curl: split curl_find_state/curl_init_state

If curl_easy_init fails, a CURLState is left with s->in_use = 1.  Split
curl_init_state in two, so that we can distinguish the two failures and
call curl_clean_state if needed.

While at it, simplify curl_find_state, removing a dummy loop.  The
aio_poll loop is moved to the sole caller that needs it.
Reviewed-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20170515100059.15795-5-pbonzini@redhat.com
Signed-off-by: NJeff Cody <jcody@redhat.com>

block/curl.c

@@ -456,34 +456,27 @@ static void curl_multi_timeout_do(void *arg)
 }
 
 /* Called with s->mutex held.  */
-static CURLState *curl_init_state(BlockDriverState *bs, BDRVCURLState *s)
+static CURLState *curl_find_state(BDRVCURLState *s)
 {
     CURLState *state = NULL;
-    int i, j;
-
-    do {
-        for (i=0; i<CURL_NUM_STATES; i++) {
-            for (j=0; j<CURL_NUM_ACB; j++)
-                if (s->states[i].acb[j])
-                    continue;
-            if (s->states[i].in_use)
-                continue;
+    int i;
 
+    for (i = 0; i < CURL_NUM_STATES; i++) {
+        if (!s->states[i].in_use) {
             state = &s->states[i];
             state->in_use = 1;
             break;
         }
-        if (!state) {
-            qemu_mutex_unlock(&s->mutex);
-            aio_poll(bdrv_get_aio_context(bs), true);
-            qemu_mutex_lock(&s->mutex);
-        }
-    } while(!state);
+    }
+    return state;
+}
 
+static int curl_init_state(BDRVCURLState *s, CURLState *state)
+{
     if (!state->curl) {
         state->curl = curl_easy_init();
         if (!state->curl) {
-            return NULL;
+            return -EIO;
         }
         curl_easy_setopt(state->curl, CURLOPT_URL, s->url);
         curl_easy_setopt(state->curl, CURLOPT_SSL_VERIFYPEER,
@@ -536,7 +529,7 @@ static CURLState *curl_init_state(BlockDriverState *bs, BDRVCURLState *s)
     QLIST_INIT(&state->sockets);
     state->s = s;
 
-    return state;
+    return 0;
 }
 
 /* Called with s->mutex held.  */
@@ -778,13 +771,18 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags,
     s->aio_context = bdrv_get_aio_context(bs);
     s->url = g_strdup(file);
     qemu_mutex_lock(&s->mutex);
-    state = curl_init_state(bs, s);
+    state = curl_find_state(s);
     qemu_mutex_unlock(&s->mutex);
-    if (!state)
+    if (!state) {
         goto out_noclean;
+    }
 
     // Get file size
 
+    if (curl_init_state(s, state) < 0) {
+        goto out;
+    }
+
     s->accept_range = false;
     curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1);
     curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION,
@@ -879,8 +877,18 @@ static void curl_readv_bh_cb(void *p)
     }
 
     // No cache found, so let's start a new request
-    state = curl_init_state(acb->common.bs, s);
-    if (!state) {
+    for (;;) {
+        state = curl_find_state(s);
+        if (state) {
+            break;
+        }
+        qemu_mutex_unlock(&s->mutex);
+        aio_poll(bdrv_get_aio_context(bs), true);
+        qemu_mutex_lock(&s->mutex);
+    }
+
+    if (curl_init_state(s, state) < 0) {
+        curl_clean_state(state);
         ret = -EIO;
         goto out;
     }