git: 360ff2ca4710 - stable/15 - dup(2): document the handling of filedescriptor flags

The branch stable/15 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=360ff2ca47101240d34e1bf56cb788bd5ffb7c96

commit 360ff2ca47101240d34e1bf56cb788bd5ffb7c96
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-03-28 08:51:42 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-03-31 04:07:17 +0000

    dup(2): document the handling of filedescriptor flags
    
    (cherry picked from commit 6cc99baea607255859ee958608e4db6e2ff24793)
---
 lib/libc/gen/dup3.3 | 2 ++
 lib/libsys/dup.2    | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/libc/gen/dup3.3 b/lib/libc/gen/dup3.3
index 338a9ae74c64..ec89ef77cf17 100644
--- a/lib/libc/gen/dup3.3
+++ b/lib/libc/gen/dup3.3
@@ -52,6 +52,8 @@ The close-on-fork flag on the new file descriptor is determined by the
 bit in
 .Fa flags .
 .Pp
+The resolve-beneath flag on the new file descriptor is preserved.
+.Pp
 If
 .Fa oldd
 \*(Ne
diff --git a/lib/libsys/dup.2 b/lib/libsys/dup.2
index 524fd7688670..9c1e3e8d648b 100644
--- a/lib/libsys/dup.2
+++ b/lib/libsys/dup.2
@@ -81,7 +81,10 @@ object reference to the file must be obtained by issuing an
 additional
 .Xr open 2
 system call.
-The close-on-exec flag on the new file descriptor is unset.
+The close-on-exec and close-on-fork flags on the new file descriptor
+are unset.
+The resolve-beneath flag on the new file descriptor is set to the same
+state as on the old file descriptor.
 .Pp
 In
 .Fn dup2 ,