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
124 lines
3.3 KiB
Markdown
124 lines
3.3 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: CURLOPT_PROGRESSFUNCTION
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_NOPROGRESS (3)
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- CURLOPT_VERBOSE (3)
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- CURLOPT_XFERINFOFUNCTION (3)
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Protocol:
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- All
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---
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# NAME
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CURLOPT_PROGRESSFUNCTION - progress meter callback
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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int progress_callback(void *clientp,
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double dltotal,
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double dlnow,
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double ultotal,
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double ulnow);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROGRESSFUNCTION,
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progress_callback);
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~~~
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# DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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This option is deprecated and we encourage users to use the
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newer CURLOPT_XFERINFOFUNCTION(3) instead, if you can.
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This function gets called by libcurl instead of its internal equivalent with a
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frequent interval. While data is being transferred it is invoked frequently,
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and during slow periods like when nothing is being transferred it can slow
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down to about one call per second.
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*clientp* is the pointer set with CURLOPT_PROGRESSDATA(3), it is not
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used by libcurl but is only passed along from the application to the callback.
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The callback gets told how much data libcurl is about to transfer and has
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transferred, in number of bytes. *dltotal* is the total number of bytes
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libcurl expects to download in this transfer. *dlnow* is the number of
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bytes downloaded so far. *ultotal* is the total number of bytes libcurl
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expects to upload in this transfer. *ulnow* is the number of bytes
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uploaded so far.
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Unknown/unused argument values passed to the callback are be set to zero (like
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if you only download data, the upload size remains 0). Many times the callback
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is called one or more times first, before it knows the data sizes so a program
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must be made to handle that.
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If your callback function returns CURL_PROGRESSFUNC_CONTINUE it causes libcurl
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to continue executing the default progress function.
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Returning any other non-zero value from this callback makes libcurl abort the
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transfer and return *CURLE_ABORTED_BY_CALLBACK*.
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If you transfer data with the multi interface, this function is not called
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during periods of idleness unless you call the appropriate libcurl function
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that performs transfers.
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CURLOPT_NOPROGRESS(3) must be set to 0 to make this function actually
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get called.
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# DEFAULT
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By default, libcurl has an internal progress meter. That is rarely wanted by
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users.
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# EXAMPLE
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~~~c
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struct progress {
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char *private;
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size_t size;
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};
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static size_t progress_callback(void *clientp,
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double dltotal,
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double dlnow,
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double ultotal,
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double ulnow)
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{
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struct progress *memory = clientp;
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printf("private: %p\n", memory->private);
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/* use the values */
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return 0; /* all is good */
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}
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int main(void)
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{
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struct progress data;
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CURL *curl = curl_easy_init();
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if(curl) {
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/* pass struct to callback */
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curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, &data);
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curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_callback);
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curl_easy_perform(curl);
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}
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}
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~~~
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# AVAILABILITY
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Deprecated since 7.32.0.
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# RETURN VALUE
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Returns CURLE_OK.
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