s2-mod/deps/curl/docs/libcurl/curl_multi_socket.md
2025-04-29 02:51:27 -04:00

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---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: curl_multi_socket
Section: 3
Source: libcurl
See-also:
- curl_multi_cleanup (3)
- curl_multi_fdset (3)
- curl_multi_info_read (3)
- curl_multi_init (3)
- the hiperfifo.c example
Protocol:
- All
Added-in: 7.15.4
---
# NAME
curl_multi_socket - read/write available data
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLMcode curl_multi_socket(CURLM *multi_handle, curl_socket_t sockfd,
int *running_handles);
~~~
# DESCRIPTION
This function is deprecated. Use curl_multi_socket_action(3) instead with
**ev_bitmask** set to 0.
At return, the integer **running_handles** points to contains the number of
still running easy handles within the multi handle. When this number reaches
zero, all transfers are complete/done. Note that when you call
curl_multi_socket(3) on a specific socket and the counter decreases by one, it
DOES NOT necessarily mean that this exact socket/transfer is the one that
completed. Use curl_multi_info_read(3) to figure out which easy handle that
completed.
The curl_multi_socket(3) functions inform the application about updates in the
socket (file descriptor) status by doing none, one, or multiple calls to the
socket callback function set with the CURLMOPT_SOCKETFUNCTION(3) option to
curl_multi_setopt(3). They update the status with changes since the previous
time the callback was called.
Get the timeout time by setting the CURLMOPT_TIMERFUNCTION(3) option with
curl_multi_setopt(3). Your application then gets called with information on
how long to wait for socket actions at most before doing the timeout action:
call the curl_multi_socket_action(3) function with the **sockfd** argument set
to CURL_SOCKET_TIMEOUT. You can also use the curl_multi_timeout(3) function to
poll the value at any given time, but for an event-based system using the
callback is far better than relying on polling the timeout value.
# %PROTOCOLS%
# EXAMPLE
~~~c
int main(void)
{
/* the event-library gets told when there activity on the socket 'fd',
which we translate to a call to curl_multi_socket_action() */
int running;
int rc;
int fd;
CURLM *multi;
rc = curl_multi_socket(multi, fd, &running);
}
~~~
# DEPRECATED
curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3) instead.
# %AVAILABILITY%
# RETURN VALUE
This function returns a CURLMcode indicating success or error.
CURLM_OK (0) means everything was OK, non-zero means an error occurred, see
libcurl-errors(3).
The return code is for the whole multi stack. Problems still might have
occurred on individual transfers even when one of these functions return OK.