From e05087ee1c7b850a331b8a326c9b21b05cfefa5e Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Fri, 20 Sep 2024 19:28:23 +0300
Subject: [PATCH] Add proc_nfiles(9)

(cherry picked from commit 9c3e516ad08145ad47248633b54fd1b7fc0ef981)
---
 sys/kern/kern_descrip.c | 46 ++++++++++++++++++++++++++++++-----------
 sys/sys/filedesc.h      |  2 ++
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 35e9afea462..9036e3a25ab 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -4331,13 +4331,43 @@ filedesc_to_leader_share(struct filedesc_to_leader *fdtol, struct filedesc *fdp)
 }
 
 static int
-sysctl_kern_proc_nfds(SYSCTL_HANDLER_ARGS)
+filedesc_nfiles(struct filedesc *fdp)
 {
 	NDSLOTTYPE *map;
-	struct filedesc *fdp;
-	u_int namelen;
 	int count, off, minoff;
 
+	if (fdp == NULL)
+		return (0);
+	count = 0;
+	FILEDESC_SLOCK(fdp);
+	map = fdp->fd_map;
+	off = NDSLOT(fdp->fd_nfiles - 1);
+	for (minoff = NDSLOT(0); off >= minoff; --off)
+		count += bitcountl(map[off]);
+	FILEDESC_SUNLOCK(fdp);
+	return (count);
+}
+
+int
+proc_nfiles(struct proc *p)
+{
+	struct filedesc *fdp;
+	int res;
+
+	PROC_LOCK(p);
+	fdp = fdhold(p);
+	PROC_UNLOCK(p);
+	res = filedesc_nfiles(fdp);
+	fddrop(fdp);
+	return (res);
+}
+
+static int
+sysctl_kern_proc_nfds(SYSCTL_HANDLER_ARGS)
+{
+	u_int namelen;
+	int count;
+
 	namelen = arg2;
 	if (namelen != 1)
 		return (EINVAL);
@@ -4345,15 +4375,7 @@ sysctl_kern_proc_nfds(SYSCTL_HANDLER_ARGS)
 	if (*(int *)arg1 != 0)
 		return (EINVAL);
 
-	fdp = curproc->p_fd;
-	count = 0;
-	FILEDESC_SLOCK(fdp);
-	map = fdp->fd_map;
-	off = NDSLOT(fdp->fd_nfiles - 1);
-	for (minoff = NDSLOT(0); off >= minoff; --off)
-		count += bitcountl(map[off]);
-	FILEDESC_SUNLOCK(fdp);
-
+	count = filedesc_nfiles(curproc->p_fd);
 	return (SYSCTL_OUT(req, &count, sizeof(count)));
 }
 
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 06e086fba15..c0fb4e3834e 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -337,6 +337,8 @@ fd_modified(struct filedesc *fdp, int fd, seqc_t seqc)
 }
 #endif
 
+int	proc_nfiles(struct proc *p);
+
 /* cdir/rdir/jdir manipulation functions. */
 struct pwddesc *pdcopy(struct pwddesc *pdp);
 void	pdescfree(struct thread *td);