RPC: Keep .cookie if it was replaced after being generated

Github-Pull: bitcoin#28784
Rebased-From: d95dde9441fb791046394ed3784a840a54ef2ab9

Author: luke-jr

src/rpc/request.cpp

@@ -92,7 +92,7 @@ static fs::path GetAuthCookieFile(bool temp=false)
     return AbsPathForConfigVal(gArgs, arg);
 }
 
-static bool g_generated_cookie = false;
+static std::optional<std::string> g_generated_cookie;
 
 bool GenerateAuthCookie(std::string* cookie_out, std::optional<fs::perms> cookie_perms)
 {
@@ -128,7 +128,7 @@ bool GenerateAuthCookie(std::string* cookie_out, std::optional<fs::perms> cookie
         }
     }
 
-    g_generated_cookie = true;
+    g_generated_cookie = cookie;
     LogInfo("Generated RPC authentication cookie %s\n", fs::PathToString(filepath));
     LogInfo("Permissions used for cookie: %s\n", PermsToSymbolicString(fs::status(filepath).permissions()));
 
@@ -156,8 +156,9 @@ bool GetAuthCookie(std::string *cookie_out)
 void DeleteAuthCookie()
 {
     try {
-        if (g_generated_cookie) {
-            // Delete the cookie file if it was generated by this process
+        std::string existing_cookie;
+        if (GetAuthCookie(&existing_cookie) && g_generated_cookie == existing_cookie) {
+            // Delete the cookie file if it exists and was generated by this process
             fs::remove(GetAuthCookieFile());
         }
     } catch (const fs::filesystem_error& e) {