io_util_md.c

/*
 * Copyright (c) 2001, 2010, 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 "jvm.h"
#include "io_util.h"
#include "io_util_md.h"
#include <string.h>

void
fileOpen(JNIEnv *env, jobject this, jstring path, jfieldID fid, int flags)
{
    WITH_PLATFORM_STRING(env, path, ps) {
        FD fd;

#ifdef __linux__
        /* Remove trailing slashes, since the kernel won't */
        char *p = (char *)ps + strlen(ps) - 1;
        while ((p > ps) && (*p == '/'))
            *p-- = '\0';
#endif
        fd = JVM_Open(ps, flags, 0666);
        if (fd >= 0) {
            SET_FD(this, fd, fid);
        } else {
            throwFileNotFoundException(env, path);
        }
    } END_PLATFORM_STRING(env, ps);
}


void
fileClose(JNIEnv *env, jobject this, jfieldID fid)
{
    FD fd = GET_FD(this, fid);
    if (fd == -1) {
        return;
    }

    /* Set the fd to -1 before closing it so that the timing window
     * of other threads using the wrong fd (closed but recycled fd,
     * that gets re-opened with some other filename) is reduced.
     * Practically the chance of its occurance is low, however, we are
     * taking extra precaution over here.
     */
    SET_FD(this, -1, fid);

    /*
     * Don't close file descriptors 0, 1, or 2. If we close these stream
     * then a subsequent file open or socket will use them. Instead we
     * just redirect these file descriptors to /dev/null.
     */
    if (fd >= STDIN_FILENO && fd <= STDERR_FILENO) {
        int devnull = open("/dev/null", O_WRONLY);
        if (devnull < 0) {
            SET_FD(this, fd, fid); // restore fd
            JNU_ThrowIOExceptionWithLastError(env, "open /dev/null failed");
        } else {
            dup2(devnull, fd);
            close(devnull);
        }
    } else if (JVM_Close(fd) == -1) {
        JNU_ThrowIOExceptionWithLastError(env, "close failed");
    }
}