From: Rico Tzschichholz <ricotz@ubuntu.com>
Date: Sun, 24 May 2020 17:25:41 +0000 (+0200)
Subject: codegen: Improve array-dup-wrapper for empty arrays
X-Git-Tag: 0.49.1~117
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=48679761c7298f14bdab9c6ea3bd4c48db192cf5;p=thirdparty%2Fvala.git

codegen: Improve array-dup-wrapper for empty arrays

Guard against negative lengths and consistently return NULL if allocated
size would be 0.

See https://gitlab.gnome.org/GNOME/vala/issues/999
---

diff --git a/codegen/valaccodearraymodule.vala b/codegen/valaccodearraymodule.vala
index 5fa9ea23d..0192f2cc9 100644
--- a/codegen/valaccodearraymodule.vala
+++ b/codegen/valaccodearraymodule.vala
@@ -541,9 +541,13 @@ public class Vala.CCodeArrayModule : CCodeMethodCallModule {
 			}
 
 			CCodeExpression length_expr = new CCodeIdentifier ("length");
+			CCodeBinaryOperator length_check_op;
 			// add extra item to have array NULL-terminated for all reference types
 			if (array_type.element_type.type_symbol != null && array_type.element_type.type_symbol.is_reference_type ()) {
 				length_expr = new CCodeBinaryExpression (CCodeBinaryOperator.PLUS, length_expr, new CCodeConstant ("1"));
+				length_check_op = CCodeBinaryOperator.GREATER_THAN_OR_EQUAL;
+			} else {
+				length_check_op = CCodeBinaryOperator.GREATER_THAN;
 			}
 			gnew.add_argument (length_expr);
 
@@ -553,6 +557,10 @@ public class Vala.CCodeArrayModule : CCodeMethodCallModule {
 				gnew.add_argument (csizeof);
 			}
 
+			// only attempt to dup if length >=/> 0, this deals with negative lengths and returns NULL
+			var length_check = new CCodeBinaryExpression (length_check_op, new CCodeIdentifier ("length"), new CCodeConstant ("0"));
+			ccode.open_if (length_check);
+
 			ccode.add_declaration (get_ccode_name (array_type), cvardecl);
 			ccode.add_assignment (new CCodeIdentifier ("result"), gnew);
 
@@ -566,7 +574,14 @@ public class Vala.CCodeArrayModule : CCodeMethodCallModule {
 			ccode.close ();
 
 			ccode.add_return (new CCodeIdentifier ("result"));
+
+			ccode.close ();
+			ccode.add_return (new CCodeIdentifier ("NULL"));
 		} else {
+			// only dup if length > 0, this deals with negative lengths and returns NULL
+			var length_check = new CCodeBinaryExpression (CCodeBinaryOperator.GREATER_THAN, new CCodeIdentifier ("length"), new CCodeConstant ("0"));
+			ccode.open_if (length_check);
+
 			var sizeof_call = new CCodeFunctionCall (new CCodeIdentifier ("sizeof"));
 			sizeof_call.add_argument (new CCodeIdentifier (get_ccode_name (array_type.element_type)));
 			var length_expr = new CCodeIdentifier ("length");
@@ -597,6 +612,9 @@ public class Vala.CCodeArrayModule : CCodeMethodCallModule {
 
 				ccode.add_return (dup_call);
 			}
+
+			ccode.close ();
+			ccode.add_return (new CCodeIdentifier ("NULL"));
 		}
 
 		// append to file
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 78c939a2f..263e8975e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -79,6 +79,7 @@ TESTS = \
 	arrays/cast-silent-invalid.test \
 	arrays/class-field-length-cname.vala \
 	arrays/constant-element-access.vala \
+	arrays/empty-length-0.vala \
 	arrays/expression-bracket.test \
 	arrays/fixed-length-init0-not-allowed.vala \
 	arrays/field-global-length-cname.vala \
@@ -949,6 +950,7 @@ LINUX_TESTS = \
 
 POSIX_TESTS = \
 	basic-types/arrays.vala \
+	arrays/empty-length-0.vala \
 	structs/struct_only.vala \
 	delegates/delegate_only.vala \
 	enums/enum_only.vala \
diff --git a/tests/arrays/empty-length-0.vala b/tests/arrays/empty-length-0.vala
new file mode 100644
index 000000000..8d64f304a
--- /dev/null
+++ b/tests/arrays/empty-length-0.vala
@@ -0,0 +1,52 @@
+struct Manam {
+	string s;
+}
+
+string[] foo;
+int[] bar;
+Manam[] manam;
+
+string[] get_foo () {
+	return foo;
+}
+
+int[] get_bar () {
+	return bar;
+}
+
+Manam[] get_manam () {
+	return manam;
+}
+
+void main () {
+	{
+		foo = new string[0];
+		assert (foo != null);
+		assert (get_foo () != null);
+	}
+	{
+		foo = {};
+		assert (foo != null);
+		assert (get_foo () != null);
+	}
+	{
+		bar = new int[0];
+		//assert (bar != null);
+		assert (get_bar () == null);
+	}
+	{
+		bar = {};
+		//assert (bar != null);
+		assert (get_bar () == null);
+	}
+	{
+		manam = new Manam[0];
+		//assert (manam != null);
+		assert (get_manam () == null);
+	}
+	{
+		manam = {};
+		//assert (manam != null);
+		assert (get_manam () == null);
+	}
+}