Ruby: Split standard library modeling

Split the classes modeling various standard library concepts into a
structured group of multiple files.

Things that are part of the core language live in framworks/core and
standard libraries (that aren't part of core) live in frameworks/stdlib.

This mirrors the structure followed by the Ruby docs
(https://docs.ruby-lang.org/en/3.1/).

Tests are split in a followup commit.

Author: hmac

ruby/ql/lib/codeql/ruby/Frameworks.qll

@@ -2,14 +2,15 @@
  * Helper file that imports all framework modeling.
  */
 
+private import codeql.ruby.frameworks.Core
 private import codeql.ruby.frameworks.ActionController
 private import codeql.ruby.frameworks.ActiveRecord
 private import codeql.ruby.frameworks.ActiveStorage
 private import codeql.ruby.frameworks.ActionView
 private import codeql.ruby.frameworks.ActiveSupport
 private import codeql.ruby.frameworks.GraphQL
 private import codeql.ruby.frameworks.Rails
-private import codeql.ruby.frameworks.StandardLibrary
+private import codeql.ruby.frameworks.Stdlib
 private import codeql.ruby.frameworks.Files
 private import codeql.ruby.frameworks.HttpClients
 private import codeql.ruby.frameworks.XmlParsing

ruby/ql/lib/codeql/ruby/frameworks/ActiveRecord.qll

@@ -5,7 +5,8 @@ private import codeql.ruby.DataFlow
 private import codeql.ruby.dataflow.internal.DataFlowDispatch
 private import codeql.ruby.ast.internal.Module
 private import codeql.ruby.ApiGraphs
-private import codeql.ruby.frameworks.StandardLibrary
+private import codeql.ruby.frameworks.Stdlib
+private import codeql.ruby.frameworks.Core
 
 /// See https://api.rubyonrails.org/classes/ActiveRecord/Persistence.html
 private string activeRecordPersistenceInstanceMethodName() {

ruby/ql/lib/codeql/ruby/frameworks/Core.qll

@@ -0,0 +1,76 @@
+private import codeql.ruby.Concepts
+private import codeql.ruby.DataFlow
+private import codeql.ruby.dataflow.FlowSummary
+import core.BasicObject::BasicObject
+import core.Object::Object
+import core.Kernel::Kernel
+import core.Module
+import core.Array
+import core.Regexp
+
+/**
+ * A `Method` call that has no known target.
+ * These will typically be calls to methods inherited from a superclass.
+ */
+class UnknownMethodCall extends MethodCall {
+  UnknownMethodCall() { not exists(this.(Call).getATarget()) }
+}
+
+/**
+ * A system command executed via subshell literal syntax.
+ * E.g.
+ * ```ruby
+ * `cat foo.txt`
+ * %x(cat foo.txt)
+ * %x[cat foo.txt]
+ * %x{cat foo.txt}
+ * %x/cat foo.txt/
+ * ```
+ */
+class SubshellLiteralExecution extends SystemCommandExecution::Range {
+  SubshellLiteral literal;
+
+  SubshellLiteralExecution() { this.asExpr().getExpr() = literal }
+
+  override DataFlow::Node getAnArgument() { result.asExpr().getExpr() = literal.getComponent(_) }
+
+  override predicate isShellInterpreted(DataFlow::Node arg) { arg = this.getAnArgument() }
+}
+
+/**
+ * A system command executed via shell heredoc syntax.
+ * E.g.
+ * ```ruby
+ * <<`EOF`
+ * cat foo.text
+ * EOF
+ * ```
+ */
+class SubshellHeredocExecution extends SystemCommandExecution::Range {
+  HereDoc heredoc;
+
+  SubshellHeredocExecution() { this.asExpr().getExpr() = heredoc and heredoc.isSubShell() }
+
+  override DataFlow::Node getAnArgument() { result.asExpr().getExpr() = heredoc.getComponent(_) }
+
+  override predicate isShellInterpreted(DataFlow::Node arg) { arg = this.getAnArgument() }
+}
+
+private class SplatSummary extends SummarizedCallable {
+  SplatSummary() { this = "*(splat)" }
+
+  override SplatExpr getACall() { any() }
+
+  override predicate propagatesFlowExt(string input, string output, boolean preservesValue) {
+    (
+      // *1 = [1]
+      input = "Receiver" and
+      output = "ArrayElement[0] of ReturnValue"
+      or
+      // *[1] = [1]
+      input = "Receiver" and
+      output = "ReturnValue"
+    ) and
+    preservesValue = true
+  }
+}

ruby/ql/lib/codeql/ruby/frameworks/Files.qll

@@ -6,7 +6,7 @@ private import ruby
 private import codeql.ruby.Concepts
 private import codeql.ruby.ApiGraphs
 private import codeql.ruby.DataFlow
-private import codeql.ruby.frameworks.StandardLibrary
+private import codeql.ruby.frameworks.Core
 private import codeql.ruby.dataflow.FlowSummary
 
 private DataFlow::Node ioInstanceInstantiation() {