git: 592f2e599f24 - stable/14 - devfs readdir: handle short buffer same as UFS

The branch stable/14 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=592f2e599f242826a68a08186f2e65e29c2eb887

commit 592f2e599f242826a68a08186f2e65e29c2eb887
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-08-01 08:22:14 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-08-08 04:16:47 +0000

    devfs readdir: handle short buffer same as UFS
    
    (cherry picked from commit 011efaa5cd246a67bbe6e37364baa18178a9f7bd)
---
 sys/fs/devfs/devfs_vnops.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 4b6845602218..2a4576320286 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -1452,6 +1452,7 @@ devfs_readdir(struct vop_readdir_args *ap)
 	struct devfs_mount *dmp;
 	off_t off;
 	int *tmp_ncookies = NULL;
+	ssize_t startresid;
 
 	if (ap->a_vp->v_type != VDIR)
 		return (ENOTDIR);
@@ -1484,6 +1485,7 @@ devfs_readdir(struct vop_readdir_args *ap)
 	error = 0;
 	de = ap->a_vp->v_data;
 	off = 0;
+	startresid = uio->uio_resid;
 	TAILQ_FOREACH(dd, &de->de_dlist, de_list) {
 		KASSERT(dd->de_cdp != (void *)0xdeadc0de, ("%s %d\n", __func__, __LINE__));
 		if (dd->de_flags & (DE_COVERED | DE_WHITEOUT))
@@ -1496,8 +1498,13 @@ devfs_readdir(struct vop_readdir_args *ap)
 			de = dd;
 		dp = dd->de_dirent;
 		MPASS(dp->d_reclen == GENERIC_DIRSIZ(dp));
-		if (dp->d_reclen > uio->uio_resid)
+		if (dp->d_reclen > uio->uio_resid) {
+			/* Nothing was copied out, return EINVAL. */
+			if (uio->uio_resid == startresid)
+				error = EINVAL;
+			/* Otherwise stop. */
 			break;
+		}
 		dp->d_fileno = de->de_inode;
 		/* NOTE: d_off is the offset for the *next* entry. */
 		dp->d_off = off + dp->d_reclen;