quickjs-tart

quickjs-based runtime for wallet-core logic
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CURLOPT_ERRORBUFFER.md (3070B)

      1 ---
      2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
      3 SPDX-License-Identifier: curl
      4 Title: CURLOPT_ERRORBUFFER
      5 Section: 3
      6 Source: libcurl
      7 See-also:
      8   - CURLOPT_DEBUGFUNCTION (3)
      9   - CURLOPT_VERBOSE (3)
     10   - curl_easy_strerror (3)
     11   - curl_multi_strerror (3)
     12   - curl_share_strerror (3)
     13   - curl_url_strerror (3)
     14 Protocol:
     15   - All
     16 Added-in: 7.1
     17 ---
     18 
     19 # NAME
     20 
     21 CURLOPT_ERRORBUFFER - error buffer for error messages
     22 
     23 # SYNOPSIS
     24 
     25 ~~~c
     26 #include <curl/curl.h>
     27 
     28 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ERRORBUFFER, char *buf);
     29 ~~~
     30 
     31 # DESCRIPTION
     32 
     33 Pass a char pointer to a buffer that libcurl may use to store human readable
     34 error messages on failures or problems. This may be more helpful than just the
     35 return code from curl_easy_perform(3) and related functions. The buffer must
     36 be at least **CURL_ERROR_SIZE** bytes big.
     37 
     38 You must keep the associated buffer available until libcurl no longer needs
     39 it. Failing to do so might cause odd behavior or even crashes. libcurl might
     40 need it until you call curl_easy_cleanup(3) or you set the same option again
     41 to use a different pointer.
     42 
     43 Do not rely on the contents of the buffer unless an error code was returned.
     44 Since 7.60.0 libcurl initializes the contents of the error buffer to an empty
     45 string before performing the transfer. For earlier versions if an error code
     46 was returned but there was no error detail then the buffer was untouched.
     47 
     48 Do not attempt to set the contents of the buffer yourself, including in any
     49 callbacks you write that may be called by libcurl. The library may overwrite
     50 the buffer after your callback returns.
     51 
     52 Consider CURLOPT_VERBOSE(3) and CURLOPT_DEBUGFUNCTION(3) to better debug and
     53 trace why errors happen.
     54 
     55 Using this option multiple times makes the last set pointer override the
     56 previous ones. Set it to NULL to disable its use again.
     57 
     58 # DEFAULT
     59 
     60 NULL
     61 
     62 # %PROTOCOLS%
     63 
     64 # EXAMPLE
     65 
     66 ~~~c
     67 #include <string.h> /* for strlen() */
     68 int main(void)
     69 {
     70   CURL *curl = curl_easy_init();
     71   if(curl) {
     72     CURLcode res;
     73     char errbuf[CURL_ERROR_SIZE];
     74 
     75     curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
     76 
     77     /* provide a buffer to store errors in */
     78     curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errbuf);
     79 
     80     /* set the error buffer as empty before performing a request */
     81     errbuf[0] = 0;
     82 
     83     /* perform the request */
     84     res = curl_easy_perform(curl);
     85 
     86     /* if the request did not complete correctly, show the error
     87     information. if no detailed error information was written to errbuf
     88     show the more generic information from curl_easy_strerror instead.
     89     */
     90     if(res != CURLE_OK) {
     91       size_t len = strlen(errbuf);
     92       fprintf(stderr, "\nlibcurl: (%d) ", res);
     93       if(len)
     94         fprintf(stderr, "%s%s", errbuf,
     95                 ((errbuf[len - 1] != '\n') ? "\n" : ""));
     96       else
     97         fprintf(stderr, "%s\n", curl_easy_strerror(res));
     98     }
     99   }
    100 }
    101 ~~~
    102 
    103 # %AVAILABILITY%
    104 
    105 # RETURN VALUE
    106 
    107 curl_easy_setopt(3) returns a CURLcode indicating success or error.
    108 
    109 CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
    110 libcurl-errors(3).