decomp: avoid unreliable waitall mode of net_Read()

modules/stream_filter/decomp.c

@@ -237,16 +237,15 @@ static int Peek (stream_t *stream, const uint8_t **pbuf, unsigned int len)
     if ((p_sys->peeked = peeked) == NULL)
         return 0;
 
-    if (curlen < len)
+    while (curlen < len)
     {
         ssize_t val = net_Read (stream, fd, NULL, peeked->p_buffer + curlen,
-                                len - curlen, true);
-        if (val >= 0)
-        {
+                                len - curlen, false);
+        if (val <= 0)
+            break;
         curlen += val;
         peeked->i_buffer = curlen;
     }
-    }
     *pbuf = peeked->p_buffer;
     return curlen;
 }