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 sections 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.
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 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 ter-
minated 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
CURLFORM_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 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_CONTENTSLENGTH
followed by a long setting the length of the contents.
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
content-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 CURLFORM_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, pos-
sibly 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.
CURLFORM_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 CURL-
FORM_BUFFER). The buffer containing this data must not be freed
until after curl_easy_cleanup(3) is called. You must also use
CURLFORM_BUFFERLENGTH to set the length of the given buffer
area.
CURLFORM_BUFFERLENGTH
followed by a long with the size of the CURLFORM_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
CURLformoption 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 section. This takes a
curl_slist prepared in the usual way using curl_slist_append and
appends the list of headers to those libcurl automatically gen-
erates. 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 han-
dle.
See example below.
RETURN VALUE
0 means everything was ok, non-zero means an error occurred as
<curl/curl.h> defines.
EXAMPLE
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[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)
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