curl_formadd(3) libcurl Manual curl_formadd(3)NAMEcurl_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, ...);
DESCRIPTIONcurl_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 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 point-
ing 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
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 applica-
tion 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
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your application, you must make sure it remains until
curl no longer needs it. 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_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 exten-
sion. 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
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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.
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 CURLFORM_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 generates. The list must
exist while the POST occurs, if you free it before the
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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 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);
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/* 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 ALSOcurl_easy_setopt(3), curl_formfree(3)libcurl 7.9.8 Last change: 24 June 2002 5
