examples: consistent variable naming across examples

- 'CURL *' handles are called 'curl'
- 'CURLM *' handles are called 'multi'
- write callbacks are called 'write_cb'
- read callbacs are called 'read_cb'
- CURLcode variables are called 'res'

It makes the examples look and feel more consistent. It allows for
easier copy and pasting between examples.

Closes #19299

docs/examples/http2-serverpush.c

@@ -89,11 +89,11 @@ static void dump(const char *text, unsigned char *ptr, size_t size, char nohex)
   }
 }
 
-static int my_trace(CURL *handle, curl_infotype type,
+static int my_trace(CURL *curl, curl_infotype type,
                     char *data, size_t size, void *userp)
 {
   const char *text;
-  (void)handle;
+  (void)curl;
   (void)userp;
   switch(type) {
   case CURLINFO_TEXT:
@@ -127,32 +127,32 @@ static int my_trace(CURL *handle, curl_infotype type,
 
 #define OUTPUTFILE "dl"
 
-static int setup(CURL *hnd, const char *url)
+static int setup(CURL *curl, const char *url)
 {
   out_download = fopen(OUTPUTFILE, "wb");
   if(!out_download)
     return 1;  /* failed */
 
   /* set the same URL */
-  curl_easy_setopt(hnd, CURLOPT_URL, url);
+  curl_easy_setopt(curl, CURLOPT_URL, url);
 
   /* HTTP/2 please */
-  curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
+  curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
 
   /* we use a self-signed test server, skip verification during debugging */
-  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYPEER, 0L);
-  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYHOST, 0L);
+  curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
+  curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
 
   /* write to this file */
-  curl_easy_setopt(hnd, CURLOPT_WRITEDATA, out_download);
+  curl_easy_setopt(curl, CURLOPT_WRITEDATA, out_download);
 
   /* please be verbose */
-  curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
-  curl_easy_setopt(hnd, CURLOPT_DEBUGFUNCTION, my_trace);
+  curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, my_trace);
 
 #if CURLPIPE_MULTIPLEX > 0
   /* wait for pipe connection to confirm */
-  curl_easy_setopt(hnd, CURLOPT_PIPEWAIT, 1L);
+  curl_easy_setopt(curl, CURLOPT_PIPEWAIT, 1L);
 #endif
   return 0; /* all is good */
 }
@@ -161,7 +161,7 @@ static FILE *out_push;
 
 /* called when there is an incoming push */
 static int server_push_callback(CURL *parent,
-                                CURL *easy,
+                                CURL *curl,
                                 size_t num_headers,
                                 struct curl_pushheaders *headers,
                                 void *userp)
@@ -185,7 +185,7 @@ static int server_push_callback(CURL *parent,
   }
 
   /* write to this file */
-  curl_easy_setopt(easy, CURLOPT_WRITEDATA, out_push);
+  curl_easy_setopt(curl, CURLOPT_WRITEDATA, out_push);
 
   fprintf(stderr, "**** push callback approves stream %u, got %lu headers!\n",
           count, (unsigned long)num_headers);
@@ -211,8 +211,8 @@ static int server_push_callback(CURL *parent,
 int main(int argc, char *argv[])
 {
   CURLcode res;
-  CURL *easy;
-  CURLM *multi_handle;
+  CURL *curl;
+  CURLM *multi;
   int transfers = 1; /* we start with one */
   const char *url = "https://localhost:8443/index.html";
 
@@ -224,33 +224,33 @@ int main(int argc, char *argv[])
     return (int)res;
 
   /* init a multi stack */
-  multi_handle = curl_multi_init();
-  if(!multi_handle)
+  multi = curl_multi_init();
+  if(!multi)
     goto error;
 
-  easy = curl_easy_init();
+  curl = curl_easy_init();
 
   /* set options */
-  if(!easy || setup(easy, url)) {
+  if(!curl || setup(curl, url)) {
     fprintf(stderr, "failed\n");
     goto error;
   }
 
-  curl_multi_setopt(multi_handle, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
-  curl_multi_setopt(multi_handle, CURLMOPT_PUSHFUNCTION, server_push_callback);
-  curl_multi_setopt(multi_handle, CURLMOPT_PUSHDATA, &transfers);
+  curl_multi_setopt(multi, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
+  curl_multi_setopt(multi, CURLMOPT_PUSHFUNCTION, server_push_callback);
+  curl_multi_setopt(multi, CURLMOPT_PUSHDATA, &transfers);
 
   /* add the easy transfer */
-  curl_multi_add_handle(multi_handle, easy);
+  curl_multi_add_handle(multi, curl);
 
   do {
     struct CURLMsg *m;
     int still_running; /* keep number of running handles */
-    CURLMcode mc = curl_multi_perform(multi_handle, &still_running);
+    CURLMcode mc = curl_multi_perform(multi, &still_running);
 
     if(still_running)
       /* wait for activity, timeout or "nothing" */
-      mc = curl_multi_poll(multi_handle, NULL, 0, 1000, NULL);
+      mc = curl_multi_poll(multi, NULL, 0, 1000, NULL);
 
     if(mc)
       break;
@@ -262,12 +262,12 @@ int main(int argc, char *argv[])
      */
     do {
       int msgq = 0;
-      m = curl_multi_info_read(multi_handle, &msgq);
+      m = curl_multi_info_read(multi, &msgq);
       if(m && (m->msg == CURLMSG_DONE)) {
-        CURL *e = m->easy_handle;
+        curl = m->easy_handle;
         transfers--;
-        curl_multi_remove_handle(multi_handle, e);
-        curl_easy_cleanup(e);
+        curl_multi_remove_handle(multi, curl);
+        curl_easy_cleanup(curl);
       }
     } while(m);
 
@@ -275,8 +275,8 @@ int main(int argc, char *argv[])
 
 error:
 
-  if(multi_handle)
-    curl_multi_cleanup(multi_handle);
+  if(multi)
+    curl_multi_cleanup(multi);
 
   curl_global_cleanup();