/* Install a given filp in a given files_struct, with CLOEXEC set.
* Safe for files != current->files.
* Mostly cut-and-paste from linux-2.6.0/fs/fcntl.c:locate_fd()
*/
int cr_dup_other(struct files_struct *files, struct file *filp)
{
unsigned int newfd;
unsigned int start;
unsigned int max_fds;
int error;
cr_fdtable_t *fdt;
spin_lock(&files->file_lock);
repeat:
fdt = cr_fdtable(files);
start = CR_NEXT_FD(files, fdt);
newfd = start;
max_fds = CR_MAX_FDS(fdt);
if (start < max_fds) {
newfd = find_next_zero_bit(CR_OPEN_FDS_BITS(fdt),
max_fds, start);
}
/* XXX: Really shouldn't be using current here.
* However, I haven't bothered to figure out the locking
* requirements for using anything else.
* XXX: Probably could just pass the limit in.
* XXX: Later kernels push this into expand_files()
*/
error = -EMFILE;
if (newfd >= CR_RLIM(current)[RLIMIT_NOFILE].rlim_cur) {
goto out;
}
error = expand_files(files, newfd);
if (error < 0) {
goto out;
} else if (error) {
/* grew - search again (also reacquires fdt) */
goto repeat;
}
CR_NEXT_FD(files, fdt) = newfd + 1;
/* Claim */
cr_set_open_fd(newfd, fdt);
cr_set_close_on_exec(newfd, fdt);
/* Install */
get_file(filp);
rcu_assign_pointer(fdt->fd[newfd], filp);
error = newfd;
out:
spin_unlock(&files->file_lock);
return error;
}
/*
* cr_fd_claim
*
* Atomically checks and claims an fd
*
* returns < 0 on conflict w/ an existing fd
*/
int
cr_fd_claim(int fd)
{
cr_fdtable_t *fdt;
int retval;
/* Mark the fd in use */
spin_lock(¤t->files->file_lock);
fdt = cr_fdtable(current->files);
if (FD_ISSET(fd, fdt->open_fds)) {
retval = -EBUSY;
} else {
retval = 0;
FD_SET(fd, fdt->open_fds);
FD_CLR(fd, fdt->close_on_exec);
}
spin_unlock(¤t->files->file_lock);
return retval;
}
/*
* cr_fd_claim
*
* Atomically checks and claims an fd
*
* returns < 0 on conflict w/ an existing fd
*/
int
cr_fd_claim(int fd)
{
cr_fdtable_t *fdt;
int retval;
/* Mark the fd in use */
spin_lock(¤t->files->file_lock);
fdt = cr_fdtable(current->files);
if (cr_read_open_fd(fd, fdt)) {
retval = -EBUSY;
} else {
retval = 0;
cr_set_open_fd(fd, fdt);
cr_clear_close_on_exec(fd, fdt);
}
spin_unlock(¤t->files->file_lock);
return retval;
}
