curl/docs/libcurl/opts/CURLOPT_MIME_OPTIONS.3

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.TH CURLOPT_MIME_OPTIONS 3 "2 Oct 2021" "libcurl 7.81.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_MIME_OPTIONS \- set MIME option flags
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MIME_OPTIONS, long options);
.fi
.SH DESCRIPTION
Pass a long that holds a bitmask of CURLMIMEOPT_* defines. Each bit is a
Boolean flag used while encoding a MIME tree or multipart form data.

Available bits are:
.IP CURLMIMEOPT_FORMESCAPE
Tells libcurl to escape multipart form field and file names using the
backslash-escaping algorithm rather than percent-encoding (HTTP only).

Backslash-escaping consists in preceding backslashes and double quotes with
a backslash. Percent encoding maps all occurrences of double quote,
carriage return and line feed to %22, %0D and %0A respectively.

Before version 7.81.0, percent-encoding was never applied.

HTTP browsers used to do backslash-escaping in the past but have over time
transitioned to use percent-encoding. This option allows to address
server-side applications that have not yet have been converted.

As an example, consider field or file name \fIstrange\\name"kind\fP.
When the containing multipart form is sent, this is normally transmitted as
\fIstrange\\name%22kind\fP. When this option is set, it is sent as
\fIstrange\\\\name\\"kind\fP.
.SH DEFAULT
0, meaning disabled.
.SH PROTOCOLS
HTTP, IMAP, SMTP
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
curl_mime *form = NULL;

if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
  curl_easy_setopt(curl, CURLOPT_MIME_OPTIONS, CURLMIMEOPT_FORMESCAPE);

  form = curl_mime_init(curl);
  if(form) {
    curl_mimepart *part = curl_mime_addpart(form);

    if(part) {
      curl_mime_filedata(part, "strange\\\\file\\\\name");
      curl_mime_name(part, "strange\\"field\\"name");
      curl_easy_setopt(curl, CURLOPT_MIMEPOST, form);

      /* Perform the request */
      curl_easy_perform(curl);
    }
  }

  curl_easy_cleanup(curl);
  curl_mime_free(mime);
}
.fi
.SH AVAILABILITY
Option added in 7.81.0.
.SH RETURN VALUE
Returns CURLE_OK
.SH "SEE ALSO"
.BR CURLOPT_MIMEPOST "(3), " CURLOPT_HTTPPOST "(3)"