curl_formadd(3) libcurl Manual curl_formadd(3)
NAME
curl_formadd - add a section to a multipart/formdata HTTP POST
SYNOPSIS
#include
CURLFORMcode curl_formadd(struct curl_httppost ** firstitem, struct curl_httppost **
lastitem, ...);
DESCRIPTION
curl_formadd() is used to append sections when building a multipart/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 param-
eter 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 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 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 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 CURL-
FORM_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_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, 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 CURL-
FORM_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 contain-
ing 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 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 struc-
ture 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 CURL-
FORM_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 head-
ers 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 defines.
EXAMPLE
struct HttpPost* post = NULL;
struct HttpPost* last = NULL;
char namebuffer[] = "name buffer";
long namelength = strlen(namebuffer);
char buffer[] = "test buffer";
char htmlbuffer[] = "test buffer";
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, "",
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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