--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/services/writeableFlags.cpp	Tue Dec 02 19:47:45 2014 +0100
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/javaClasses.hpp"
+#include "runtime/arguments.hpp"
+#include "runtime/java.hpp"
+#include "runtime/jniHandles.hpp"
+#include "services/writeableFlags.hpp"
+
+// set a boolean global flag
+int WriteableFlags::set_bool_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  int value = true;
+
+  if (sscanf(arg, "%d", &value)) {
+    return set_bool_flag(name, value != 0, origin, err_msg);
+  }
+  err_msg.print("flag value must be a boolean (1 or 0)");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_bool_flag(const char* name, bool value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::boolAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a intx global flag
+int WriteableFlags::set_intx_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  intx value;
+
+  if (sscanf(arg, INTX_FORMAT, &value)) {
+    return set_intx_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_intx_flag(const char* name, intx value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::intxAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a uintx global flag
+int WriteableFlags::set_uintx_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  uintx value;
+
+  if (sscanf(arg, UINTX_FORMAT, &value)) {
+    return set_uintx_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_uintx_flag(const char* name, uintx value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  if (strncmp(name, "MaxHeapFreeRatio", 17) == 0) {
+      if (!Arguments::verify_MaxHeapFreeRatio(err_msg, value)) {
+        return OUT_OF_BOUNDS;
+      }
+    } else if (strncmp(name, "MinHeapFreeRatio", 17) == 0) {
+      if (!Arguments::verify_MinHeapFreeRatio(err_msg, value)) {
+        return OUT_OF_BOUNDS;
+      }
+    }
+    return CommandLineFlags::uintxAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a uint64_t global flag
+int WriteableFlags::set_uint64_t_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  uint64_t value;
+
+  if (sscanf(arg, UINT64_FORMAT, &value)) {
+    return set_uint64_t_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned 64-bit integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_uint64_t_flag(const char* name, uint64_t value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::uint64_tAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a size_t global flag
+int WriteableFlags::set_size_t_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  size_t value;
+
+  if (sscanf(arg, SIZE_FORMAT, &value)) {
+    return set_size_t_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_size_t_flag(const char* name, size_t value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::size_tAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a string global flag using value from AttachOperation
+int WriteableFlags::set_ccstr_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  bool res = CommandLineFlags::ccstrAtPut((char*)name, &arg, origin);
+
+  return res? SUCCESS : ERR_OTHER;
+}
+
+/* sets a writeable flag to the provided value
+ *
+ * - return status is one of the WriteableFlags::err enum values
+ * - an eventual error message will be generated to the provided err_msg buffer
+ */
+int WriteableFlags::set_flag(const char* flag_name, const char* flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return set_flag(flag_name, &flag_value, set_flag_from_char, origin, err_msg);
+}
+
+/* sets a writeable flag to the provided value
+ *
+ * - return status is one of the WriteableFlags::err enum values
+ * - an eventual error message will be generated to the provided err_msg buffer
+ */
+int WriteableFlags::set_flag(const char* flag_name, jvalue flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return set_flag(flag_name, &flag_value, set_flag_from_jvalue, origin, err_msg);
+}
+
+// a writeable flag setter accepting either 'jvalue' or 'char *' values
+int WriteableFlags::set_flag(const char* name, const void* value, int(*setter)(Flag*,const void*,Flag::Flags,FormatBuffer<80>&), Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  if (name == NULL) {
+    err_msg.print("flag name is missing");
+    return MISSING_NAME;
+  }
+  if (value == NULL) {
+    err_msg.print("flag value is missing");
+    return MISSING_VALUE;
+  }
+
+  Flag* f = Flag::find_flag((char*)name, strlen(name));
+  if (f) {
+    // only writeable flags are allowed to be set
+    if (f->is_writeable()) {
+      return setter(f, value, origin, err_msg);
+    } else {
+      err_msg.print("only 'writeable' flags can be set");
+      return NON_WRITABLE;
+    }
+  }
+
+  err_msg.print("flag %s does not exist", name);
+  return INVALID_FLAG;
+}
+
+// a writeable flag setter accepting 'char *' values
+int WriteableFlags::set_flag_from_char(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  char* flag_value = *(char**)value;
+  if (flag_value == NULL) {
+    err_msg.print("flag value is missing");
+    return MISSING_VALUE;
+  }
+  if (f->is_bool()) {
+    return set_bool_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_intx()) {
+    return set_intx_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_uintx()) {
+    return set_uintx_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_uint64_t()) {
+    return set_uint64_t_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_size_t()) {
+    return set_size_t_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_ccstr()) {
+    return set_ccstr_flag(f->_name, flag_value, origin, err_msg);
+  } else {
+    ShouldNotReachHere();
+  }
+  return ERR_OTHER;
+}
+
+// a writeable flag setter accepting 'jvalue' values
+int WriteableFlags::set_flag_from_jvalue(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  jvalue new_value = *(jvalue*)value;
+  if (f->is_bool()) {
+    bool bvalue = (new_value.z == JNI_TRUE ? true : false);
+    return set_bool_flag(f->_name, bvalue, origin, err_msg);
+  } else if (f->is_intx()) {
+    intx ivalue = (intx)new_value.j;
+    return set_intx_flag(f->_name, ivalue, origin, err_msg);
+  } else if (f->is_uintx()) {
+    uintx uvalue = (uintx)new_value.j;
+    return set_uintx_flag(f->_name, uvalue, origin, err_msg);
+  } else if (f->is_uint64_t()) {
+    uint64_t uvalue = (uint64_t)new_value.j;
+    return set_uint64_t_flag(f->_name, uvalue, origin, err_msg);
+  } else if (f->is_size_t()) {
+    size_t svalue = (size_t)new_value.j;
+    return set_size_t_flag(f->_name, svalue, origin, err_msg);
+  } else if (f->is_ccstr()) {
+    oop str = JNIHandles::resolve_external_guard(new_value.l);
+    if (str == NULL) {
+      err_msg.print("flag value is missing");
+      return MISSING_VALUE;
+    }
+    ccstr svalue = java_lang_String::as_utf8_string(str);
+    int ret = WriteableFlags::set_ccstr_flag(f->_name, svalue, origin, err_msg);
+    if (ret != SUCCESS) {
+      FREE_C_HEAP_ARRAY(char, svalue);
+    }
+    return ret;
+  } else {
+    ShouldNotReachHere();
+  }
+  return ERR_OTHER;
+}
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