curl/docs/libcurl/opts/CURLOPT_ERRORBUFFER.3

.\" **************************************************************************
.\" *                                  _   _ ____  _
.\" *  Project                     ___| | | |  _ \| |
.\" *                             / __| | | | |_) | |
.\" *                            | (__| |_| |  _ <| |___
.\" *                             \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 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 https://curl.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.
.\" *
.\" * SPDX-License-Identifier: curl
.\" *
.\" **************************************************************************
.\"
.TH CURLOPT_ERRORBUFFER 3 "17 Jun 2014" libcurl libcurl
.SH NAME
CURLOPT_ERRORBUFFER \- error buffer for error messages
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ERRORBUFFER, char *buf);
.fi
.SH DESCRIPTION
Pass a char * to a buffer that libcurl may use to store human readable error
messages on failures or problems. This may be more helpful than just the
return code from \fIcurl_easy_perform(3)\fP and related functions. The buffer
must be at least \fBCURL_ERROR_SIZE\fP bytes big.

You must keep the associated buffer available until libcurl no longer needs
it. Failing to do so might cause odd behavior or even crashes. libcurl might
need it until you call \fIcurl_easy_cleanup(3)\fP or you set the same option
again to use a different pointer.

Do not rely on the contents of the buffer unless an error code was returned.
Since 7.60.0 libcurl initializes the contents of the error buffer to an empty
string before performing the transfer. For earlier versions if an error code
was returned but there was no error detail then the buffer was untouched.

Consider \fICURLOPT_VERBOSE(3)\fP and \fICURLOPT_DEBUGFUNCTION(3)\fP to better
debug and trace why errors happen.
.SH DEFAULT
NULL
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
curl = curl_easy_init();
if(curl) {
  CURLcode res;
  char errbuf[CURL_ERROR_SIZE];

  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

  /* provide a buffer to store errors in */
  curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errbuf);

  /* set the error buffer as empty before performing a request */
  errbuf[0] = 0;

  /* perform the request */
  res = curl_easy_perform(curl);

  /* if the request did not complete correctly, show the error
  information. if no detailed error information was written to errbuf
  show the more generic information from curl_easy_strerror instead.
  */
  if(res != CURLE_OK) {
    size_t len = strlen(errbuf);
    fprintf(stderr, "\\nlibcurl: (%d) ", res);
    if(len)
      fprintf(stderr, "%s%s", errbuf,
              ((errbuf[len - 1] != '\\n') ? "\\n" : ""));
    else
      fprintf(stderr, "%s\\n", curl_easy_strerror(res));
  }
}
.fi
.SH AVAILABILITY
Always
.SH RETURN VALUE
Returns CURLE_OK
.SH "SEE ALSO"
.BR CURLOPT_DEBUGFUNCTION "(3), " CURLOPT_VERBOSE "(3), "
.BR curl_easy_strerror "(3), " curl_multi_strerror "(3), "
.BR curl_share_strerror "(3), " curl_url_strerror "(3)"