On Fri, Oct 11, 2019 at 05:09:29PM +0200, Jann Horn wrote:
> On Wed, Oct 9, 2019 at 6:10 PM Christian Kellner <ckellner@xxxxxxxxxx> wrote:
> > Add tests that check that if pid namespaces are configured the fdinfo
> > file of a pidfd contains an NSpid: entry containing the process id
> > in the current and additionally all nested namespaces.
> [...]
> > +static int compare_fdinfo_nspid(int pidfd, char *expect, size_t len)
> > +{
> > + char path[512];
> > + FILE *f;
> > + size_t n = 0;
> > + ssize_t k;
> > + char *line = NULL;
> > + int r = -1;
> > +
> > + snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
>
> (Maybe at some point the selftests code should add some more concise
> alternative to snprintf() calls on separate lines. A macro or
> something like that so that you can write stuff like `f =
> fopen(tprintf("/proc/self/fdinfo/%d", pidfd), "re")`.)
>
> > + f = fopen(path, "re");
> > + if (!f)
> > + return -1;
> > +
> > + while ((k = getline(&line, &n, f)) != -1) {
> > + if (strncmp(line, "NSpid:", 6))
> > + continue;
> > +
> > + line[k - 1] = '\0';
> > + ksft_print_msg("Child: fdinfo NSpid line: '%s'.\n", line);
> > + r = strncmp(line + 6, expect, len);
>
> Wouldn't it be better to get rid of the nullbyte assignment and change
> the strncmp() into a strcmp() here...
>
> [...]
> > + /* The child will have pid 1 in the new pid namespace,
> > + * so the line must be 'NSPid:\t<pid>\t1'
> > + */
> > + n = snprintf(expect, sizeof(expect), "\t%d\t%d", pid, 1);
>
> ... and add a "\n" to the format string? It's shorter and doesn't
> silently ignore it if the line doesn't end at that point.
Also, what Christian just told me and what I wanted to suggest is that
we add tests for sending around pidfds and reading fdinfo too.
