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libc/string: add strdupa(3) and strndupa(3)

Browse source 
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D54066
This commit is contained in:
Konstantin Belousov 2025-12-04 01:56:26 +02:00
parent 98b7cca018
commit a98e5d7850
3 changed files with 64 additions and 2 deletions
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28
include/string.h
View file

@ -154,6 +154,34 @@ void swab(const void * __restrict, void * __restrict, ssize_t);
int timingsafe_bcmp(const void *, const void *, size_t);
int timingsafe_memcmp(const void *, const void *, size_t);
#if __has_builtin(__builtin_alloca)
#define strdupa(_Str) (__extension__({ \
const char *_Str1; \
size_t _Len; \
char *_Copy; \
\
_Str1 = (_Str); \
_Len = strlen(_Str1) + 1; \
_Copy = (char *)__builtin_alloca(_Len); \
memcpy(_Copy, _Str1, _Len); \
_Copy; \
}))
#define strndupa(_Str, _Maxlen) (__extension__({ \
const char *_Str1; \
char *_Copy; \
size_t _Len; \
\
_Str1 = (_Str); \
_Len = strnlen((_Str1), (_Maxlen)); \
_Copy = __builtin_alloca(_Len + 1); \
(void)memcpy(_Copy, _Str1, _Len); \
_Copy[_Len] = '\0'; \
_Copy; \
}))
#endif
#endif /* __BSD_VISIBLE */
#if __POSIX_VISIBLE >= 200112 || defined(_XLOCALE_H_)

4
lib/libc/string/Makefile.inc
View file

@ -174,7 +174,9 @@ MLINKS+=strcoll.3 strcoll_l.3
MLINKS+=strcpy.3 stpcpy.3 \
strcpy.3 stpncpy.3 \
strcpy.3 strncpy.3
MLINKS+=strdup.3 strndup.3
MLINKS+=strdup.3 strndup.3 \
strdup.3 strdupa.3 \
strdup.3 strndupa.3
MLINKS+=strerror.3 perror.3 \
strerror.3 strerror_l.3 \
strerror.3 strerror_r.3 \

34
lib/libc/string/strdup.3
View file

@ -30,7 +30,9 @@
.Os
.Sh NAME
.Nm strdup ,
.Nm strndup
.Nm strdupa ,
.Nm strndup ,
.Nm strndupa
.Nd save a copy of a string
.Sh LIBRARY
.Lb libc
@ -39,7 +41,11 @@
.Ft char *
.Fn strdup "const char *str"
.Ft char *
.Fn strdupa "const char *str"
.Ft char *
.Fn strndup "const char *str" "size_t len"
.Ft char *
.Fn strndupa "const char *str" "size_t len"
.Sh DESCRIPTION
The
.Fn strdup
@ -63,6 +69,19 @@ characters from the string
always
.Dv NUL
terminating the copied string.
.Pp
The
.Fn strdupa
function is identical to
.Fn strdup
but allocates the memory with
.Xr alloca 3 .
Similarly, the
.Fn strndupa
function is identical to
.Fn strndup ,
but allocates the memory with
.Xr alloca 3 .
.Sh RETURN VALUES
If insufficient memory is available, NULL is returned and
.Va errno
@ -72,6 +91,7 @@ Otherwise, the
.Fn strdup
family of functions return a pointer to the copied string.
.Sh SEE ALSO
.Xr alloca 3 ,
.Xr free 3 ,
.Xr malloc 3 ,
.Xr wcsdup 3
@ -84,6 +104,12 @@ The
.Fn strndup
function is specified by
.St -p1003.1-2008 .
The
.Fn strdupa
and
.Fn strndupa
functions are extensions,
taken from glibc.
.Sh HISTORY
The
.Fn strdup
@ -93,3 +119,9 @@ The
.Fn strndup
function was added in
.Fx 7.2 .
The
.Fn strdupa
and
.Fn strndupa
functions were added in
.Fx 15.1 .