Use __builtin___stpncpy_chk when available
Commit Message
The builtin has been available in gcc since 4.7.0 and in clang since
2.6. This fixes stpncpy fortification with clang since it does a
better job of plugging in __stpncpy_chk in the right place than the
header hackery.
This has been tested by building and running all tests with gcc 10.2.1
and also with clang tip as of a few days ago (just the tests in debug/
since running all tests don't work with clang at the moment) to make
sure that both compilers pass the stpncpy tests.
---
string/bits/string_fortified.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
Comments
The 11/12/2020 13:29, Siddhesh Poyarekar via Libc-alpha wrote:
> The builtin has been available in gcc since 4.7.0 and in clang since
> 2.6. This fixes stpncpy fortification with clang since it does a
> better job of plugging in __stpncpy_chk in the right place than the
> header hackery.
>
> This has been tested by building and running all tests with gcc 10.2.1
> and also with clang tip as of a few days ago (just the tests in debug/
> since running all tests don't work with clang at the moment) to make
> sure that both compilers pass the stpncpy tests.
this change looks good to me.
> ---
> string/bits/string_fortified.h | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/string/bits/string_fortified.h b/string/bits/string_fortified.h
> index c8d3051af8..4c1aeb45f1 100644
> --- a/string/bits/string_fortified.h
> +++ b/string/bits/string_fortified.h
> @@ -91,7 +91,13 @@ __NTH (strncpy (char *__restrict __dest, const char *__restrict __src,
> return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
> }
>
> -/* XXX We have no corresponding builtin yet. */
> +#if __GNUC_PREREQ (4, 7) || __glibc_clang_prereq (2, 6)
> +__fortify_function char *
> +__NTH (stpncpy (char *__dest, const char *__src, size_t __n))
> +{
> + return __builtin___stpncpy_chk (__dest, __src, __n, __bos (__dest));
> +}
> +#else
> extern char *__stpncpy_chk (char *__dest, const char *__src, size_t __n,
> size_t __destlen) __THROW
> __attr_access ((__write_only__, 1, 3)) __attr_access ((__read_only__, 2));
> @@ -106,6 +112,7 @@ __NTH (stpncpy (char *__dest, const char *__src, size_t __n))
> return __stpncpy_chk (__dest, __src, __n, __bos (__dest));
> return __stpncpy_alias (__dest, __src, __n);
> }
> +#endif
>
>
> __fortify_function char *
> --
> 2.26.2
>
--
@@ -91,7 +91,13 @@ __NTH (strncpy (char *__restrict __dest, const char *__restrict __src,
return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
}
-/* XXX We have no corresponding builtin yet. */
+#if __GNUC_PREREQ (4, 7) || __glibc_clang_prereq (2, 6)
+__fortify_function char *
+__NTH (stpncpy (char *__dest, const char *__src, size_t __n))
+{
+ return __builtin___stpncpy_chk (__dest, __src, __n, __bos (__dest));
+}
+#else
extern char *__stpncpy_chk (char *__dest, const char *__src, size_t __n,
size_t __destlen) __THROW
__attr_access ((__write_only__, 1, 3)) __attr_access ((__read_only__, 2));
@@ -106,6 +112,7 @@ __NTH (stpncpy (char *__dest, const char *__src, size_t __n))
return __stpncpy_chk (__dest, __src, __n, __bos (__dest));
return __stpncpy_alias (__dest, __src, __n);
}
+#endif
__fortify_function char *