ladybird/Kernel/Syscalls/fcntl.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>

namespace Kernel {

int Process::sys$fcntl(int fd, int cmd, u32 arg)
{
    REQUIRE_PROMISE(stdio);
#ifdef DEBUG_IO
    dbg() << "sys$fcntl: fd=" << fd << ", cmd=" << cmd << ", arg=" << arg;
#endif
    auto description = file_description(fd);
    if (!description)
        return -EBADF;
    // NOTE: The FD flags are not shared between FileDescription objects.
    //       This means that dup() doesn't copy the FD_CLOEXEC flag!
    switch (cmd) {
    case F_DUPFD: {
        int arg_fd = (int)arg;
        if (arg_fd < 0)
            return -EINVAL;
        int new_fd = alloc_fd(arg_fd);
        if (new_fd < 0)
            return new_fd;
        m_fds[new_fd].set(*description);
        return new_fd;
    }
    case F_GETFD:
        return m_fds[fd].flags();
    case F_SETFD:
        m_fds[fd].set_flags(arg);
        break;
    case F_GETFL:
        return description->file_flags();
    case F_SETFL:
        description->set_file_flags(arg);
        break;
    case F_ISTTY:
        return description->is_tty();
    default:
        return -EINVAL;
    }
    return 0;
}
}