Avoid assuming layout of fd_set

POSIX doesn't specify the internal layout of the fd_set object, so let's
not assume it is just a bit mask. This increases compatibility with
systems that have a different layout.

The assumption is also worthless as we already refuse to use file
descriptors over FD_SETSIZE anyway. Meaning that the default size of
fd_set is quite sufficient.

diff --git a/openbsd-compat/bsd-poll.c b/openbsd-compat/bsd-poll.c
index 9a9794f5863be1509765a9f7c6e1cc9a936444df..967f947b21fd6035c6daa1300d61a0650913f924 100644 (file)
--- a/openbsd-compat/bsd-poll.c
+++ b/openbsd-compat/bsd-poll.c
@@ -47,9 +47,8 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
     const sigset_t *sigmask)
 {
        nfds_t i;
-       int saved_errno, ret, fd, maxfd = 0;
-       fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
-       size_t nmemb;
+       int ret, fd, maxfd = 0;
+       fd_set readfds, writefds, exceptfds;
 
        for (i = 0; i < nfds; i++) {
                fd = fds[i].fd;
@@ -60,30 +59,23 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
                maxfd = MAX(maxfd, fd);
        }
 
-       nmemb = howmany(maxfd + 1 , NFDBITS);
-       if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
-           (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
-           (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
-               saved_errno = ENOMEM;
-               ret = -1;
-               goto out;
-       }
-
        /* populate event bit vectors for the events we're interested in */
+       FD_ZERO(&readfds);
+       FD_ZERO(&writefds);
+       FD_ZERO(&exceptfds);
        for (i = 0; i < nfds; i++) {
                fd = fds[i].fd;
                if (fd == -1)
                        continue;
                if (fds[i].events & POLLIN)
-                       FD_SET(fd, readfds);
+                       FD_SET(fd, &readfds);
                if (fds[i].events & POLLOUT)
-                       FD_SET(fd, writefds);
+                       FD_SET(fd, &writefds);
                if (fds[i].events & POLLPRI)
-                       FD_SET(fd, exceptfds);
+                       FD_SET(fd, &exceptfds);
        }
 
-       ret = pselect(maxfd + 1, readfds, writefds, exceptfds, tmoutp, sigmask);
-       saved_errno = errno;
+       ret = pselect(maxfd + 1, &readfds, &writefds, &exceptfds, tmoutp, sigmask);
 
        /* scan through select results and set poll() flags */
        for (i = 0; i < nfds; i++) {
@@ -91,20 +83,14 @@ ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
                fds[i].revents = 0;
                if (fd == -1)
                        continue;
-               if ((fds[i].events & POLLIN) && FD_ISSET(fd, readfds))
+               if ((fds[i].events & POLLIN) && FD_ISSET(fd, &readfds))
                        fds[i].revents |= POLLIN;
-               if ((fds[i].events & POLLOUT) && FD_ISSET(fd, writefds))
+               if ((fds[i].events & POLLOUT) && FD_ISSET(fd, &writefds))
                        fds[i].revents |= POLLOUT;
-               if ((fds[i].events & POLLPRI) && FD_ISSET(fd, exceptfds))
+               if ((fds[i].events & POLLPRI) && FD_ISSET(fd, &exceptfds))
                        fds[i].revents |= POLLPRI;
        }
 
-out:
-       free(readfds);
-       free(writefds);
-       free(exceptfds);
-       if (ret == -1)
-               errno = saved_errno;
        return ret;
 }
 #endif /* !HAVE_PPOLL || BROKEN_POLL */