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Faraz Vahedi
d08296c7ab
Several standard library functions are specified to return an unqualified pointer while accepting a pointer to a potentially const-qualified object. N3020 addresses this behaviour, discarding qualifiers due to incompatible pointer types, by introducing qualifier-preserving macros for the affected set of standard library functions. Add `__qualsel()` helper to `<sys/cdefs.h>`, implemented using the generic selection, and define qualifier-preserving macros for that set of functions in `<string.h>`, `<wchar.h>`, and `<stdlib.h>`. Macros are gated on `_STDC_VERSION__ >= 202311L && !__cplusplus`, therefore there is no behavioural change for earlier C modes or C++ translation units. The kernel is likewise unaffected, as it does not include userland headers. As function-like macros, they are transparent except at a call site where the address-of operator is applied, the macro is suppressed via `#undef`, or the identifier appears in parenthesised form; all of which cause the underlying function designator to be used instead. Reviewed by: fuz Approved by: fuz (mentor) MFC after: 1 month Pull Request: https://github.com/freebsd/freebsd-src/pull/2288
116 lines
3.2 KiB
Plaintext
116 lines
3.2 KiB
Plaintext
.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Chris Torek.
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd June 21, 2026
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.Dt BSTRING 3
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.Os
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.Sh NAME
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.Nm bcmp ,
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.Nm bcopy ,
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.Nm bzero ,
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.Nm memccpy ,
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.Nm memchr ,
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.Nm memcmp ,
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.Nm memcpy ,
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.Nm memmove ,
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.Nm memset
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.Nd byte string operations
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In string.h
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.Ft int
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.Fn bcmp "const void *b1" "const void *b2" "size_t len"
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.Ft void
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.Fn bcopy "const void *src" "void *dst" "size_t len"
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.Ft void
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.Fn bzero "void *b" "size_t len"
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.Ft void *
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.Fn memchr "const void *b" "int c" "size_t len"
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.Ft int
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.Fn memcmp "const void *b1" "const void *b2" "size_t len"
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.Ft void *
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.Fo memccpy
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.Fa "void * restrict dst"
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.Fa "const void * restrict src"
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.Fa "int c"
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.Fa "size_t len"
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.Fc
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.Ft void *
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.Fn memcpy "void *dst" "const void *src" "size_t len"
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.Ft void *
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.Fn memmove "void *dst" "const void *src" "size_t len"
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.Ft void *
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.Fn memset "void *b" "int c" "size_t len"
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.Sh DESCRIPTION
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These functions operate on variable length strings of bytes.
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They do not check for terminating null bytes as the routines
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listed in
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.Xr string 3
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do.
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.Pp
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See the specific manual pages for more information.
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.Sh SEE ALSO
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.Xr bcmp 3 ,
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.Xr bcopy 3 ,
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.Xr bzero 3 ,
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.Xr memccpy 3 ,
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.Xr memchr 3 ,
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.Xr memcmp 3 ,
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.Xr memcpy 3 ,
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.Xr memmove 3 ,
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.Xr memset 3
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.Sh STANDARDS
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The functions
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.Fn memcmp ,
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.Fn memcpy ,
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.Fn memmove ,
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and
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.Fn memset
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conform to
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.St -isoC .
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.Pp
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The
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.Fn memchr
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function conforms to
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.St -isoC-2023 ,
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where it is specified as a qualifier-preserving function.
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.Sh HISTORY
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The functions
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.Fn bzero
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and
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.Fn memccpy
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appeared in
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.Bx 4.3 ;
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the functions
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.Fn bcmp ,
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.Fn bcopy ,
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appeared in
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.Bx 4.2 .
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