tpm: fix crash when FD >= 1024 and unnecessary errors due to EINTR

Replace select() with poll() to fix a crash when QEMU has a large number
of FDs. Also use RETRY_ON_EINTR to avoid unnecessary errors due to EINTR.

Cc: qemu-stable@nongnu.org
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2020133


Fixes: 56a3c24f ("tpm: Probe for connected TPM 1.2 or TPM 2")
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

backends/tpm/tpm_util.c

@@ -112,12 +112,8 @@ static int tpm_util_request(int fd,
                             void *response,
                             size_t responselen)
 {
-    fd_set readfds;
+    GPollFD fds[1] = { {.fd = fd, .events = G_IO_IN } };
     int n;
-    struct timeval tv = {
-        .tv_sec = 1,
-        .tv_usec = 0,
-    };
 
     n = write(fd, request, requestlen);
     if (n < 0) {
@@ -127,11 +123,8 @@ static int tpm_util_request(int fd,
         return -EFAULT;
     }
 
-    FD_ZERO(&readfds);
-    FD_SET(fd, &readfds);
-
     /* wait for a second */
-    n = select(fd + 1, &readfds, NULL, NULL, &tv);
+    n = RETRY_ON_EINTR(g_poll(fds, 1, 1000));
     if (n != 1) {
         return -errno;
     }