linux-kernel - Re: [PATCH] bcachefs: replace deprecated strncpy() with strscpy()

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Message-ID: <bmjvipermsvb454mdh5zmlmw4gv4oub5fgh4eowedlit75gqei@3or3va3e52ce>
Date: Wed, 26 Mar 2025 08:19:32 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Alan Huang <mmpgouride@...il.com>
Cc: Roxana Nicolescu <nicolescu.roxana@...tonmail.com>, 
	linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org, skhan@...uxfoundation.org, 
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] bcachefs: replace deprecated strncpy() with strscpy()

On Wed, Mar 26, 2025 at 06:02:31PM +0800, Alan Huang wrote:
> On Mar 26, 2025, at 17:44, Roxana Nicolescu <nicolescu.roxana@...tonmail.com> wrote:
> > 
> > strncpy() is deprecated for NUL-terminated destination buffers. Use
> > strscpy() instead.
> > 
> > Link: https://github.com/KSPP/linux/issues/90
> > Signed-off-by: Roxana Nicolescu <nicolescu.roxana@...tonmail.com>
> > ---
> > fs/bcachefs/btree_trans_commit.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/bcachefs/btree_trans_commit.c b/fs/bcachefs/btree_trans_commit.c
> > index c4f524b2ca9a..7ab25b425d11 100644
> > --- a/fs/bcachefs/btree_trans_commit.c
> > +++ b/fs/bcachefs/btree_trans_commit.c
> > @@ -364,7 +364,7 @@ static noinline void journal_transaction_name(struct btree_trans *trans)
> > struct jset_entry_log *l =
> > container_of(entry, struct jset_entry_log, entry);
> > 
> > - strncpy(l->d, trans->fn, JSET_ENTRY_LOG_U64s * sizeof(u64));
> > + strscpy(l->d, trans->fn, JSET_ENTRY_LOG_U64s * sizeof(u64));
> 
> The last time I asked Kent about this line, he didn’t want this.

Yes, the destination buffer isn't required to be nul terminated.

But it seems we should add a comment explaining that :)