Change the strerror_override handling to check $_JSON_C_STRERROR_OVERRIDE instead of using a variable, so we don't need to export it.

strerror_override.c

@@ -59,7 +59,8 @@ static struct
 /* clang-format on */
 
 // Enabled during tests
-int _json_c_strerror_enable = 0;
+static int _json_c_strerror_enable = 0;
+extern char *getenv(const char *name); // Avoid including stdlib.h
 
 #define PREFIX "ERRNO="
 static char errno_buf[128] = PREFIX;
@@ -70,6 +71,8 @@ char *_json_c_strerror(int errno_in)
 	int ii, jj;
 
 	if (!_json_c_strerror_enable)
+		_json_c_strerror_enable = (getenv("_JSON_C_STRERROR_ENABLE") == NULL) ? -1 : 1;
+	if (_json_c_strerror_enable == -1)
 		return strerror(errno_in);
 
 	// Avoid standard functions, so we don't need to include any

tests/CMakeLists.txt

@@ -37,6 +37,10 @@ foreach(TESTNAME
 	test_object_iterator)
 
 add_executable(${TESTNAME} ${TESTNAME}.c)
+if(${TESTNAME} STREQUAL test_util_file)
+# For output consistency, we need _json_c_strerror() in some tests:
+target_sources(${TESTNAME} PRIVATE ../strerror_override.c)
+endif()
 add_test(NAME ${TESTNAME} COMMAND ${PROJECT_SOURCE_DIR}/tests/${TESTNAME}.test)
 
 # XXX using the non-target_ versions of these doesn't work :(

tests/test_basic.test

@@ -1,5 +1,7 @@
 #!/bin/sh
 
+export _JSON_C_STRERROR_ENABLE=1
+
 # Common definitions
 if test -z "$srcdir"; then
     srcdir="${0%/*}"

tests/test_json_pointer.c

@@ -1,9 +1,8 @@
-#include "strerror_override.h"
-#include "strerror_override_private.h"
 #ifdef NDEBUG
 #undef NDEBUG
 #endif
 #include <assert.h>
+#include <errno.h>
 #include <stdio.h>
 #include <string.h>
 
@@ -320,8 +319,6 @@ static void test_wrong_inputs_set(void)
 
 int main(int argc, char **argv)
 {
-	_json_c_strerror_enable = 1;
-
 	test_example_get();
 	test_recursion_get();
 	test_wrong_inputs_get();

tests/test_util_file.c

@@ -127,8 +127,6 @@ int main(int argc, char **argv)
 	//	json_object_to_file(file, obj);
 	//	json_object_to_file_ext(file, obj, flags);
 
-	_json_c_strerror_enable = 1;
-
 	const char *testdir;
 	if (argc < 2)
 	{