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e3fe020089
Remove the PROTOCOLS section from the source files completely and instead generate them based on the header data in the curldown files. It also generates TLS backend information for options marked for TLS as protocol. Closes #13175
105 lines
2.9 KiB
Markdown
105 lines
2.9 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: curl_multi_info_read
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Section: 3
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Source: libcurl
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See-also:
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- curl_multi_cleanup (3)
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- curl_multi_init (3)
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- curl_multi_perform (3)
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Protocol:
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- All
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---
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# NAME
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curl_multi_info_read - read multi stack information
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLMsg *curl_multi_info_read(CURLM *multi_handle, int *msgs_in_queue);
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~~~
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# DESCRIPTION
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Ask the multi handle if there are any messages from the individual
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transfers. Messages may include information such as an error code from the
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transfer or just the fact that a transfer is completed. More details on these
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should be written down as well.
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Repeated calls to this function returns a new struct each time, until a NULL
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is returned as a signal that there is no more to get at this point. The
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integer pointed to with *msgs_in_queue* contains the number of remaining
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messages after this function was called.
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When you fetch a message using this function, it is removed from the internal
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queue so calling this function again does not return the same message
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again. It instead returns new messages at each new invoke until the queue is
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emptied.
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**WARNING:** The data the returned pointer points to does not survive
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calling curl_multi_cleanup(3), curl_multi_remove_handle(3) or
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curl_easy_cleanup(3).
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The *CURLMsg* struct is simple and only contains basic information. If
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more involved information is wanted, the particular "easy handle" is present
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in that struct and can be used in subsequent regular
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curl_easy_getinfo(3) calls (or similar):
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~~~c
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struct CURLMsg {
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CURLMSG msg; /* what this message means */
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CURL *easy_handle; /* the handle it concerns */
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union {
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void *whatever; /* message-specific data */
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CURLcode result; /* return code for transfer */
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} data;
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};
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~~~
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When **msg** is *CURLMSG_DONE*, the message identifies a transfer that
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is done, and then **result** contains the return code for the easy handle
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that just completed.
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At this point, there are no other **msg** types defined.
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURLM *multi = curl_multi_init();
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CURL *curl = curl_easy_init();
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if(curl) {
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struct CURLMsg *m;
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/* call curl_multi_perform or curl_multi_socket_action first, then loop
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through and check if there are any transfers that have completed */
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do {
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int msgq = 0;
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m = curl_multi_info_read(multi, &msgq);
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if(m && (m->msg == CURLMSG_DONE)) {
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CURL *e = m->easy_handle;
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/* m->data.result holds the error code for the transfer */
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curl_multi_remove_handle(multi, e);
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curl_easy_cleanup(e);
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}
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} while(m);
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}
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}
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~~~
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# AVAILABILITY
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Added in 7.9.6
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# RETURN VALUE
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A pointer to a filled-in struct, or NULL if it failed or ran out of
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structs. It also writes the number of messages left in the queue (after this
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read) in the integer the second argument points to.
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