On Wed, 2024-11-20 at 15:27 +0100, Miklos Szeredi wrote:
> Move common code from opt_array/opt_sec_array to helper. This helper
> does more than just unescape options, so rename to
> statmount_opt_process().
>
> Handle corner case of just a single character in options.
>
> Rename some local variables to better describe their function.
>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> ---
> fs/namespace.c | 44 +++++++++++++++++++-------------------------
> 1 file changed, 19 insertions(+), 25 deletions(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index eb34a5160f64..23e81c2a1e3f 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -5057,21 +5057,32 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq)
> return 0;
> }
>
> -static inline int statmount_opt_unescape(struct seq_file *seq, char *buf_start)
> +static inline int statmount_opt_process(struct seq_file *seq, size_t start)
> {
> - char *buf_end, *opt_start, *opt_end;
> + char *buf_end, *opt_end, *src, *dst;
> int count = 0;
>
> + if (unlikely(seq_has_overflowed(seq)))
> + return -EAGAIN;
> +
> buf_end = seq->buf + seq->count;
> + dst = seq->buf + start;
> + src = dst + 1; /* skip initial comma */
> +
> + if (src >= buf_end) {
> + seq->count = start;
> + return 0;
> + }
> +
> *buf_end = '\0';
> - for (opt_start = buf_start + 1; opt_start < buf_end; opt_start = opt_end + 1) {
> - opt_end = strchrnul(opt_start, ',');
> + for (; src < buf_end; src = opt_end + 1) {
> + opt_end = strchrnul(src, ',');
> *opt_end = '\0';
> - buf_start += string_unescape(opt_start, buf_start, 0, UNESCAPE_OCTAL) + 1;
> + dst += string_unescape(src, dst, 0, UNESCAPE_OCTAL) + 1;
> if (WARN_ON_ONCE(++count == INT_MAX))
> return -EOVERFLOW;
> }
> - seq->count = buf_start - 1 - seq->buf;
> + seq->count = dst - 1 - seq->buf;
> return count;
> }
>
> @@ -5080,24 +5091,16 @@ static int statmount_opt_array(struct kstatmount *s, struct seq_file *seq)
> struct vfsmount *mnt = s->mnt;
> struct super_block *sb = mnt->mnt_sb;
> size_t start = seq->count;
> - char *buf_start;
> int err;
>
> if (!sb->s_op->show_options)
> return 0;
>
> - buf_start = seq->buf + start;
> err = sb->s_op->show_options(seq, mnt->mnt_root);
> if (err)
> return err;
>
> - if (unlikely(seq_has_overflowed(seq)))
> - return -EAGAIN;
> -
> - if (seq->count == start)
> - return 0;
> -
> - err = statmount_opt_unescape(seq, buf_start);
> + err = statmount_opt_process(seq, start);
> if (err < 0)
> return err;
>
> @@ -5110,22 +5113,13 @@ static int statmount_opt_sec_array(struct kstatmount *s, struct seq_file *seq)
> struct vfsmount *mnt = s->mnt;
> struct super_block *sb = mnt->mnt_sb;
> size_t start = seq->count;
> - char *buf_start;
> int err;
>
> - buf_start = seq->buf + start;
> -
> err = security_sb_show_options(seq, sb);
> if (err)
> return err;
>
> - if (unlikely(seq_has_overflowed(seq)))
> - return -EAGAIN;
> -
> - if (seq->count == start)
> - return 0;
> -
> - err = statmount_opt_unescape(seq, buf_start);
> + err = statmount_opt_process(seq, start);
> if (err < 0)
> return err;
>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
