These two patches work around an ISO C compliance bug of wmemcmp() on several platforms.
The point is that in ISO C, a "wide character" is any wchar_t value. A "wide character" is not constrained to the range 0..INT_MAX. For the precise reasoning, see <https://www.openwall.com/lists/musl/2023/04/18/5>. 2023-04-18 Bruno Haible <[email protected]> wmemcmp: Add tests. * tests/test-wmemcmp.c: New file, based on tests/unistr/test-cmp.h. * modules/wmemcmp-tests: New file. wmemcmp: Work around ISO C compliance bug on several platforms. * lib/wchar.in.h (wmemcmp): Consider REPLACE_WMEMCMP. * lib/wmemcmp-impl.h (wmemcmp): Don't assume that the two wide characters are in the range 0..INT_MAX. * m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Test whether wmemcmp works for all wide characters. Set REPLACE_WMEMCMP. * m4/wchar_h.m4 (gl_WCHAR_H_DEFAULTS): Initialize REPLACE_WMEMCMP. * modules/wchar (Makefile.am): Substitute REPLACE_WMEMCMP. * modules/wmemcmp (configure.ac): Consider REPLACE_WMEMCMP. * doc/posix-functions/wmemcmp.texi: Mention the bug.
>From 6c28538c9d6bbf692ab12972de6cc035e54b0c67 Mon Sep 17 00:00:00 2001 From: Bruno Haible <[email protected]> Date: Wed, 19 Apr 2023 01:01:56 +0200 Subject: [PATCH 1/2] wmemcmp: Work around ISO C compliance bug on several platforms. * lib/wchar.in.h (wmemcmp): Consider REPLACE_WMEMCMP. * lib/wmemcmp-impl.h (wmemcmp): Don't assume that the two wide characters are in the range 0..INT_MAX. * m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Test whether wmemcmp works for all wide characters. Set REPLACE_WMEMCMP. * m4/wchar_h.m4 (gl_WCHAR_H_DEFAULTS): Initialize REPLACE_WMEMCMP. * modules/wchar (Makefile.am): Substitute REPLACE_WMEMCMP. * modules/wmemcmp (configure.ac): Consider REPLACE_WMEMCMP. * doc/posix-functions/wmemcmp.texi: Mention the bug. --- ChangeLog | 13 +++++++++ doc/posix-functions/wmemcmp.texi | 4 +++ lib/wchar.in.h | 16 +++++++++-- lib/wmemcmp-impl.h | 5 ++-- m4/wchar_h.m4 | 3 +- m4/wmemcmp.m4 | 49 +++++++++++++++++++++++++++++++- modules/wchar | 1 + modules/wmemcmp | 3 +- 8 files changed, 87 insertions(+), 7 deletions(-) diff --git a/ChangeLog b/ChangeLog index 4b8c72490b..6e885d865c 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,16 @@ +2023-04-18 Bruno Haible <[email protected]> + + wmemcmp: Work around ISO C compliance bug on several platforms. + * lib/wchar.in.h (wmemcmp): Consider REPLACE_WMEMCMP. + * lib/wmemcmp-impl.h (wmemcmp): Don't assume that the two wide + characters are in the range 0..INT_MAX. + * m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Test whether wmemcmp works for all + wide characters. Set REPLACE_WMEMCMP. + * m4/wchar_h.m4 (gl_WCHAR_H_DEFAULTS): Initialize REPLACE_WMEMCMP. + * modules/wchar (Makefile.am): Substitute REPLACE_WMEMCMP. + * modules/wmemcmp (configure.ac): Consider REPLACE_WMEMCMP. + * doc/posix-functions/wmemcmp.texi: Mention the bug. + 2023-04-18 Bruno Haible <[email protected]> doc: Update platform list for posix_spawnp. diff --git a/doc/posix-functions/wmemcmp.texi b/doc/posix-functions/wmemcmp.texi index 8d3262c5cb..cebacfb664 100644 --- a/doc/posix-functions/wmemcmp.texi +++ b/doc/posix-functions/wmemcmp.texi @@ -11,6 +11,10 @@ @item This function is missing on some platforms: HP-UX 11.00, IRIX 6.5, MSVC 14. +@item +This function compares the wide characters as if they were unsigned, although +@code{wchar_t} is signed, on some platforms: +glibc 2.14.1 on x86 or x86_64, musl libc 1.2.3, NetBSD 9.0, OpenBSD 7.2, Solaris 11.4. @end itemize Portability problems not fixed by Gnulib: diff --git a/lib/wchar.in.h b/lib/wchar.in.h index 80b6652e95..6a5b18d39d 100644 --- a/lib/wchar.in.h +++ b/lib/wchar.in.h @@ -641,13 +641,25 @@ _GL_WARN_ON_USE (wmemchr, "wmemchr is unportable - " /* Compare N wide characters of S1 and S2. */ #if @GNULIB_WMEMCMP@ -# if !@HAVE_WMEMCMP@ +# if @REPLACE_WMEMCMP@ +# if !(defined __cplusplus && defined GNULIB_NAMESPACE) +# undef wmemcmp +# define wmemcmp rpl_wmemcmp +# endif +_GL_FUNCDECL_RPL (wmemcmp, int, + (const wchar_t *s1, const wchar_t *s2, size_t n) + _GL_ATTRIBUTE_PURE); +_GL_CXXALIAS_RPL (wmemcmp, int, + (const wchar_t *s1, const wchar_t *s2, size_t n)); +# else +# if !@HAVE_WMEMCMP@ _GL_FUNCDECL_SYS (wmemcmp, int, (const wchar_t *s1, const wchar_t *s2, size_t n) _GL_ATTRIBUTE_PURE); -# endif +# endif _GL_CXXALIAS_SYS (wmemcmp, int, (const wchar_t *s1, const wchar_t *s2, size_t n)); +# endif # if __GLIBC__ >= 2 _GL_CXXALIASWARN (wmemcmp); # endif diff --git a/lib/wmemcmp-impl.h b/lib/wmemcmp-impl.h index 2b8125fe26..6148220de7 100644 --- a/lib/wmemcmp-impl.h +++ b/lib/wmemcmp-impl.h @@ -27,8 +27,9 @@ wmemcmp (const wchar_t *s1, const wchar_t *s2, size_t n) n--; continue; } - /* Note that wc1 and wc2 each have at most 31 bits. */ - return (int)wc1 - (int)wc2; + /* ISO C requires wmemcmp to work with all wchar_t values. + We cannot assume that wc1 and wc2 are in the range 0..INT_MAX. */ + return _GL_CMP (wc1, wc2); /* > 0 if wc1 > wc2, < 0 if wc1 < wc2. */ } return 0; diff --git a/m4/wchar_h.m4 b/m4/wchar_h.m4 index 8cc38ef804..dfd154f8e9 100644 --- a/m4/wchar_h.m4 +++ b/m4/wchar_h.m4 @@ -7,7 +7,7 @@ dnl Written by Eric Blake. -# wchar_h.m4 serial 57 +# wchar_h.m4 serial 58 AC_DEFUN_ONCE([gl_WCHAR_H], [ @@ -255,5 +255,6 @@ AC_DEFUN([gl_WCHAR_H_DEFAULTS] REPLACE_WCSFTIME=0; AC_SUBST([REPLACE_WCSFTIME]) REPLACE_WCSSTR=0; AC_SUBST([REPLACE_WCSSTR]) REPLACE_WCSTOK=0; AC_SUBST([REPLACE_WCSTOK]) + REPLACE_WMEMCMP=0; AC_SUBST([REPLACE_WMEMCMP]) REPLACE_WMEMPCPY=0; AC_SUBST([REPLACE_WMEMPCPY]) ]) diff --git a/m4/wmemcmp.m4 b/m4/wmemcmp.m4 index 534dde10cc..c804dc8a4a 100644 --- a/m4/wmemcmp.m4 +++ b/m4/wmemcmp.m4 @@ -1,4 +1,4 @@ -# wmemcmp.m4 serial 5 +# wmemcmp.m4 serial 6 dnl Copyright (C) 2011-2023 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -7,6 +7,7 @@ AC_DEFUN([gl_FUNC_WMEMCMP], [ AC_REQUIRE([gl_WCHAR_H_DEFAULTS]) + AC_REQUIRE([AC_CANONICAL_HOST]) dnl We cannot use AC_CHECK_FUNCS here, because the MSVC 9 header files dnl provide this function as an inline function definition. AC_CACHE_CHECK([for wmemcmp], [gl_cv_func_wmemcmp], @@ -21,5 +22,51 @@ AC_DEFUN([gl_FUNC_WMEMCMP] ]) if test $gl_cv_func_wmemcmp = no; then HAVE_WMEMCMP=0 + else + AC_CACHE_CHECK([whether wmemcmp works for all wide characters], + [gl_cv_func_wmemcmp_works], + [AC_RUN_IFELSE( + [AC_LANG_SOURCE([[ + #include <wchar.h> + int main () + { + wchar_t a = (wchar_t) 0x76547654; + wchar_t b = (wchar_t) 0x9abc9abc; + int cmp = wmemcmp (&a, &b, 1); + if ((wchar_t)-1 < 0) + return !(cmp > 0); + else + return !(cmp < 0); + } + ]]) + ], + [gl_cv_func_wmemcmp_works=yes], + [gl_cv_func_wmemcmp_works=no], + [case "$host_on" in + # Guess no on glibc versions < 2.15. + *-gnu* | gnu*) + AC_EGREP_CPP([Unlucky], + [ +#include <features.h> +#ifdef __GNU_LIBRARY__ + #if (__GLIBC__ == 2 && __GLIBC_MINOR__ < 15) + Unlucky GNU user + #endif +#endif + ], + [gl_cv_func_wmemcmp_works="guessing no"], + [gl_cv_func_wmemcmp_works="guessing yes"]) + ;; + # Guess no on musl systems. + *-musl* | midipix*) gl_cv_func_wmemcmp_works="guessing no" ;; + # If we don't know, obey --enable-cross-guesses. + *) gl_cv_func_wmemcmp_works="$gl_cross_guess_normal" ;; + esac + ]) + ]) + case "$gl_cv_func_wmemcmp_works" in + *yes) ;; + *) REPLACE_WMEMCMP=1 ;; + esac fi ]) diff --git a/modules/wchar b/modules/wchar index feacaffff1..180c94309c 100644 --- a/modules/wchar +++ b/modules/wchar @@ -144,6 +144,7 @@ wchar.h: wchar.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) -e 's|@''REPLACE_WCSFTIME''@|$(REPLACE_WCSFTIME)|g' \ -e 's|@''REPLACE_WCSSTR''@|$(REPLACE_WCSSTR)|g' \ -e 's|@''REPLACE_WCSTOK''@|$(REPLACE_WCSTOK)|g' \ + -e 's|@''REPLACE_WMEMCMP''@|$(REPLACE_WMEMCMP)|g' \ -e 's|@''REPLACE_WMEMPCPY''@|$(REPLACE_WMEMPCPY)|g' \ -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \ -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \ diff --git a/modules/wmemcmp b/modules/wmemcmp index 219f3c3754..c0e19a5184 100644 --- a/modules/wmemcmp +++ b/modules/wmemcmp @@ -11,7 +11,8 @@ wchar configure.ac: gl_FUNC_WMEMCMP -gl_CONDITIONAL([GL_COND_OBJ_WMEMCMP], [test $HAVE_WMEMCMP = 0]) +gl_CONDITIONAL([GL_COND_OBJ_WMEMCMP], + [test $HAVE_WMEMCMP = 0 || test $REPLACE_WMEMCMP = 1]) gl_WCHAR_MODULE_INDICATOR([wmemcmp]) Makefile.am: -- 2.34.1
>From 312f211ba66f4b3f58fdb4399c61c58c0dcf6e75 Mon Sep 17 00:00:00 2001 From: Bruno Haible <[email protected]> Date: Wed, 19 Apr 2023 01:10:32 +0200 Subject: [PATCH 2/2] wmemcmp: Add tests. * tests/test-wmemcmp.c: New file, based on tests/unistr/test-cmp.h. * modules/wmemcmp-tests: New file. --- ChangeLog | 4 ++ modules/wmemcmp-tests | 12 ++++++ tests/test-wmemcmp.c | 91 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 107 insertions(+) create mode 100644 modules/wmemcmp-tests create mode 100644 tests/test-wmemcmp.c diff --git a/ChangeLog b/ChangeLog index 6e885d865c..17596c4b23 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,9 @@ 2023-04-18 Bruno Haible <[email protected]> + wmemcmp: Add tests. + * tests/test-wmemcmp.c: New file, based on tests/unistr/test-cmp.h. + * modules/wmemcmp-tests: New file. + wmemcmp: Work around ISO C compliance bug on several platforms. * lib/wchar.in.h (wmemcmp): Consider REPLACE_WMEMCMP. * lib/wmemcmp-impl.h (wmemcmp): Don't assume that the two wide diff --git a/modules/wmemcmp-tests b/modules/wmemcmp-tests new file mode 100644 index 0000000000..c42df6ec27 --- /dev/null +++ b/modules/wmemcmp-tests @@ -0,0 +1,12 @@ +Files: +tests/test-wmemcmp.c +tests/signature.h +tests/macros.h + +Depends-on: + +configure.ac: + +Makefile.am: +TESTS += test-wmemcmp +check_PROGRAMS += test-wmemcmp diff --git a/tests/test-wmemcmp.c b/tests/test-wmemcmp.c new file mode 100644 index 0000000000..998dff2653 --- /dev/null +++ b/tests/test-wmemcmp.c @@ -0,0 +1,91 @@ +/* Test of wmemcmp() function. + Copyright (C) 2008-2023 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <[email protected]>, 2023. */ + +#include <config.h> + +#include <wchar.h> + +#include "signature.h" +SIGNATURE_CHECK (wmemcmp, int, (const wchar_t *, const wchar_t *, size_t)); + +#include "macros.h" + +int +main (int argc, char *argv[]) +{ + /* Test equal / not equal distinction. */ + { + static const wchar_t input1[] = { 'f', 'o', 'o', 0 }; + static const wchar_t input2[] = { 'f', 'o', 'o', 'b', 'a', 'r', 0 }; + ASSERT (wmemcmp (input1, input2, 2) == 0); + ASSERT (wmemcmp (input1, input2, 3) == 0); + ASSERT (wmemcmp (input1, input2, 4) != 0); + } + { + static const wchar_t input1[] = { 'f', 'o', 'o', 0 }; + static const wchar_t input2[] = { 'b', 'a', 'r', 0 }; + ASSERT (wmemcmp (input1, input2, 1) != 0); + ASSERT (wmemcmp (input1, input2, 3) != 0); + } + + /* Test less / equal / greater distinction. */ + { + static const wchar_t input1[] = { 'f', 'o', 'o', 0 }; + static const wchar_t input2[] = { 'm', 'o', 'o', 0 }; + ASSERT (wmemcmp (input1, input2, 4) < 0); + ASSERT (wmemcmp (input2, input1, 4) > 0); + } + { + static const wchar_t input1[] = { 'o', 'o', 'm', 'p', 'h', 0 }; + static const wchar_t input2[] = { 'o', 'o', 'p', 's', 0 }; + ASSERT (wmemcmp (input1, input2, 3) < 0); + ASSERT (wmemcmp (input2, input1, 3) > 0); + } + { + static const wchar_t input1[] = { 'f', 'o', 'o', 0 }; + static const wchar_t input2[] = { 'f', 'o', 'o', 'b', 'a', 'r', 0 }; + ASSERT (wmemcmp (input1, input2, 4) < 0); + ASSERT (wmemcmp (input2, input1, 4) > 0); + } + + /* ISO C requires wmemcmp to work with all wchar_t values. */ + { + static const wchar_t input1[] = { (wchar_t) 0x76547654 }; + static const wchar_t input2[] = { (wchar_t) 0x9abc9abc }; + if ((wchar_t)-1 < 0) + { + /* wchar_t is signed. */ + ASSERT (wmemcmp (input1, input2, 1) > 0); + ASSERT (wmemcmp (input2, input1, 1) < 0); + } + else + { + /* wchar_t is unsigned. */ + ASSERT (wmemcmp (input1, input2, 1) < 0); + ASSERT (wmemcmp (input2, input1, 1) > 0); + } + } + { + static const wchar_t input1[] = { (wchar_t) 0x9abc9abc }; + static const wchar_t input2[] = { (wchar_t) 0x9bdf9bdf }; + ASSERT (wmemcmp (input1, input2, 1) < 0); + ASSERT (wmemcmp (input2, input1, 1) > 0); + } + + return 0; +} -- 2.34.1
