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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).
106 .IP CURLFORM_CONTENTTYPE
107 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
108 string which provides the content-type for this part, possibly instead of an
109 internally chosen one.
110 .IP CURLFORM_FILENAME
111 is used in combination with \fICURLFORM_FILE\fP. Followed by a pointer to a
112 string, it tells libcurl to use the given string as the \fIfilename\fP in the
113 file upload part instead of the actual file name.
115 is used for custom file upload parts without use of \fICURLFORM_FILE\fP. It
116 tells libcurl that the file contents are already present in a buffer. The
117 parameter is a string which provides the \fIfilename\fP field in the content
119 .IP CURLFORM_BUFFERPTR
120 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a pointer
121 to the buffer to be uploaded. This buffer must not be freed until after
122 \fIcurl_easy_cleanup(3)\fP is called. You must also use
123 \fICURLFORM_BUFFERLENGTH\fP to set the number of bytes in the buffer.
124 .IP CURLFORM_BUFFERLENGTH
125 is used in combination with \fICURLFORM_BUFFER\fP. The parameter is a
126 long which gives the length of the buffer.
128 Tells libcurl to use the \fICURLOPT_READFUNCTION(3)\fP callback to get
129 data. The parameter you pass to \fICURLFORM_STREAM\fP is the pointer passed on
130 to the read callback's fourth argument. If you want the part to look like a
131 file upload one, set the \fICURLFORM_FILENAME\fP parameter as well. Note that
132 when using \fICURLFORM_STREAM\fP, \fICURLFORM_CONTENTSLENGTH\fP must also be
133 set with the total expected length of the part. (Option added in libcurl
136 Another possibility to send options to curl_formadd() is the
137 \fBCURLFORM_ARRAY\fP option, that passes a struct curl_forms array pointer as
138 its value. Each curl_forms structure element has a CURLformoption and a char
139 pointer. The final element in the array must be a CURLFORM_END. All available
140 options can be used in an array, except the CURLFORM_ARRAY option itself! The
141 last argument in such an array must always be \fBCURLFORM_END\fP.
142 .IP CURLFORM_CONTENTHEADER
143 specifies extra headers for the form POST section. This takes a curl_slist
144 prepared in the usual way using \fBcurl_slist_append\fP and appends the list
145 of headers to those libcurl automatically generates. The list must exist while
146 the POST occurs, if you free it before the post completes you may experience
149 When you've passed the HttpPost pointer to \fIcurl_easy_setopt(3)\fP (using
150 the \fICURLOPT_HTTPPOST(3)\fP option), you must not free the list until after
151 you've called \fIcurl_easy_cleanup(3)\fP for the curl handle.
155 0 means everything was ok, non-zero means an error occurred corresponding
156 to a CURL_FORMADD_* constant defined in
161 struct curl_httppost* post = NULL;
162 struct curl_httppost* last = NULL;
163 char namebuffer[] = "name buffer";
164 long namelength = strlen(namebuffer);
165 char buffer[] = "test buffer";
166 char htmlbuffer[] = "<HTML>test buffer</HTML>";
167 long htmlbufferlength = strlen(htmlbuffer);
168 struct curl_forms forms[3];
169 char file1[] = "my-face.jpg";
170 char file2[] = "your-face.jpg";
171 /* add null character into htmlbuffer, to demonstrate that
172 transfers of buffers containing null characters actually work
174 htmlbuffer[8] = '\\0';
176 /* Add simple name/content section */
177 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name",
178 CURLFORM_COPYCONTENTS, "content", CURLFORM_END);
180 /* Add simple name/content/contenttype section */
181 curl_formadd(&post, &last, CURLFORM_COPYNAME, "htmlcode",
182 CURLFORM_COPYCONTENTS, "<HTML></HTML>",
183 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
185 /* Add name/ptrcontent section */
186 curl_formadd(&post, &last, CURLFORM_COPYNAME, "name_for_ptrcontent",
187 CURLFORM_PTRCONTENTS, buffer, CURLFORM_END);
189 /* Add ptrname/ptrcontent section */
190 curl_formadd(&post, &last, CURLFORM_PTRNAME, namebuffer,
191 CURLFORM_PTRCONTENTS, buffer, CURLFORM_NAMELENGTH,
192 namelength, CURLFORM_END);
194 /* Add name/ptrcontent/contenttype section */
195 curl_formadd(&post, &last, CURLFORM_COPYNAME, "html_code_with_hole",
196 CURLFORM_PTRCONTENTS, htmlbuffer,
197 CURLFORM_CONTENTSLENGTH, htmlbufferlength,
198 CURLFORM_CONTENTTYPE, "text/html", CURLFORM_END);
200 /* Add simple file section */
201 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
202 CURLFORM_FILE, "my-face.jpg", CURLFORM_END);
204 /* Add file/contenttype section */
205 curl_formadd(&post, &last, CURLFORM_COPYNAME, "picture",
206 CURLFORM_FILE, "my-face.jpg",
207 CURLFORM_CONTENTTYPE, "image/jpeg", CURLFORM_END);
209 /* Add two file section */
210 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
211 CURLFORM_FILE, "my-face.jpg",
212 CURLFORM_FILE, "your-face.jpg", CURLFORM_END);
214 /* Add two file section using CURLFORM_ARRAY */
215 forms[0].option = CURLFORM_FILE;
216 forms[0].value = file1;
217 forms[1].option = CURLFORM_FILE;
218 forms[1].value = file2;
219 forms[2].option = CURLFORM_END;
221 /* Add a buffer to upload */
222 curl_formadd(&post, &last,
223 CURLFORM_COPYNAME, "name",
224 CURLFORM_BUFFER, "data",
225 CURLFORM_BUFFERPTR, record,
226 CURLFORM_BUFFERLENGTH, record_length,
229 /* no option needed for the end marker */
230 curl_formadd(&post, &last, CURLFORM_COPYNAME, "pictures",
231 CURLFORM_ARRAY, forms, CURLFORM_END);
232 /* Add the content of a file as a normal post text value */
233 curl_formadd(&post, &last, CURLFORM_COPYNAME, "filecontent",
234 CURLFORM_FILECONTENT, ".bashrc", CURLFORM_END);
235 /* Set the form info */
236 curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
239 .BR curl_easy_setopt "(3), "
240 .BR curl_formfree "(3)"