/* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
/* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */

/* Copyright (C) 2014 OSCAR lab, Stony Brook University
   This file is part of Graphene Library OS.

   Graphene Library OS is free software: you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   Graphene Library OS 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 for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/*
 * fs.c
 *
 * This file contains codes for implementation of 'pipe' filesystem.
 */

#include <shim_internal.h>
#include <shim_thread.h>
#include <shim_handle.h>
#include <shim_fs.h>
#include <shim_profile.h>

#include <pal.h>
#include <pal_error.h>
#include <pal_debug.h>

#include <errno.h>

#include <linux/stat.h>
#include <linux/fcntl.h>

#include <asm/fcntl.h>
#include <asm/mman.h>
#include <asm/unistd.h>
#include <asm/prctl.h>
#include <asm/fcntl.h>
#include <shim_profile.h>

static int pipe_read (struct shim_handle * hdl, void * buf,
                      size_t count)
{
    int rv = 0;

    if (!count)
        goto out;

    rv = DkStreamRead(hdl->pal_handle, 0, count, buf, NULL, 0) ? :
         -PAL_ERRNO;
out:
    return rv;
}

static int pipe_write (struct shim_handle * hdl, const void * buf,
                       size_t count)
{
    if (!count)
        return 0;

    int bytes = DkStreamWrite(hdl->pal_handle, 0, count, (void *) buf, NULL);

    if (!bytes)
        return -PAL_ERRNO;

    return bytes;
}

static int pipe_hstat (struct shim_handle * hdl, struct stat * stat)
{
    if (!stat)
        return 0;

    struct shim_thread * thread = get_cur_thread();

    stat->st_dev    = (dev_t) 0;     /* ID of device containing file */
    stat->st_ino    = (ino_t) 0;     /* inode number */
    stat->st_nlink  = (nlink_t) 0;   /* number of hard links */
    stat->st_uid    = (uid_t) thread->uid;    /* user ID of owner */
    stat->st_gid    = (gid_t) thread->gid;    /* group ID of owner */
    stat->st_rdev   = (dev_t) 0;     /* device ID (if special file) */
    stat->st_size   = (off_t) 0;     /* total size, in bytes */
    stat->st_blksize = 0;            /* blocksize for file system I/O */
    stat->st_blocks = 0;             /* number of 512B blocks allocated */
    stat->st_atime  = (time_t) 0;    /* access time */
    stat->st_mtime  = (time_t) 0;    /* last modification */
    stat->st_ctime  = (time_t) 0;    /* last status change */
    stat->st_mode   = S_IRUSR|S_IWUSR|S_IFIFO;

    return 0;
}

static int pipe_checkout (struct shim_handle * hdl)
{
    hdl->fs = NULL;
    return 0;
}

static int pipe_poll (struct shim_handle * hdl, int poll_type)
{
    int ret = 0;

    lock(hdl->lock);

    if (!hdl->pal_handle) {
        ret = -EBADF;
        goto out;
    }

    PAL_STREAM_ATTR attr;
    if (!DkStreamAttributesQuerybyHandle(hdl->pal_handle, &attr)) {
        ret = -PAL_ERRNO;
        goto out;
    }

    if (poll_type == FS_POLL_SZ) {
        ret = attr.pending_size;
        goto out;
    }

    ret = 0;
    if (attr.disconnected)
        ret |= FS_POLL_ER;
    if ((poll_type & FS_POLL_RD) && attr.readable)
        ret |= FS_POLL_RD;
    if ((poll_type & FS_POLL_WR) && attr.writeable)
        ret |= FS_POLL_WR;

out:
    unlock(hdl->lock);
    return ret;
}

static int pipe_setflags (struct shim_handle * hdl, int flags)
{
    if (!hdl->pal_handle)
        return 0;

    PAL_STREAM_ATTR attr;

    if (!DkStreamAttributesQuerybyHandle(hdl->pal_handle, &attr))
        return -PAL_ERRNO;

    if (attr.nonblocking) {
        if (flags & O_NONBLOCK)
            return 0;

        attr.nonblocking = PAL_FALSE;
    } else {
        if (!(flags & O_NONBLOCK))
            return 0;

        attr.nonblocking = PAL_TRUE;
    }

    if (!DkStreamAttributesSetbyHandle(hdl->pal_handle, &attr))
       return -PAL_ERRNO;

    return 0;
}

struct shim_fs_ops pipe_fs_ops = {
        .read       = &pipe_read,
        .write      = &pipe_write,
        .hstat      = &pipe_hstat,
        .checkout   = &pipe_checkout,
        .poll       = &pipe_poll,
        .setflags   = &pipe_setflags,
    };

struct shim_mount pipe_builtin_fs = { .type = "pipe",
                                      .fs_ops = &pipe_fs_ops, };