1 files changed, 526 insertions, 0 deletions

diff --git a/libntp/work_fork.c b/libntp/work_fork.c
new file mode 100644
index 0000000..10329e7
--- /dev/null
+++ b/libntp/work_fork.c
@@ -0,0 +1,526 @@
+/*
+ * work_fork.c - fork implementation for blocking worker child.
+ */
+#include <config.h>
+#include "ntp_workimpl.h"
+
+#ifdef WORK_FORK
+#include <stdio.h>
+#include <ctype.h>
+#include <signal.h>
+
+#include "iosignal.h"
+#include "ntp_stdlib.h"
+#include "ntp_malloc.h"
+#include "ntp_syslog.h"
+#include "ntpd.h"
+#include "ntp_io.h"
+#include "ntp_assert.h"
+#include "ntp_unixtime.h"
+#include "ntp_worker.h"
+
+/* === variables === */
+	int			worker_process;
+	addremove_io_fd_func	addremove_io_fd;
+static	volatile int		worker_sighup_received;
+
+/* === function prototypes === */
+static	void		fork_blocking_child(blocking_child *);
+static	RETSIGTYPE	worker_sighup(int);
+static	void		send_worker_home_atexit(void);
+static	void		cleanup_after_child(blocking_child *);
+
+/* === functions === */
+/*
+ * exit_worker()
+ *
+ * On some systems _exit() is preferred to exit() for forked children.
+ * For example, http://netbsd.gw.com/cgi-bin/man-cgi?fork++NetBSD-5.0
+ * recommends _exit() to avoid double-flushing C runtime stream buffers
+ * and also to avoid calling the parent's atexit() routines in the
+ * child.  On those systems WORKER_CHILD_EXIT is _exit.  Since _exit
+ * bypasses CRT cleanup, fflush() files we know might have output
+ * buffered.
+ */
+void
+exit_worker(
+	int	exitcode
+	)
+{
+	if (syslog_file != NULL)
+		fflush(syslog_file);
+	fflush(stdout);
+	fflush(stderr);
+	WORKER_CHILD_EXIT (exitcode);	/* space before ( required */
+}
+
+
+static RETSIGTYPE
+worker_sighup(
+	int sig
+	)
+{
+	if (SIGHUP == sig)
+		worker_sighup_received = 1;
+}
+
+
+int
+worker_sleep(
+	blocking_child *	c,
+	time_t			seconds
+	)
+{
+	u_int sleep_remain;
+
+	sleep_remain = (u_int)seconds;
+	do {
+		if (!worker_sighup_received)
+			sleep_remain = sleep(sleep_remain);
+		if (worker_sighup_received) {
+			TRACE(1, ("worker SIGHUP with %us left to sleep",
+				  sleep_remain));
+			worker_sighup_received = 0;
+			return -1;
+		}
+	} while (sleep_remain);
+
+	return 0;
+}
+
+
+void
+interrupt_worker_sleep(void)
+{
+	u_int			idx;
+	blocking_child *	c;
+	int			rc;
+
+	for (idx = 0; idx < blocking_children_alloc; idx++) {
+		c = blocking_children[idx];
+
+		if (NULL == c || c->reusable == TRUE)
+			continue;
+
+		rc = kill(c->pid, SIGHUP);
+		if (rc < 0)
+			msyslog(LOG_ERR,
+				"Unable to signal HUP to wake child pid %d: %m",
+				c->pid);
+	}
+}
+
+
+/*
+ * req_child_exit() runs in the parent.
+ */
+int
+req_child_exit(
+	blocking_child *	c
+	)
+{
+	if (-1 != c->req_write_pipe) {
+		close(c->req_write_pipe);
+		c->req_write_pipe = -1;
+		return 0;
+	}
+	return -1;
+}
+
+
+/*
+ * cleanup_after_child() runs in parent.
+ */
+static void
+cleanup_after_child(
+	blocking_child *	c
+	)
+{
+	if (-1 != c->req_write_pipe) {
+		close(c->req_write_pipe);
+		c->req_write_pipe = -1;
+	}
+	if (-1 != c->resp_read_pipe) {
+		(*addremove_io_fd)(c->resp_read_pipe, c->ispipe, TRUE);
+		close(c->resp_read_pipe);
+		c->resp_read_pipe = -1;
+	}
+	c->pid = 0;
+	c->resp_read_ctx = NULL;
+	DEBUG_INSIST(-1 == c->req_read_pipe);
+	DEBUG_INSIST(-1 == c->resp_write_pipe);
+	c->reusable = TRUE;
+}
+
+
+static void
+send_worker_home_atexit(void)
+{
+	u_int			idx;
+	blocking_child *	c;
+
+	if (worker_process)
+		return;
+
+	for (idx = 0; idx < blocking_children_alloc; idx++) {
+		c = blocking_children[idx];
+		if (NULL == c)
+			continue;
+		req_child_exit(c);
+	}
+}
+
+
+int
+send_blocking_req_internal(
+	blocking_child *	c,
+	blocking_pipe_header *	hdr,
+	void *			data
+	)
+{
+	int octets;
+	int rc;
+
+	DEBUG_REQUIRE(hdr != NULL);
+	DEBUG_REQUIRE(data != NULL);
+	DEBUG_REQUIRE(BLOCKING_REQ_MAGIC == hdr->magic_sig);
+
+	if (-1 == c->req_write_pipe) {
+		fork_blocking_child(c);
+		DEBUG_INSIST(-1 != c->req_write_pipe);
+	}
+
+	octets = sizeof(*hdr);
+	rc = write(c->req_write_pipe, hdr, octets);
+
+	if (rc == octets) {
+		octets = hdr->octets - sizeof(*hdr);
+		rc = write(c->req_write_pipe, data, octets);
+
+		if (rc == octets)
+			return 0;
+	}
+
+	if (rc < 0)
+		msyslog(LOG_ERR,
+			"send_blocking_req_internal: pipe write: %m");
+	else
+		msyslog(LOG_ERR,
+			"send_blocking_req_internal: short write %d of %d",
+			rc, octets);
+
+	exit(1);	/* otherwise would be return -1 */
+}
+
+
+blocking_pipe_header *
+receive_blocking_req_internal(
+	blocking_child *	c
+	)
+{
+	blocking_pipe_header	hdr;
+	blocking_pipe_header *	req;
+	int			rc;
+	long			octets;
+
+	DEBUG_REQUIRE(-1 != c->req_read_pipe);
+
+	req = NULL;
+
+	do {
+		rc = read(c->req_read_pipe, &hdr, sizeof(hdr));
+	} while (rc < 0 && EINTR == errno);
+
+	if (rc < 0) {
+		msyslog(LOG_ERR,
+			"receive_blocking_req_internal: pipe read %m");
+	} else if (0 == rc) {
+		TRACE(4, ("parent closed request pipe, child %d terminating\n",
+			  c->pid));
+	} else if (rc != sizeof(hdr)) {
+		msyslog(LOG_ERR,
+			"receive_blocking_req_internal: short header read %d of %lu",
+			rc, (u_long)sizeof(hdr));
+	} else {
+		INSIST(sizeof(hdr) < hdr.octets && hdr.octets < 4 * 1024);
+		req = emalloc(hdr.octets);
+		memcpy(req, &hdr, sizeof(*req));
+		octets = hdr.octets - sizeof(hdr);
+		rc = read(c->req_read_pipe, (char *)req + sizeof(*req),
+			  octets);
+
+		if (rc < 0)
+			msyslog(LOG_ERR,
+				"receive_blocking_req_internal: pipe data read %m");
+		else if (rc != octets)
+			msyslog(LOG_ERR,
+				"receive_blocking_req_internal: short read %d of %ld",
+				rc, octets);
+		else if (BLOCKING_REQ_MAGIC != req->magic_sig)
+			msyslog(LOG_ERR,
+				"receive_blocking_req_internal: packet header mismatch (0x%x)",
+				req->magic_sig);
+		else
+			return req;
+	}
+
+	if (req != NULL)
+		free(req);
+
+	return NULL;
+}
+
+
+int
+send_blocking_resp_internal(
+	blocking_child *	c,
+	blocking_pipe_header *	resp
+	)
+{
+	long	octets;
+	int	rc;
+
+	DEBUG_REQUIRE(-1 != c->resp_write_pipe);
+
+	octets = resp->octets;
+	rc = write(c->resp_write_pipe, resp, octets);
+	free(resp);
+
+	if (octets == rc)
+		return 0;
+
+	if (rc < 0)
+		TRACE(1, ("send_blocking_resp_internal: pipe write %m\n"));
+	else
+		TRACE(1, ("send_blocking_resp_internal: short write %d of %ld\n",
+			  rc, octets));
+
+	return -1;
+}
+
+
+blocking_pipe_header *
+receive_blocking_resp_internal(
+	blocking_child *	c
+	)
+{
+	blocking_pipe_header	hdr;
+	blocking_pipe_header *	resp;
+	int			rc;
+	long			octets;
+
+	DEBUG_REQUIRE(c->resp_read_pipe != -1);
+
+	resp = NULL;
+	rc = read(c->resp_read_pipe, &hdr, sizeof(hdr));
+
+	if (rc < 0) {
+		TRACE(1, ("receive_blocking_resp_internal: pipe read %m\n"));
+	} else if (0 == rc) {
+		/* this is the normal child exited indication */
+	} else if (rc != sizeof(hdr)) {
+		TRACE(1, ("receive_blocking_resp_internal: short header read %d of %lu\n",
+			  rc, (u_long)sizeof(hdr)));
+	} else if (BLOCKING_RESP_MAGIC != hdr.magic_sig) {
+		TRACE(1, ("receive_blocking_resp_internal: header mismatch (0x%x)\n",
+			  hdr.magic_sig));
+	} else {
+		INSIST(sizeof(hdr) < hdr.octets &&
+		       hdr.octets < 16 * 1024);
+		resp = emalloc(hdr.octets);
+		memcpy(resp, &hdr, sizeof(*resp));
+		octets = hdr.octets - sizeof(hdr);
+		rc = read(c->resp_read_pipe,
+			  (char *)resp + sizeof(*resp),
+			  octets);
+
+		if (rc < 0)
+			TRACE(1, ("receive_blocking_resp_internal: pipe data read %m\n"));
+		else if (rc < octets)
+			TRACE(1, ("receive_blocking_resp_internal: short read %d of %ld\n",
+				  rc, octets));
+		else
+			return resp;
+	}
+
+	cleanup_after_child(c);
+
+	if (resp != NULL)
+		free(resp);
+
+	return NULL;
+}
+
+
+#if defined(HAVE_DROPROOT) && defined(WORK_FORK)
+void
+fork_deferred_worker(void)
+{
+	u_int			idx;
+	blocking_child *	c;
+
+	REQUIRE(droproot && root_dropped);
+
+	for (idx = 0; idx < blocking_children_alloc; idx++) {
+		c = blocking_children[idx];
+		if (NULL == c)
+			continue;
+		if (-1 != c->req_write_pipe && 0 == c->pid)
+			fork_blocking_child(c);
+	}
+}
+#endif
+
+
+static void
+fork_blocking_child(
+	blocking_child *	c
+	)
+{
+	static int	atexit_installed;
+	static int	blocking_pipes[4] = { -1, -1, -1, -1 };
+	int		rc;
+	int		was_pipe;
+	int		is_pipe;
+	int		saved_errno;
+	int		childpid;
+	int		keep_fd;
+	int		fd;
+
+	/*
+	 * parent and child communicate via a pair of pipes.
+	 * 
+	 * 0 child read request
+	 * 1 parent write request
+	 * 2 parent read response
+	 * 3 child write response
+	 */
+	if (-1 == c->req_write_pipe) {
+		rc = pipe_socketpair(&blocking_pipes[0], &was_pipe);
+		if (0 != rc) {
+			saved_errno = errno;
+		} else {
+			rc = pipe_socketpair(&blocking_pipes[2], &is_pipe);
+			if (0 != rc) {
+				saved_errno = errno;
+				close(blocking_pipes[0]);
+				close(blocking_pipes[1]);
+			} else {
+				INSIST(was_pipe == is_pipe);
+			}
+		}
+		if (0 != rc) {
+			errno = saved_errno;
+			msyslog(LOG_ERR, "unable to create worker pipes: %m");
+			exit(1);
+		}
+
+		/*
+		 * Move the descriptors the parent will keep open out of the
+		 * low descriptors preferred by C runtime buffered FILE *.
+		 */
+		c->req_write_pipe = move_fd(blocking_pipes[1]);
+		c->resp_read_pipe = move_fd(blocking_pipes[2]);
+		/*
+		 * wake any worker child on orderly shutdown of the
+		 * daemon so that it can notice the broken pipes and
+		 * go away promptly.
+		 */
+		if (!atexit_installed) {
+			atexit(&send_worker_home_atexit);
+			atexit_installed = TRUE;
+		}
+	}
+
+#ifdef HAVE_DROPROOT
+	/* defer the fork until after root is dropped */
+	if (droproot && !root_dropped)
+		return;
+#endif
+	if (syslog_file != NULL)
+		fflush(syslog_file);
+	fflush(stdout);
+	fflush(stderr);
+
+	signal_no_reset(SIGCHLD, SIG_IGN);
+
+	childpid = fork();
+	if (-1 == childpid) {
+		msyslog(LOG_ERR, "unable to fork worker: %m");
+		exit(1);
+	}
+
+	if (childpid) {
+		/* this is the parent */
+		TRACE(1, ("forked worker child (pid %d)\n", childpid));
+		c->pid = childpid;
+		c->ispipe = is_pipe;
+
+		/* close the child's pipe descriptors. */
+		close(blocking_pipes[0]);
+		close(blocking_pipes[3]);
+
+		memset(blocking_pipes, -1, sizeof(blocking_pipes));
+
+		/* wire into I/O loop */
+		(*addremove_io_fd)(c->resp_read_pipe, is_pipe, FALSE);
+
+		return;		/* parent returns */
+	}
+
+	/*
+	 * The parent gets the child pid as the return value of fork().
+	 * The child must work for it.
+	 */
+	c->pid = getpid();
+	worker_process = TRUE;
+
+	/*
+	 * In the child, close all files except stdin, stdout, stderr,
+	 * and the two child ends of the pipes.
+	 */
+	DEBUG_INSIST(-1 == c->req_read_pipe);
+	DEBUG_INSIST(-1 == c->resp_write_pipe);
+	c->req_read_pipe = blocking_pipes[0];
+	c->resp_write_pipe = blocking_pipes[3];
+
+	kill_asyncio(0);
+	closelog();
+	if (syslog_file != NULL) {
+		fclose(syslog_file);
+		syslog_file = NULL;
+		syslogit = TRUE;
+	}
+	keep_fd = max(c->req_read_pipe, c->resp_write_pipe);
+	for (fd = 3; fd < keep_fd; fd++)
+		if (fd != c->req_read_pipe && 
+		    fd != c->resp_write_pipe)
+			close(fd);
+	close_all_beyond(keep_fd);
+	/*
+	 * We get signals from refclock serial I/O on NetBSD in the
+	 * worker if we do not reset SIGIO's handler to the default.
+	 * It is not conditionalized for NetBSD alone because on
+	 * systems where it is not needed, it is harmless, and that
+	 * allows us to handle unknown others with NetBSD behavior.
+	 * [Bug 1386]
+	 */
+#if defined(USE_SIGIO)
+	signal_no_reset(SIGIO, SIG_DFL);
+#elif defined(USE_SIGPOLL)
+	signal_no_reset(SIGPOLL, SIG_DFL);
+#endif
+	signal_no_reset(SIGHUP, worker_sighup);
+	init_logging("ntp_intres", 0, FALSE);
+	setup_logfile(NULL);
+
+	/*
+	 * And now back to the portable code
+	 */
+	exit_worker(blocking_child_common(c));
+}
+
+
+#else	/* !WORK_FORK follows */
+char work_fork_nonempty_compilation_unit;
+#endif