CURLOPT_UPLOAD(3) Library Functions Manual CURLOPT_UPLOAD(3)
NAME
CURLOPT_UPLOAD - data upload
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPLOAD, long upload);
DESCRIPTION
The long parameter upload set to 1 tells the library to prepare for and
perform an upload. The CURLOPT_READDATA(3) and CURLOPT_INFILESIZE(3) or
CURLOPT_INFILESIZE_LARGE(3) options are also interesting for uploads. If
the protocol is HTTP, uploading means using the PUT request unless you
tell libcurl otherwise.
Using PUT with HTTP 1.1 implies the use of a "Expect: 100-continue"
header. You can disable this header with CURLOPT_HTTPHEADER(3) as
usual.
If you use PUT to an HTTP 1.1 server, you can upload data without know-
ing the size before starting the transfer. The library enables this by
adding a header "Transfer-Encoding: chunked". With HTTP 1.0 or if you
prefer not to use chunked transfer, you must specify the size of the
data with CURLOPT_INFILESIZE(3) or CURLOPT_INFILESIZE_LARGE(3).
DEFAULT
0
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
static size_t read_cb(char *ptr, size_t size, size_t nmemb, void *userdata)
{
FILE *src = userdata;
/* copy as much data as possible into the 'ptr' buffer, but no more than
'size' * 'nmemb' bytes */
size_t retcode = fread(ptr, size, nmemb, src);
return retcode;
}
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
FILE *src = fopen("local-file", "r");
curl_off_t fsize = 1234; /* set this to the size of the input file */
/* we want to use our own read function */
curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_cb);
/* enable uploading */
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
/* specify target */
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/dir/to/newfile");
/* now specify which pointer to pass to our callback */
curl_easy_setopt(curl, CURLOPT_READDATA, src);
/* Set the size of the file to upload */
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t)fsize);
/* Now run off and do what you have been told */
curl_easy_perform(curl);
}
}
AVAILABILITY
Added in curl 7.1
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_INFILESIZE_LARGE(3), CURLOPT_PUT(3), CURLOPT_READFUNCTION(3)
libcurl 2026-07-12 CURLOPT_UPLOAD(3)
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