Add Argument.getACorrespondingSyntacticArgument

Author: owen-mc

go/ql/lib/semmle/go/Concepts.qll

@@ -121,11 +121,7 @@ private class DefaultFileSystemAccess extends FileSystemAccess::Range, DataFlow:
   }
 
   override DataFlow::Node getAPathArgument() {
-    not pathArgument instanceof DataFlow::ImplicitVarargsSlice and
-    result = pathArgument
-    or
-    pathArgument instanceof DataFlow::ImplicitVarargsSlice and
-    result = this.getAnImplicitVarargsArgument()
+    result = pathArgument.getACorrespondingSyntacticArgument()
   }
 }
 
@@ -378,19 +374,15 @@ module LoggerCall {
 }
 
 private class DefaultLoggerCall extends LoggerCall::Range, DataFlow::CallNode {
-  DataFlow::ArgumentNode messageComponent;
+  DataFlow::ArgumentNode messageArgument;
 
   DefaultLoggerCall() {
-    sinkNode(messageComponent, "log-injection") and
-    this = messageComponent.getCall()
+    sinkNode(messageArgument, "log-injection") and
+    this = messageArgument.getCall()
   }
 
   override DataFlow::Node getAMessageComponent() {
-    not messageComponent instanceof DataFlow::ImplicitVarargsSlice and
-    result = messageComponent
-    or
-    messageComponent instanceof DataFlow::ImplicitVarargsSlice and
-    result = this.getAnImplicitVarargsArgument()
+    result = messageArgument.getACorrespondingSyntacticArgument()
   }
 }
 

go/ql/lib/semmle/go/concepts/HTTP.qll

@@ -332,13 +332,7 @@ module Http {
         )
       }
 
-      override DataFlow::Node getUrl() {
-        not url instanceof DataFlow::ImplicitVarargsSlice and
-        result = url
-        or
-        url instanceof DataFlow::ImplicitVarargsSlice and
-        result = this.getAnImplicitVarargsArgument()
-      }
+      override DataFlow::Node getUrl() { result = url.getACorrespondingSyntacticArgument() }
 
       override Http::ResponseWriter getResponseWriter() {
         rw = -1 and result.getANode() = this.getReceiver()

go/ql/lib/semmle/go/dataflow/internal/DataFlowNodes.qll

@@ -841,11 +841,7 @@ module Public {
         or
         preupd = getAWrittenNode()
         or
-        (
-          preupd instanceof ArgumentNode and not preupd instanceof ImplicitVarargsSlice
-          or
-          preupd = any(CallNode c).getAnImplicitVarargsArgument()
-        ) and
+        preupd = any(ArgumentNode arg).getACorrespondingSyntacticArgument() and
         mutableType(preupd.getType())
       ) and
       (
@@ -889,6 +885,21 @@ module Public {
      * Gets this argument's position.
      */
     int getPosition() { result = i }
+
+    /**
+     * Gets a data-flow node for a syntactic argument corresponding this this
+     * argument. If this argument is not an implicit varargs slice then this
+     * will just be the argument itself. If this argument is an implicit
+     * varargs slice then this will be a data-flow node that for an argument
+     * that is stored in the implicit varargs slice.
+     */
+    Node getACorrespondingSyntacticArgument() {
+      not this instanceof DataFlow::ImplicitVarargsSlice and
+      result = this
+      or
+      this instanceof DataFlow::ImplicitVarargsSlice and
+      result = c.getAnImplicitVarargsArgument()
+    }
   }
 
   /**

go/ql/lib/semmle/go/frameworks/SQL.qll

@@ -70,11 +70,7 @@ module SQL {
     private class DefaultQueryString extends Range {
       DefaultQueryString() {
         exists(DataFlow::ArgumentNode arg | sinkNode(arg, "sql-injection") |
-          not arg instanceof DataFlow::ImplicitVarargsSlice and
-          this = arg
-          or
-          arg instanceof DataFlow::ImplicitVarargsSlice and
-          this = arg.getCall().getAnImplicitVarargsArgument()
+          this = arg.getACorrespondingSyntacticArgument()
         )
       }
     }

go/ql/lib/semmle/go/frameworks/SystemCommandExecutors.qll

@@ -16,11 +16,7 @@ private class DefaultSystemCommandExecution extends SystemCommandExecution::Rang
   }
 
   override DataFlow::Node getCommandName() {
-    not commandName instanceof DataFlow::ImplicitVarargsSlice and
-    result = commandName
-    or
-    commandName instanceof DataFlow::ImplicitVarargsSlice and
-    result = this.getAnImplicitVarargsArgument()
+    result = commandName.getACorrespondingSyntacticArgument()
   }
 }