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22 .TH curl_formadd 3 "24 June 2002" "libcurl 7.9.8" "libcurl Manual"
24 curl_formadd - add a section to a multipart/formdata HTTP POST
26 .B #include <curl/curl.h>
28 .BI "CURLFORMcode curl_formadd(struct curl_httppost ** " firstitem,
29 .BI "struct curl_httppost ** " lastitem, " ...);"
32 curl_formadd() is used to append sections when building a multipart/formdata
33 HTTP POST (sometimes referred to as RFC2388-style posts). Append one section
34 at a time until you've added all the sections you want included and then you
35 pass the \fIfirstitem\fP pointer as parameter to \fBCURLOPT_HTTPPOST(3)\fP.
36 \fIlastitem\fP is set after each \fIcurl_formadd(3)\fP call and on repeated
37 invokes it should be left as set to allow repeated invokes to find the end of
40 After the \fIlastitem\fP pointer follow the real arguments.
42 The pointers \fIfirstitem\fP and \fIlastitem\fP should both be pointing to
43 NULL in the first call to this function. All list-data will be allocated by
44 the function itself. You must call \fIcurl_formfree(3)\fP on the
45 \fIfirstitem\fP after the form post has been done to free the resources.
47 Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header.
48 You can disable this header with \fICURLOPT_HTTPHEADER(3)\fP as usual.
50 First, there are some basics you need to understand about multipart/formdata
51 posts. Each part consists of at least a NAME and a CONTENTS part. If the part
52 is made for file upload, there are also a stored CONTENT-TYPE and a FILENAME.
53 Below, we'll discuss what options you use to set these properties in the
54 parts you want to add to your post.
56 The options listed first are for making normal parts. The options from
57 \fICURLFORM_FILE\fP through \fICURLFORM_BUFFERLENGTH\fP are for file upload
61 followed by a string which provides the \fIname\fP of this part. libcurl
62 copies the string so your application doesn't need to keep it around after
63 this function call. If the name isn't NUL-terminated, or if you'd
64 like it to contain zero bytes, you must set its length with
65 \fBCURLFORM_NAMELENGTH\fP. The copied data will be freed by
66 \fIcurl_formfree(3)\fP.
68 followed by a string which provides the \fIname\fP of this part. libcurl
69 will use the pointer and refer to the data in your application, so you
70 must make sure it remains until curl no longer needs it. If the name
71 isn't NUL-terminated, or if you'd like it to contain zero
72 bytes, you must set its length with \fBCURLFORM_NAMELENGTH\fP.
73 .IP CURLFORM_COPYCONTENTS
74 followed by a pointer to the contents of this part, the actual data
75 to send away. libcurl copies the provided data, so your application doesn't
76 need to keep it around after this function call. If the data isn't null
77 terminated, or if you'd like it to contain zero bytes, you must
78 set the length of the name with \fBCURLFORM_CONTENTSLENGTH\fP. The copied
79 data will be freed by \fIcurl_formfree(3)\fP.
80 .IP CURLFORM_PTRCONTENTS
81 followed by a pointer to the contents of this part, the actual data
82 to send away. libcurl will use the pointer and refer to the data in your
83 application, so you must make sure it remains until curl no longer needs it.
84 If the data isn't NUL-terminated, or if you'd like it to contain zero bytes,
85 you must set its length with \fBCURLFORM_CONTENTSLENGTH\fP.
86 .IP CURLFORM_CONTENTSLENGTH
87 followed by a long giving the length of the contents. Note that for
88 \fICURLFORM_STREAM\fP contents, this option is mandatory.
90 If you pass a 0 (zero) for this option, libcurl will instead do a strlen() on
91 the contents to figure out the size. If you really want to send a zero byte
92 content then you must make sure strlen() on the data pointer returns zero.
93 .IP CURLFORM_FILECONTENT
94 followed by a filename, causes that file to be read and its contents used
95 as data in this part. This part does \fInot\fP automatically become a file
96 upload part simply because its data was read from a file.
98 followed by a filename, makes this part a file upload part. It sets the
99 \fIfilename\fP field to the basename of the provided filename, it reads the
100 contents of the file and passes them as data and sets the content-type if the
101 given file match one of the internally known file extensions. For
102 \fBCURLFORM_FILE\fP the user may send one or more files in one part by
103 providing multiple \fBCURLFORM_FILE\fP arguments each followed by the filename
104 (and each \fICURLFORM_FILE\fP is allowed to have a
105 \fICURLFORM_CONTENTTYPE\fP).
107 The given upload file has to exist in its full in the file system already when
108 the upload starts, as libcurl needs to read the correct file size beforehand.
109 .IP CURLFORM_CONTENTTYPE
110 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
111 string which provides the content-type for this part, possibly instead of an
112 internally chosen one.
113 .IP CURLFORM_FILENAME
114 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
115 string, it tells libcurl to use the given string as the \fIfilename\fP in the
116 file upload part instead of the actual file name.
118 is used for custom file upload parts without use of \fICURLFORM_FILE\fP. It
119 tells libcurl that the file contents are already present in a buffer. The
120 parameter is a string which provides the \fIfilename\fP field in the content
122 .IP CURLFORM_BUFFERPTR
123 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a pointer
124 to the buffer to be uploaded. This buffer must not be freed until after
125 \fIcurl_easy_cleanup(3)\fP is called. You must also use
126 \fICURLFORM_BUFFERLENGTH\fP to set the number of bytes in the buffer.
127 .IP CURLFORM_BUFFERLENGTH
128 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a
129 long which gives the length of the buffer.
131 Tells libcurl to use the \fICURLOPT_READFUNCTION(3)\fP callback to get
132 data. The parameter you pass to \fICURLFORM_STREAM\fP is the pointer passed on
133 to the read callback's fourth argument. If you want the part to look like a
134 file upload one, set the \fICURLFORM_FILENAME\fP parameter as well. Note that
135 when using \fICURLFORM_STREAM\fP, \fICURLFORM_CONTENTSLENGTH\fP must also be
136 set with the total expected length of the part. (Option added in libcurl
139 Another possibility to send options to curl_formadd() is the
140 \fBCURLFORM_ARRAY\fP option, that passes a struct curl_forms array pointer as
141 its value. Each curl_forms structure element has a CURLformoption and a char
142 pointer. The final element in the array must be a CURLFORM_END. All available
143 options can be used in an array, except the CURLFORM_ARRAY option itself! The
144 last argument in such an array must always be \fBCURLFORM_END\fP.
145 .IP CURLFORM_CONTENTHEADER
146 specifies extra headers for the form POST section. This takes a curl_slist
147 prepared in the usual way using \fBcurl_slist_append\fP and appends the list
148 of headers to those libcurl automatically generates. The list must exist while
149 the POST occurs, if you free it before the post completes you may experience
152 When you've passed the HttpPost pointer to \fIcurl_easy_setopt(3)\fP (using
153 the \fICURLOPT_HTTPPOST(3)\fP option), you must not free the list until after
154 you've called \fIcurl_easy_cleanup(3)\fP for the curl handle.
158 0 means everything was ok, non-zero means an error occurred corresponding
159 to a CURL_FORMADD_* constant defined in
164 struct curl_httppost* post = NULL;
165 struct curl_httppost* last = NULL;
166 char namebuffer[] = "name buffer";
167 long namelength = strlen(namebuffer);
168 char buffer[] = "test buffer";
169 char htmlbuffer[] = "<HTML>test buffer</HTML>";
170 long htmlbufferlength = strlen(htmlbuffer);
171 struct curl_forms forms[3];
172 char file1[] = "my-face.jpg";
173 char file2[] = "your-face.jpg";
174 /* add null character into htmlbuffer, to demonstrate that
175 transfers of buffers containing null characters actually work
177 htmlbuffer[8] = '\\0';
179 /* Add simple name/content section */
180 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name",
181 CURLFORM_COPYCONTENTS, "content", CURLFORM_END);
183 /* Add simple name/content/contenttype section */
184 curl_formadd(&post, &last, CURLFORM_COPYNAME, "htmlcode",
185 CURLFORM_COPYCONTENTS, "<HTML></HTML>",
186 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
188 /* Add name/ptrcontent section */
189 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name_for_ptrcontent",
190 CURLFORM_PTRCONTENTS, buffer, CURLFORM_END);
192 /* Add ptrname/ptrcontent section */
193 curl_formadd(&post, &last, CURLFORM_PTRNAME, namebuffer,
194 CURLFORM_PTRCONTENTS, buffer, CURLFORM_NAMELENGTH,
195 namelength, CURLFORM_END);
197 /* Add name/ptrcontent/contenttype section */
198 curl_formadd(&post, &last, CURLFORM_COPYNAME, "html_code_with_hole",
199 CURLFORM_PTRCONTENTS, htmlbuffer,
200 CURLFORM_CONTENTSLENGTH, htmlbufferlength,
201 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
203 /* Add simple file section */
204 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
205 CURLFORM_FILE, "my-face.jpg", CURLFORM_END);
207 /* Add file/contenttype section */
208 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
209 CURLFORM_FILE, "my-face.jpg",
210 CURLFORM_CONTENTTYPE, "image/jpeg", CURLFORM_END);
212 /* Add two file section */
213 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
214 CURLFORM_FILE, "my-face.jpg",
215 CURLFORM_FILE, "your-face.jpg", CURLFORM_END);
217 /* Add two file section using CURLFORM_ARRAY */
218 forms[0].option = CURLFORM_FILE;
219 forms[0].value = file1;
220 forms[1].option = CURLFORM_FILE;
221 forms[1].value = file2;
222 forms[2].option = CURLFORM_END;
224 /* Add a buffer to upload */
225 curl_formadd(&post, &last,
226 CURLFORM_COPYNAME, "name",
227 CURLFORM_BUFFER, "data",
228 CURLFORM_BUFFERPTR, record,
229 CURLFORM_BUFFERLENGTH, record_length,
232 /* no option needed for the end marker */
233 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
234 CURLFORM_ARRAY, forms, CURLFORM_END);
235 /* Add the content of a file as a normal post text value */
236 curl_formadd(&post, &last, CURLFORM_COPYNAME, "filecontent",
237 CURLFORM_FILECONTENT, ".bashrc", CURLFORM_END);
238 /* Set the form info */
239 curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
242 .BR curl_easy_setopt "(3), "
243 .BR curl_formfree "(3)"