curl_formadd
curl_formadd(3) libcurl Manual curl_formadd(3)
NAME
curl_formadd - add a section to a multipart/formdata HTTP POST
SYNOPSIS
#include <curl/curl.h>
CURLFORMcode curl_formadd(struct curl_httppost ** firstitem, struct
curl_httppost ** lastitem, ...);
DESCRIPTION
curl_formadd() is used to append sections when building a multi-
part/formdata HTTP POST (sometimes referred to as rfc1867-style
posts). Append one section at a time until you’ve added all the sec-
tions you want included and then you pass the firstitem pointer as
parameter to CURLOPT_HTTPPOST. lastitem is set after each 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. You must call curl_formfree after the form post
has been done to free the resources again.
First, there are some basics you need to understand about multi-
part/formdata posts. Each part consists of at least a NAME and a CON-
TENTS part. If the part is made for file upload, there are also a
stored CONTENT-TYPE and a FILENAME. Below here, we’ll discuss on what
options you use to set these properties in the parts you want to add
to your post.
OPTIONS
CURLFORM_COPYNAME followed by string is used to set the name of this
part. libcurl copies the given data, so your application doesn’t need
to keep it around after this function call. If the name isn’t zero
terminated properly, or if you’d like it to contain zero bytes, you
need to set the length of the name with CURLFORM_NAMELENGTH.
CURLFORM_PTRNAME followed by a string is used for the name of this
part. libcurl will use the pointer and refer to the data in your
application, you must make sure it remains until curl no longer needs
it. If the name isn’t zero terminated properly, or if you’d like it to
contain zero bytes, you need to set the length of the name with CURL-
FORM_NAMELENGTH.
CURLFORM_COPYCONTENTS followed by a string is used for the contents of
this part, the actual data to send away. libcurl copies the given
data, so your application doesn’t need to keep it around after this
function call. If the data isn’t zero terminated properly, or if you’d
like it to contain zero bytes, you need to set the length of the name
with CURLFORM_CONTENTSLENGTH.
CURLFORM_PTRCONTENTS followed by a string is used for the contents of
this part, the actual data to send away. libcurl will use the pointer
and refer to the data in your application, you must make sure it
remains until curl no longer needs it. If the data isn’t zero termi-
nated properly, or if you’d like it to contain zero bytes, you need to
set the length of the name with CURLFORM_CONTENTSLENGTH.
CURLFORM_FILECONTENT followed by a file name, makes that file read and
the contents will be used in as data in this part.
CURLFORM_FILE followed by a file name, makes this part a file upload
part. It sets the file name field to the actual file name used here,
it gets the contents of the file and passes as data and sets the con-
tent-type if the given file match one of the new internally known file
extension. For CURLFORM_FILE the user may send one or more files in
one part by providing multiple CURLFORM_FILE arguments each followed
by the filename (and each CURLFORM_FILE is allowed to have a CURL-
FORM_CONTENTTYPE).
CURLFORM_CONTENTTYPE followed by a pointer to a string with a content-
type will make curl use this given content-type for this file upload
part, possibly instead of an internally chosen one.
CURLFORM_FILENAME followed by a pointer to a string to a name, will
make libcurl use the given name in the file upload part, instead of
the actual file name given to CURLFORM_FILE.
BCURLFORM_BUFFER followed by a string, tells libcurl that a buffer is
to be used to upload data instead of using a file. The given string is
used as the value of the file name field in the content header.
CURLFORM_BUFFERPTR followed by a pointer to a data area, tells libcurl
the address of the buffer containing data to upload (as indicated with
CURLFORM_BUFFER). The buffer containing this data must not be freed
until after curl_easy_cleanup(3) is called.
CURLFORM_BUFFERLENGTH followed by a long with the size of the CURL-
FORM_BUFFERPTR data area, tells libcurl the length of the buffer to
upload.
CURLFORM_ARRAY Another possibility to send options to curl_formadd()
is the CURLFORM_ARRAY option, that passes a struct curl_forms array
pointer as its value. Each curl_forms structure element has a CURLfor-
moption and a char pointer. The final element in the array must be a
CURLFORM_END. 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 CURLFORM_END.
CURLFORM_CONTENTHEADER specifies extra headers for the form POST sec-
tion. This takes a curl_slist prepared in the usual way using
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.
When you’ve passed the HttpPost pointer to curl_easy_setopt(3) (using
the CURLOPT_HTTPPOST option), you must not free the list until after
you’ve called curl_easy_cleanup(3) for the curl handle.
See example below.
RETURN VALUE
0 means everything was ok, non-zero means an error occurred as
<curl/curl.h> defines.
EXAMPLE
struct HttpPost* post = NULL;
struct 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[3];
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[8] = ’\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 simple file section */
curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
CURLFORM_FILE, "my-face.jpg", CURLFORM_END);
/* Add file/contenttype section */
curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
CURLFORM_FILE, "my-face.jpg",
CURLFORM_CONTENTTYPE, "image/jpeg", CURLFORM_END);
/* Add two file section */
curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
CURLFORM_FILE, "my-face.jpg",
CURLFORM_FILE, "your-face.jpg", CURLFORM_END);
/* Add two file section using CURLFORM_ARRAY */
forms[0].option = CURLFORM_FILE;
forms[0].value = file1;
forms[1].option = CURLFORM_FILE;
forms[1].value = file2;
forms[2].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);
/* Add the content of a file as a normal post text value */
curl_formadd(&post, &last, CURLFORM_COPYNAME, "filecontent",
CURLFORM_FILECONTENT, ".bashrc", CURLFORM_END);
/* Set the form info */
curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
SEE ALSO
curl_easy_setopt(3), curl_formfree(3)
libcurl 7.9.8 24 June 2002 curl_formadd(3)
