[PATCH] string: Declare POSIX.1-2024 string functions [BZ #34466]
Alex Gao
gaoxiang@kylinos.cn
Fri Aug 14 02:06:40 GMT 2026
在 2026/8/13 19:46, Adhemerval Zanella Netto 写道:
>
>
> On 13/08/26 00:13, Gao Xiang wrote:
>> From: Xiang Gao <gaoxiang@kylinos.cn>
>>
>> POSIX.1-2024 adds memmem, strlcpy and strlcat to string.h.
>> glibc already implements these functions. but their public
>> declarations are currently only exports by __USE_MISC.
>> Applications built in POSIX.1-2024 mode with _POSIX_C_SOURCE=
>> 202405L will fail with implicit function declaration errors.
>>
>> Using existed feature macro to expose the declarations required
>> by POSIX.1-2024.
>>
>> Add string/tst-posix2024 to verify strict POSIX.1-2024 header
>> visibility.
>>
>> Tested on x86_64 Fedora 42.
>>
>> The following tests passed without regressions:
>> make test t=string/tst-posix2024
>> make check subdirs=string
>> make check subdirs=conform
>>
>> Signed-off-by: Xiang Gao <gaoxiang@kylinos.cn>
>
> We already have a similar patch [1], already approved by DJ. Does this add
> or fix something else?
>
> [1] https://patchwork.sourceware.org/project/glibc/patch/20260805080213.3533189-1-matthias.goergens@gmail.com/
>
>> ---
>> conform/data/string.h-data | 7 ++++++
>> string/Makefile | 2 ++
>> string/string.h | 6 ++++--
>> string/tst-posix2024.c | 44 ++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 57 insertions(+), 2 deletions(-)
>> create mode 100644 string/tst-posix2024.c
>>
>> diff --git a/conform/data/string.h-data b/conform/data/string.h-data
>> index abc6b12b5d..c9526e06d0 100644
>> --- a/conform/data/string.h-data
>> +++ b/conform/data/string.h-data
>> @@ -13,6 +13,9 @@ function int memcmp (const void*, const void*, size_t)
>> function {void*} memcpy (void*, const void*, size_t)
>> function {void*} memmove (void*, const void*, size_t)
>> function {void*} memset (void*, int, size_t)
>> +#if defined XOPEN2K24 || defined POSIX2024
>> +function {void*} memmem (const void*, size_t, const void*, size_t)
>> +#endif
>> #if defined XOPEN2K8 || defined XOPEN2K24 || defined POSIX2008 || defined POSIX2024
>> function {char*} stpcpy (char*, const char*)
>> function {char*} stpncpy (char*, const char*, size_t)
>> @@ -38,6 +41,10 @@ function int strerror_r (int, char*, size_t)
>> function {char*} strerror_l (int, locale_t)
>> #endif
>> function size_t strlen (const char*)
>> +#if defined XOPEN2K24 || defined POSIX2024
>> +function size_t strlcat (char*, const char*, size_t)
>> +function size_t strlcpy (char*, const char*, size_t)
>> +#endif
>> function {char*} strncat (char*, const char*, size_t)
>> function int strncmp (const char*, const char*, size_t)
>> function {char*} strncpy (char*, const char*, size_t)
>> diff --git a/string/Makefile b/string/Makefile
>> index aa0b0c2f57..a968994fcb 100644
>> --- a/string/Makefile
>> +++ b/string/Makefile
>> @@ -201,6 +201,7 @@ tests := \
>> tst-endian \
>> tst-inlcall \
>> tst-memmove-overflow \
>> + tst-posix2024 \
>> tst-strerror-fail \
>> tst-strfry \
>> tst-strlcat \
>> @@ -270,6 +271,7 @@ CFLAGS-tst-inlcall.c += -fno-builtin
>> CFLAGS-tst-xbzero-opt.c += -O3
>> CFLAGS-tst-xmemset-opt.c += -O3
>> CFLAGS-test-endian-sign-conversion.c += -Werror -Wsign-conversion
>> +CFLAGS-tst-posix2024.c += -std=c17 -Werror=implicit-function-declaration
>> # BZ 21006: Resolve all functions but at least explicit_bzero at startup.
>> # Otherwise the test fails on s390x as the memcpy in prepare_test_buffer is
>> # done by loading r4 / r5 with the test_pattern and using store multiple
>> diff --git a/string/string.h b/string/string.h
>> index 743395b3e3..15959356a2 100644
>> --- a/string/string.h
>> +++ b/string/string.h
>> @@ -414,7 +414,7 @@ extern char *strcasestr (const char *__haystack, const char *__needle)
>> # endif
>> #endif
>>
>> -#ifdef __USE_MISC
>> +#if defined __USE_MISC || defined __USE_XOPEN2K24
>> /* Find the first occurrence of NEEDLE in HAYSTACK.
>> NEEDLE is NEEDLELEN bytes long;
>> HAYSTACK is HAYSTACKLEN bytes long. */
>> @@ -423,7 +423,9 @@ extern void *memmem (const void *__haystack, size_t __haystacklen,
>> __THROW __attribute_pure__ __nonnull ((1, 3))
>> __attr_access ((__read_only__, 1, 2))
>> __attr_access ((__read_only__, 3, 4));
>> +#endif
>>
>> +#ifdef __USE_MISC
>> /* Copy N bytes of SRC to DEST, return pointer to bytes after the
>> last written byte. */
>> extern void *__mempcpy (void *__restrict __dest,
>> @@ -533,7 +535,7 @@ extern char *stpncpy (char *__restrict __dest,
>> __THROW __nonnull ((1, 2));
>> #endif
>>
>> -#ifdef __USE_MISC
>> +#if defined __USE_MISC || defined __USE_XOPEN2K24
>> /* Copy at most N - 1 characters from SRC to DEST. */
>> extern size_t strlcpy (char *__restrict __dest,
>> const char *__restrict __src, size_t __n)
>> diff --git a/string/tst-posix2024.c b/string/tst-posix2024.c
>> new file mode 100644
>> index 0000000000..0e25d0770f
>> --- /dev/null
>> +++ b/string/tst-posix2024.c
>> @@ -0,0 +1,44 @@
>> +/* Test POSIX.1-2024 <string.h> declarations.
>> + Copyright (C) 2026 Free Software Foundation, Inc.
>> + This file is part of the GNU C Library.
>> +
>> + The GNU C Library is free software; you can redistribute it and/or
>> + modify it under the terms of the GNU Lesser General Public
>> + License as published by the Free Software Foundation; either
>> + version 2.1 of the License, or (at your option) any later version.
>> +
>> + The GNU C Library 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
>> + Lesser General Public License for more details.
>> +
>> + You should have received a copy of the GNU Lesser General Public
>> + License along with the GNU C Library; if not, see
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +/* Undo _GNU_SOURCE define before the first public header is included so that
>> + this test checks strict POSIX.1-2024 visibility. */
>> +
>> +#undef _GNU_SOURCE
>> +#define _POSIX_C_SOURCE 202405L
>> +
>> +#include <string.h>
>> +#include <support/check.h>
>> +
>> +static int
>> +do_test (void)
>> +{
>> + char buffer[8];
>> +
>> + TEST_COMPARE (strlcpy (buffer, "abc", sizeof buffer), 3);
>> + TEST_COMPARE_STRING (buffer, "abc");
>> +
>> + TEST_COMPARE (strlcat (buffer, "defgh", sizeof buffer), 8);
>> + TEST_COMPARE_STRING (buffer, "abcdefg");
>> +
>> + TEST_VERIFY (memmem (buffer, strlen (buffer), "cde", 3) == buffer + 2);
>> +
>> + return 0;
>> +}
>> +
>> +#include <support/test-driver.c>
>
Thanks for pointing this out.
No, my patch does not fix anything beyound Matthias' s patch. I misssed
that earlier patch thread when I started looking at BZ#34466.
Plase disregard my patch, Matthias' s version is more complete because
it also covers the fortify path.
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