source: vbox/trunk/src/VBox/Additions/linux/sharedfolders/lnkops.c@ 76938

/* $Id: lnkops.c 76938 2019-01-22 16:50:18Z vboxsync $ */
/** @file
 * vboxsf - VBox Linux Shared Folders VFS, operations for symbolic links.
 */

/*
 * Copyright (C) 2010-2019 Oracle Corporation
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include "vfsmod.h"

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 0)

# if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
#  if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
static const char *sf_follow_link(struct dentry *dentry, void **cookie)
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
static void *sf_follow_link(struct dentry *dentry, struct nameidata *nd)
#else
static int sf_follow_link(struct dentry *dentry, struct nameidata *nd)
#  endif
{
        struct inode *inode = dentry->d_inode;
        struct sf_glob_info *sf_g = GET_GLOB_INFO(inode->i_sb);
        struct sf_inode_info *sf_i = GET_INODE_INFO(inode);
        int error = -ENOMEM;
        char *path = (char *)get_zeroed_page(GFP_KERNEL);
        int rc;

        if (path) {
                error = 0;
                rc = VbglR0SfReadLink(&client_handle, &sf_g->map, sf_i->path,
                                      PATH_MAX, path);
                if (RT_FAILURE(rc)) {
                        LogFunc(("VbglR0SfReadLink failed, caller=%s, rc=%Rrc\n", __func__, rc));
                        free_page((unsigned long)path);
                        error = -EPROTO;
                }
        }
#  if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
        return error ? ERR_PTR(error) : (*cookie = path);
#  else
        nd_set_link(nd, error ? ERR_PTR(error) : path);
# if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
        return NULL;
# else
        return 0;
# endif
#endif
}

#  if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
# if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
static void sf_put_link(struct dentry *dentry, struct nameidata *nd,
                        void *cookie)
#else
static void sf_put_link(struct dentry *dentry, struct nameidata *nd)
#endif
{
        char *page = nd_get_link(nd);
        if (!IS_ERR(page))
                free_page((unsigned long)page);
}
#  endif

# else  /* LINUX_VERSION_CODE >= 4.5.0 */
static const char *sf_get_link(struct dentry *dentry, struct inode *inode,
                               struct delayed_call *done)
{
        struct sf_glob_info *sf_g = GET_GLOB_INFO(inode->i_sb);
        struct sf_inode_info *sf_i = GET_INODE_INFO(inode);
        char *path;
        int rc;

        if (!dentry)
                return ERR_PTR(-ECHILD);
        path = kzalloc(PAGE_SIZE, GFP_KERNEL);
        if (!path)
                return ERR_PTR(-ENOMEM);
        rc = VbglR0SfReadLink(&client_handle, &sf_g->map, sf_i->path, PATH_MAX,
                              path);
        if (RT_FAILURE(rc)) {
                LogFunc(("VbglR0SfReadLink failed, caller=%s, rc=%Rrc\n",
                         __func__, rc));
                kfree(path);
                return ERR_PTR(-EPROTO);
        }
        set_delayed_call(done, kfree_link, path);
        return path;
}
# endif /* LINUX_VERSION_CODE >= 4.5.0 */

struct inode_operations sf_lnk_iops = {
# if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0)
        .readlink = generic_readlink,
# endif
# if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
        .get_link = sf_get_link
# elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
        .follow_link = sf_follow_link,
        .put_link = free_page_put_link,
# else
        .follow_link = sf_follow_link,
        .put_link = sf_put_link
# endif
};

#endif  /* LINUX_VERSION_CODE >= 2.6.0 */