asyn: use 'struct thread_data *' instead of 'void *'

To reduce use of types that can't be checked at compile time. Also
removes several typecasts.

... and rename the struct field from 'os_specific' to 'tdata'.

Closes #6239
Reviewed-by: Jay Satiro

lib/asyn-ares.c

@@ -85,7 +85,7 @@
 #include "curl_memory.h"
 #include "memdebug.h"
 
-struct ResolverResults {
+struct thread_data {
   int num_pending; /* number of ares_gethostbyname() requests */
   struct Curl_addrinfo *temp_ai; /* intermediary result while fetching c-ares
                                     parts */
@@ -229,8 +229,8 @@ static void destroy_async_data(struct Curl_async *async)
 {
   free(async->hostname);
 
-  if(async->os_specific) {
-    struct ResolverResults *res = (struct ResolverResults *)async->os_specific;
+  if(async->tdata) {
+    struct thread_data *res = async->tdata;
     if(res) {
       if(res->temp_ai) {
         Curl_freeaddrinfo(res->temp_ai);
@@ -238,7 +238,7 @@ static void destroy_async_data(struct Curl_async *async)
       }
       free(res);
     }
-    async->os_specific = NULL;
+    async->tdata = NULL;
   }
 
   async->hostname = NULL;
@@ -349,8 +349,7 @@ CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
                                    struct Curl_dns_entry **dns)
 {
   struct Curl_easy *data = conn->data;
-  struct ResolverResults *res = (struct ResolverResults *)
-    conn->async.os_specific;
+  struct thread_data *res = conn->async.tdata;
   CURLcode result = CURLE_OK;
 
   DEBUGASSERT(dns);
@@ -498,7 +497,7 @@ CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
 }
 
 /* Connects results to the list */
-static void compound_results(struct ResolverResults *res,
+static void compound_results(struct thread_data *res,
                              struct Curl_addrinfo *ai)
 {
   struct Curl_addrinfo *ai_tail;
@@ -527,7 +526,7 @@ static void query_completed_cb(void *arg,  /* (struct connectdata *) */
                                struct hostent *hostent)
 {
   struct connectdata *conn = (struct connectdata *)arg;
-  struct ResolverResults *res;
+  struct thread_data *res;
 
 #ifdef HAVE_CARES_CALLBACK_TIMEOUTS
   (void)timeouts; /* ignored */
@@ -538,7 +537,7 @@ static void query_completed_cb(void *arg,  /* (struct connectdata *) */
        be valid so only defer it when we know the 'status' says its fine! */
     return;
 
-  res = (struct ResolverResults *)conn->async.os_specific;
+  res = conn->async.tdata;
   if(res) {
     res->num_pending--;
 
@@ -653,20 +652,20 @@ struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
 
   bufp = strdup(hostname);
   if(bufp) {
-    struct ResolverResults *res = NULL;
+    struct thread_data *res = NULL;
     free(conn->async.hostname);
     conn->async.hostname = bufp;
     conn->async.port = port;
     conn->async.done = FALSE;   /* not done */
     conn->async.status = 0;     /* clear */
     conn->async.dns = NULL;     /* clear */
-    res = calloc(sizeof(struct ResolverResults), 1);
+    res = calloc(sizeof(struct thread_data), 1);
     if(!res) {
       free(conn->async.hostname);
       conn->async.hostname = NULL;
       return NULL;
     }
-    conn->async.os_specific = res;
+    conn->async.tdata = res;
 
     /* initial status - failed */
     res->last_status = ARES_ENOTFOUND;

lib/asyn-thread.c

@@ -185,7 +185,7 @@ struct thread_data {
 
 static struct thread_sync_data *conn_thread_sync_data(struct connectdata *conn)
 {
-  return &(((struct thread_data *)conn->async.os_specific)->tsd);
+  return &(conn->async.tdata->tsd);
 }
 
 /* Destroy resolver thread synchronization data */
@@ -294,7 +294,7 @@ static int getaddrinfo_complete(struct connectdata *conn)
  */
 static unsigned int CURL_STDCALL getaddrinfo_thread(void *arg)
 {
-  struct thread_sync_data *tsd = (struct thread_sync_data*)arg;
+  struct thread_sync_data *tsd = (struct thread_sync_data *)arg;
   struct thread_data *td = tsd->td;
   char service[12];
   int rc;
@@ -380,8 +380,8 @@ static unsigned int CURL_STDCALL gethostbyname_thread(void *arg)
  */
 static void destroy_async_data(struct Curl_async *async)
 {
-  if(async->os_specific) {
-    struct thread_data *td = (struct thread_data*) async->os_specific;
+  if(async->tdata) {
+    struct thread_data *td = async->tdata;
     int done;
 #ifdef USE_SOCKETPAIR
     curl_socket_t sock_rd = td->tsd.sock_pair[0];
@@ -406,7 +406,7 @@ static void destroy_async_data(struct Curl_async *async)
 
       destroy_thread_sync_data(&td->tsd);
 
-      free(async->os_specific);
+      free(async->tdata);
     }
 #ifdef USE_SOCKETPAIR
     /*
@@ -418,7 +418,7 @@ static void destroy_async_data(struct Curl_async *async)
     sclose(sock_rd);
 #endif
   }
-  async->os_specific = NULL;
+  async->tdata = NULL;
 
   free(async->hostname);
   async->hostname = NULL;
@@ -437,7 +437,7 @@ static bool init_resolve_thread(struct connectdata *conn,
   struct thread_data *td = calloc(1, sizeof(struct thread_data));
   int err = ENOMEM;
 
-  conn->async.os_specific = (void *)td;
+  conn->async.tdata = td;
   if(!td)
     goto errno_exit;
 
@@ -448,7 +448,7 @@ static bool init_resolve_thread(struct connectdata *conn,
   td->thread_hnd = curl_thread_t_null;
 
   if(!init_thread_sync_data(td, hostname, port, hints)) {
-    conn->async.os_specific = NULL;
+    conn->async.tdata = NULL;
     free(td);
     goto errno_exit;
   }
@@ -519,7 +519,7 @@ static CURLcode thread_wait_resolv(struct connectdata *conn,
                                    struct Curl_dns_entry **entry,
                                    bool report)
 {
-  struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
+  struct thread_data *td = conn->async.tdata;
   CURLcode result = CURLE_OK;
 
   DEBUGASSERT(conn && td);
@@ -557,7 +557,7 @@ static CURLcode thread_wait_resolv(struct connectdata *conn,
  */
 void Curl_resolver_kill(struct connectdata *conn)
 {
-  struct thread_data *td = (struct thread_data*) conn->async.os_specific;
+  struct thread_data *td = conn->async.tdata;
 
   /* If we're still resolving, we must wait for the threads to fully clean up,
      unfortunately.  Otherwise, we can simply cancel to clean up any resolver
@@ -596,7 +596,7 @@ CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
                                    struct Curl_dns_entry **entry)
 {
   struct Curl_easy *data = conn->data;
-  struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
+  struct thread_data *td = conn->async.tdata;
   int done = 0;
 
   DEBUGASSERT(entry);
@@ -656,7 +656,7 @@ int Curl_resolver_getsock(struct connectdata *conn,
   struct Curl_easy *data = conn->data;
   struct resdata *reslv = (struct resdata *)data->state.resolver;
 #ifdef USE_SOCKETPAIR
-  struct thread_data *td = (struct thread_data*)conn->async.os_specific;
+  struct thread_data *td = conn->async.tdata;
 #else
   (void)socks;
 #endif

lib/urldata.h

@@ -519,7 +519,7 @@ struct Curl_async {
   int port;
   struct Curl_dns_entry *dns;
   int status; /* if done is TRUE, this is the status from the callback */
-  void *os_specific;  /* 'struct thread_data' for Windows */
+  struct thread_data *tdata;
   BIT(done);  /* set TRUE when the lookup is complete */
 };