romenskiy2012/curl

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docs: add CURLOPT type change history, drop casts where present

Some CURLOPT constants defined in the curl public headers were initially
enums (= ints), or macros with bare numeric values. Recent curl releases
upgraded them to `long` constants, to make them pass correctly to
`curl_easy_setop()` by default, i.e. without requiring a `(long)` cast.

This patch drops such casts from the examples embedded in the docs. At
the same time it documents which curl release made them `long` types,
to keep them useful when working with previous libcurl versions.

Also:
- drop a `(long)` cast that was never necessary.
- CURLOPT_ALTSVC_CTRL.md: bump local copy of macros to long.
- test1119: make it ignore symbols ending with an underscore, to skip
  wildcard, e.g. `**CURLAUTH_***`.

Closes #18130

2025-08-02 00:05:33 +02:00

2.5 KiB

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SPDX-License-Identifier

Title

Section

Source

See-also

Protocol

Added-in

curl

CURLOPT_MIME_OPTIONS

libcurl

CURLOPT_HTTPPOST (3)

CURLOPT_MIMEPOST (3)

HTTP

IMAP

SMTP

7.81.0

NAME

CURLOPT_MIME_OPTIONS - set MIME option flags

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MIME_OPTIONS, long options);

DESCRIPTION

Pass a long that holds a bitmask of options. Each bit is a boolean flag used while encoding a MIME tree or multipart form data.

Available bits are:

CURLMIMEOPT_FORMESCAPE

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 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 one to address server-side applications that have not yet have 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.

DEFAULT

0, meaning disabled.

%PROTOCOLS%

EXAMPLE

int main(void)
{
  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(form);
  }
}

HISTORY

CURLMIMEOPT_FORMESCAPE macro became long type in 8.16.0, prior to this version a long cast was necessary when passed to curl_easy_setopt(3).

%AVAILABILITY%

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).

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