crt-test: Wrap parameters to tested string functions to avoid optimizing them

When some of the parameters to standard C functions are known
constants, the compiler can optimize out the call to the actual
function.

When built with fortification enabled, the compiler previously
didn't actually end up calling the __<func>_chk functions in
most cases, as it could optimize out much of the calls. Now all
tested function calls should end up emitted as intended, making
this actually do functional testing of the __<func>_chk function
implementations.

test/crt-test.c

@@ -138,6 +138,9 @@ const char *context = "";
         } \
     } while (0)
 
+char char_wrap_impl(char c) {
+    return c;
+}
 double double_wrap_impl(double f) {
     return f;
 }
@@ -153,18 +156,25 @@ long long longlong_wrap_impl(long long l) {
 unsigned long long ulonglong_wrap_impl(unsigned long long u) {
     return u;
 }
+const char *str_wrap_impl(const char *str) {
+    return str;
+}
 
+char (*char_wrap)(char c) = char_wrap_impl;
 double (*double_wrap)(double f) = double_wrap_impl;
 long (*long_wrap)(long l) = long_wrap_impl;
 unsigned long (*ulong_wrap)(unsigned long u) = ulong_wrap_impl;
 long long (*longlong_wrap)(long long l) = longlong_wrap_impl;
 unsigned long long (*ulonglong_wrap)(unsigned long long l) = ulonglong_wrap_impl;
+const char *(*str_wrap)(const char *str) = str_wrap_impl;
 
+#define C(x) char_wrap(x)
 #define F(x) double_wrap(x)
 #define L(x) long_wrap(x)
 #define UL(x) ulong_wrap(x)
 #define LL(x) longlong_wrap(x)
 #define ULL(x) ulonglong_wrap(x ## ULL)
+#define S(x) str_wrap(x)
 
 int vsscanf_wrap(const char* str, const char* fmt, ...) {
     va_list ap;
@@ -196,14 +206,14 @@ int main(int argc, char* argv[]) {
     void *retptr;
 
     memset(buf, '#', sizeof(buf));
-    retptr = memcpy(buf, "foo", 4);
+    retptr = memcpy(buf, S("foo"), L(4));
     TEST(retptr == buf);
     TEST_STR(buf, "foo");
     TEST_INT(buf[5], '#');
 
 #if defined(__GLIBC__) || defined(__MINGW32__)
     memset(buf, '#', sizeof(buf));
-    retptr = mempcpy(buf, "foo", 4);
+    retptr = mempcpy(buf, S("foo"), L(4));
     TEST(retptr == buf + 4);
     TEST_STR(buf, "foo");
     TEST_INT(buf[5], '#');
@@ -211,57 +221,57 @@ int main(int argc, char* argv[]) {
 
     memset(buf, '#', sizeof(buf));
     memcpy(buf, "foobar", 7);
-    retptr = memmove(buf + 2, buf, 3);
+    retptr = memmove(buf + 2, S(buf), L(3));
     TEST(retptr == buf + 2);
     TEST_STR(buf, "fofoor");
     TEST_INT(buf[8], '#');
 
     memset(buf, '#', sizeof(buf));
     memcpy(buf, "foobar", 7);
-    retptr = memmove(buf, buf + 2, 3);
+    retptr = memmove(buf, S(buf + 2), L(3));
     TEST(retptr == buf);
     TEST_STR(buf, "obabar");
     TEST_INT(buf[8], '#');
 
-    retptr = memset(buf, '#', sizeof(buf));
+    retptr = memset(buf, C('#'), sizeof(buf) + L(0));
     TEST(retptr == buf);
     TEST_INT(buf[0], '#');
     TEST_INT(buf[sizeof(buf)-1], '#');
 
     memset(buf, '#', sizeof(buf));
-    retptr = strcpy(buf, "foo");
+    retptr = strcpy(buf, S("foo"));
     TEST(retptr == buf);
     TEST_STR(buf, "foo");
     TEST_INT(buf[5], '#');
 
     memset(buf, '#', sizeof(buf));
-    retptr = strncpy(buf, "foobar", 3);
+    retptr = strncpy(buf, S("foobar"), L(3));
     TEST(retptr == buf);
     TEST_INT(buf[3], '#');
     buf[3] = '\0';
     TEST_STR(buf, "foo");
 
     memset(buf, '#', sizeof(buf));
-    retptr = strncpy(buf, "foobar", sizeof(buf));
+    retptr = strncpy(buf, S("foobar"), sizeof(buf) + L(0));
     TEST(retptr == buf);
     TEST_STR(buf, "foobar");
     TEST_INT(buf[sizeof(buf)-1], '\0');
 
     memset(buf, '#', sizeof(buf));
     strcpy(buf, "foo");
-    retptr = strcat(buf, "bar");
+    retptr = strcat(buf, S("bar"));
     TEST(retptr == buf);
     TEST_STR(buf, "foobar");
 
     memset(buf, '#', sizeof(buf));
     strcpy(buf, "foo");
-    retptr = strncat(buf, "bar", 5);
+    retptr = strncat(buf, S("bar"), L(5));
     TEST(retptr == buf);
     TEST_STR(buf, "foobar");
 
     memset(buf, '#', sizeof(buf));
     strcpy(buf, "foo");
-    retptr = strncat(buf, "bar", 2);
+    retptr = strncat(buf, S("bar"), L(2));
     TEST(retptr == buf);
     TEST_STR(buf, "fooba");