X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type
	:content-transfer-encoding; q=dns; s=default; b=NBUa+WjRF0zpliKl
	NN+pP3Q23ftmeDKyqawfceQbkSvcdZCw2aJ/COgAlsSdIX9n0/ZzwPUuCc2Bz+jC
	eVPv4wDvc8G22jWLyR/NlYTgHnybUg94K6Gv3JeD1pyB7sGqT+f7ZFXY10k9/KlE
	TNBHYso5dVNs1LJk92Pj42FrVZg=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type
	:content-transfer-encoding; s=default; bh=+M+2VVoon1ixhjC6iC93je
	ysoIM=; b=QigUXnk5T6pn2wK8qlx/BxgyRPmvS9qXWbwLrq6s3WTBfsQio3lPjn
	C1Efkbqv0FeWOn+gHVtcoLdy9tzxTNH/RCwJs+DMFSLmg9IW9Yn1vJCq0UB0VHqK
	qrTKEmpOAHHGbbdwIR3xj5QS0hW6Mr41PYizm/c3Xo2d8xPAiaA0M=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Virus-Found:	No
X-Spam-SWARE-Status:	No, score=-2.2 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=Upon, Tony, cook, Cook
X-HELO:	mail-wm0-f49.google.com
X-Google-DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=6iczzzA6LRb5G/MtLQhJ7+KExWouA9sFyxOGTO5xCBs=; b=THEdsSaukDGJVHte+VSEe7/l2k8dR3pJF7kN4OZJ2NeLNGybnkL349GRw6QWedfKwn RRP3pBmdh3XTV/m0NCGQeLlnxovVgj4RvgUnS67OTwX7LM58gcefb4EptBOtlkzt6pv5 pk2TRNL/a1ZewN3R2ftC3GpxtqVfFQfC/n32XQ/TwKehbujb3W+/8jnyknMTnaZVULOT fHEyyN9XOMySXTJGoGjWuqB0wpgRuM7omnsyfjqZKL7dq5T1Fuz1GBAK6qmseKc9Z5bj 51S5AsirCj1eRX6+kv235FmnYVJQLIHon1GxLgd4GZdm6nM/zCnjxdJrBUdTgSl8kBEt OtWg==
X-Gm-Message-State:	AD7BkJITAlUI7fkr3FiUQPZal7W8JKnBMNfxAHhCRPM1y5U3UdI39QQcVx2QFUIiqZBqNQ==
X-Received:	by 10.28.175.201 with SMTP id y192mr23940779wme.54.1460450126801; Tue, 12 Apr 2016 01:35:26 -0700 (PDT)
Subject:	Re: strxfrm() returns an incorrect value on a short buffer
To:	cygwin AT cygwin DOT com
References:	<20160412050722 DOT GE12445 AT mars DOT tony DOT develop-help DOT com>
From:	Marco Atzeri <marco DOT atzeri AT gmail DOT com>
Message-ID:	<570CB34D.60200@gmail.com>
Date:	Tue, 12 Apr 2016 10:35:25 +0200
User-Agent:	Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2
MIME-Version:	1.0
In-Reply-To:	<20160412050722.GE12445@mars.tony.develop-help.com>
X-IsSubscribed:	yes

On 12/04/2016 07:07, Tony Cook wrote:
> strxfrm() returns an incorrect value if you supply an output buffer
> and that buffer is too short for the result.
>
> With the code following:
>
> #include <string.h>
> #include <locale.h>
> #include <stdio.h>
>
> int main() {
>    char xbuf[5] = "";
>    char *lc = setlocale(LC_ALL, "en_AU.utf8");
>    if (!lc) {
>      perror("setlocale");
>      return 1;
>    }
>    size_t sza = strxfrm(xbuf, "alphabet", sizeof(xbuf));
>    printf("sz: %zd\n", sza);
>    size_t szb = strxfrm(NULL, "alphabet", 0);
>    printf("sz: %zd\n", szb);
>
>    return 0;
> }
>
> On cygwin:
>
> tony AT phobos ~
> $ gcc -ostrxfrmtest strxfrmtest.c
>
> tony AT phobos ~
> $ ./strxfrmtest
> sz: 5
> sz: 20
>
> tony AT phobos ~
> $ uname -a
> CYGWIN_NT-6.1-WOW phobos 2.5.0(0.297/5/3) 2016-04-11 09:55 i686 Cygwin
>
> On Linux:
>
> tony AT mars:~$ gcc -ostrxfrmtest strxfrmtest.c
> tony AT mars:~$ ./strxfrmtest
> sz: 26
> sz: 26
> tony AT mars:~$ uname -a
> Linux mars 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3 (2016-01-17) x86_64 GNU/Linux
>
>  From looking at the source:
>
> https://cygwin.com/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=winsup/cygwin/nlsfuncs.cc;h=9dbd9b16d53094c60aa835756c967c054ced8e62;hb=HEAD#l1286
>
> It appears that strxfrm() is just returning the size of the output
> buffer on an overflow error rather than calling LCMapString() again
> with cchDest set to zero to get the required buffer length that
> strxfrm() is meant to return on a short buffer.
>
> This came out of the discussion in:
>
> https://rt.perl.org/Ticket/Display.html?id=121734
>
> (not that I've reproduced that issue.)
>
> Tony
>

You should check the error output.
Both cygwin and Linux seem IMHO to report an insufficient buffer
and s1 is not guaranteed.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/strxfrm.html

     Upon successful completion, strxfrm() [CX] [Option Start]  and 
strxfrm_l() [Option End]  shall return the length of the transformed 
string (not including the terminating NUL character). If the value 
returned is n or more, the contents of the array pointed to by s1 are 
unspecified.

     On error, strxfrm() [CX] [Option Start]  and strxfrm_l() [Option 
End]  may set errno but no return value is reserved to indicate an error.


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

- Raw text -