CURLOPT_BUFFERSIZE - Man Page

receive buffer size

Synopsis

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_BUFFERSIZE, long size);

Description

Pass a long specifying your preferred size (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 CURL_MAX_WRITE_SIZE (16kB). The maximum buffer size allowed to be set is CURL_MAX_READ_SIZE (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.

Default

CURL_MAX_WRITE_SIZE (16kB)

Protocols

All

Example

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);
}

Availability

Added in 7.10.  Growing the buffer was added in 7.53.0.

Return Value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

See Also

CURLOPT_MAX_RECV_SPEED_LARGE(3), CURLOPT_WRITEFUNCTION(3),

Referenced By

curl_easy_setopt(3), CURLOPT_MAX_RECV_SPEED_LARGE(3), CURLOPT_UPLOAD_BUFFERSIZE(3).

September 08, 2021 libcurl 7.79.0 curl_easy_setopt options