Tells libcurl to escape multipart form field and filenames 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 libcurl 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 one to address server-side applications that have not yet been converted.
As an example, consider field or filename strangename"kind. When the
containing multipart form is sent, this is normally transmitted as
strangename%22kind. When this option is set, it is sent as strangename\"kind.
Available since libcurl 7.81.0.
MIME option flags for use with CURLOPT_MIME_OPTIONS
These flags control how MIME structures and multipart form data are encoded.
CURLMIMEOPT_FORMESCAPEbecomesCurlMimeOpt.FormEscape