curl_mime_encoder(3) Library Functions Manual curl_mime_encoder(3)
NAME
curl_mime_encoder - set a mime part's encoder and content transfer en-
coding
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_mime_encoder(curl_mimepart *part, const char *encoding);
DESCRIPTION
curl_mime_encoder() requests a mime part's content to be encoded before
being transmitted.
part is the part's handle to assign an encoder. encoding is a pointer
to a null-terminated encoding scheme. It may be set to NULL to disable
an encoder previously attached to the part. The encoding scheme storage
may safely be reused after this function returns.
Setting a part's encoder multiple times is valid: only the value set by
the last call is retained.
Upon multipart rendering, the part's content is encoded according to the
pertaining scheme and a corresponding "Content-Transfer-Encoding" header
is added to the part.
Supported encoding schemes are:
"binary": the data is left unchanged, the header is added.
"8bit": header added, no data change.
"7bit": the data is unchanged, but is each byte is checked to be a 7-bit
value; if not, a read error occurs.
"base64": Data is converted to base64 encoding, then split in CRLF-ter-
minated lines of at most 76 characters.
"quoted-printable": data is encoded in quoted printable lines of at most
76 characters. Since the resulting size of the final data cannot be de-
termined prior to reading the original data, it is left as unknown,
causing chunked transfer in HTTP. For the same reason, this encoder may
not be used with IMAP. This encoder targets text data that is mostly
ASCII and should not be used with other types of data.
If the original data is already encoded in such a scheme, a custom Con-
tent-Transfer-Encoding header should be added with curl_mime_headers(3)
instead of setting a part encoder.
Encoding should not be applied to multiparts, thus the use of this func-
tion on a part with content set with curl_mime_subparts(3) is strongly
discouraged.
PROTOCOLS
This functionality affects http, imap and smtp
EXAMPLE
int main(void)
{
curl_mime *mime;
curl_mimepart *part;
CURL *curl = curl_easy_init();
if(curl) {
/* create a mime handle */
mime = curl_mime_init(curl);
/* add a part */
part = curl_mime_addpart(mime);
/* send a file */
curl_mime_filedata(part, "image.png");
/* encode file data in base64 for transfer */
curl_mime_encoder(part, "base64");
}
}
AVAILABILITY
Added in curl 7.56.0
RETURN VALUE
This function returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3). If CURLOPT_ERRORBUFFER(3) was set with
curl_easy_setopt(3) there can be an error message stored in the error
buffer when non-zero is returned.
SEE ALSO
curl_mime_addpart(3), curl_mime_headers(3), curl_mime_subparts(3)
libcurl 2026-07-12 curl_mime_encoder(3)
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