FileChannelImpl.c

/*
 * Copyright (c) 2000, 2020, 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/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>

#if defined(__linux__)
#include <sys/sendfile.h>
#elif defined(_AIX)
#include <string.h>
#include <sys/socket.h>
#elif defined(_ALLBSD_SOURCE)
#include <sys/socket.h>
#include <sys/uio.h>
#define lseek64 lseek
#define mmap64 mmap
#endif

#include "jni.h"
#include "jni_util.h"
#include "jlong.h"
#include "nio.h"
#include "nio_util.h"
#include "sun_nio_ch_FileChannelImpl.h"
#include "java_lang_Integer.h"
#include <assert.h>

static jfieldID chan_fd;        /* jobject 'fd' in sun.nio.ch.FileChannelImpl */

JNIEXPORT jlong JNICALL
Java_sun_nio_ch_FileChannelImpl_initIDs(JNIEnv *env, jclass clazz)
{
    jlong pageSize = sysconf(_SC_PAGESIZE);
    chan_fd = (*env)->GetFieldID(env, clazz, "fd", "Ljava/io/FileDescriptor;");
    return pageSize;
}

static jlong
handle(JNIEnv *env, jlong rv, char *msg)
{
    if (rv >= 0)
        return rv;
    if (errno == EINTR)
        return IOS_INTERRUPTED;
    JNU_ThrowIOExceptionWithLastError(env, msg);
    return IOS_THROWN;
}


JNIEXPORT jlong JNICALL
Java_sun_nio_ch_FileChannelImpl_map0(JNIEnv *env, jobject this,
                                     jint prot, jlong off, jlong len, jboolean map_sync)
{
    void *mapAddress = 0;
    jobject fdo = (*env)->GetObjectField(env, this, chan_fd);
    jint fd = fdval(env, fdo);
    int protections = 0;
    int flags = 0;

    // should never be called with map_sync and prot == PRIVATE
    assert((prot != sun_nio_ch_FileChannelImpl_MAP_PV) || !map_sync);

    if (prot == sun_nio_ch_FileChannelImpl_MAP_RO) {
        protections = PROT_READ;
        flags = MAP_SHARED;
    } else if (prot == sun_nio_ch_FileChannelImpl_MAP_RW) {
        protections = PROT_WRITE | PROT_READ;
        flags = MAP_SHARED;
    } else if (prot == sun_nio_ch_FileChannelImpl_MAP_PV) {
        protections =  PROT_WRITE | PROT_READ;
        flags = MAP_PRIVATE;
    }

    // if MAP_SYNC and MAP_SHARED_VALIDATE are not defined then it is
    // best to define them here. This ensures the code compiles on old
    // OS releases which do not provide the relevant headers. If run
    // on the same machine then it will work if the kernel contains
    // the necessary support otherwise mmap should fail with an
    // invalid argument error

#ifndef MAP_SYNC
#define MAP_SYNC 0x80000
#endif
#ifndef MAP_SHARED_VALIDATE
#define MAP_SHARED_VALIDATE 0x03
#endif

    if (map_sync) {
        // ensure
        //  1) this is Linux on AArch64, x86_64, or PPC64 LE
        //  2) the mmap APIs are available at compile time
#if !defined(LINUX) || ! (defined(aarch64) || (defined(amd64) && defined(_LP64)) || defined(ppc64le))
        // TODO - implement for solaris/AIX/BSD/WINDOWS and for 32 bit
        JNU_ThrowInternalError(env, "should never call map on platform where MAP_SYNC is unimplemented");
        return IOS_THROWN;
#else
        flags |= MAP_SYNC | MAP_SHARED_VALIDATE;
#endif
    }

    mapAddress = mmap64(
        0,                    /* Let OS decide location */
        len,                  /* Number of bytes to map */
        protections,          /* File permissions */
        flags,                /* Changes are shared */
        fd,                   /* File descriptor of mapped file */
        off);                 /* Offset into file */

    if (mapAddress == MAP_FAILED) {
        if (map_sync && errno == ENOTSUP) {
            JNU_ThrowIOExceptionWithLastError(env, "map with mode MAP_SYNC unsupported");
            return IOS_THROWN;
        }

        if (errno == ENOMEM) {
            JNU_ThrowOutOfMemoryError(env, "Map failed");
            return IOS_THROWN;
        }
        return handle(env, -1, "Map failed");
    }

    return ((jlong) (unsigned long) mapAddress);
}


JNIEXPORT jint JNICALL
Java_sun_nio_ch_FileChannelImpl_unmap0(JNIEnv *env, jobject this,
                                       jlong address, jlong len)
{
    void *a = (void *)jlong_to_ptr(address);
    return handle(env,
                  munmap(a, (size_t)len),
                  "Unmap failed");
}

JNIEXPORT jlong JNICALL
Java_sun_nio_ch_FileChannelImpl_transferTo0(JNIEnv *env, jobject this,
                                            jobject srcFDO,
                                            jlong position, jlong count,
                                            jobject dstFDO)
{
    jint srcFD = fdval(env, srcFDO);
    jint dstFD = fdval(env, dstFDO);

#if defined(__linux__)
    off64_t offset = (off64_t)position;
    jlong 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;
#elif defined(__APPLE__)
    off_t numBytes;
    int result;

    numBytes = count;

    result = sendfile(srcFD, dstFD, position, &numBytes, NULL, 0);

    if (numBytes > 0)
        return numBytes;

    if (result == -1) {
        if (errno == EAGAIN)
            return IOS_UNAVAILABLE;
        if (errno == EOPNOTSUPP || errno == ENOTSOCK || errno == ENOTCONN)
            return IOS_UNSUPPORTED_CASE;
        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 result;

#elif defined(_AIX)
    jlong max = (jlong)java_lang_Integer_MAX_VALUE;
    struct sf_parms sf_iobuf;
    jlong result;

    if (position > max)
        return IOS_UNSUPPORTED_CASE;

    if (count > max)
        count = max;

    memset(&sf_iobuf, 0, sizeof(sf_iobuf));
    sf_iobuf.file_descriptor = srcFD;
    sf_iobuf.file_offset = (off_t)position;
    sf_iobuf.file_bytes = count;

    result = send_file(&dstFD, &sf_iobuf, SF_SYNC_CACHE);

    /* AIX send_file() will return 0 when this operation complete successfully,
     * return 1 when partial bytes transfered and return -1 when an error has
     * Occured.
     */
    if (result == -1) {
        if (errno == EWOULDBLOCK)
            return IOS_UNAVAILABLE;
        if ((errno == EINVAL) && ((ssize_t)count >= 0))
            return IOS_UNSUPPORTED_CASE;
        if (errno == EINTR)
            return IOS_INTERRUPTED;
        if (errno == ENOTSOCK)
            return IOS_UNSUPPORTED;
        JNU_ThrowIOExceptionWithLastError(env, "Transfer failed");
        return IOS_THROWN;
    }

    if (sf_iobuf.bytes_sent > 0)
        return (jlong)sf_iobuf.bytes_sent;

    return IOS_UNSUPPORTED_CASE;
#else
    return IOS_UNSUPPORTED_CASE;
#endif
}