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Message-ID: <20120608144423.GN163@brightrain.aerifal.cx>
Date: Fri, 8 Jun 2012 10:44:23 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: printf POSIX compliance
On Fri, Jun 08, 2012 at 11:34:04AM +0100, Reuben Thomas wrote:
> I notice that the musl FAQ says "the fundamentally broken freadahead
> function in gnulib cannot be fixed by adding features to the C
> library". I found this question because a user complained about my use
> of gnulib in a package I maintain.
>
> I contacted the gnulib maintainers, one of whom replied:
>
> "IIRC, gnulib's freadahead use is caused by musl's printf not being
> posix compliant, causing gnulib to pull in its printf replacement,
> which doesn't work on musl."
The first failing test I found was invalid. It's a test for whether
printf supports printing non-finite long double values. gnulib is
constructing an illegal long double representation (which they call
"pseudo-denormal") that will never occur as a value and passing it to
printf:
| { /* Pseudo-Denormal. */
| static union { unsigned int word[4]; long double value; } x =
| { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
| if (sprintf (buf, "%Lf", x.value) < 0
| || !strisnan (buf, 0, strlen (buf)))
| result |= 64;
This test should simply be removed; there is no reason printf should
handle invalid bit patterns that cannot occur as values.
The second failing test actually caught a slight bug in %ls with
precision modifiers. I've fixed it in musl git.
Still working on finding whether this long double issue is what's
causign the gnulib junk to get pulled in...
Rich
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