The pidfd interface was extended with:
* PIDFD_GET_INFO and pidfd_info (along with related extra flags) to
allow get information about the process without the need to parse
/proc (commit cdda1f26e74ba, Linux 6.13).
* PIDFD_SELF_{THREAD,THREAD_GROUP,SELF,SELF_PROCESS} to allow
pidfd_send_signal refer to the own process or thread lead groups
without the need of allocating a file descriptor (commit f08d0c3a71114,
Linux 6.15).
* PIDFD_INFO_COREDUMP that extends PIDFD_GET_INFO to obtain coredump
information.
Linux uAPI header defines both PIDFD_SELF_THREAD and
PIDFD_SELF_THREAD_GROUP on linux/fcntl.h (since they reserve part of the
AT_* values), however for glibc I do not see any good reason to add pidfd
definitions on fcntl-linux.h.
The tst-pidfd.c is extended with some PIDFD_SELF_* tests and a new
‘tst-pidfd_getinfo.c’ test is added to check PIDFD_GET_INFO. The
PIDFD_INFO_COREDUMP tests would require very large and complex tests
that are already covered by kernel tests.
Checked on aarch64-linux-gnu and x86_64-linux-gnu on kernels 6.8 and
6.17.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This interface allows to obtain the associated process ID from the
process file descriptor. It is done by parsing the procps fdinfo
information. Its prototype is:
pid_t pidfd_getpid (int fd)
It returns the associated pid or -1 in case of an error and sets the
errno accordingly. The possible errno values are those from open, read,
and close (used on procps parsing), along with:
- EBADF if the FD is negative, does not have a PID associated, or if
the fdinfo fields contain a value larger than pid_t.
- EREMOTE if the PID is in a separate namespace.
- ESRCH if the process is already terminated.
Checked on x86_64-linux-gnu on Linux 4.15 (no CLONE_PIDFD or waitid
support), Linux 5.4 (full support), and Linux 6.2.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
pidfd_getfd can fail for a valid pidfd with errno EPERM for various
reasons in a restricted environment. Use FAIL_UNSUPPORTED in that case.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
To check for the pidfd functions pidfd_open, pidfd_getfd, pid_send_signal,
and waitid with P_PIDFD.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
