examples/complicated: fix warnings, bump deprecated callback, tidy up

Also: make them C89, add consts.

Closes #15785

docs/examples/crawler.c

@@ -30,14 +30,6 @@
  * </DESC>
  */
 
-/* Parameters */
-int max_con = 200;
-int max_total = 20000;
-int max_requests = 500;
-int max_link_per_page = 5;
-int follow_relative_links = 0;
-char *start_page = "https://www.reuters.com";
-
 #include <libxml/HTMLparser.h>
 #include <libxml/xpath.h>
 #include <libxml/uri.h>
@@ -47,9 +39,18 @@ char *start_page = "https://www.reuters.com";
 #include <math.h>
 #include <signal.h>
 
-int pending_interrupt = 0;
-void sighandler(int dummy)
+/* Parameters */
+static int max_con = 200;
+static int max_total = 20000;
+static int max_requests = 500;
+static size_t max_link_per_page = 5;
+static int follow_relative_links = 0;
+static const char *start_page = "https://www.reuters.com";
+
+static int pending_interrupt = 0;
+static void sighandler(int dummy)
 {
+  (void)dummy;
   pending_interrupt = 1;
 }
 
@@ -59,7 +60,7 @@ typedef struct {
   size_t size;
 } memory;
 
-size_t grow_buffer(void *contents, size_t sz, size_t nmemb, void *ctx)
+static size_t grow_buffer(void *contents, size_t sz, size_t nmemb, void *ctx)
 {
   size_t realsize = sz * nmemb;
   memory *mem = (memory*) ctx;
@@ -75,16 +76,17 @@ size_t grow_buffer(void *contents, size_t sz, size_t nmemb, void *ctx)
   return realsize;
 }
 
-CURL *make_handle(char *url)
+static CURL *make_handle(const char *url)
 {
   CURL *handle = curl_easy_init();
+  memory *mem;
 
   /* Important: use HTTP2 over HTTPS */
   curl_easy_setopt(handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
   curl_easy_setopt(handle, CURLOPT_URL, url);
 
   /* buffer body */
-  memory *mem = malloc(sizeof(memory));
+  mem = malloc(sizeof(memory));
   mem->size = 0;
   mem->buf = malloc(1);
   curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, grow_buffer);
@@ -117,37 +119,43 @@ CURL *make_handle(char *url)
 }
 
 /* HREF finder implemented in libxml2 but could be any HTML parser */
-size_t follow_links(CURLM *multi_handle, memory *mem, char *url)
+static size_t follow_links(CURLM *multi_handle, memory *mem, const char *url)
 {
   int opts = HTML_PARSE_NOBLANKS | HTML_PARSE_NOERROR | \
              HTML_PARSE_NOWARNING | HTML_PARSE_NONET;
-  htmlDocPtr doc = htmlReadMemory(mem->buf, mem->size, url, NULL, opts);
+  htmlDocPtr doc = htmlReadMemory(mem->buf, (int)mem->size, url, NULL, opts);
+  size_t count;
+  int i;
+  xmlChar *xpath;
+  xmlNodeSetPtr nodeset;
+  xmlXPathContextPtr context;
+  xmlXPathObjectPtr result;
   if(!doc)
     return 0;
-  xmlChar *xpath = (xmlChar*) "//a/@href";
-  xmlXPathContextPtr context = xmlXPathNewContext(doc);
-  xmlXPathObjectPtr result = xmlXPathEvalExpression(xpath, context);
+  xpath = (xmlChar*) "//a/@href";
+  context = xmlXPathNewContext(doc);
+  result = xmlXPathEvalExpression(xpath, context);
   xmlXPathFreeContext(context);
   if(!result)
     return 0;
-  xmlNodeSetPtr nodeset = result->nodesetval;
+  nodeset = result->nodesetval;
   if(xmlXPathNodeSetIsEmpty(nodeset)) {
     xmlXPathFreeObject(result);
     return 0;
   }
-  size_t count = 0;
-  int i;
+  count = 0;
   for(i = 0; i < nodeset->nodeNr; i++) {
     double r = rand();
-    int x = r * nodeset->nodeNr / RAND_MAX;
+    int x = (int)(r * nodeset->nodeNr / RAND_MAX);
     const xmlNode *node = nodeset->nodeTab[x]->xmlChildrenNode;
     xmlChar *href = xmlNodeListGetString(doc, node, 1);
+    char *link;
     if(follow_relative_links) {
       xmlChar *orig = href;
       href = xmlBuildURI(href, (xmlChar *) url);
       xmlFree(orig);
     }
-    char *link = (char *) href;
+    link = (char *) href;
     if(!link || strlen(link) < 20)
       continue;
     if(!strncmp(link, "http://", 7) || !strncmp(link, "https://", 8)) {
@@ -161,17 +169,23 @@ size_t follow_links(CURLM *multi_handle, memory *mem, char *url)
   return count;
 }
 
-int is_html(char *ctype)
+static int is_html(char *ctype)
 {
   return ctype != NULL && strlen(ctype) > 10 && strstr(ctype, "text/html");
 }
 
 int main(void)
 {
+  CURLM *multi_handle;
+  int msgs_left;
+  int pending;
+  int complete;
+  int still_running;
+
   signal(SIGINT, sighandler);
-  LIBXML_TEST_VERSION;
+  LIBXML_TEST_VERSION
   curl_global_init(CURL_GLOBAL_DEFAULT);
-  CURLM *multi_handle = curl_multi_init();
+  multi_handle = curl_multi_init();
   curl_multi_setopt(multi_handle, CURLMOPT_MAX_TOTAL_CONNECTIONS, max_con);
   curl_multi_setopt(multi_handle, CURLMOPT_MAX_HOST_CONNECTIONS, 6L);
 
@@ -183,17 +197,18 @@ int main(void)
   /* sets html start page */
   curl_multi_add_handle(multi_handle, make_handle(start_page));
 
-  int msgs_left;
-  int pending = 0;
-  int complete = 0;
-  int still_running = 1;
+  pending = 0;
+  complete = 0;
+  still_running = 1;
   while(still_running && !pending_interrupt) {
     int numfds;
+    CURLMsg *m;
+
     curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
     curl_multi_perform(multi_handle, &still_running);
 
     /* See how the transfers went */
-    CURLMsg *m = NULL;
+    m = NULL;
     while((m = curl_multi_info_read(multi_handle, &msgs_left))) {
       if(m->msg == CURLMSG_DONE) {
         CURL *handle = m->easy_handle;