Better detection of typedefs in C++ (#1896)

Fraunhofer-AISEC · Dec 12, 2024 · 9898155 · 9898155
1 parent f1cb0dc
commit 9898155
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Showing 6 changed files with 107 additions and 12 deletions.
diff --git a/cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/ScopeManager.kt b/cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/ScopeManager.kt
@@ -818,7 +818,7 @@ class ScopeManager : ScopeProvider {
                 // This process has several steps:
                 // First, do a quick local lookup, to see if we have a typedef our current scope
                 // (only do this if the name is not qualified)
-                if (!alias.isQualified() && current == currentScope) {
+                if (!alias.isQualified() && current == scope) {
                     val decl = current.typedefs[alias]
                     if (decl != null) {
                         return decl.type

diff --git a/cpg-language-cxx/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/cxx/DeclarationHandler.kt b/cpg-language-cxx/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/cxx/DeclarationHandler.kt
@@ -242,18 +242,20 @@ class DeclarationHandler(lang: CXXLanguageFrontend) :
      */
     private val IASTSimpleDeclaration.isTypedef: Boolean
         get() {
-            return if (this.rawSignature.contains("typedef")) {
-                if (this.declSpecifier is CPPASTCompositeTypeSpecifier) {
-                    // we need to make a difference between structs that have typedefs and structs
-                    // that are typedefs themselves
-                    this.declSpecifier.toString() == "struct" &&
-                        this.rawSignature.trim().startsWith("typedef")
+            return if (this.declSpecifier is IASTCompositeTypeSpecifier) {
+                if (this.declSpecifier.rawSignature.contains("typedef")) {
+                    // This is very stupid. For composite type specifiers, we need to make sure that
+                    // we do not match simply because our declarations contain a typedef.
+                    // The problem is that we cannot correctly detect the case where both our "main"
+                    // declaration and our sub declarations contain a typedef :(
+                    (this.declSpecifier as IASTCompositeTypeSpecifier).getDeclarations(true).none {
+                        it.rawSignature.contains("typedef")
+                    }
                 } else {
-
-                    true
+                    false
                 }
             } else {
-                false
+                this.declSpecifier.rawSignature.contains("typedef")
             }
         }
 

diff --git a/cpg-language-cxx/src/test/kotlin/de/fraunhofer/aisec/cpg/enhancements/types/TypedefTest.kt b/cpg-language-cxx/src/test/kotlin/de/fraunhofer/aisec/cpg/enhancements/types/TypedefTest.kt
@@ -25,6 +25,8 @@
  */
 package de.fraunhofer.aisec.cpg.enhancements.types
 
+import de.fraunhofer.aisec.cpg.InferenceConfiguration.Companion.builder
+import de.fraunhofer.aisec.cpg.frontends.cxx.CLanguage
 import de.fraunhofer.aisec.cpg.frontends.cxx.CPPLanguage
 import de.fraunhofer.aisec.cpg.graph.*
 import de.fraunhofer.aisec.cpg.graph.declarations.ValueDeclaration
@@ -34,6 +36,7 @@ import de.fraunhofer.aisec.cpg.graph.types.NumericType
 import de.fraunhofer.aisec.cpg.graph.types.ObjectType
 import de.fraunhofer.aisec.cpg.graph.variables
 import de.fraunhofer.aisec.cpg.test.*
+import java.io.File
 import java.nio.file.Path
 import kotlin.test.*
 
@@ -187,16 +190,23 @@ internal class TypedefTest : BaseTest() {
     fun testArbitraryTypedefLocation() {
         val tu =
             analyzeAndGetFirstTU(
-                listOf(topLevel.resolve("typedefs.cpp").toFile()),
+                listOf(topLevel.resolve("weird_typedefs.cpp").toFile()),
                 topLevel,
                 true
             ) {
                 it.registerLanguage<CPPLanguage>()
             }
 
         val ullong1 = tu.variables["someUllong1"]
+        assertNotNull(ullong1)
+
         val ullong2 = tu.variables["someUllong2"]
-        assertEquals(ullong1?.type, ullong2?.type)
+        assertNotNull(ullong2)
+        assertEquals(ullong1.type, ullong2.type)
+
+        val records = tu.records
+        assertEquals(2, records.size)
+        assertEquals(listOf("bar", "foo"), records.map { it.name.localName })
     }
 
     @Test
@@ -243,4 +253,40 @@ internal class TypedefTest : BaseTest() {
         assertNotNull(size)
         assertRefersTo(size, sizeField)
     }
+
+    @Test
+    fun testTypedefStructCPP() {
+        val file = File("src/test/resources/cxx/typedef_struct.cpp")
+        val tu =
+            analyzeAndGetFirstTU(listOf(file), file.parentFile.toPath(), true) {
+                it.registerLanguage<CPPLanguage>()
+                it.inferenceConfiguration(builder().enabled(false).build())
+            }
+        with(tu) {
+            val me = tu.memberExpressions
+            me.forEach { assertNotNull(it.refersTo) }
+
+            val test = tu.records.singleOrNull()
+            assertNotNull(test)
+            assertLocalName("test", test)
+        }
+    }
+
+    @Test
+    fun testTypedefStructC() {
+        val file = File("src/test/resources/c/typedef_struct.c")
+        val tu =
+            analyzeAndGetFirstTU(listOf(file), file.parentFile.toPath(), true) {
+                it.registerLanguage<CLanguage>()
+                it.inferenceConfiguration(builder().enabled(false).build())
+            }
+        with(tu) {
+            val me = tu.memberExpressions
+            me.forEach { assertNotNull(it.refersTo) }
+
+            val test = tu.records.singleOrNull()
+            assertNotNull(test)
+            assertLocalName("test", test)
+        }
+    }
 }
diff --git a/cpg-language-cxx/src/test/resources/c/typedef_struct.c b/cpg-language-cxx/src/test/resources/c/typedef_struct.c
@@ -0,0 +1,13 @@
+typedef struct test {
+  int a;
+  int b;
+} S;
+
+int structs() {
+  S s;
+  S t;
+  S* p=&s;
+  s.a=1;
+  s.b=2;
+  printf("%d %d\n", s.a, s.b);
+ }
diff --git a/cpg-language-cxx/src/test/resources/cxx/typedef_struct.cpp b/cpg-language-cxx/src/test/resources/cxx/typedef_struct.cpp
@@ -0,0 +1,15 @@
+typedef struct test {
+  int a;
+  int b;
+} S;
+
+int structs() {
+  S s;
+  S t;
+  S* p=&s;
+  s.a=1;
+  s.b=2;
+  printf("%d %d\n", s.a, s.b);
+ }
+
+ long typedef bla;
diff --git a/cpg-language-cxx/src/test/resources/typedefs/weird_typedefs.cpp b/cpg-language-cxx/src/test/resources/typedefs/weird_typedefs.cpp
@@ -0,0 +1,19 @@
+// typedef can be used anywhere in the decl-specifier-seq
+// more conventionally spelled "typedef unsigned long long int ullong;"
+unsigned long typedef long int ullong;
+
+// usage of type that is identical to typedef
+unsigned long long int someUllong1;
+// usage of typedef
+ullong someUllong2;
+
+// also possible with structs
+struct bar {
+  int a;
+  int b;
+} typedef baz;
+
+// just some type that contains a typedef for more confusion
+struct foo {
+  typedef const int a;
+};