change low FDs are handled in Samba

We now only close fds 0, 1, 2 when we are a forked daemon, and take
care not to close a file descriptor that we might need for foreground
stdin monitoring.

This should fix stdout logging in the lsa and epmapper deamons (ie in
make test).

Andrew Bartlett

3 files changed, 23 insertions, 12 deletions

diff --git a/lib/util/become_daemon.c b/lib/util/become_daemon.c
index 2af16316b5..4c1d29e5a7 100644
--- a/lib/util/become_daemon.c
+++ b/lib/util/become_daemon.c
@@ -29,14 +29,16 @@
  Close the low 3 fd's and open dev/null in their place.
 ********************************************************************/
 
-_PUBLIC_ void close_low_fds(bool stderr_too)
+_PUBLIC_ void close_low_fds(bool stdin_too, bool stdout_too, bool stderr_too)
 {
 #ifndef VALGRIND
 	int fd;
 	int i;
 
-	close(0);
-	close(1);
+	if (stdin_too)
+		close(0);
+	if (stdout_too)
+		close(1);
 
 	if (stderr_too)
 		close(2);
@@ -44,6 +46,10 @@ _PUBLIC_ void close_low_fds(bool stderr_too)
 	/* try and use up these file descriptors, so silly
 		library routines writing to stdout etc won't cause havoc */
 	for (i=0;i<3;i++) {
+		if (i == 0 && !stdin_too)
+			continue;
+		if (i == 1 && !stdout_too)
+			continue;
 		if (i == 2 && !stderr_too)
 			continue;
 
@@ -87,9 +93,9 @@ _PUBLIC_ void become_daemon(bool do_fork, bool no_process_group, bool log_stdout
 	}
 #endif /* HAVE_SETSID */
 
-	if (!log_stdout) {
-		/* Close fd's 0,1,2. Needed if started by rsh */
-		close_low_fds(false);  /* Don't close stderr, let the debug system
-					  attach it to the logfile */
-	}
+	/* Close fd's 0,1,2 as appropriate. Needed if started by rsh. */
+	/* stdin must be open if we do not fork, for monitoring for
+	 * close.  stdout must be open if we are logging there, and we
+	 * never close stderr (but debug might dup it onto a log file) */
+	close_low_fds(do_fork, !log_stdout, false);
 }
diff --git a/lib/util/debug.c b/lib/util/debug.c
index a6388513c7..a7e2a0f78e 100644
--- a/lib/util/debug.c
+++ b/lib/util/debug.c
@@ -592,9 +592,14 @@ bool reopen_logs_internal(void)
 	(void)umask(oldumask);
 
 	/* Take over stderr to catch output into logs */
-	if (state.fd > 0 && dup2(state.fd, 2) == -1) {
-		close_low_fds(true); /* Close stderr too, if dup2 can't point it
-					at the logfile */
+	if (state.fd > 0) {
+		if (dup2(state.fd, 2) == -1) {
+			/* Close stderr too, if dup2 can't point it -
+			   at the logfile.  There really isn't much
+			   that can be done on such a fundemental
+			   failure... */
+			close_low_fds(false, false, true);
+		}
 	}
 
 	state.reopening_logs = false;
diff --git a/lib/util/samba_util.h b/lib/util/samba_util.h
index a0989d5479..13fe831995 100644
--- a/lib/util/samba_util.h
+++ b/lib/util/samba_util.h
@@ -824,7 +824,7 @@ _PUBLIC_ int idr_remove(struct idr_context *idp, int id);
 /**
  Close the low 3 fd's and open dev/null in their place
 **/
-_PUBLIC_ void close_low_fds(bool stderr_too);
+_PUBLIC_ void close_low_fds(bool stdin_too, bool stdout_too, bool stderr_too);
 
 /**
  Become a daemon, discarding the controlling terminal.