Add probe for nl_langinfo_l (thread-safe)

[metaconfig.git] / U / threads / d_nl_langinfo_l.U

?RCS: $Id$
?RCS:
?RCS: Copyright (c) 2017 Karl Williamson
?RCS:
?RCS: You may distribute under the terms of either the GNU General Public
?RCS: License or the Artistic License, as specified in the README file.
?RCS:
?MAKE:d_thread_safe_nl_langinfo_l: Compile cat rm_try Oldconfig \
	i_pthread i_stdlib i_string i_langinfo i_locale		\
	usethreads run
?MAKE:	-pick add $@ %<
?S:d_thread_safe_nl_langinfo_l:
?S:	This variable contains the eventual value of the
?S:	HAS_THREAD_SAFE_NL_LANGINFO_L symbol, which indicates if the
?S:	nl_langinfo_l() function exists and is thread-safe.
?S:.
?C:HAS_THREAD_SAFE_NL_LANGINFO_L:
?C:	This symbol, when defined, indicates presence of the nl_langinfo_l()
?C:	function, and that it is thread-safe.
?C:.
?H:#$d_thread_safe_nl_langinfo_l HAS_THREAD_SAFE_NL_LANGINFO_L	/**/
?H:.
?F:!try
: check for thread_safe_nl_langinfo_l item
$cat <<EOM

Checking to see if you have nl_langinfo_l() and that it is thread-safe
EOM
?X: Despite claiming that nl_langinfo_l() is thread-safe, the POSIX 2008
?X: standard allows for a non-safe implementation:
?X:
?X:    "nl_langinfo_l() uses an internal per-thread buffer, and nl_langinfo()
?X:	uses (in all threads) the same buffer that nl_langinfo_l() uses in the
?X:	initial thread. There can be interactions, but only when
?X:	nl_langinfo_l() is called in the initial thread"
?X:
?X: If nl_langinfo_l() isn't thread safe, might as well just use plain
?X: nl_langinfo().
?X:
?X: This program calls nl_langinfo_l(), then creates a thread, calling plain
?X: nl_langinfo() from within it, then sees if the buffer in the original
?X: thread was changed.
$cat >try.c <<EOCP
#$i_stdlib I_STDLIB
#ifdef I_STDLIB
#  include <stdlib.h>
#endif
#$i_string I_STRING
#ifdef I_STRING
#  include <string.h>
#endif
#$i_langinfo I_LANGINFO
#ifdef I_LANGINFO
#  include <langinfo.h>
#endif
#$i_pthread I_PTHREAD
#ifdef I_PTHREAD
#  include <pthread.h>
#endif
#$i_locale I_LOCALE
#ifdef I_LOCALE
#  include <locale.h>
#endif

void *
thread_start(void * arg)
{
    nl_langinfo(RADIXCHAR);
}
    
int main() {
	char * main_buffer;
	char save_main_buffer[1000];
        pthread_t subthread;
        pthread_attr_t attr;
	
	main_buffer = nl_langinfo_l(CODESET, newlocale(LC_ALL_MASK, "C", 0));

	/* If too large for our generous allowance, just assume we don't have
	 * it. */
	if (strlen(main_buffer) >= sizeof(save_main_buffer)) {
	    exit(1);
	}

	strcpy(save_main_buffer, main_buffer);

	if (pthread_attr_init(&attr) != 0) {
	    exit(1);
	}

	if (pthread_create(&subthread, &attr, thread_start, NULL) != 0) {
	    exit(1);
	}

	if (pthread_join(subthread, NULL) != 0) {
	    exit(1);
	}

        exit(! (strcmp(main_buffer, save_main_buffer) == 0));
}
EOCP
case "$usethreads" in
    define)
	set try
	if eval $compile; then
		echo "Your system has nl_langinfo_l()..." >&4
		if $run ./try; then
		    echo "and it is thread-safe (just as I'd hoped)." >&4
		    d_thread_safe_nl_langinfo_l="$define"
		    echo "$d_thread_safe_nl_langinfo_l" >&4
		else 
		    echo "but it isn't thread-safe, so we won't use it." >&4
		fi
	else
		echo "your system does not have nl_langinfo_l()" >&4
	fi
	;;
    *) echo "Since threads aren't selected, we won't bother looking for nl_langinfo_l()" >&4
    esac
$rm_try