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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 \fICURLOPT_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_CONTENTLEN
87 followed by a curl_off_t value giving the length of the contents. Note that
88 for \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.
94 (Option added in 7.46.0)
95 .IP CURLFORM_CONTENTSLENGTH
96 (This option is deprecated. Use \fICURLFORM_CONTENTLEN\fP instead!)
98 followed by a long giving the length of the contents. Note that for
99 \fICURLFORM_STREAM\fP contents, this option is mandatory.
101 If you pass a 0 (zero) for this option, libcurl will instead do a strlen() on
102 the contents to figure out the size. If you really want to send a zero byte
103 content then you must make sure strlen() on the data pointer returns zero.
104 .IP CURLFORM_FILECONTENT
105 followed by a filename, causes that file to be read and its contents used
106 as data in this part. This part does \fInot\fP automatically become a file
107 upload part simply because its data was read from a file.
109 The specified file needs to kept around until the associated transfer is done.
111 followed by a filename, makes this part a file upload part. It sets the
112 \fIfilename\fP field to the basename of the provided filename, it reads the
113 contents of the file and passes them as data and sets the content-type if the
114 given file match one of the internally known file extensions. For
115 \fBCURLFORM_FILE\fP the user may send one or more files in one part by
116 providing multiple \fBCURLFORM_FILE\fP arguments each followed by the filename
117 (and each \fICURLFORM_FILE\fP is allowed to have a
118 \fICURLFORM_CONTENTTYPE\fP).
120 The given upload file has to exist in its full in the file system already when
121 the upload starts, as libcurl needs to read the correct file size beforehand.
123 The specified file needs to kept around until the associated transfer is done.
124 .IP CURLFORM_CONTENTTYPE
125 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
126 string which provides the content-type for this part, possibly instead of an
127 internally chosen one.
128 .IP CURLFORM_FILENAME
129 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
130 string, it tells libcurl to use the given string as the \fIfilename\fP in the
131 file upload part instead of the actual file name.
133 is used for custom file upload parts without use of \fICURLFORM_FILE\fP. It
134 tells libcurl that the file contents are already present in a buffer. The
135 parameter is a string which provides the \fIfilename\fP field in the content
137 .IP CURLFORM_BUFFERPTR
138 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a pointer
139 to the buffer to be uploaded. This buffer must not be freed until after
140 \fIcurl_easy_cleanup(3)\fP is called. You must also use
141 \fICURLFORM_BUFFERLENGTH\fP to set the number of bytes in the buffer.
142 .IP CURLFORM_BUFFERLENGTH
143 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a
144 long which gives the length of the buffer.
146 Tells libcurl to use the \fICURLOPT_READFUNCTION(3)\fP callback to get
147 data. The parameter you pass to \fICURLFORM_STREAM\fP is the pointer passed on
148 to the read callback's fourth argument. If you want the part to look like a
149 file upload one, set the \fICURLFORM_FILENAME\fP parameter as well. Note that
150 when using \fICURLFORM_STREAM\fP, \fICURLFORM_CONTENTSLENGTH\fP must also be
151 set with the total expected length of the part unless the formpost is sent
152 chunked encoded. (Option added in libcurl 7.18.2)
154 Another possibility to send options to curl_formadd() is the
155 \fBCURLFORM_ARRAY\fP option, that passes a struct curl_forms array pointer as
156 its value. Each curl_forms structure element has a CURLformoption and a char
157 pointer. The final element in the array must be a CURLFORM_END. All available
158 options can be used in an array, except the CURLFORM_ARRAY option itself! The
159 last argument in such an array must always be \fBCURLFORM_END\fP.
160 .IP CURLFORM_CONTENTHEADER
161 specifies extra headers for the form POST section. This takes a curl_slist
162 prepared in the usual way using \fBcurl_slist_append\fP and appends the list
163 of headers to those libcurl automatically generates. The list must exist while
164 the POST occurs, if you free it before the post completes you may experience
167 When you've passed the HttpPost pointer to \fIcurl_easy_setopt(3)\fP (using
168 the \fICURLOPT_HTTPPOST(3)\fP option), you must not free the list until after
169 you've called \fIcurl_easy_cleanup(3)\fP for the curl handle.
173 0 means everything was ok, non-zero means an error occurred corresponding
174 to a CURL_FORMADD_* constant defined in
179 struct curl_httppost* post = NULL;
180 struct curl_httppost* last = NULL;
181 char namebuffer[] = "name buffer";
182 long namelength = strlen(namebuffer);
183 char buffer[] = "test buffer";
184 char htmlbuffer[] = "<HTML>test buffer</HTML>";
185 long htmlbufferlength = strlen(htmlbuffer);
186 struct curl_forms forms[3];
187 char file1[] = "my-face.jpg";
188 char file2[] = "your-face.jpg";
189 /* add null character into htmlbuffer, to demonstrate that
190 transfers of buffers containing null characters actually work
192 htmlbuffer[8] = '\\0';
194 /* Add simple name/content section */
195 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name",
196 CURLFORM_COPYCONTENTS, "content", CURLFORM_END);
198 /* Add simple name/content/contenttype section */
199 curl_formadd(&post, &last, CURLFORM_COPYNAME, "htmlcode",
200 CURLFORM_COPYCONTENTS, "<HTML></HTML>",
201 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
203 /* Add name/ptrcontent section */
204 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name_for_ptrcontent",
205 CURLFORM_PTRCONTENTS, buffer, CURLFORM_END);
207 /* Add ptrname/ptrcontent section */
208 curl_formadd(&post, &last, CURLFORM_PTRNAME, namebuffer,
209 CURLFORM_PTRCONTENTS, buffer, CURLFORM_NAMELENGTH,
210 namelength, CURLFORM_END);
212 /* Add name/ptrcontent/contenttype section */
213 curl_formadd(&post, &last, CURLFORM_COPYNAME, "html_code_with_hole",
214 CURLFORM_PTRCONTENTS, htmlbuffer,
215 CURLFORM_CONTENTSLENGTH, htmlbufferlength,
216 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
218 /* Add simple file section */
219 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
220 CURLFORM_FILE, "my-face.jpg", CURLFORM_END);
222 /* Add file/contenttype section */
223 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
224 CURLFORM_FILE, "my-face.jpg",
225 CURLFORM_CONTENTTYPE, "image/jpeg", CURLFORM_END);
227 /* Add two file section */
228 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
229 CURLFORM_FILE, "my-face.jpg",
230 CURLFORM_FILE, "your-face.jpg", CURLFORM_END);
232 /* Add two file section using CURLFORM_ARRAY */
233 forms[0].option = CURLFORM_FILE;
234 forms[0].value = file1;
235 forms[1].option = CURLFORM_FILE;
236 forms[1].value = file2;
237 forms[2].option = CURLFORM_END;
239 /* Add a buffer to upload */
240 curl_formadd(&post, &last,
241 CURLFORM_COPYNAME, "name",
242 CURLFORM_BUFFER, "data",
243 CURLFORM_BUFFERPTR, record,
244 CURLFORM_BUFFERLENGTH, record_length,
247 /* no option needed for the end marker */
248 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
249 CURLFORM_ARRAY, forms, CURLFORM_END);
250 /* Add the content of a file as a normal post text value */
251 curl_formadd(&post, &last, CURLFORM_COPYNAME, "filecontent",
252 CURLFORM_FILECONTENT, ".bashrc", CURLFORM_END);
253 /* Set the form info */
254 curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
257 .BR curl_easy_setopt "(3), "
258 .BR curl_formfree "(3)"