Re: [PATCH 1/2] remove all uses of printf's %n

From: Jiri Slaby
Date: Fri Sep 20 2013 - 04:08:21 EST


On 09/20/2013 06:09 AM, Tetsuo Handa wrote:
> --- a/fs/proc/consoles.c
> +++ b/fs/proc/consoles.c
...
> @@ -47,11 +46,10 @@ static int show_console_dev(struct seq_file *m, void *v)
> con_flags[a].name : ' ';
> flags[a] = 0;
>
> - seq_printf(m, "%s%d%n", con->name, con->index, &len);
> - len = 21 - len;
> - if (len < 1)
> - len = 1;
> - seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-',
> + seq_setwidth(m, 21 - 1);
> + seq_printf(m, "%s%d", con->name, con->index);
> + seq_pad(m, ' ');
> + seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',
> con->write ? 'W' : '-', con->unblank ? 'U' : '-',
> flags);

Hello, do you really need seq_setwidth? It makes it really ugly...

Or do we need that all? Couldn't we simply have seq_printf_padded? Or
maybe some % modifier in seq_printf to pad the string?

> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
...
> @@ -2548,15 +2549,15 @@ static int fib_route_seq_show(struct seq_file *seq, void *v)
> (fi->fib_advmss ?
> fi->fib_advmss + 40 : 0),
> fi->fib_window,
> - fi->fib_rtt >> 3, &len);
> + fi->fib_rtt >> 3);
> else
> seq_printf(seq,
> "*\t%08X\t%08X\t%04X\t%d\t%u\t"
> - "%d\t%08X\t%d\t%u\t%u%n",
> + "%d\t%08X\t%d\t%u\t%u",
> prefix, 0, flags, 0, 0, 0,
> - mask, 0, 0, 0, &len);
> + mask, 0, 0, 0);
>
> - seq_printf(seq, "%*s\n", 127 - len, "");
> + seq_pad(seq, '\n');

Hmm, seq_pad is unintuitive. I would say it pads the string by '\n'. Of
course it does not, but...

thanks,
--
js
suse labs
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