docs/libcurl/opts/CURLOPT_BUFFERSIZE.3

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.TH CURLOPT_BUFFERSIZE 3 "May 06, 2021" "libcurl 7.78.0" "curl_easy_setopt options"

.SH NAME
CURLOPT_BUFFERSIZE \- set preferred receive buffer size
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_BUFFERSIZE, long size);
.SH DESCRIPTION
Pass a long specifying your preferred \fIsize\fP (in bytes) for the receive
buffer in libcurl.  The main point of this would be that the write callback
gets called more often and with smaller chunks. Secondly, for some protocols,
there's a benefit of having a larger buffer for performance.

This is just treated as a request, not an order. You cannot be guaranteed to
actually get the given size.

This buffer size is by default \fICURL_MAX_WRITE_SIZE\fP (16kB). The maximum
buffer size allowed to be set is \fICURL_MAX_READ_SIZE\fP (512kB). The minimum
buffer size allowed to be set is 1024.

DO NOT set this option on a handle that is currently used for an active
transfer as that may lead to unintended consequences.
.SH DEFAULT
CURL_MAX_WRITE_SIZE (16kB)
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/foo.bin");

  /* ask libcurl to allocate a larger receive buffer */
  curl_easy_setopt(curl, CURLOPT_BUFFERSIZE, 120000L);

  ret = curl_easy_perform(curl);

  curl_easy_cleanup(curl);
}
.fi
.SH AVAILABILITY
Added in 7.10.  Growing the buffer was added in 7.53.0.
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_MAX_RECV_SPEED_LARGE "(3), " CURLOPT_WRITEFUNCTION "(3), "