Allow using snprintf() instead of sprintf() in wrappers

We aim to produce code that works with C90 or C++98 so we can't
assume snprintf() is available, but it almost always is (even
on systems from before it was standardised) so having a way to
use it is helpful.

Enable this automatically if the compiler claims conformance
with at least C90 or C++98 and check SWIG_HAVE_SNPRINTF to allow
turning on manually, but disable if SWIG_NO_SNPRINTF if defined.

The fallback is to call sprintf() without a buffer size check -
checking after the call is really shutting the stable door after
the horse has bolted, and most of our uses either have a fixed maximum
possible size or dynamically allocate a buffer that's large enough.

Fixes: #2502 (sprintf deprecation warnings on macos)
Fixes: #2548

3 files changed, 8 insertions, 6 deletions

diff --git a/Lib/ruby/rubycontainer.swg b/Lib/ruby/rubycontainer.swg
index 597ae83d2..ab2eeae83 100644
--- a/Lib/ruby/rubycontainer.swg
+++ b/Lib/ruby/rubycontainer.swg
@@ -186,7 +186,7 @@ namespace swig
 	return swig::as<T>(item);
       } catch (const std::invalid_argument& e) {
 	char msg[1024];
-	sprintf(msg, "in sequence element %d ", _index);
+	SWIG_snprintf(msg, sizeof(msg), "in sequence element %d ", _index);
 	VALUE lastErr = rb_gv_get("$!");
 	if ( lastErr == Qnil ) {
 	  %type_error(swig::type_name<T>());
diff --git a/Lib/ruby/rubyerrors.swg b/Lib/ruby/rubyerrors.swg
index 434544bc9..ad71d1d39 100644
--- a/Lib/ruby/rubyerrors.swg
+++ b/Lib/ruby/rubyerrors.swg
@@ -110,7 +110,7 @@ const char* Ruby_Format_TypeError( const char* msg,
     }
 
   str = rb_str_cat2( str, "Expected argument " );
-  sprintf( buf, "%d of type ", argn-1 );
+  SWIG_snprintf( buf, sizeof( buf), "%d of type ", argn-1 );
   str = rb_str_cat2( str, buf );
   str = rb_str_cat2( str, type );
   str = rb_str_cat2( str, ", but got " );
diff --git a/Lib/ruby/rubyrun.swg b/Lib/ruby/rubyrun.swg
index 885292481..456bd9d8f 100644
--- a/Lib/ruby/rubyrun.swg
+++ b/Lib/ruby/rubyrun.swg
@@ -151,8 +151,9 @@ SWIG_Ruby_InitRuntime(void)
 SWIGRUNTIME void
 SWIG_Ruby_define_class(swig_type_info *type)
 {
-  char *klass_name = (char *) malloc(4 + strlen(type->name) + 1);
-  sprintf(klass_name, "TYPE%s", type->name);
+  size_t klass_len = 4 + strlen(type->name) + 1;
+  char *klass_name = (char *) malloc(klass_len);
+  SWIG_snprintf(klass_name, klass_len, "TYPE%s", type->name);
   if (NIL_P(_cSWIG_Pointer)) {
     _cSWIG_Pointer = rb_define_class_under(_mSWIG, "Pointer", rb_cObject);
     rb_undef_method(CLASS_OF(_cSWIG_Pointer), "new");
@@ -208,8 +209,9 @@ SWIG_Ruby_NewPointerObj(void *ptr, swig_type_info *type, int flags)
       SWIG_RubyAddTracking(ptr, obj);
     }
   } else {
-    klass_name = (char *) malloc(4 + strlen(type->name) + 1);
-    sprintf(klass_name, "TYPE%s", type->name);
+    size_t klass_len = 4 + strlen(type->name) + 1;
+    klass_name = (char *) malloc(klass_len);
+    SWIG_snprintf(klass_name, klass_len, "TYPE%s", type->name);
     klass = rb_const_get(_mSWIG, rb_intern(klass_name));
     free((void *) klass_name);
     obj = Data_Wrap_Struct(klass, 0, 0, ptr);