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Annotation of embedaddon/curl/docs/examples/post-callback.c, revision 1.1.1.1

1.1       misho       1: /***************************************************************************
                      2:  *                                  _   _ ____  _
                      3:  *  Project                     ___| | | |  _ \| |
                      4:  *                             / __| | | | |_) | |
                      5:  *                            | (__| |_| |  _ <| |___
                      6:  *                             \___|\___/|_| \_\_____|
                      7:  *
                      8:  * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
                      9:  *
                     10:  * This software is licensed as described in the file COPYING, which
                     11:  * you should have received as part of this distribution. The terms
                     12:  * are also available at https://curl.haxx.se/docs/copyright.html.
                     13:  *
                     14:  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
                     15:  * copies of the Software, and permit persons to whom the Software is
                     16:  * furnished to do so, under the terms of the COPYING file.
                     17:  *
                     18:  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
                     19:  * KIND, either express or implied.
                     20:  *
                     21:  ***************************************************************************/
                     22: /* <DESC>
                     23:  * Issue an HTTP POST and provide the data through the read callback.
                     24:  * </DESC>
                     25:  */
                     26: #include <stdio.h>
                     27: #include <string.h>
                     28: #include <curl/curl.h>
                     29: 
                     30: /* silly test data to POST */
                     31: static const char data[]="Lorem ipsum dolor sit amet, consectetur adipiscing "
                     32:   "elit. Sed vel urna neque. Ut quis leo metus. Quisque eleifend, ex at "
                     33:   "laoreet rhoncus, odio ipsum semper metus, at tempus ante urna in mauris. "
                     34:   "Suspendisse ornare tempor venenatis. Ut dui neque, pellentesque a varius "
                     35:   "eget, mattis vitae ligula. Fusce ut pharetra est. Ut ullamcorper mi ac "
                     36:   "sollicitudin semper. Praesent sit amet tellus varius, posuere nulla non, "
                     37:   "rhoncus ipsum.";
                     38: 
                     39: struct WriteThis {
                     40:   const char *readptr;
                     41:   size_t sizeleft;
                     42: };
                     43: 
                     44: static size_t read_callback(void *dest, size_t size, size_t nmemb, void *userp)
                     45: {
                     46:   struct WriteThis *wt = (struct WriteThis *)userp;
                     47:   size_t buffer_size = size*nmemb;
                     48: 
                     49:   if(wt->sizeleft) {
                     50:     /* copy as much as possible from the source to the destination */
                     51:     size_t copy_this_much = wt->sizeleft;
                     52:     if(copy_this_much > buffer_size)
                     53:       copy_this_much = buffer_size;
                     54:     memcpy(dest, wt->readptr, copy_this_much);
                     55: 
                     56:     wt->readptr += copy_this_much;
                     57:     wt->sizeleft -= copy_this_much;
                     58:     return copy_this_much; /* we copied this many bytes */
                     59:   }
                     60: 
                     61:   return 0; /* no more data left to deliver */
                     62: }
                     63: 
                     64: int main(void)
                     65: {
                     66:   CURL *curl;
                     67:   CURLcode res;
                     68: 
                     69:   struct WriteThis wt;
                     70: 
                     71:   wt.readptr = data;
                     72:   wt.sizeleft = strlen(data);
                     73: 
                     74:   /* In windows, this will init the winsock stuff */
                     75:   res = curl_global_init(CURL_GLOBAL_DEFAULT);
                     76:   /* Check for errors */
                     77:   if(res != CURLE_OK) {
                     78:     fprintf(stderr, "curl_global_init() failed: %s\n",
                     79:             curl_easy_strerror(res));
                     80:     return 1;
                     81:   }
                     82: 
                     83:   /* get a curl handle */
                     84:   curl = curl_easy_init();
                     85:   if(curl) {
                     86:     /* First set the URL that is about to receive our POST. */
                     87:     curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/index.cgi");
                     88: 
                     89:     /* Now specify we want to POST data */
                     90:     curl_easy_setopt(curl, CURLOPT_POST, 1L);
                     91: 
                     92:     /* we want to use our own read function */
                     93:     curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
                     94: 
                     95:     /* pointer to pass to our read function */
                     96:     curl_easy_setopt(curl, CURLOPT_READDATA, &wt);
                     97: 
                     98:     /* get verbose debug output please */
                     99:     curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
                    100: 
                    101:     /*
                    102:       If you use POST to a HTTP 1.1 server, you can send data without knowing
                    103:       the size before starting the POST if you use chunked encoding. You
                    104:       enable this by adding a header like "Transfer-Encoding: chunked" with
                    105:       CURLOPT_HTTPHEADER. With HTTP 1.0 or without chunked transfer, you must
                    106:       specify the size in the request.
                    107:     */
                    108: #ifdef USE_CHUNKED
                    109:     {
                    110:       struct curl_slist *chunk = NULL;
                    111: 
                    112:       chunk = curl_slist_append(chunk, "Transfer-Encoding: chunked");
                    113:       res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk);
                    114:       /* use curl_slist_free_all() after the *perform() call to free this
                    115:          list again */
                    116:     }
                    117: #else
                    118:     /* Set the expected POST size. If you want to POST large amounts of data,
                    119:        consider CURLOPT_POSTFIELDSIZE_LARGE */
                    120:     curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long)wt.sizeleft);
                    121: #endif
                    122: 
                    123: #ifdef DISABLE_EXPECT
                    124:     /*
                    125:       Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue"
                    126:       header.  You can disable this header with CURLOPT_HTTPHEADER as usual.
                    127:       NOTE: if you want chunked transfer too, you need to combine these two
                    128:       since you can only set one list of headers with CURLOPT_HTTPHEADER. */
                    129: 
                    130:     /* A less good option would be to enforce HTTP 1.0, but that might also
                    131:        have other implications. */
                    132:     {
                    133:       struct curl_slist *chunk = NULL;
                    134: 
                    135:       chunk = curl_slist_append(chunk, "Expect:");
                    136:       res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk);
                    137:       /* use curl_slist_free_all() after the *perform() call to free this
                    138:          list again */
                    139:     }
                    140: #endif
                    141: 
                    142:     /* Perform the request, res will get the return code */
                    143:     res = curl_easy_perform(curl);
                    144:     /* Check for errors */
                    145:     if(res != CURLE_OK)
                    146:       fprintf(stderr, "curl_easy_perform() failed: %s\n",
                    147:               curl_easy_strerror(res));
                    148: 
                    149:     /* always cleanup */
                    150:     curl_easy_cleanup(curl);
                    151:   }
                    152:   curl_global_cleanup();
                    153:   return 0;
                    154: }