From: Christian Brauner <christian.brauner@ubuntu.com>
To: Jann Horn <jannh@google.com>
Cc: Christian Kellner <ckellner@redhat.com>,
kernel list <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Christian Kellner <christian@kellner.me>,
Shuah Khan <shuah@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Michal Hocko <mhocko@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
Elena Reshetova <elena.reshetova@intel.com>,
Roman Gushchin <guro@fb.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
Al Viro <viro@zeniv.linux.org.uk>,
"Dmitry V. Levin" <ldv@altlinux.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] pidfd: add tests for NSpid info in fdinfo
Date: Fri, 11 Oct 2019 19:08:50 +0200 [thread overview]
Message-ID: <20191011170848.nbfxzzl5qckkshkr@wittgenstein> (raw)
In-Reply-To: <CAG48ez0MyiTKO2MpNVQqavoTKo7FZXYAyohx1JTR=M9Uw=QJWQ@mail.gmail.com>
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@redhat.com> 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.
next prev parent reply other threads:[~2019-10-11 17:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191008133641.23019-1-ckellner@redhat.com>
[not found] ` <20191009160532.20674-1-ckellner@redhat.com>
2019-10-09 16:05 ` [PATCH v2 2/2] pidfd: add tests for NSpid info in fdinfo Christian Kellner
2019-10-11 15:09 ` Jann Horn
2019-10-11 17:08 ` Christian Brauner [this message]
[not found] ` <20191011122323.7770-1-ckellner@redhat.com>
2019-10-11 12:23 ` [PATCH v3 " Christian Kellner
2019-10-11 13:18 ` Christian Brauner
[not found] ` <20191014162034.2185-1-ckellner@redhat.com>
2019-10-14 16:20 ` [PATCH v4 " Christian Kellner
2019-10-15 10:07 ` Christian Brauner
2019-11-13 11:52 ` Naresh Kamboju
2019-11-13 12:20 ` Christian Brauner
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