From e8123154675eeed1ed15e4d7602f5291e4836e37 Mon Sep 17 00:00:00 2001
From: Antonio Aversa <antonio.aversa@sonarsource.com>
Date: Mon, 13 Feb 2023 11:33:09 +0100
Subject: [PATCH] Modify rule S2445: Add C# specifics, Move Java specifics

---
 rules/S2445/csharp/message.adoc             | 10 +++++
 rules/S2445/csharp/metadata.json            |  2 +-
 rules/S2445/csharp/rule-except-see.adoc     | 47 +++++++++++++++++++++
 rules/S2445/csharp/rule.adoc                |  4 +-
 rules/S2445/{ => java}/rule-except-see.adoc |  0
 rules/S2445/java/rule.adoc                  |  2 +-
 rules/S2445/rule.adoc                       |  2 -
 7 files changed, 62 insertions(+), 5 deletions(-)
 create mode 100644 rules/S2445/csharp/message.adoc
 create mode 100644 rules/S2445/csharp/rule-except-see.adoc
 rename rules/S2445/{ => java}/rule-except-see.adoc (100%)

diff --git a/rules/S2445/csharp/message.adoc b/rules/S2445/csharp/message.adoc
new file mode 100644
index 00000000000..02e7d72473e
--- /dev/null
+++ b/rules/S2445/csharp/message.adoc
@@ -0,0 +1,10 @@
+=== Message
+
+"xxx" is not "private readonly", and should not be used for locking.
+
+"xxx" is a local variable, and should not be used for locking.
+
+Locking on a new instance is a no-op.
+
+Strings can be interned, and should not be used for locking.
+
diff --git a/rules/S2445/csharp/metadata.json b/rules/S2445/csharp/metadata.json
index 17971333806..3c98a88d67a 100644
--- a/rules/S2445/csharp/metadata.json
+++ b/rules/S2445/csharp/metadata.json
@@ -1,3 +1,3 @@
 {
-  
+    "title": "Blocks should be synchronized on \"private readonly\" fields"
 }
diff --git a/rules/S2445/csharp/rule-except-see.adoc b/rules/S2445/csharp/rule-except-see.adoc
new file mode 100644
index 00000000000..7c6e5e75329
--- /dev/null
+++ b/rules/S2445/csharp/rule-except-see.adoc
@@ -0,0 +1,47 @@
+Locking on a class field synchronizes not on the field itself, but on the object assigned to it. So locking on a non-``++readonly++`` field makes it possible for the field's value to change while a thread is in a block locked on the old value. That would allow a second thread, locked on the new value, to enter the block at the same time.
+
+
+The story is very similar for locking on a local variable or on a new instance; two different threads running the method in parallel would lock on two different object instances, completely undermining the synchronization.
+
+
+== Noncompliant Code Example
+
+[source,csharp]
+----
+private string color = "red";
+
+private void DoSomething()
+{
+  lock (color) // Noncompliant; lock is actually on object instance "red" referred to by the color variable
+  {
+    //...
+    color = "green"; // other threads now allowed into this block
+    // ...
+  }
+  lock (new object()) // Noncompliant this is a no-op.
+  {
+     // ...
+  }
+}
+----
+
+
+== Compliant Solution
+
+[source,csharp]
+----
+private string color = "red";
+private readonly object lockObj = new object();
+
+private void DoSomething()
+{
+  lock (lockObj) 
+  {
+    //...
+    color = "green";
+    // ...
+  }
+}
+----
+
+
diff --git a/rules/S2445/csharp/rule.adoc b/rules/S2445/csharp/rule.adoc
index f5db9e87ac5..ff1f6afbfe0 100644
--- a/rules/S2445/csharp/rule.adoc
+++ b/rules/S2445/csharp/rule.adoc
@@ -1,4 +1,6 @@
-include::../rule.adoc[]
+include::rule-except-see.adoc[]
+
+include::../see.adoc[]
 
 ifdef::env-github,rspecator-view[]
 
diff --git a/rules/S2445/rule-except-see.adoc b/rules/S2445/java/rule-except-see.adoc
similarity index 100%
rename from rules/S2445/rule-except-see.adoc
rename to rules/S2445/java/rule-except-see.adoc
diff --git a/rules/S2445/java/rule.adoc b/rules/S2445/java/rule.adoc
index 00a912506cd..cb515687e5e 100644
--- a/rules/S2445/java/rule.adoc
+++ b/rules/S2445/java/rule.adoc
@@ -1,4 +1,4 @@
-include::../rule-except-see.adoc[]
+include::rule-except-see.adoc[]
 
 include::see.adoc[]
 
diff --git a/rules/S2445/rule.adoc b/rules/S2445/rule.adoc
index 63e957dbfed..6d518fe68a3 100644
--- a/rules/S2445/rule.adoc
+++ b/rules/S2445/rule.adoc
@@ -1,3 +1 @@
-include::rule-except-see.adoc[]
-
 include::see.adoc[]