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* bug with printf positional arguments?
@ 2023-06-28 13:28 Jon Turney
  2023-07-03 11:14 ` Corinna Vinschen
  0 siblings, 1 reply; 4+ messages in thread
From: Jon Turney @ 2023-06-28 13:28 UTC (permalink / raw)
  To: newlib

The following trivial program (extracted from a glib testcase)

> #include <stdio.h>
> int main()
> {
>   printf ("%1$*2$.*3$s", "abc", 5, 2);
> }

does not produce the expected output of "   ab", on 64-bit Cygwin.

 From a bit of staring at and stepping through get_args() in 
libc/stdio/vfprintf.c, it looks like the problem is (something like) we 
don't have the knowledge that the first positional variadic argument 
should be treated as a pointer, at the point that we store it's value, 
so it gets treated as an integer (the default), which is going to lead 
to truncation on LP64 platforms.

A straightforward way to fix this eludes me.

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2023-07-26 13:27 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-06-28 13:28 bug with printf positional arguments? Jon Turney
2023-07-03 11:14 ` Corinna Vinschen
2023-07-03 14:49   ` Jon Turney
2023-07-26 13:26     ` Corinna Vinschen

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