Daniel Stenberg e694c8284a

docs/libcurl/opts: clarify the return values

Expand a little.

- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
  varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes

Closes #15900

2025-01-02 17:13:33 +01:00

1.5 KiB

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SPDX-License-Identifier

Title

Section

Source

See-also

Protocol

Added-in

curl

CURLINFO_XFER_ID

libcurl

CURLINFO_CONN_ID (3)

curl_easy_getinfo (3)

curl_easy_setopt (3)

All

8.2.0

NAME

CURLINFO_XFER_ID - get the ID of a transfer

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_XFER_ID,
                           curl_off_t *xfer_id);

DESCRIPTION

Pass a pointer to a curl_off_t to receive the identifier of the current/last transfer done with the handle. Stores -1 if no transfer has been started yet for the handle.

The transfer id is unique among all transfers performed using the same connection cache. This is implicitly the case for all transfers in the same multi handle.

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

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

    if(!res) {
      curl_off_t xfer_id;
      res = curl_easy_getinfo(curl, CURLINFO_XFER_ID, &xfer_id);
      if(!res) {
        printf("Transfer ID: %" CURL_FORMAT_CURL_OFF_T "\n", xfer_id);
      }
    }
  }
}

%AVAILABILITY%

RETURN VALUE

curl_easy_getinfo(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

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