select: fix poll-based check not detecting connect failure

This commit changes Curl_socket_check to use POLLPRI to
check for connect failure on the write socket, because
POLLPRI maps to fds_err. This is in line with select(2).

The select-based socket check correctly checks for connect
failures by adding the write socket also to fds_err.

The poll-based implementation (which internally can itself
fallback to select again) did not previously check for
connect failure by using POLLPRI with the write socket.

See the follow up commit to this for more information.

This commit makes sure connect failures can be detected
and handled if HAVE_POLL_FINE is defined, eg. on msys2-devel.

Reviewed-by: Daniel Stenberg
Reviewed-by: Jay Satiro
Replaces #5509
Prepares #5707

diff --git a/lib/select.c b/lib/select.c
index abb124ae8fe6a70c5c1b889a1271885ea2cc4b57..3928b12dc59d0f941bfe2da076fd2ca87e4c0c89 100644 (file)
--- a/lib/select.c
+++ b/lib/select.c
@@ -288,7 +288,7 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
   }
   if(writefd != CURL_SOCKET_BAD) {
     pfd[num].fd = writefd;
-    pfd[num].events = POLLWRNORM|POLLOUT;
+    pfd[num].events = POLLWRNORM|POLLOUT|POLLPRI;
     pfd[num].revents = 0;
     num++;
   }
@@ -316,7 +316,7 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
   if(writefd != CURL_SOCKET_BAD) {
     if(pfd[num].revents & (POLLWRNORM|POLLOUT))
       ret |= CURL_CSELECT_OUT;
-    if(pfd[num].revents & (POLLERR|POLLHUP|POLLNVAL))
+    if(pfd[num].revents & (POLLERR|POLLHUP|POLLPRI|POLLNVAL))
       ret |= CURL_CSELECT_ERR;
   }