Re: [PATCH] open: introduce O_NOSTD

Florian Weimer
2009-08-27T14:35:55Z

* Eric Blake:

> int open_safer (const char *name, int flags, int mode)
> {
> int fd = open (name, flags | O_CLOEXEC, mode);
> if (0 <= fd && fd <= 2)
> {
> int dup = fcntl (fd, ((flags & O_CLOEXEC)
> ? F_DUPFD_CLOEXEC : F_DUPFD), 3);
> int saved_errno = errno;
> close (fd);
> errno = saved_errno;
> fd = dup;
> }
> else if (!(flags & O_CLOEXEC))
> {
> if ((flags = fcntl (fd, F_GETFD)) < 0
> || fcntl (fd, F_SETFD, flags & ~FD_CLOEXEC) == -1)
> {
> int saved_errno = errno;
> close (fd);
> fd = -1;
> errno = saved_errno;
> }
> }
> return fd;
> }

> This solves the fd leak,

It's still buggy. You need something like this:

int open_safer(const char *name, int flags, int mode)
{
int opened_fd[3] = {0, 0, 0};
int fd, i, errno_saved;
while (1) {
fd = open(name, flags | O_CLOEXEC, mode);
if (fd < 0 || fd > 2) {
break;
}
opened_fd[fd] = 1;
}
for (int i = 0; i <= 2; ++i) {
if (opened_fd[i]) {
errno_saved = errno;
close(i);
errno = errno_saved;
}
}
return fd;
}

It's untested, so it's probably still buggy.

(O_CLOEXEC should have been a thread attribute, like the base path in
the *_at functions. *sigh*)

--
Florian Weimer <fweimer@bfk.de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99