From: Rich Felker <dalias@libc.org>
To: Bruno Haible <bruno@clisp.org>
Cc: musl@lists.openwall.com
Subject: Re: [musl] swprintf: minimum width ignored for %lc
Date: Mon, 20 Mar 2023 08:18:42 -0400 [thread overview]
Message-ID: <20230320121841.GR4163@brightrain.aerifal.cx> (raw)
In-Reply-To: <11995006.zapYfy813O@nimes>
On Mon, Mar 20, 2023 at 01:29:47AM +0100, Bruno Haible wrote:
> On musl-1.2.3 I see this violation of the POSIX specification of swprintf [1]:
>
> ==================================== foo1.c ====================================
> #include <stdio.h>
> #include <wchar.h>
>
> int main ()
> {
> static wint_t L_x = (wchar_t) 'x';
> wchar_t buf[12] =
> { 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF,
> 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF, 0xDEADBEEF };
> int ret = swprintf (buf, 12, L"%10lc", L_x);
> printf ("ret = %d, buf[0] = 0x%x, buf[1] = 0x%x, buf[9] = 0x%x, buf[10] = 0x%x, buf[11] = 0x%x\n",
> ret,
> (unsigned int) buf[0], (unsigned int) buf[1],
> (unsigned int) buf[9], (unsigned int) buf[10], (unsigned int) buf[11]);
> return 0;
> }
> /*
> glibc: ret = 10, buf[0] = 0x20, buf[1] = 0x20, buf[9] = 0x78, buf[10] = 0x0, buf[11] = 0xdeadbeef
> musl libc: ret = 1, buf[0] = 0x78, buf[1] = 0x0, buf[9] = 0xdeadbeef, buf[10] = 0xdeadbeef, buf[11] = 0xdeadbeef
> */
> ================================================================================
>
> $ gcc -Wall foo1.c
> $ ./a.out
> ret = 1, buf[0] = 0x78, buf[1] = 0x0, buf[9] = 0xdeadbeef, buf[10] = 0xdeadbeef, buf[11] = 0xdeadbeef
>
> The POSIX specification [1] says:
> "An optional minimum field width. If the converted value has fewer wide
> characters than the field width, it shall be padded with <space> characters
> by default on the left; it shall be padded on the right, if the left-
> adjustment flag ( '-' ), described below, is given to the field width. The
> field width takes the form of an <asterisk> ( '*' ), described below, or a
> decimal integer."
>
> Here, the minimum field width specification of 10 was apparently ignored.
Indeed, it's very clear from the code that it was just ignored. This
has a simple direct fix.
Rich
prev parent reply other threads:[~2023-03-20 12:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 0:29 Bruno Haible
2023-03-20 12:18 ` Rich Felker [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230320121841.GR4163@brightrain.aerifal.cx \
--to=dalias@libc.org \
--cc=bruno@clisp.org \
--cc=musl@lists.openwall.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).