Re: [PATCH] selftests: proc: include fcntl.h in proc-pidns

[Amin Vakil]

On 6/18/26 6:54 PM, Shuah Khan wrote:
> On 6/18/26 09:14, Amin Vakil wrote:
> > proc-pidns.c uses open() and O_* flags, but does not include
> > <fcntl.h>. This breaks the proc selftests build with errors such as:
> >
> >    error: implicit declaration of function 'open'
> >    error: 'O_WRONLY' undeclared
> >    error: 'O_CREAT' undeclared
> >    error: 'O_RDONLY' undeclared
> >
> > Include <fcntl.h> to provide the declaration and flag definitions.
>
> Did you install headers before compiling the test?

Sorry, no I hadn't.

But seems like problem is still relevant after make headers, I've tested 
now with these commands:

make -C tools/testing/selftests TARGETS=proc clean
make headers
make -C tools/testing/selftests TARGETS=proc
  CC       proc-pidns
proc-pidns.c: In function ‘touch’:
proc-pidns.c:34:18: error: implicit declaration of function ‘open’; did 
you mean ‘popen’? [-Wimplicit-function-declaration]
   34 |         int fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC, 0644);
      |                  ^~~~
      |                  popen
proc-pidns.c:34:29: error: ‘O_WRONLY’ undeclared (first use in this 
function)
   34 |         int fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC, 0644);
      |                             ^~~~~~~~
proc-pidns.c:34:29: note: each undeclared identifier is reported only 
once for each function it appears in
proc-pidns.c:34:38: error: ‘O_CREAT’ undeclared (first use in this function)
   34 |         int fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC, 0644);
      |                                      ^~~~~~~
proc-pidns.c: In function ‘ns_setup’:
proc-pidns.c:49:54: error: ‘O_RDONLY’ undeclared (first use in this 
function); did you mean ‘MS_RDONLY’?
   49 |         self->host_mntns = open("/proc/self/ns/mnt", 
O_RDONLY|O_CLOEXEC);
      |                                                      ^~~~~~~~
      |                                                      MS_RDONLY

After applying the patch I've sent, error is gone.

My environment if relevant:
$ gcc --version
gcc (GCC) 16.1.1 20260430
$ make --version
GNU Make 4.4.1
Built for x86_64-pc-linux-gnu
$ ldd --version
ldd (GNU libc) 2.43
$ getconf GNU_LIBC_VERSION
glibc 2.43
> > Fixes: 5554d820f71c ("selftests/proc: add tests for new pidns APIs")
> > Tested with:
> >    make -C tools/testing/selftests TARGETS=proc
> >
> > Signed-off-by: Amin Vakil <info@xxxxxxxxxxxxx>
> > ---
> >   tools/testing/selftests/proc/proc-pidns.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/tools/testing/selftests/proc/proc-pidns.c b/tools/ 
> > testing/selftests/proc/proc-pidns.c
> > index 25b9a2933c45..6f7c10fe97b3 100644
> > --- a/tools/testing/selftests/proc/proc-pidns.c
> > +++ b/tools/testing/selftests/proc/proc-pidns.c
> > @@ -6,6 +6,7 @@
> >   #include <assert.h>
> >   #include <errno.h>
> > +#include <fcntl.h>
> >   #include <sched.h>
> >   #include <stdbool.h>
> >   #include <stdlib.h>
>
> thanks,
> -- Shuah

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