Create a dedicated function for ensuring that cdir and rdir are populated.

Previously several places were doing it on its own, partially
incorrectly (e.g. without the filedesc locked) or even actively harmful
by populating jdir or assigning rootvnode without vrefing it.

Reviewed by:	kib

1 files changed, 19 insertions, 0 deletions

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 7e54d18..4229cc9 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -68,6 +68,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sbuf.h>
 #include <sys/signalvar.h>
 #include <sys/socketvar.h>
+#include <sys/kdb.h>
 #include <sys/stat.h>
 #include <sys/sx.h>
 #include <sys/syscallsubr.h>
@@ -308,6 +309,24 @@ fdfree(struct filedesc *fdp, int fd)
 #endif
 }
 
+void
+pwd_ensure_dirs(void)
+{
+	struct filedesc *fdp;
+
+	fdp = curproc->p_fd;
+	FILEDESC_XLOCK(fdp);
+	if (fdp->fd_cdir == NULL) {
+		fdp->fd_cdir = rootvnode;
+		VREF(rootvnode);
+	}
+	if (fdp->fd_rdir == NULL) {
+		fdp->fd_rdir = rootvnode;
+		VREF(rootvnode);
+	}
+	FILEDESC_XUNLOCK(fdp);
+}
+
 /*
  * System calls on descriptors.
  */