test536: do not fail with threaded DNS resolver

Also tweaked comments in certain examples using curl_multi_fdset().

1 files changed, 5 insertions, 3 deletions

diff --git a/docs/examples/multi-post.c b/docs/examples/multi-post.c
index 229e84306..0d3f78e5e 100644
--- a/docs/examples/multi-post.c
+++ b/docs/examples/multi-post.c
@@ -77,7 +77,7 @@ int main(int argc, char *argv[])
       fd_set fdread;
       fd_set fdwrite;
       fd_set fdexcep;
-      int maxfd;
+      int maxfd = -1;
 
       FD_ZERO(&fdread);
       FD_ZERO(&fdwrite);
@@ -91,8 +91,10 @@ int main(int argc, char *argv[])
       curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
 
       /* In a real-world program you OF COURSE check the return code of the
-         function calls, *and* you make sure that maxfd is bigger than -1
-         so that the call to select() below makes sense! */
+         function calls.  On success, the value of maxfd is guaranteed to be
+         greater or equal than -1.  We call select(maxfd + 1, ...), specially in
+         case of (maxfd == -1), we call select(0, ...), which is basically equal
+         to sleep. */
 
       rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);