su: (pty) simplify stdin usage in poll()

Not sure why I have problem with this years ago for script(1), but it
seems .fd=-1 is really enough to the ignore the FD.

Reported-by: Vaclav Dolezal <vdolezal@redhat.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/login-utils/su-common.c b/login-utils/su-common.c
index f873c23bcb8931d2f744697abbf51077fc14c9fd..bc96967be60832db03eed1c8c5e4ee8f6d8a2b7d 100644 (file)
--- a/login-utils/su-common.c
+++ b/login-utils/su-common.c
@@ -442,11 +442,11 @@ static int pty_handle_signal(struct su_context *su, int fd)
 static void pty_proxy_master(struct su_context *su)
 {
        sigset_t ourset;
-       int rc = 0, ret, ignore_stdin = 0, eof = 0;
+       int rc = 0, ret, eof = 0;
        enum {
                POLLFD_SIGNAL = 0,
                POLLFD_MASTER,
-               POLLFD_STDIN    /* optional; keep it last, see ignore_stdin */
+               POLLFD_STDIN
 
        };
        struct pollfd pfd[] = {
@@ -490,7 +490,7 @@ static void pty_proxy_master(struct su_context *su)
                DBG(PTY, ul_debug("calling poll()"));
 
                /* wait for input or signal */
-               ret = poll(pfd, ARRAY_SIZE(pfd) - ignore_stdin, su->poll_timeout);
+               ret = poll(pfd, ARRAY_SIZE(pfd), su->poll_timeout);
                errsv = errno;
                DBG(PTY, ul_debug("poll() rc=%d", ret));
 
@@ -505,7 +505,7 @@ static void pty_proxy_master(struct su_context *su)
                        break;
                }
 
-               for (i = 0; i < ARRAY_SIZE(pfd) - ignore_stdin; i++) {
+               for (i = 0; i < ARRAY_SIZE(pfd); i++) {
                        rc = 0;
 
                        if (pfd[i].revents == 0)
@@ -531,10 +531,7 @@ static void pty_proxy_master(struct su_context *su)
                                if ((pfd[i].revents & POLLHUP) || eof) {
                                        DBG(PTY, ul_debug(" ignore FD"));
                                        pfd[i].fd = -1;
-                                       /* according to man poll() set FD to -1 can't be used to ignore
-                                        * STDIN, so let's remove the FD from pool at all */
                                        if (i == POLLFD_STDIN) {
-                                               ignore_stdin = 1;
                                                write_eof_to_child(su);
                                                DBG(PTY, ul_debug("  ignore STDIN"));
                                        }