Nucleus

/*
 * This file handles mounting various file systems into the VFS.  This is the
 * mount system call.
 */

#include <sys/errno.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <nucleus/lib.h>
#include <nucleus/memory.h>
#include <nucleus/task.h>
#include <nucleus/vfs.h>
#include "namespace.h"

Inode *lookup(const char *path, ObjectList *newcustody);
int mount_fstype(const char *name, int flags, const char *src, void *data,
                 Inode **root);

/* Mount a file system */
int
mount(const char *src, const char *target, const char *type,
      unsigned long flags, void *data)
{
	if (!src || !type)
		return -EFAULT;
	if (!verify_access(src, strnlen(src, PATH_MAX), PROT_READ))
		return -EFAULT;
	if (!verify_access(target, strnlen(target, PATH_MAX), PROT_READ))
		return -EFAULT;
	if (!verify_access(type, strnlen(type, 16), PROT_READ))
		return -EFAULT;

	Inode *mnt = NULL;
	int res = mount_fstype(type, flags, src, data, &mnt);
	if (res < 0)
		return res;
	if (!mnt)
		return -ENODEV;

	/* Mount as VFS root */
	if (!target && !current->fs->root) {
		current->fs->root = get(mnt);
		current->fs->cwd = get(mnt);
		return 0;
	}

	/* Find target's directory entry */
	ObjectList *custody = create_list(&dirEntryType, LIST_NORMAL);
	Inode *root = lookup(target, custody);
	if (!root) {
		destroy_list(custody);
		return -ENOENT;
	}
	if (!S_ISDIR(root->mode)) {
		put(root);
		destroy_list(custody);
		return -ENOTDIR;
	}
	DirEntry *de = get_nth_item(custody, count(custody) - 1);
	de->mnt = de->inode;
	de->inode = get(mnt);
	put(root);
	destroy_list(custody);

	return 0;
}