emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

telnetd: fix problem with zombies (by Paul Fox <pgf@brightstareng.com>)

Browse Source 
syslogd: strip trailing NULs
This commit is contained in:
Denis Vlasenko
2007-11-06 01:38:46 +00:00
parent cb981638f5
commit 018b155ad9
3 changed files with 41 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
networking/telnetd.c
View File

@@ -279,6 +279,10 @@ make_new_session(
/* make new session and process group */
setsid();
/* Restore default signal handling */
signal(SIGCHLD, SIG_DFL);
signal(SIGPIPE, SIG_DFL);
/* open the child's side of the tty. */
/* NB: setsid() disconnects from any previous ctty's. Therefore
* we must open child's side of the tty AFTER setsid! */
@@ -302,14 +306,18 @@ make_new_session(
/* Uses FILE-based I/O to stdout, but does fflush(stdout),
* so should be safe with vfork.
* I fear, though, that some users will have ridiculously big
* issue files, and they may block writing to fd 1. */
* issue files, and they may block writing to fd 1,
* (parent is supposed to read it, but parent waits
* for vforked child to exec!) */
print_login_issue(issuefile, NULL);
/* Exec shell / login / whatever */
login_argv[0] = loginpath;
login_argv[1] = NULL;
execvp(loginpath, (char **)login_argv);
/* Safer with vfork, and we shouldn't send message
/* exec busybox applet (if PREFER_APPLETS=y), if that fails,
* exec external program */
BB_EXECVP(loginpath, (char **)login_argv);
/* _exit is safer with vfork, and we shouldn't send message
* to remote clients anyway */
_exit(1); /*bb_perror_msg_and_die("execv %s", loginpath);*/
}
@@ -374,7 +382,7 @@ free_session(struct tsession *ts)
#else /* !FEATURE_TELNETD_STANDALONE */
/* Used in main() only, thus exits. */
/* Used in main() only, thus "return 0" actually is exit(0). */
#define free_session(ts) return 0
#endif
@@ -384,20 +392,22 @@ static void handle_sigchld(int sig)
pid_t pid;
struct tsession *ts;
pid = waitpid(-1, &sig, WNOHANG);
if (pid > 0) {
/* Looping: more than one child may have exited */
while (1) {
pid = waitpid(-1, NULL, WNOHANG);
if (pid <= 0)
break;
ts = sessions;
while (ts) {
if (ts->shell_pid == pid) {
ts->shell_pid = -1;
return;
break;
}
ts = ts->next;
}
}
}
int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int telnetd_main(int argc, char **argv)
{
@@ -430,7 +440,7 @@ int telnetd_main(int argc, char **argv)
if (!(opt & OPT_FOREGROUND)) {
/* DAEMON_CHDIR_ROOT was giving inconsistent
* behavior with/without -F, -i */
bb_daemonize_or_rexec(0 /*DAEMON_CHDIR_ROOT*/, argv);
bb_daemonize_or_rexec(0 /*was DAEMON_CHDIR_ROOT*/, argv);
}
}
/* Redirect log to syslog early, if needed */
@@ -466,6 +476,8 @@ int telnetd_main(int argc, char **argv)
if (opt & OPT_WATCHCHILD)
signal(SIGCHLD, handle_sigchld);
else /* prevent dead children from becoming zombies */
signal(SIGCHLD, SIG_IGN);
/*
This is how the buffers are used. The arrows indicate the movement
@@ -497,7 +509,7 @@ int telnetd_main(int argc, char **argv)
while (ts) {
struct tsession *next = ts->next; /* in case we free ts. */
if (ts->shell_pid == -1) {
/* Child died ad we detected that */
/* Child died and we detected that */
free_session(ts);
} else {
if (ts->size1 > 0) /* can write to pty */
@@ -514,7 +526,7 @@ int telnetd_main(int argc, char **argv)
if (!IS_INETD) {
FD_SET(master_fd, &rdfdset);
/* This is needed because free_session() does not
* take into account master_fd when it finds new
* take master_fd into account when it finds new
* maxfd among remaining fd's */
if (master_fd > maxfd)
maxfd = master_fd;