8350703: Add standard system property stdin.encoding

src/java.base/share/classes/java/lang/System.java

@@ -116,15 +116,23 @@ private System() {
 
     /**
      * The "standard" input stream. This stream is already
-     * open and ready to supply input data. Typically this stream
+     * open and ready to supply input data. This stream
      * corresponds to keyboard input or another input source specified by
-     * the host environment or user. In case this stream is wrapped
-     * in a {@link java.io.InputStreamReader}, {@link Console#charset()}
-     * should be used for the charset, or consider using
-     * {@link Console#reader()}.
+     * the host environment or user. The encoding specified by the
+     * {@link ##stdin.encoding stdin.encoding} property should be used
+     * to convert input bytes to character data.
      *
-     * @see Console#charset()
-     * @see Console#reader()
+     * @apiNote
+     * The typical approach to read character data is to wrap {@code System.in}
+     * within an {@link java.io.InputStreamReader InputStreamReader} or other object
+     * that handles character encoding. After this is done, subsequent reading should
+     * use only the wrapper object; operating directly on {@code System.in} results
+     * in unspecified behavior.
+     * <p>
+     * For handling interactive input, consider using {@link Console}.
+     *
+     * @see Console
+     * @see ##stdin.encoding stdin.encoding
      */
     public static final InputStream in = null;
 
@@ -575,17 +583,22 @@ public static native void arraycopy(Object src,  int  srcPos,
      * <tr><th scope="row">{@systemProperty user.dir}</th>
      *     <td>User's current working directory</td></tr>
      * <tr><th scope="row">{@systemProperty native.encoding}</th>
-     *     <td>Character encoding name derived from the host environment and/or
-     *     the user's settings. Setting this system property has no effect.</td></tr>
+     *     <td>Character encoding name derived from the host environment and
+     *     the user's settings. Setting this system property on the command line
+     *     has no effect.</td></tr>
+     * <tr><th scope="row">{@systemProperty stdin.encoding}</th>
+     *     <td>Character encoding name for {@link System#in System.in}.
+     *     The Java runtime can be started with the system property set to {@code UTF-8}.
+     *     Starting it with the property set to another value results in unspecified behavior.
      * <tr><th scope="row">{@systemProperty stdout.encoding}</th>
      *     <td>Character encoding name for {@link System#out System.out} and
      *     {@link System#console() System.console()}.
-     *     The Java runtime can be started with the system property set to {@code UTF-8},
-     *     starting it with the property set to another value leads to undefined behavior.
+     *     The Java runtime can be started with the system property set to {@code UTF-8}.
+     *     Starting it with the property set to another value results in unspecified behavior.
      * <tr><th scope="row">{@systemProperty stderr.encoding}</th>
      *     <td>Character encoding name for {@link System#err System.err}.
-     *     The Java runtime can be started with the system property set to {@code UTF-8},
-     *     starting it with the property set to another value leads to undefined behavior.
+     *     The Java runtime can be started with the system property set to {@code UTF-8}.
+     *     Starting it with the property set to another value results in unspecified behavior.
      * </tbody>
      * </table>
      * <p>
@@ -639,7 +652,7 @@ public static native void arraycopy(Object src,  int  srcPos,
      *     the value {@code COMPAT} then the value is replaced with the
      *     value of the {@code native.encoding} property during startup.
      *     Setting the property to a value other than {@code UTF-8} or
-     *     {@code COMPAT} leads to unspecified behavior.
+     *     {@code COMPAT} results in unspecified behavior.
      *     </td></tr>
      * </tbody>
      * </table>

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

@@ -88,9 +88,12 @@ public static Map<String, String> initProperties() {
             put(props, "file.encoding", nativeEncoding);
         }
 
-        // "stdout/err.encoding", prepared for System.out/err. For compatibility
-        // purposes, substitute them with "sun.*" if they don't exist. If "sun.*" aren't
-        // available either, fall back to "native.encoding".
+        // Encoding properties for stdin, stdout, and stderr. For stdout and stderr,
+        // check "sun.*.encoding" properties before falling back to the
+        // "native.encoding" property.
+        putIfAbsent(props, "stdin.encoding",
+                raw.propDefault(Raw._stdin_encoding_NDX));
+        putIfAbsent(props, "stdin.encoding", nativeEncoding);
         putIfAbsent(props, "stdout.encoding", props.getOrDefault("sun.stdout.encoding",
                 raw.propDefault(Raw._stdout_encoding_NDX)));
         putIfAbsent(props, "stdout.encoding", nativeEncoding);
@@ -241,7 +244,8 @@ public static class Raw {
         @Native private static final int _socksProxyHost_NDX = 1 + _socksNonProxyHosts_NDX;
         @Native private static final int _socksProxyPort_NDX = 1 + _socksProxyHost_NDX;
         @Native private static final int _stderr_encoding_NDX = 1 + _socksProxyPort_NDX;
-        @Native private static final int _stdout_encoding_NDX = 1 + _stderr_encoding_NDX;
+        @Native private static final int _stdin_encoding_NDX = 1 + _stderr_encoding_NDX;
+        @Native private static final int _stdout_encoding_NDX = 1 + _stdin_encoding_NDX;
         @Native private static final int _sun_arch_abi_NDX = 1 + _stdout_encoding_NDX;
         @Native private static final int _sun_arch_data_model_NDX = 1 + _sun_arch_abi_NDX;
         @Native private static final int _sun_cpu_endian_NDX = 1 + _sun_arch_data_model_NDX;

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

@@ -154,6 +154,7 @@ Java_jdk_internal_util_SystemProps_00024Raw_platformProperties(JNIEnv *env, jcla
     PUTPROP(propArray, _sun_jnu_encoding_NDX, sprops->sun_jnu_encoding);
 
     /* encodings for standard streams, may be NULL */
+    PUTPROP(propArray, _stdin_encoding_NDX, sprops->stdin_encoding);
     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

@@ -65,6 +65,7 @@ typedef struct {
     char *display_variant;
     char *encoding;             /* always set non-NULL by platform code */
     char *sun_jnu_encoding;     /* always set non-NULL by platform code */
+    char *stdin_encoding;
     char *stdout_encoding;
     char *stderr_encoding;
 

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

@@ -464,6 +464,9 @@ GetJavaProperties(JNIEnv *env)
     sprops.sun_jnu_encoding = sprops.encoding;
 #endif
 
+    if (isatty(STDIN_FILENO) == 1) {
+        sprops.stdin_encoding = sprops.encoding;
+    }
     if (isatty(STDOUT_FILENO) == 1) {
         sprops.stdout_encoding = sprops.encoding;
     }

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

@@ -634,6 +634,7 @@ GetJavaProperties(JNIEnv* env)
         LCID userDefaultUILCID = MAKELCID(userDefaultUILang, SORTIDFROMLCID(userDefaultLCID));
 
         {
+            HANDLE hStdIn;
             HANDLE hStdOutErr;
 
             // Windows UI Language selection list only cares "language"
@@ -677,6 +678,11 @@ GetJavaProperties(JNIEnv* env)
                 sprops.sun_jnu_encoding = "MS950_HKSCS";
             }
 
+            hStdIn = GetStdHandle(STD_INPUT_HANDLE);
+            if (hStdIn != INVALID_HANDLE_VALUE &&
+                GetFileType(hStdIn) == FILE_TYPE_CHAR) {
+                sprops.stdin_encoding = getConsoleEncoding(FALSE);
+            }
             hStdOutErr = GetStdHandle(STD_OUTPUT_HANDLE);
             if (hStdOutErr != INVALID_HANDLE_VALUE &&
                 GetFileType(hStdOutErr) == FILE_TYPE_CHAR) {

test/jdk/java/lang/System/PropertyTest.java

@@ -81,6 +81,7 @@ static Object[][] requiredProperties() {
                 {"java.runtime.version"},
                 {"java.runtime.name"},
                 {"native.encoding"},
+                {"stdin.encoding"},
                 {"stdout.encoding"},
                 {"stderr.encoding"},
         };