privsep: Drain the log when the root process is exiting

So we stand a better chance of printing the exit messages.

Author: rsmarples

src/logerr.c

@@ -395,11 +395,11 @@ logsetfd(int fd)
 #endif
 }
 
-int
+ssize_t
 logreadfd(int fd)
 {
 	struct logctx *ctx = &_logctx;
-	int len, pri;
+	int pri;
 	pid_t pid;
 	char buf[LOGERR_SYSLOGBUF] = { '\0' };
 	struct iovec iov[] = {
@@ -411,10 +411,11 @@ logreadfd(int fd)
 		.msg_iov = iov,
 		.msg_iovlen = sizeof(iov) / sizeof(iov[0])
 	};
+	ssize_t len;
 
-	len = (int)recvmsg(fd, &msg, MSG_WAITALL);
+	len = recvmsg(fd, &msg, MSG_WAITALL);
 	if (len == -1 || len == 0)
-		return -1;
+		return len;
 	/* Ensure we received the minimum and at least one character to log */
 	if ((size_t)len < sizeof(pri) + sizeof(pid) + 1 ||
 	    msg.msg_flags & MSG_TRUNC) {

src/logerr.h

@@ -79,7 +79,7 @@ __printflike(2, 3) void logerrmessage(int pri, const char *fmt, ...);
 /* For logging in a chroot using SOCK_SEQPACKET */
 int loggetfd(void);
 void logsetfd(int);
-int logreadfd(int);
+ssize_t logreadfd(int);
 
 unsigned int loggetopts(void);
 void logsetopts(unsigned int);

src/privsep-root.c

@@ -89,10 +89,8 @@ ps_root_readerrorcb(void *arg, unsigned short events)
 	ssize_t len;
 	int exit_code = EXIT_FAILURE;
 
-	if (events & ELE_HANGUP) {
-		logerrx("%s: hangup", __func__);
+	if (events & ELE_HANGUP)
 		goto out;
-	}
 
 	if (events != ELE_READ)
 		logerrx("%s: unexpected event 0x%04x", __func__, events);
@@ -982,12 +980,20 @@ ps_root_stop(struct dhcpcd_ctx *ctx)
 	    ctx->eloop == NULL)
 		return 0;
 
+
 	/* If we are the root process then remove the pidfile */
-	if (ctx->options & DHCPCD_PRIVSEPROOT &&
-	    !(ctx->options & DHCPCD_TEST))
-	{
-		if (unlink(ctx->pidfile) == -1)
+	if (ctx->options & DHCPCD_PRIVSEPROOT) {
+		if (!(ctx->options & DHCPCD_TEST) && unlink(ctx->pidfile) == -1)
 			logerr("%s: unlink: %s", __func__, ctx->pidfile);
+
+		/* drain the log */
+		if (ctx->ps_log_root_fd != -1) {
+			ssize_t loglen;
+
+			do {
+				loglen = logreadfd(ctx->ps_log_root_fd);
+			} while (loglen != 0 && loglen != -1);
+		}
 	}
 
 	/* Only the manager process gets past this point. */