nc: fix nc -ll; report vfork errors; make select loop faster

function                                             old     new   delta
nc_main                                              933     946     +13

Signed-off-by: Tomoya Adachi <adachi@il.is.s.u-tokyo.ac.jp>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/nc.c b/networking/nc.c
index e4db238959138c7db3e86b7fe3a466e6e248772c..243c47976b9e6a0f5e1ad183840c5cb39f353314 100644 (file)
--- a/networking/nc.c
+++ b/networking/nc.c
@@ -135,29 +135,27 @@ int nc_main(int argc, char **argv)
 
        /* -e given? */
        if (execparam) {
-               signal(SIGCHLD, SIG_IGN);
-               // With more than one -l, repeatedly act as server.
-               if (do_listen > 1 && vfork()) {
-                       /* parent */
-                       // This is a bit weird as cleanup goes, since we wind up with no
-                       // stdin/stdout/stderr.  But it's small and shouldn't hurt anything.
-                       // We check for cfd == 0 above.
-                       logmode = LOGMODE_NONE;
-                       close(0);
-                       close(1);
-                       close(2);
+               pid_t pid;
+               /* With more than one -l, repeatedly act as server */
+               if (do_listen > 1 && (pid = vfork()) != 0) {
+                       /* parent or error */
+                       if (pid < 0)
+                               bb_perror_msg_and_die("vfork");
+                       /* prevent zombies */
+                       signal(SIGCHLD, SIG_IGN);
+                       close(cfd);
                        goto accept_again;
                }
-               /* child (or main thread if no multiple -l) */
+               /* child, or main thread if only one -l */
                xmove_fd(cfd, 0);
                xdup2(0, 1);
                xdup2(0, 2);
                IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
-               /* Don't print stuff or it will go over the wire.... */
+               /* Don't print stuff or it will go over the wire... */
                _exit(127);
        }
 
-       // Select loop copying stdin to cfd, and cfd to stdout.
+       /* Select loop copying stdin to cfd, and cfd to stdout */
 
        FD_ZERO(&readfds);
        FD_SET(cfd, &readfds);
@@ -170,11 +168,12 @@ int nc_main(int argc, char **argv)
 
                testfds = readfds;
 
-               if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
+               if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0)
                        bb_perror_msg_and_die("select");
 
 #define iobuf bb_common_bufsiz1
-               for (fd = 0; fd < FD_SETSIZE; fd++) {
+               fd = STDIN_FILENO;
+               while (1) {
                        if (FD_ISSET(fd, &testfds)) {
                                nread = safe_read(fd, iobuf, sizeof(iobuf));
                                if (fd == cfd) {
@@ -182,17 +181,21 @@ int nc_main(int argc, char **argv)
                                                exit(EXIT_SUCCESS);
                                        ofd = STDOUT_FILENO;
                                } else {
-                                       if (nread<1) {
-                                               // Close outgoing half-connection so they get EOF, but
-                                               // leave incoming alone so we can see response.
+                                       if (nread < 1) {
+                                               /* Close outgoing half-connection so they get EOF,
+                                                * but leave incoming alone so we can see response */
                                                shutdown(cfd, 1);
                                                FD_CLR(STDIN_FILENO, &readfds);
                                        }
                                        ofd = cfd;
                                }
                                xwrite(ofd, iobuf, nread);
-                               if (delay > 0) sleep(delay);
+                               if (delay > 0)
+                                       sleep(delay);
                        }
+                       if (fd == cfd)
+                               break;
+                       fd = cfd;
                }
        }
 }