8293121: (fs) Refactor UnixFileSystem copying into generic Unix, Linux, and BSD implementations

Reviewed-by: alanb

src/java.base/linux/classes/sun/nio/fs/LinuxFileSystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 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
@@ -25,10 +25,16 @@
 
 package sun.nio.fs;
 
-import java.nio.file.*;
+import java.nio.file.FileStore;
+import java.nio.file.WatchService;
 import java.io.IOException;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
 import static sun.nio.fs.LinuxNativeDispatcher.*;
+import static sun.nio.fs.UnixConstants.*;
 
 /**
  * Linux implementation of FileSystem
@@ -121,10 +127,56 @@ class LinuxFileSystem extends UnixFileSystem {
         return getMountEntries("/etc/mtab");
     }
 
-
-
     @Override
     FileStore getFileStore(UnixMountEntry entry) throws IOException {
         return new LinuxFileStore(this, entry);
     }
+
+    // --- file copying ---
+
+    @Override
+    void bufferedCopy(int dst, int src, long address,
+                      int size, long addressToPollForCancel)
+        throws UnixException
+    {
+        int advice = POSIX_FADV_SEQUENTIAL | // sequential data access
+                     POSIX_FADV_NOREUSE    | // will access only once
+                     POSIX_FADV_WILLNEED;    // will access in near future
+        posix_fadvise(src, 0, 0, advice);
+
+        super.bufferedCopy(dst, src, address, size, addressToPollForCancel);
+    }
+
+    @Override
+    int directCopy(int dst, int src, long addressToPollForCancel)
+        throws UnixException
+    {
+        int advice = POSIX_FADV_SEQUENTIAL | // sequential data access
+                     POSIX_FADV_NOREUSE    | // will access only once
+                     POSIX_FADV_WILLNEED;    // will access in near future
+        posix_fadvise(src, 0, 0, advice);
+
+        return directCopy0(dst, src, addressToPollForCancel);
+    }
+
+    // -- native methods --
+
+    /**
+     * Copies data between file descriptors {@code src} and {@code dst} using
+     * a platform-specific function or system call possibly having kernel
+     * support.
+     *
+     * @param dst destination file descriptor
+     * @param src source file descriptor
+     * @param addressToPollForCancel address to check for cancellation
+     *        (a non-zero value written to this address indicates cancel)
+     *
+     * @return 0 on success, UNAVAILABLE if the platform function would block,
+     *         UNSUPPORTED_CASE if the call does not work with the given
+     *         parameters, or UNSUPPORTED if direct copying is not supported
+     *         on this platform
+     */
+    private static native int directCopy0(int dst, int src,
+                                          long addressToPollForCancel)
+        throws UnixException;
 }

src/java.base/linux/classes/sun/nio/fs/LinuxNativeDispatcher.java

@@ -62,6 +62,12 @@ class LinuxNativeDispatcher extends UnixNativeDispatcher {
      */
     static native void endmntent(long stream) throws UnixException;
 
+    /**
+     * int posix_fadvise(int fd, off_t offset, off_t len, int advice);
+     */
+    static native int posix_fadvise(int fd, long offset, long len, int advice)
+        throws UnixException;
+
     // initialize
     private static native void init();
 

src/java.base/linux/native/libnio/fs/LinuxFileSystem.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 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 "jni.h"
+#include "jni_util.h"
+#include "jlong.h"
+
+#include "nio.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <sys/sendfile.h>
+#include <fcntl.h>
+
+#include "sun_nio_fs_LinuxFileSystem.h"
+
+#define RESTARTABLE(_cmd, _result) do { \
+  do { \
+    _result = _cmd; \
+  } while((_result == -1) && (errno == EINTR)); \
+} while(0)
+
+static void throwUnixException(JNIEnv* env, int errnum) {
+    jobject x = JNU_NewObjectByName(env, "sun/nio/fs/UnixException",
+        "(I)V", errnum);
+    if (x != NULL) {
+        (*env)->Throw(env, x);
+    }
+}
+
+// Copy all bytes from src to dst, within the kernel if possible,
+// and return zero, otherwise return the appropriate status code.
+//
+// Return value
+//   0 on success
+//   IOS_UNAVAILABLE if the platform function would block
+//   IOS_UNSUPPORTED_CASE if the call does not work with the given parameters
+//   IOS_UNSUPPORTED if direct copying is not supported on this platform
+//   IOS_THROWN if a Java exception is thrown
+//
+JNIEXPORT jint JNICALL
+Java_sun_nio_fs_LinuxFileSystem_directCopy0
+    (JNIEnv* env, jclass this, jint dst, jint src, jlong cancelAddress)
+{
+    volatile jint* cancel = (jint*)jlong_to_ptr(cancelAddress);
+
+    // Transfer within the kernel
+    const size_t count = cancel != NULL ?
+        1048576 :   // 1 MB to give cancellation a chance
+        0x7ffff000; // maximum number of bytes that sendfile() can transfer
+    ssize_t bytes_sent;
+
+    do {
+        RESTARTABLE(sendfile64(dst, src, NULL, count), bytes_sent);
+        if (bytes_sent < 0) {
+            if (errno == EAGAIN)
+                return IOS_UNAVAILABLE;
+            if (errno == EINVAL || errno == ENOSYS)
+                return IOS_UNSUPPORTED_CASE;
+            throwUnixException(env, errno);
+            return IOS_THROWN;
+        }
+        if (cancel != NULL && *cancel != 0) {
+            throwUnixException(env, ECANCELED);
+            return IOS_THROWN;
+        }
+    } while (bytes_sent > 0);
+
+    return 0;
+}

src/java.base/linux/native/libnio/fs/LinuxNativeDispatcher.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 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
@@ -33,6 +33,7 @@
 #include <dlfcn.h>
 #include <errno.h>
 #include <mntent.h>
+#include <fcntl.h>
 
 #include "sun_nio_fs_LinuxNativeDispatcher.h"
 
@@ -139,6 +140,13 @@ JNIEXPORT void JNICALL
 Java_sun_nio_fs_LinuxNativeDispatcher_endmntent(JNIEnv* env, jclass this, jlong stream)
 {
     FILE* fp = jlong_to_ptr(stream);
-    /* FIXME - man page doesn't explain how errors are returned */
+    // The endmntent() function always returns 1.
     endmntent(fp);
 }
+
+JNIEXPORT jint JNICALL
+Java_sun_nio_fs_LinuxNativeDispatcher_posix_1fadvise(JNIEnv* env, jclass this,
+    jint fd, jlong offset, jlong len, jint advice)
+{
+    return posix_fadvise64((int)fd, (off64_t)offset, (off64_t)len, (int)advice);
+}