docs/libcurl/opts/CURLOPT_ERRORBUFFER.3

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.TH CURLOPT_ERRORBUFFER 3 "November 04, 2020" "libcurl 7.78.0" "curl_easy_setopt options"

.SH NAME
CURLOPT_ERRORBUFFER \- set error buffer for error messages
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ERRORBUFFER, char *buf);
.SH DESCRIPTION
Pass a char * to a buffer that libcurl \fBmay\fP 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
\fBmust be at least CURL_ERROR_SIZE bytes big\fP.

You must keep the associated buffer available until libcurl no longer needs
it. Failing to do so will cause very odd behavior or even crashes. libcurl
will 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 will initialize 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 is 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) "