Messages in this thread | | | Date | Sat, 28 Dec 2013 19:57:50 +0100 | Subject | Re: [PATCH] lib/vsprintf: add %pT[C012] format specifier | From | Geert Uytterhoeven <> |
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On Sat, Dec 28, 2013 at 4:43 AM, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> wrote: > Andrew Morton wrote: >> which is painful, so we also provide the new vsprintf token as a >> convenience: >> >> pr_warn("%|: hair on fire\n"); >> >> but I don't know what we can use in place of %|. > > We are using %pEXTENSION where EXTENSION is [A-Za-z0-9]* because compiler does > not need to understand what EXTENSION does; compiler needs to care about what > character follows the % character and check type of corresponding argument if > __printf() attribute is given.
Indeed,
> If we introduce a character which compiler does not know that follows the % > character, compiler would be confused when checking type of corresponding > argument. > >> I wonder if there's some way in which we can invent a vsprintf token >> which means "insert corrent->comm here" and which doesn't require that >> the caller pass in the additional argument? > > Therefore, if we want to omit passing corresponding argument, we should not > introduce new character which compiler does not know that follows the % > character. > > Also, % is the only character which everybody knows that it is reserved for the > beginning of format specifier and %% is the only characters which everybody > knows that it is reserved for literal % character. > > Therefore, what we could do for printing current thread's attributes would be > either reserve a new character and add EXTENSION like > > pr_warn("$comm$: hair on fire\n"); > pr_warn("Process $pid$: hair on fire\n"); > > or add EXTENSION after the %% characters like > > pr_warn("%%comm%%: hair on fire\n"); > pr_warn("Process %%pid%%: hair on fire\n");
ESC sequences? So far printk() doesn't parse them (a bit unfortunate, as I always liked the idea of printing error messages in red, warnings in yellow, etc.).
Is any of the "\x" (backslash + character) unused and thus available?
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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