#include <curl/curl.h> CURLFORMcode curl_formadd(struct curl_httppost ** firstitem, struct curl_httppost ** lastitem, ...);
|firstitem||Pointer to the first item in a multipart/formdata HTTP POST.|
|lastitem||Pointer to the first item in a multipart/formdata HTTP POST.|
|Additional parameters for each section of
the multipart/formdata HTTP POST.
|For information, see the CURLFORM Options listed below.|
curl_formadd is used to append sections when building a multipart/formdata HTTP POST (occasionally referred to as RFC 2388-style posts). Append one section at a time until
you have added all the sections you want included and then you pass the firstitem pointer as parameter to
CURLOPT_HTTPPOST. lastitem is set
curl_formadd call and
on repeated invokes it should be left as set to allow repeated invokes to find the end of the list faster.
After the lastitem pointer follow the real arguments.
The pointers firstitem and lastitem should both be pointing to
NULL in the first call to this function. All list-data will be allocated by the function itself.
curl_formfree on the firstitem after the form post has been done to free the resources.
Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with
CURLOPT_HTTPHEADER as usual.
First, there are some basics you need to understand about multipart/formdata posts. Each part consists of at least a
NAME and a
CONTENTS part. If the part is made for file upload,
there are also a stored
CONTENT-TYPE and a
FILENAME. Below, discusses what options you use to set these properties in the parts you want to add to your post.
The options listed first are for making normal parts. The options from
CURLFORM_BUFFERLENGTH are for file upload parts.
Followed by a string which provides the
name of this part. libcurl copies the string so your application does not need to keep it around after this function
call. If the name is not
NULL-terminated, or if you'd like it to contain zero bytes, set its length with
CURLFORM_NAMELENGTH. The copied data will
be freed by
Followed by a string which provides the
name of this part. libcurl will use the pointer and refer to the data in your application, so make sure
it remains until curl no longer needs it. If the name is not NUL-terminated, or if you'd like it to contain zero bytes, set its length with
Followed by a pointer to the contents of this part, the actual data to send away. libcurl copies the provided data, so your application does not need to keep it
around after this function call. If the data is not null-terminated, or if you'd like it to contain zero bytes, set the length of the name
with CURLFORM_CONTENTSLENGTH. The copied data will be freed by
Followed by a pointer to the contents of this part, the actual data to send away. libcurl will use the pointer and refer to the data in your application, so make sure it remains until curl no longer needs it. If the data is not
NULL-terminated, or if you'd like it to contain zero bytes,
set its length with CURLFORM_CONTENTSLENGTH.
Followed by a long giving the length of the contents. Note that for CURLFORM_STREAM contents, this option is mandatory.
Used in combination with
CURLFORM_FILE. Followed by a pointer to a string, it tells libcurl to use the given string as the
filename in the file upload.
Used for custom file upload parts without use of
CURLFORM_FILE. It tells libcurl that the file contents are already present in a buffer. The parameter is a
string which provides the
filename field in the content header.
Used in combination with CURLFORM_BUFFER. The parameter is a pointer to the buffer to be uploaded. This buffer must not be
freed until after
curl_easy_cleanup is called. Also use CURLFORM_BUFFERLENGTH to set the
number of bytes in the buffer.
Used in combination with CURLFORM_BUFFER. The parameter is a long which provides the length of the buffer.
Tells libcurl to use the
CURLOPT_READFUNCTION callback to get data. The parameter you pass to CURLFORM_STREAM is the pointer passed
on to the read callback's fourth argument. If you want the part to look like a file upload one, set the CURLFORM_FILENAME parameter as well. Note that when
using CURLFORM_STREAM, CURLFORM_CONTENTSLENGTH must also be set with the total expected length of the part.
Another possibility to send options to
curl_formadd is the CURLFORM_ARRAY option, that passes a struct
pointer as its value. Each
curl_forms structure element has a
CURLformoption and a char pointer. The final element in the array must be a
All available options can be used in an array, except the
CURLFORM_ARRAY option itself! The last argument in such an array must always be
Specifies extra headers for the form POST section. This takes a
curl_slist prepared in the usual way
curl_slist_append and appends the list of headers to those libcurl automatically generates. The list must exist while
the POST occurs, if you free it before the post completes you may experience problems.
struct curl_httppost* post = NULL; struct curl_httppost* last = NULL; char namebuffer = "name buffer"; long namelength = strlen(namebuffer); char buffer = "test buffer"; char htmlbuffer = "<HTML>test buffer</HTML> long htmlbufferlength = strlen(htmlbuffer); struct curl_forms forms; char file1 = "my-face.jpg"; char file2 = "your-face.jpg"; /* add null character into htmlbuffer, to demonstrate that transfers of buffers containing null characters actually work */ htmlbuffer = '\0'; /* Add simple name/content section */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "name", CURLFORM_COPYCONTENTS, "content", CURLFORM_END); /* Add simple name/content/contenttype section */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "htmlcode", CURLFORM_COPYCONTENTS, "<HTML></HTML>", CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END); /* Add name/ptrcontent section */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "name_for_ptrcontent", CURLFORM_PTRCONTENTS, buffer, CURLFORM_END); /* Add ptrname/ptrcontent section */ curl_formadd(&post, &last, CURLFORM_PTRNAME, namebuffer, CURLFORM_PTRCONTENTS, buffer, CURLFORM_NAMELENGTH, namelength, CURLFORM_END); /* Add name/ptrcontent/contenttype section */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "html_code_with_hole", CURLFORM_PTRCONTENTS, htmlbuffer, CURLFORM_CONTENTSLENGTH, htmlbufferlength, CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END); /* Add two file section using CURLFORM_ARRAY */ forms.option = CURLFORM_FILE; forms.value = file1; forms.option = CURLFORM_FILE; forms.value = file2; forms.option = CURLFORM_END; /* Add a buffer to upload */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "name", CURLFORM_BUFFER, "data", CURLFORM_BUFFERPTR, record, CURLFORM_BUFFERLENGTH, record_length, CURLFORM_END); /* no option needed for the end marker */ curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures", CURLFORM_ARRAY, forms, CURLFORM_END);
2013/11/27 Worked anchors.
2013/05/08 Automated cleanup pass.
2012/05/04 Initial version.