8351740: Clean up some code around initialization of encoding properties

src/java.base/share/classes/jdk/internal/util/SystemProps.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2025, 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
@@ -74,20 +74,18 @@ public static Map<String, String> initProperties() {
         putIfAbsent(props, "user.dir", raw.propDefault(Raw._user_dir_NDX));
         putIfAbsent(props, "user.name", raw.propDefault(Raw._user_name_NDX));
 
-        // Platform defined encoding cannot be overridden on the command line
+        // Platform defined encodings cannot be overridden on the command line
         put(props, "sun.jnu.encoding", raw.propDefault(Raw._sun_jnu_encoding_NDX));
-        var nativeEncoding = ((raw.propDefault(Raw._file_encoding_NDX) == null)
-                ? raw.propDefault(Raw._sun_jnu_encoding_NDX)
-                : raw.propDefault(Raw._file_encoding_NDX));
+        String nativeEncoding = raw.propDefault(Raw._native_encoding_NDX);
         put(props, "native.encoding", nativeEncoding);
 
         // "file.encoding" defaults to "UTF-8", unless specified in the command line
         // where "COMPAT" designates the native encoding.
-        var fileEncoding = props.getOrDefault("file.encoding", "UTF-8");
-        if ("COMPAT".equals(fileEncoding)) {
+        String fileEncoding = props.get("file.encoding");
+        if (fileEncoding == null) {
+            put(props, "file.encoding", "UTF-8");
+        } else if ("COMPAT".equals(fileEncoding)) {
             put(props, "file.encoding", nativeEncoding);
-        } else {
-            putIfAbsent(props, "file.encoding", fileEncoding);
         }
 
         // "stdout/err.encoding", prepared for System.out/err. For compatibility
@@ -209,17 +207,17 @@ private static void fillI18nProps(HashMap<String, String> cmdProps,
     }
 
     /**
-     * Read the raw properties from native System.c.
+     * Read raw property values from the JVM command line and from
+     * platform-specific code using native methods in System.c.
      */
     public static class Raw {
-        // Array indices written by native vmProperties()
+        // Indexes of array elements written by native platformProperties()
         // The order is arbitrary (but alphabetic for convenience)
         @Native private static final int _display_country_NDX = 0;
         @Native private static final int _display_language_NDX = 1 + _display_country_NDX;
         @Native private static final int _display_script_NDX = 1 + _display_language_NDX;
         @Native private static final int _display_variant_NDX = 1 + _display_script_NDX;
-        @Native private static final int _file_encoding_NDX = 1 + _display_variant_NDX;
-        @Native private static final int _file_separator_NDX = 1 + _file_encoding_NDX;
+        @Native private static final int _file_separator_NDX = 1 + _display_variant_NDX;
         @Native private static final int _format_country_NDX = 1 + _file_separator_NDX;
         @Native private static final int _format_language_NDX = 1 + _format_country_NDX;
         @Native private static final int _format_script_NDX = 1 + _format_language_NDX;
@@ -234,7 +232,8 @@ public static class Raw {
         @Native private static final int _https_proxyPort_NDX = 1 + _https_proxyHost_NDX;
         @Native private static final int _java_io_tmpdir_NDX = 1 + _https_proxyPort_NDX;
         @Native private static final int _line_separator_NDX = 1 + _java_io_tmpdir_NDX;
-        @Native private static final int _os_arch_NDX = 1 + _line_separator_NDX;
+        @Native private static final int _native_encoding_NDX = 1 + _line_separator_NDX;
+        @Native private static final int _os_arch_NDX = 1 + _native_encoding_NDX;
         @Native private static final int _os_name_NDX = 1 + _os_arch_NDX;
         @Native private static final int _os_version_NDX = 1 + _os_name_NDX;
         @Native private static final int _path_separator_NDX = 1 + _os_version_NDX;
@@ -255,7 +254,7 @@ public static class Raw {
         @Native private static final int _user_name_NDX = 1 + _user_home_NDX;
         @Native private static final int FIXED_LENGTH = 1 + _user_name_NDX;
 
-        // Array of Strings returned from the VM and Command line properties
+        // Array of property values returned from platform-specific native code
         // The array is not used after initialization is complete.
         private final String[] platformProps;
 
@@ -264,27 +263,26 @@ private Raw() {
         }
 
         /**
-         * Return the value for a well known default from native.
-         * @param index the index of the known property
-         * @return the value
+         * Returns a property value obtained from platform-specific native code.
+         * @param index the index of the property
+         * @return the property value, may be null
          */
         String propDefault(int index) {
             return platformProps[index];
         }
 
         /**
-         * Return a Properties instance of the command line and VM options
-         * defined by name and value.
-         * The Properties instance is sized to include the fixed properties.
+         * Returns a HashMap containing properties obtained from the command line
+         * and from the JVM. The HashMap is sized to include the platform properties.
          *
-         * @return return a Properties instance of the command line and VM options
+         * @return return a HashMap containing command line and JVM properties
          */
         private HashMap<String, String> cmdProperties() {
             String[] vmProps = vmProperties();
-            // While optimal initialCapacity here would be the exact number of properties
-            // divided by LOAD_FACTOR, a large portion of the properties in Raw are
-            // usually not set, so for typical cases the chosen capacity avoids resizing
-            var cmdProps = new HashMap<String, String>((vmProps.length / 2) + Raw.FIXED_LENGTH);
+            // Many platformProperties are null, so this initial size is an overestimate.
+            // However, more properties are added later, including encoding properties
+            // and version properties, so the excess space is justified.
+            HashMap<String, String> cmdProps = HashMap.newHashMap((vmProps.length / 2) + Raw.FIXED_LENGTH);
             for (int i = 0; i < vmProps.length;) {
                 String k = vmProps[i++];
                 if (k != null) {

src/java.base/share/native/libjava/System.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1994, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1994, 2025, 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
@@ -146,20 +146,19 @@ Java_jdk_internal_util_SystemProps_00024Raw_platformProperties(JNIEnv *env, jcla
     PUTPROP(propArray, _path_separator_NDX, sprops->path_separator);
     PUTPROP(propArray, _line_separator_NDX, sprops->line_separator);
 
+    /* basic encoding properties, always non-NULL */
 #ifdef MACOSX
     /*
      * Since sun_jnu_encoding is now hard-coded to UTF-8 on Mac, we don't
-     * want to use it to overwrite file.encoding
+     * want to use it to overwrite native.encoding
      */
-    PUTPROP(propArray, _file_encoding_NDX, sprops->encoding);
+    PUTPROP(propArray, _native_encoding_NDX, sprops->encoding);
 #else
-    PUTPROP(propArray, _file_encoding_NDX, sprops->sun_jnu_encoding);
+    PUTPROP(propArray, _native_encoding_NDX, sprops->sun_jnu_encoding);
 #endif
     PUTPROP(propArray, _sun_jnu_encoding_NDX, sprops->sun_jnu_encoding);
 
-    /*
-     * file encoding for stdout and stderr
-     */
+    /* encodings for standard streams, may be NULL */
     PUTPROP(propArray, _stdout_encoding_NDX, sprops->stdout_encoding);
     PUTPROP(propArray, _stderr_encoding_NDX, sprops->stderr_encoding);
 

src/java.base/share/native/libjava/java_props.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2025, 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
@@ -63,8 +63,8 @@ typedef struct {
     char *display_country;
     char *format_variant;
     char *display_variant;
-    char *encoding;
-    char *sun_jnu_encoding;
+    char *encoding;             /* always set non-NULL by platform code */
+    char *sun_jnu_encoding;     /* always set non-NULL by platform code */
     char *stdout_encoding;
     char *stderr_encoding;
 

src/java.base/unix/native/libjava/java_props_md.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2025, 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
@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <ctype.h>
 #endif
+#include <assert.h>
 #include <pwd.h>
 #include <locale.h>
 #ifndef ARCHPROPNAME
@@ -463,6 +464,10 @@ GetJavaProperties(JNIEnv *env)
 #else
     sprops.sun_jnu_encoding = sprops.encoding;
 #endif
+
+    assert(sprops.encoding != NULL);
+    assert(sprops.sun_jnu_encoding != NULL);
+
     if (isatty(STDOUT_FILENO) == 1) {
         sprops.stdout_encoding = sprops.encoding;
     }

src/java.base/windows/native/libjava/java_props_md.c

@@ -26,6 +26,7 @@
 #include "jni.h"
 #include "jni_util.h"
 
+#include <assert.h>
 #include <windows.h>
 #include <shlobj.h>
 #include <objidl.h>
@@ -667,10 +668,15 @@ GetJavaProperties(JNIEnv* env)
                            &sprops.display_variant,
                            &display_encoding);
 
+            if (sprops.encoding == NULL) {
+                sprops.encoding = "UTF-8";
+            }
+
             sprops.sun_jnu_encoding = getEncodingInternal(0);
             if (sprops.sun_jnu_encoding == NULL) {
                 sprops.sun_jnu_encoding = "UTF-8";
             }
+
             if (LANGIDFROMLCID(userDefaultLCID) == 0x0c04 && majorVersion == 6) {
                 // MS claims "Vista has built-in support for HKSCS-2004.
                 // All of the HKSCS-2004 characters have Unicode 4.1.
@@ -683,6 +689,9 @@ GetJavaProperties(JNIEnv* env)
                 sprops.sun_jnu_encoding = "MS950_HKSCS";
             }
 
+            assert(sprops.encoding != NULL);
+            assert(sprops.sun_jnu_encoding != NULL);
+
             hStdOutErr = GetStdHandle(STD_OUTPUT_HANDLE);
             if (hStdOutErr != INVALID_HANDLE_VALUE &&
                 GetFileType(hStdOutErr) == FILE_TYPE_CHAR) {