed";
      break;
    case IDNA_DLOPEN_ERROR:
      str = "dlopen() error";
      break;
    default:
      snprintf(buf, max, "error %d", (int)err);
      str = NULL;
      break;
  }
#else
  if ((Idna_rc)err == IDNA_SUCCESS)
    str = "No error";
  else
    str = "error";
#endif
  if (str)
    strncpy(buf, str, max);
  buf[max] = '\0';
  return (buf);
#endif
}
#endif  /* USE_LIBIDN */