85 lines
2.0 KiB
Markdown
85 lines
2.0 KiB
Markdown
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---
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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_BUFFERSIZE
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_MAXFILESIZE (3)
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- CURLOPT_MAX_RECV_SPEED_LARGE (3)
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- CURLOPT_UPLOAD_BUFFERSIZE (3)
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- CURLOPT_WRITEFUNCTION (3)
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---
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# NAME
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CURLOPT_BUFFERSIZE - receive buffer size
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_BUFFERSIZE, long size);
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~~~
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# DESCRIPTION
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Pass a long specifying your preferred *size* (in bytes) for the receive buffer
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in libcurl. The main point of this would be that the write callback gets
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called more often and with smaller chunks. Secondly, for some protocols, there
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is a benefit of having a larger buffer for performance.
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This is just treated as a request, not an order. You cannot be guaranteed to
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actually get the given size.
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This buffer size is by default *CURL_MAX_WRITE_SIZE* (16kB). The maximum
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buffer size allowed to be set is *CURL_MAX_READ_SIZE* (10MB). The minimum
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buffer size allowed to be set is 1024.
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DO NOT set this option on a handle that is currently used for an active
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transfer as that may lead to unintended consequences.
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The maximum size was 512kB until 7.88.0.
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Starting in libcurl 8.7.0, there is just a single transfer buffer allocated
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per multi handle. This buffer is used by all easy handles added to a multi
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handle no matter how many parallel transfers there are. The buffer remains
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allocated as long as there are active transfers.
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# DEFAULT
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CURL_MAX_WRITE_SIZE (16kB)
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# PROTOCOLS
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All
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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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CURL *curl = curl_easy_init();
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if(curl) {
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CURLcode res;
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curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/foo.bin");
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/* ask libcurl to allocate a larger receive buffer */
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curl_easy_setopt(curl, CURLOPT_BUFFERSIZE, 120000L);
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res = curl_easy_perform(curl);
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curl_easy_cleanup(curl);
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}
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}
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~~~
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# AVAILABILITY
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Added in 7.10. Growing the buffer was added in 7.53.0.
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# RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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