Issue #705: disable locale handling when building for a uClibc system because its duplocale() function (intentionally) crashes.

CMakeLists.txt

@@ -192,6 +192,18 @@ if (HAVE_LOCALE_H)
     check_symbol_exists(setlocale   "locale.h" HAVE_SETLOCALE)
     check_symbol_exists(uselocale   "locale.h" HAVE_USELOCALE)
 endif()
+
+# uClibc *intentionally* crashes in duplocale(), at least as of:
+# https://github.com/ffainelli/uClibc/blob/266bdc1/libc/misc/locale/locale.c#L1322
+# So, if it looks like we're compiling for a system like that just disable 
+# locale handling entirely.
+exec_program(${CMAKE_C_COMPILER} ARGS -dumpmachine OUTPUT_VARIABLE CMAKE_GNU_C_MACHINE)
+if (CMAKE_GNU_C_MACHINE MATCHES "uclibc")
+	message(STATUS "Detected uClibc compiler, disabling locale handling")
+	set(HAVE_SETLOCALE 0)
+	set(HAVE_USELOCALE 0)
+endif()
+
 if (HAVE_STRINGS_H)
     check_symbol_exists(strcasecmp  "strings.h" HAVE_STRCASECMP)
     check_symbol_exists(strncasecmp "strings.h" HAVE_STRNCASECMP)

ChangeLog

@@ -14,6 +14,8 @@ Significant changes and bug fixes
 ---------------------------------
 * When serializing with JSON_C_TO_STRING_PRETTY set, keep the opening and 
   closing curly or square braces on same line for empty objects or arrays.
+* Disable locale handling when targeting a uClibc system due to problems
+  with its duplocale() function.
 
 
 0.16 (up to commit 66dcdf5, 2022-04-13)

tests/test_locale.c

@@ -24,8 +24,6 @@ int main(int argc, char **argv)
 	json_object *new_obj;
 #ifdef HAVE_SETLOCALE
 	setlocale(LC_NUMERIC, "de_DE");
-#else
-	printf("No locale\n");
 #endif
 
 	char buf1[10], buf2[10];