8029070: memory leak in jmm_SetVMGlobal

Reviewed-by: kvn, dholmes

src/share/vm/runtime/globals.cpp

@@ -759,8 +759,6 @@ bool CommandLineFlags::ccstrAt(char* name, size_t len, ccstr* value) {
   return true;
 }
 
-// Contract:  Flag will make private copy of the incoming value.
-// Outgoing value is always malloc-ed, and caller MUST call free.
 bool CommandLineFlags::ccstrAtPut(char* name, size_t len, ccstr* value, Flag::Flags origin) {
   Flag* result = Flag::find_flag(name, len);
   if (result == NULL) return false;
@@ -784,7 +782,6 @@ bool CommandLineFlags::ccstrAtPut(char* name, size_t len, ccstr* value, Flag::Fl
   return true;
 }
 
-// Contract:  Flag will make private copy of the incoming value.
 void CommandLineFlagsEx::ccstrAtPut(CommandLineFlagWithType flag, ccstr value, Flag::Flags origin) {
   Flag* faddr = address_of_flag(flag);
   guarantee(faddr != NULL && faddr->is_ccstr(), "wrong flag type");

src/share/vm/runtime/globals.hpp

@@ -390,6 +390,8 @@ class CommandLineFlags {
 
   static bool ccstrAt(char* name, size_t len, ccstr* value);
   static bool ccstrAt(char* name, ccstr* value)    { return ccstrAt(name, strlen(name), value); }
+  // Contract:  Flag will make private copy of the incoming value.
+  // Outgoing value is always malloc-ed, and caller MUST call free.
   static bool ccstrAtPut(char* name, size_t len, ccstr* value, Flag::Flags origin);
   static bool ccstrAtPut(char* name, ccstr* value, Flag::Flags origin) { return ccstrAtPut(name, strlen(name), value, origin); }
 

src/share/vm/runtime/globals_extension.hpp

@@ -201,6 +201,7 @@ class CommandLineFlagsEx : CommandLineFlags {
   static void uintxAtPut(CommandLineFlagWithType flag, uintx value, Flag::Flags origin);
   static void uint64_tAtPut(CommandLineFlagWithType flag, uint64_t value, Flag::Flags origin);
   static void doubleAtPut(CommandLineFlagWithType flag, double value, Flag::Flags origin);
+  // Contract:  Flag will make private copy of the incoming value
   static void ccstrAtPut(CommandLineFlagWithType flag, ccstr value, Flag::Flags origin);
 
   static bool is_default(CommandLineFlag flag);

src/share/vm/services/management.cpp

@@ -1824,7 +1824,7 @@ JVM_ENTRY(void, jmm_SetVMGlobal(JNIEnv *env, jstring flag_name, jvalue new_value
               "This flag is not writeable.");
   }
 
-  bool succeed;
+  bool succeed = false;
   if (flag->is_bool()) {
     bool bvalue = (new_value.z == JNI_TRUE ? true : false);
     succeed = CommandLineFlags::boolAtPut(name, &bvalue, Flag::MANAGEMENT);
@@ -1856,6 +1856,9 @@ JVM_ENTRY(void, jmm_SetVMGlobal(JNIEnv *env, jstring flag_name, jvalue new_value
     }
     ccstr svalue = java_lang_String::as_utf8_string(str);
     succeed = CommandLineFlags::ccstrAtPut(name, &svalue, Flag::MANAGEMENT);
+    if (succeed) {
+      FREE_C_HEAP_ARRAY(char, svalue, mtInternal);
+    }
   }
   assert(succeed, "Setting flag should succeed");
 JVM_END