From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 011B4385DDD8; Tue, 11 Jun 2024 15:22:50 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 011B4385DDD8
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1718119371;
	bh=XypLzLxgdChmTeil3EdG3d1yRsN2VnEao5JpOtU2L9s=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=nvh3uedjfaNQRruifCI5UPrM0xbr0S3JJ4ELD0QGzI1wQ8mn6izk1PoG9QpaMG/yy
	 xaTbDoeYRXwkxz5bayj/WZw2rC4bLI3U1rOCs7eZEqeqDozBgxQj5Nia8uEX41f6wV
	 hhAAeJ1U2BUrAt58K+LswwzGYHqMtIbKrPnpqb24=
From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/37475] codecvt::do_in/do_out functions return "ok"
 when the output sequence has zero length
Date: Tue, 11 Jun 2024 15:22:50 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-37475-4-eJ4DKQCoP9@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-37475-4@http.gcc.gnu.org/bugzilla/>
References: <bug-37475-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D37475

--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This changes the loop to always run if the input is non-empty, and so return
partial if the destination is empty.

--- a/libstdc++-v3/config/locale/gnu/codecvt_members.cc
+++ b/libstdc++-v3/config/locale/gnu/codecvt_members.cc
@@ -131,10 +131,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     // mbsnrtowcs is *very* fast but stops if encounters NUL characters:
     // in case we store a L'\0' and then continue, in a loop.
     // NB: mbsnrtowcs is a GNU extension
-    for (__from_next =3D __from, __to_next =3D __to;
-        __from_next < __from_end && __to_next < __to_end
-        && __ret =3D=3D ok;)
+    __from_next =3D __from;
+    __to_next =3D __to;
+    while (__from_next < __from_end)
       {
+       if (__to_next >=3D __to_end)
+         {
+           __ret =3D partial;
+           break;
+         }
+
        const extern_type* __from_chunk_end;
        __from_chunk_end =3D static_cast<const extern_type*>(memchr(__from_=
next,
'\0',
                                                                  __from_end
@@ -162,12 +168,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
            __from_next =3D __from;
            __state =3D __tmp_state;
            __ret =3D error;
+           break;
          }
        else if (__from_next && __from_next < __from_chunk_end)
          {
            // It is unclear what to return in this case (see DR 382).
            __to_next +=3D __conv;
            __ret =3D partial;
+           break;
          }
        else
          {
@@ -175,7 +183,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
            __to_next +=3D __conv;
          }

-       if (__from_next < __from_end && __ret =3D=3D ok)
+       if (__from_next < __from_end)
          {
            if (__to_next < __to_end)
              {
@@ -185,7 +193,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
                *__to_next++ =3D L'\0';
              }
            else
-             __ret =3D partial;
+             {
+               __ret =3D partial;
+               break;
+             }
          }
       }=