new example for libcurl 7.9.6 or later

docs/examples/Makefile.am

@@ -7,7 +7,7 @@ AUTOMAKE_OPTIONS = foreign no-dependencies
 EXTRA_DIST = README curlgtk.c sepheaders.c simple.c postit2.c \
 	     win32sockets.c persistant.c ftpget.c Makefile.example \
 	     multithread.c getinmemory.c ftpupload.c httpput.c \
-	     simplessl.c ftpgetresp.c http-post.c
+	     simplessl.c ftpgetresp.c http-post.c post-callback.c
 
 all:
 	@echo "done"

docs/examples/post-callback.c

@@ -0,0 +1,89 @@
+/*****************************************************************************
+ *                                  _   _ ____  _     
+ *  Project                     ___| | | |  _ \| |    
+ *                             / __| | | | |_) | |    
+ *                            | (__| |_| |  _ <| |___ 
+ *                             \___|\___/|_| \_\_____|
+ *
+ * $Id$
+ *
+ * An example source code that issues a HTTP POST and we provide the actual
+ * data through a read callback.
+ *
+ * Please be aware of the fact that the size of the posted data MUST be
+ * specified before the transfer is being made (with CURLOPT_POSTFIELDSIZE).
+ * This requirement will change when libcurl starts supporting chunked-encoded
+ * sends.
+ *
+ * This example requires libcurl 7.9.6 or later.
+ */
+#include <stdio.h>
+#include <string.h>
+#include <curl/curl.h>
+
+#if LIBCURL_VERSION_NUM < 0x070906
+#error this example source requires libcurl 7.9.6 or newer
+#endif
+
+char data[]="this is what we post to the silly web server";
+
+struct WriteThis {
+  char *readptr;
+  int sizeleft;
+};
+
+size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp)
+{
+  struct WriteThis *pooh = (struct WriteThis *)userp;
+
+  if(size*nmemb < 1)
+    return 0;
+
+  if(pooh->sizeleft) {
+    *(char *)ptr = pooh->readptr[0]; /* copy one single byte */
+    pooh->readptr++;                 /* advance pointer */
+    pooh->sizeleft--;                /* less data left */
+    return 1;                        /* we return 1 byte at a time! */
+  }
+
+  return -1;                         /* no more data left to deliver */
+}
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+
+  struct WriteThis pooh;
+
+  pooh.readptr = data;
+  pooh.sizeleft = strlen(data);
+
+  curl = curl_easy_init();
+  if(curl) {
+    /* First set the URL that is about to receive our POST. */
+    curl_easy_setopt(curl, CURLOPT_URL,
+                     "http://receivingsite.com.pooh/index.cgi");
+    /* Now specify we want to POST data */
+    curl_easy_setopt(curl, CURLOPT_POST, TRUE);
+
+    /* Set the expected POST size */
+    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, pooh.sizeleft);
+
+    /* we want to use our own read function */
+    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
+
+    /* pointer to pass to our read function */
+    curl_easy_setopt(curl, CURLOPT_INFILE, &pooh);
+
+    /* get verbose debug output please */
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
+
+    /* Perform the request, res will get the return code */
+    res = curl_easy_perform(curl);
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+  }
+  return 0;
+}