---
name: "CURLOPT_COPYPOSTFIELDS"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_COPYPOSTFIELDS"
---

# CURLOPT\_COPYPOSTFIELDS(3)

have libcurl copy data to POST

## NAME

CURLOPT\_COPYPOSTFIELDS - have libcurl copy data to POST

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_COPYPOSTFIELDS, char *data);
```

## DESCRIPTION

Pass a char pointer as parameter, which should be the full *data* to post in a HTTP POST operation. It behaves as the *[CURLOPT\_POSTFIELDS(3)](/CURLOPT_POSTFIELDS/3.md)* option, but the original data is instead copied by the library, allowing the application to overwrite the original data after setting this option.

Because data are copied, care must be taken when using this option in conjunction with *[CURLOPT\_POSTFIELDSIZE(3)](/CURLOPT_POSTFIELDSIZE/3.md)* or *[CURLOPT\_POSTFIELDSIZE\_LARGE(3)](/CURLOPT_POSTFIELDSIZE_LARGE/3.md)*: If the size has not been set prior to *[CURLOPT\_COPYPOSTFIELDS(3)](/CURLOPT_COPYPOSTFIELDS/3.md)*, the data is assumed to be a null-terminated string; else the stored size informs the library about the byte count to copy. In any case, the size must not be changed after *[CURLOPT\_COPYPOSTFIELDS(3)](/CURLOPT_COPYPOSTFIELDS/3.md)*, unless another *[CURLOPT\_POSTFIELDS(3)](/CURLOPT_POSTFIELDS/3.md)* or *[CURLOPT\_COPYPOSTFIELDS(3)](/CURLOPT_COPYPOSTFIELDS/3.md)* option is issued.

## DEFAULT

NULL

## PROTOCOLS

HTTP(S)

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    char local_buffer[1024]="data to send";
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    /* size of the data to copy from the buffer and send in the request */
    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, 12L);
    /* send data from the local stack */
    curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, local_buffer);
    curl_easy_perform(curl);
  }
}
```

## AVAILABILITY

Added in 7.17.1

## RETURN VALUE

Returns CURLE\_OK if the option is supported, CURLE\_UNKNOWN\_OPTION if not, or CURLE\_OUT\_OF\_MEMORY if there was insufficient heap space.

## SEE ALSO

[**CURLOPT\_MIMEPOST**(3)](/CURLOPT_MIMEPOST/3.md), [**CURLOPT\_POSTFIELDS**(3)](/CURLOPT_POSTFIELDS/3.md), [**CURLOPT\_POSTFIELDSIZE**(3)](/CURLOPT_POSTFIELDSIZE/3.md), [**CURLOPT\_UPLOAD**(3)](/CURLOPT_UPLOAD/3.md)