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* [Bug libc/9674] New: mbtowc keeps internal state even for stateless encodings
@ 2008-12-19 1:10 bruno at clisp dot org
2008-12-22 10:15 ` [Bug libc/9674] " bonzini at gnu dot org
2008-12-26 18:56 ` drepper at redhat dot com
0 siblings, 2 replies; 6+ messages in thread
From: bruno at clisp dot org @ 2008-12-19 1:10 UTC (permalink / raw)
To: glibc-bugs
Run the following program on a system with a fr_FR.UTF-8 locale.
===================================================================
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
int main ()
{
int locale_found = setlocale (LC_ALL, "fr_FR.UTF-8") != NULL;
printf ("%d\n", locale_found);
printf ("%d\n", mbtowc (NULL, NULL, 0));
static const char input[4] = { 195, 188, 195, 159 };
wchar_t wc;
int res2a = mbtowc (&wc, input, 4);
printf ("%d\n", res2a);
int res1 = mbtowc (&wc, input, 1);
printf ("%d\n", res1);
int res2b = mbtowc (&wc, input, 4);
printf ("%d\n", res2b);
return 0;
}
===================================================================
$ gcc -O -Wall foo.c
$ ./a.out
1
0
2
-1
-1
Expected output:
1
0
2
-1
2
Rationale:
The first line shows that the locale was correctly set. So the locale encoding
is UTF-8.
The second line that the UTF-8 encoding is non state dependent.
The third and fifth line show that the same call has different results, that
is, it must depend on a hidden state.
But the mbtowc specification says that "For a state-dependent encoding ...
Subsequent calls with s as other than a null pointer shall cause the internal
state of the function to be altered as necessary."
However, the encoding in use here is not state dependent. Hence the function's
results should not depend on hidden state.
Reference:
POSIX:2008 specification of mbtowc:
<http://www.opengroup.org/onlinepubs/9699919799/functions/mbtowc.html>
--
Summary: mbtowc keeps internal state even for stateless encodings
Product: glibc
Version: 2.8
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper at redhat dot com
ReportedBy: bruno at clisp dot org
CC: glibc-bugs at sources dot redhat dot com
GCC build triplet: i686-suse-linux
GCC host triplet: i686-suse-linux
GCC target triplet: i686-suse-linux
http://sourceware.org/bugzilla/show_bug.cgi?id=9674
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* [Bug libc/9674] mbtowc keeps internal state even for stateless encodings
2008-12-19 1:10 [Bug libc/9674] New: " bruno at clisp dot org
@ 2008-12-22 10:15 ` bonzini at gnu dot org
2008-12-26 18:56 ` drepper at redhat dot com
1 sibling, 0 replies; 6+ messages in thread
From: bonzini at gnu dot org @ 2008-12-22 10:15 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From bonzini at gnu dot org 2008-12-22 10:14 -------
For completeness, I will add that this requirement is also present in ISO C at
the beginning of 7.20.7 (outside 7.20.7.2 which is where mbtowc is defined).
OTOH, the fact that "For a state-dependent encoding, each function is placed
into its initial state by a call for which its character pointer argument, s, is
a null pointer" does not imply that an implementation cannot do the same for
state-independent encodings too...
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |bonzini at gnu dot org
http://sourceware.org/bugzilla/show_bug.cgi?id=9674
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* [Bug libc/9674] mbtowc keeps internal state even for stateless encodings
2008-12-19 1:10 [Bug libc/9674] New: " bruno at clisp dot org
2008-12-22 10:15 ` [Bug libc/9674] " bonzini at gnu dot org
@ 2008-12-26 18:56 ` drepper at redhat dot com
1 sibling, 0 replies; 6+ messages in thread
From: drepper at redhat dot com @ 2008-12-26 18:56 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drepper at redhat dot com 2008-12-26 18:54 -------
The state does not only contain the shift state but also incomplete input. That
explains the behavior and it is a correct implementation according to the
wording of the specification.
You'll have to get the standard body to explicitly confirm your reading before
anything will be changed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |WAITING
http://sourceware.org/bugzilla/show_bug.cgi?id=9674
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end of thread, other threads:[~2014-07-02 7:49 UTC | newest]
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2011-05-16 0:10 ` [Bug libc/9674] mbtowc keeps internal state even for stateless encodings drepper.fsp at gmail dot com
2014-02-16 19:41 ` jackie.rosen at hushmail dot com
2014-05-28 19:43 ` schwab at sourceware dot org
2014-07-02 7:49 ` fweimer at redhat dot com
2008-12-19 1:10 [Bug libc/9674] New: " bruno at clisp dot org
2008-12-22 10:15 ` [Bug libc/9674] " bonzini at gnu dot org
2008-12-26 18:56 ` drepper at redhat dot com
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