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syslogd: Centralize operations into a kevent loop
Use kqueue(2) for socket I/O and signal notification. Previously, select(2) and traditional signal handlers were being used. This change centralizes all of the async notification delivery into a single loop so future Capsicum sandboxing will be easier. It also simplifies the code by removing boiler-plate cruft that comes with the older interfaces. Reviewed by: Slawa Olhovchenkov, markj, emaste MFC after: 3 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D41363
This commit is contained in:
Jake Freeland
Mark Johnston
parent
3f8b49dd1a
commit
f804f23650
@ -104,6 +104,7 @@ static char sccsid[] = "@(#)syslogd.c 8.3 (Berkeley) 4/4/94";
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#define RCVBUF_MINSIZE (80 * 1024) /* minimum size of dgram rcv buffer */
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#include <sys/param.h>
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#include <sys/event.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/queue.h>
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@ -371,6 +372,16 @@ static const char *TypeNames[] = {
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"FORW", "USERS", "WALL", "PIPE"
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};
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static const int sigcatch[] = {
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SIGHUP,
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SIGINT,
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SIGQUIT,
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SIGPIPE,
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SIGALRM,
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SIGTERM,
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SIGCHLD,
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};
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static bool Debug; /* debug flag */
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static bool Foreground = false; /* Run in foreground, instead of daemonizing */
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static bool resolve = true; /* resolve hostname */
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@ -402,13 +413,10 @@ static bool UniquePriority; /* Only log specified priority? */
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static int LogFacPri; /* Put facility and priority in log message: */
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/* 0=no, 1=numeric, 2=names */
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static bool KeepKernFac; /* Keep remotely logged kernel facility */
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static bool needdofsync = false; /* Are any file(s) waiting to be fsynced? */
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static bool needdofsync = true; /* Are any file(s) waiting to be fsynced? */
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static struct pidfh *pfh;
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static int sigpipe[2]; /* Pipe to catch a signal during select(). */
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static bool RFC3164OutputFormat = true; /* Use legacy format by default. */
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static volatile sig_atomic_t MarkSet, WantDie, WantInitialize, WantReapchild;
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struct iovlist;
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static int allowaddr(char *);
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@ -421,9 +429,7 @@ static int deadq_remove(struct deadq_entry *);
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static int deadq_removebypid(pid_t);
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static int decode(const char *, const CODE *);
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static void die(int) __dead2;
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static void dodie(int);
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static void dofsync(void);
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static void domark(int);
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static void fprintlog_first(struct filed *, const char *, const char *,
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const char *, const char *, const char *, const char *, int);
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static void fprintlog_write(struct filed *, struct iovlist *, int);
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@ -437,8 +443,6 @@ static void markit(void);
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static int socksetup(struct peer *);
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static int socklist_recv_file(struct socklist *);
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static int socklist_recv_sock(struct socklist *);
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static int socklist_recv_signal(struct socklist *);
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static void sighandler(int);
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static int skip_message(const char *, const char *, int);
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static int evaluate_prop_filter(const struct prop_filter *filter,
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const char *value);
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@ -526,14 +530,14 @@ addsock(struct addrinfo *ai, struct socklist *sl0)
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int
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main(int argc, char *argv[])
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{
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int ch, i, s, fdsrmax = 0;
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bool bflag = false, pflag = false, Sflag = false;
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fd_set *fdsr = NULL;
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struct timeval tv, *tvp;
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struct peer *pe;
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sigset_t sigset = { };
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struct kevent ev;
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struct socklist *sl;
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pid_t ppid = 1, spid;
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struct peer *pe;
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pid_t ppid = -1, spid;
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int ch, kq, s;
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char *p;
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bool bflag = false, pflag = false, Sflag = false;
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if (madvise(NULL, 0, MADV_PROTECT) != 0)
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dprintf("madvise() failed: %s\n", strerror(errno));
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@ -705,17 +709,6 @@ main(int argc, char *argv[])
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if (RFC3164OutputFormat && MaxForwardLen > 1024)
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errx(1, "RFC 3164 messages may not exceed 1024 bytes");
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/* Pipe to catch a signal during select(). */
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s = pipe2(sigpipe, O_CLOEXEC);
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if (s < 0) {
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err(1, "cannot open a pipe for signals");
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} else {
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addsock(NULL, &(struct socklist){
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.sl_socket = sigpipe[0],
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.sl_recv = socklist_recv_signal
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});
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}
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/* Listen by default: /dev/klog. */
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s = open(_PATH_KLOG, O_RDONLY | O_NONBLOCK | O_CLOEXEC, 0);
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if (s < 0) {
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@ -767,108 +760,82 @@ main(int argc, char *argv[])
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(void)strlcpy(consfile.fu_fname, ctty + sizeof _PATH_DEV - 1,
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sizeof(consfile.fu_fname));
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(void)strlcpy(bootfile, getbootfile(), sizeof(bootfile));
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(void)signal(SIGTERM, dodie);
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(void)signal(SIGINT, Debug ? dodie : SIG_IGN);
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(void)signal(SIGQUIT, Debug ? dodie : SIG_IGN);
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(void)signal(SIGHUP, sighandler);
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(void)signal(SIGCHLD, sighandler);
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(void)signal(SIGALRM, domark);
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(void)signal(SIGPIPE, SIG_IGN); /* We'll catch EPIPE instead. */
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kq = kqueue();
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if (kq == -1) {
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warn("failed to initialize kqueue");
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pidfile_remove(pfh);
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exit(1);
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}
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STAILQ_FOREACH(sl, &shead, next) {
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EV_SET(&ev, sl->sl_socket, EVFILT_READ, EV_ADD, 0, 0, sl);
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if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1) {
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warn("failed to add kevent to kqueue");
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pidfile_remove(pfh);
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exit(1);
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}
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}
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for (size_t i = 0; i < nitems(sigcatch); ++i) {
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EV_SET(&ev, sigcatch[i], EVFILT_SIGNAL, EV_ADD, 0, 0, NULL);
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if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1) {
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warn("failed to add kevent to kqueue");
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pidfile_remove(pfh);
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exit(1);
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}
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(void)sigaddset(&sigset, sigcatch[i]);
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}
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if (sigprocmask(SIG_BLOCK, &sigset, NULL) != 0) {
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warn("failed to apply signal mask");
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pidfile_remove(pfh);
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exit(1);
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}
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(void)alarm(TIMERINTVL);
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/* tuck my process id away */
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pidfile_write(pfh);
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dprintf("off & running....\n");
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tvp = &tv;
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tv.tv_sec = tv.tv_usec = 0;
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STAILQ_FOREACH(sl, &shead, next) {
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if (sl->sl_socket > fdsrmax)
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fdsrmax = sl->sl_socket;
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}
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fdsr = (fd_set *)calloc(howmany(fdsrmax+1, NFDBITS),
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sizeof(*fdsr));
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if (fdsr == NULL)
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errx(1, "calloc fd_set");
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init(false);
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for (;;) {
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if (!Initialized)
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init(0);
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else if (WantInitialize)
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init(WantInitialize);
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if (WantReapchild)
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reapchild(WantReapchild);
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if (MarkSet)
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markit();
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if (WantDie) {
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free(fdsr);
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die(WantDie);
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}
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bzero(fdsr, howmany(fdsrmax+1, NFDBITS) *
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sizeof(*fdsr));
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STAILQ_FOREACH(sl, &shead, next) {
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if (sl->sl_socket != -1 && sl->sl_recv != NULL)
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FD_SET(sl->sl_socket, fdsr);
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}
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i = select(fdsrmax + 1, fdsr, NULL, NULL,
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needdofsync ? &tv : tvp);
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switch (i) {
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case 0:
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if (needdofsync) {
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dofsync();
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needdofsync = false;
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if (tvp) {
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tvp = NULL;
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if (ppid != 1)
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kill(ppid, SIGALRM);
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if (ppid != -1) {
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kill(ppid, SIGALRM);
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ppid = -1;
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}
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continue;
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case -1:
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}
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if (kevent(kq, NULL, 0, &ev, 1, NULL) == -1) {
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if (errno != EINTR)
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logerror("select");
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logerror("kevent");
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continue;
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}
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STAILQ_FOREACH(sl, &shead, next) {
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if (FD_ISSET(sl->sl_socket, fdsr))
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(*sl->sl_recv)(sl);
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}
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}
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free(fdsr);
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}
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static int
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socklist_recv_signal(struct socklist *sl __unused)
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{
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ssize_t len;
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int i, nsig, signo;
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if (ioctl(sigpipe[0], FIONREAD, &i) != 0) {
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logerror("ioctl(FIONREAD)");
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err(1, "signal pipe read failed");
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}
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nsig = i / sizeof(signo);
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dprintf("# of received signals = %d\n", nsig);
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for (i = 0; i < nsig; i++) {
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len = read(sigpipe[0], &signo, sizeof(signo));
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if (len != sizeof(signo)) {
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logerror("signal pipe read failed");
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err(1, "signal pipe read failed");
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}
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dprintf("Received signal: %d from fd=%d\n", signo,
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sigpipe[0]);
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switch (signo) {
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case SIGHUP:
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WantInitialize = 1;
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switch (ev.filter) {
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case EVFILT_READ:
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sl = ev.udata;
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if (sl->sl_socket != -1 && sl->sl_recv != NULL)
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sl->sl_recv(sl);
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break;
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case SIGCHLD:
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WantReapchild = 1;
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case EVFILT_SIGNAL:
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switch (ev.ident) {
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case SIGHUP:
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init(true);
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break;
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case SIGINT:
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case SIGQUIT:
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case SIGTERM:
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if (ev.ident == SIGTERM || Debug)
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die(ev.ident);
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break;
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case SIGALRM:
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markit();
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break;
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case SIGCHLD:
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reapchild(ev.ident);
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break;
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}
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break;
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}
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}
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return (0);
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}
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static int
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@ -1758,6 +1725,7 @@ dofsync(void)
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(void)fsync(f->f_file);
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}
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}
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needdofsync = false;
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}
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/*
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@ -2259,7 +2227,6 @@ reapchild(int signo __unused)
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}
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}
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}
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WantReapchild = 0;
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}
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/*
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@ -2298,20 +2265,6 @@ cvthname(struct sockaddr *f)
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return (hname);
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}
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static void
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dodie(int signo)
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{
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WantDie = signo;
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}
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static void
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domark(int signo __unused)
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{
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MarkSet = 1;
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}
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/*
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* Print syslogd errors some place.
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*/
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@ -2536,14 +2489,6 @@ readconfigfile(const char *path)
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}
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}
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static void
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sighandler(int signo)
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{
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/* Send an wake-up signal to the select() loop. */
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write(sigpipe[1], &signo, sizeof(signo));
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}
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/*
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* INIT -- Initialize syslogd from configuration table
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*/
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@ -2558,7 +2503,6 @@ init(int signo)
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char bootfileMsg[MAXLINE + 1];
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dprintf("init\n");
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WantInitialize = 0;
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/*
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* Load hostname (may have changed).
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@ -3245,7 +3189,6 @@ markit(void)
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dq->dq_timeout--;
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}
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}
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MarkSet = 0;
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(void)alarm(TIMERINTVL);
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}
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@ -3621,6 +3564,7 @@ validate(struct sockaddr *sa, const char *hname)
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static int
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p_open(const char *prog, pid_t *rpid)
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{
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sigset_t sigset = { };
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int pfd[2], nulldesc;
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pid_t pid;
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char *argv[4]; /* sh -c cmd NULL */
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@ -3650,10 +3594,12 @@ p_open(const char *prog, pid_t *rpid)
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alarm(0);
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/* Restore signals marked as SIG_IGN. */
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(void)signal(SIGINT, SIG_DFL);
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(void)signal(SIGQUIT, SIG_DFL);
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(void)signal(SIGPIPE, SIG_DFL);
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for (size_t i = 0; i < nitems(sigcatch); ++i)
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(void)sigaddset(&sigset, sigcatch[i]);
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if (sigprocmask(SIG_UNBLOCK, &sigset, NULL) != 0) {
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logerror("sigprocmask");
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exit(1);
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}
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dup2(pfd[0], STDIN_FILENO);
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dup2(nulldesc, STDOUT_FILENO);
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