8293331: Refactor FileDispatcherImpl into operating system-specific components

Reviewed-by: alanb

src/java.base/linux/native/libnio/ch/FileDispatcherImpl.c

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2000, 2022, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 <sys/sendfile.h>
+#include <dlfcn.h>
+
+#include "jni.h"
+#include "nio.h"
+#include "nio_util.h"
+#include "sun_nio_ch_FileDispatcherImpl.h"
+
+typedef ssize_t copy_file_range_func(int, loff_t*, int, loff_t*, size_t,
+                                     unsigned int);
+static copy_file_range_func* my_copy_file_range_func = NULL;
+
+JNIEXPORT void JNICALL
+Java_sun_nio_ch_FileDispatcherImpl_init0(JNIEnv *env, jclass klass)
+{
+    my_copy_file_range_func =
+        (copy_file_range_func*) dlsym(RTLD_DEFAULT, "copy_file_range");
+}
+
+JNIEXPORT jlong JNICALL
+Java_sun_nio_ch_FileDispatcherImpl_transferFrom0(JNIEnv *env, jobject this,
+                                              jobject srcFDO, jobject dstFDO,
+                                              jlong position, jlong count,
+                                              jboolean append)
+{
+    if (my_copy_file_range_func == NULL)
+        return IOS_UNSUPPORTED;
+    // copy_file_range fails with EBADF when appending
+    if (append == JNI_TRUE)
+        return IOS_UNSUPPORTED_CASE;
+
+    jint srcFD = fdval(env, srcFDO);
+    jint dstFD = fdval(env, dstFDO);
+
+    off64_t offset = (off64_t)position;
+    size_t len = (size_t)count;
+    jlong n = my_copy_file_range_func(srcFD, NULL, dstFD, &offset, len, 0);
+    if (n < 0) {
+        if (errno == EAGAIN)
+            return IOS_UNAVAILABLE;
+        if (errno == ENOSYS)
+            return IOS_UNSUPPORTED_CASE;
+        if ((errno == EBADF || errno == EINVAL || errno == EXDEV) &&
+            ((ssize_t)count >= 0))
+            return IOS_UNSUPPORTED_CASE;
+        if (errno == EINTR) {
+            return IOS_INTERRUPTED;
+        }
+        JNU_ThrowIOExceptionWithLastError(env, "Transfer failed");
+        return IOS_THROWN;
+    }
+    return n;
+}
+
+JNIEXPORT jlong JNICALL
+Java_sun_nio_ch_FileDispatcherImpl_transferTo0(JNIEnv *env, jobject this,
+                                            jobject srcFDO,
+                                            jlong position, jlong count,
+                                            jobject dstFDO, jboolean append)
+{
+    jint srcFD = fdval(env, srcFDO);
+    jint dstFD = fdval(env, dstFDO);
+
+    // copy_file_range fails with EBADF when appending, and sendfile
+    // fails with EINVAL
+    if (append == JNI_TRUE)
+        return IOS_UNSUPPORTED_CASE;
+
+    off64_t offset = (off64_t)position;
+    jlong n;
+    if (my_copy_file_range_func != NULL) {
+        size_t len = (size_t)count;
+        n = my_copy_file_range_func(srcFD, &offset, dstFD, NULL, len, 0);
+        if (n < 0) {
+            switch (errno) {
+                case EINTR:
+                    return IOS_INTERRUPTED;
+                case EINVAL:
+                case ENOSYS:
+                case EXDEV:
+                    // ignore and try sendfile()
+                    break;
+                default:
+                    JNU_ThrowIOExceptionWithLastError(env, "Copy failed");
+                    return IOS_THROWN;
+            }
+        }
+        if (n >= 0)
+            return n;
+    }
+
+    n = sendfile64(dstFD, srcFD, &offset, (size_t)count);
+    if (n < 0) {
+        if (errno == EAGAIN)
+            return IOS_UNAVAILABLE;
+        if ((errno == EINVAL) && ((ssize_t)count >= 0))
+            return IOS_UNSUPPORTED_CASE;
+        if (errno == EINTR) {
+            return IOS_INTERRUPTED;
+        }
+        JNU_ThrowIOExceptionWithLastError(env, "Transfer failed");
+        return IOS_THROWN;
+    }
+    return n;
+}