Currently there is no proper way to set the controlling terminal through
posix_spawn in race free manner [1]. This forces shell implementations
to keep using fork+exec when launching background process groups,
even when using posix_spawn yields better performance.
This patch adds a new GNU extension so the creating process can
configure the created process terminal group. This is done with a new
flag, POSIX_SPAWN_TCSETPGROUP, along with two new attribute functions:
posix_spawnattr_tcsetpgrp_np, and posix_spawnattr_tcgetpgrp_np.
The function sets a new attribute, spawn-tcgroupfd, that references to
the controlling terminal.
The controlling terminal is set after the spawn-pgroup attribute, and
uses the spawn-tcgroupfd along with current creating process group
(so it is composable with POSIX_SPAWN_SETPGROUP).
To create a process and set the controlling terminal, one can use the
following sequence:
posix_spawnattr_t attr;
posix_spawnattr_init (&attr);
posix_spawnattr_setflags (&attr, POSIX_SPAWN_TCSETPGROUP);
posix_spawnattr_tcsetpgrp_np (&attr, tcfd);
If the idea is also to create a new process groups:
posix_spawnattr_t attr;
posix_spawnattr_init (&attr);
posix_spawnattr_setflags (&attr, POSIX_SPAWN_TCSETPGROUP
| POSIX_SPAWN_SETPGROUP);
posix_spawnattr_tcsetpgrp_np (&attr, tcfd);
posix_spawnattr_setpgroup (&attr, 0);
The controlling terminal file descriptor is ignored if the new flag is
not set.
This interface is slight different than the one provided by QNX [2],
which only provides the POSIX_SPAWN_TCSETPGROUP flag. The QNX
documentation does not specify how the controlling terminal is obtained
nor how it iteracts with POSIX_SPAWN_SETPGROUP. Since a glibc
implementation is library based, it is more straightforward and avoid
requires additional file descriptor operations to request the caller
to setup the controlling terminal file descriptor (and it also allows
a bit less error handling by posix_spawn).
Checked on x86_64-linux-gnu and i686-linux-gnu.
[1] https://github.com/ksh93/ksh/issues/79
[2] https://www.qnx.com/developers/docs/7.0.0/index.html#com.qnx.doc.neutrino.lib_ref/topic/p/posix_spawn.html
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
This patch adds a way to close a range of file descriptors on
posix_spawn as a new file action. The API is similar to the one
provided by Solaris 11 [1], where the file action causes the all open
file descriptors greater than or equal to input on to be closed when
the new process is spawned.
The function posix_spawn_file_actions_addclosefrom_np is safe to be
implemented by iterating over /proc/self/fd, since the Linux spawni.c
helper process does not use CLONE_FILES, so its has own file descriptor
table and any failure (in /proc operation) aborts the process creation
and returns an error to the caller.
I am aware that this file action might be redundant to the current
approach of POSIX in promoting O_CLOEXEC in more interfaces. However
O_CLOEXEC is still not the default and for some specific usages, the
caller needs to close all possible file descriptors to avoid them
leaking. Some examples are CPython (discussed in BZ#10353) and OpenJDK
jspawnhelper [2] (where OpenJDK spawns a helper process to exactly
closes all file descriptors). Most likely any environment which calls
functions that might open file descriptor under the hood and aim to use
posix_spawn might face the same requirement.
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
[1] https://docs.oracle.com/cd/E36784_01/html/E36874/posix-spawn-file-actions-addclosefrom-np-3c.html
[2] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Along with posix_spawn_file_actions_addchdir,
posix_spawn_file_actions_addfchdir is the subject of a change proposal
for POSIX: <http://austingroupbugs.net/view.php?id=1208>
The types affected are __sig_atomic_t, sig_atomic_t, __sigset_t,
sigset_t, sigval_t, sigevent_t, and siginfo_t. __sig_atomic_t is a
scalar, so it's now directly available from bits/types.h. The others
get bits/types/ headers.
Side effects include: There have been small changes to which
non-signal headers expose which subset of the signal-related types.
A couple of architectures' nested siginfo_t fields had to be renamed
to prevent undesired macro expansion. Internal code that wants to
manipulate signal masks must now include <sigsetops.h> (which is not
installed) and should be aware that __sigaddset, __sigandset,
__sigdelset, __sigemptyset, and __sigorset no longer return a value
(unlike the public API). Relatedly, the public signal.h no longer
declares any of those functions. The obsolete sigmask() macro no
longer has a system-specific definition -- in the cases where it
matters, it didn't work anyway.
New Linux architectures should create bits/siginfo-arch.h and/or
bits/siginfo-consts-arch.h to customize their siginfo_t, rather than
duplicating everything in bits/siginfo.h (which no longer exists).
Add new __SI_* macros if necessary. Ports to other operating systems
are strongly encouraged to generalize this scheme further.
* bits/sigevent-consts.h
* bits/siginfo-consts.h
* bits/types/__sigset_t.h
* bits/types/sigevent_t.h
* bits/types/siginfo_t.h
* sysdeps/unix/sysv/linux/bits/sigevent-consts.h
* sysdeps/unix/sysv/linux/bits/siginfo-consts.h
* sysdeps/unix/sysv/linux/bits/types/__sigset_t.h
* sysdeps/unix/sysv/linux/bits/types/sigevent_t.h
* sysdeps/unix/sysv/linux/bits/types/siginfo_t.h:
New system-dependent bits headers.
* sysdeps/unix/sysv/linux/bits/siginfo-arch.h
* sysdeps/unix/sysv/linux/bits/siginfo-consts-arch.h
* sysdeps/unix/sysv/linux/ia64/bits/siginfo-arch.h
* sysdeps/unix/sysv/linux/ia64/bits/siginfo-consts-arch.h
* sysdeps/unix/sysv/linux/mips/bits/siginfo-arch.h
* sysdeps/unix/sysv/linux/sparc/bits/siginfo-arch.h
* sysdeps/unix/sysv/linux/tile/bits/siginfo-arch.h
* sysdeps/unix/sysv/linux/tile/bits/siginfo-consts-arch.h
* sysdeps/unix/sysv/linux/x86/bits/siginfo-arch.h:
New Linux-only system-dependent bits headers.
* signal/bits/types/sig_atomic_t.h
* signal/bits/types/sigset_t.h
* signal/bits/types/sigval_t.h:
New non-system-dependent bits headers.
* sysdeps/generic/sigsetops.h
* sysdeps/unix/sysv/linux/sigsetops.h:
New internal headers.
* include/bits/types/sig_atomic_t.h
* include/bits/types/sigset_t.h
* include/bits/types/sigval_t.h:
New wrappers.
* signal/sigsetops.h
* bits/siginfo.h
* bits/sigset.h
* sysdeps/unix/sysv/linux/bits/siginfo.h
* sysdeps/unix/sysv/linux/bits/sigset.h
* sysdeps/unix/sysv/linux/ia64/bits/siginfo.h
* sysdeps/unix/sysv/linux/mips/bits/siginfo.h
* sysdeps/unix/sysv/linux/s390/bits/siginfo.h
* sysdeps/unix/sysv/linux/sparc/bits/siginfo.h
* sysdeps/unix/sysv/linux/tile/bits/siginfo.h
* sysdeps/unix/sysv/linux/x86/bits/siginfo.h:
Deleted.
* signal/Makefile, sysdeps/unix/sysv/linux/Makefile:
Update lists of installed headers.
* posix/bits/types.h: Define __sig_atomic_t here.
* signal/signal.h: Use the new bits headers; no need to handle
__need_sig_atomic_t nor __need_sigset_t. Don't use __sigmask
to define sigmask.
* include/signal.h: No need to handle __need_sig_atomic_t
nor __need_sigset_t. Don't define __sigemptyset.
* io/sys/poll.h, setjmp/setjmp.h
* sysdeps/arm/sys/ucontext.h, sysdeps/generic/sys/ucontext.h
* sysdeps/i386/sys/ucontext.h, sysdeps/m68k/sys/ucontext.h
* sysdeps/mach/hurd/i386/bits/sigcontext.h
* sysdeps/mips/sys/ucontext.h, sysdeps/powerpc/novmxsetjmp.h
* sysdeps/pthread/bits/sigthread.h
* sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
* sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
* sysdeps/unix/sysv/linux/mips/sys/ucontext.h
* sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
* sysdeps/unix/sysv/linux/s390/sys/ucontext.h
* sysdeps/unix/sysv/linux/sh/sys/ucontext.h
* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
* sysdeps/unix/sysv/linux/tile/sys/ucontext.h
* sysdeps/unix/sysv/linux/x86/sys/ucontext.h:
Use bits/types/__sigset_t.h.
* misc/sys/select.h, posix/spawn.h
* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
* sysdeps/unix/sysv/linux/sys/epoll.h
* sysdeps/unix/sysv/linux/sys/signalfd.h:
Use bits/types/sigset_t.h.
* resolv/netdb.h, rt/mqueue.h: Use bits/types/sigevent_t.h.
* rt/aio.h: Use bits/types/sigevent_t.h and bits/sigevent-consts.h.
* socket/sys/socket.h: Don't include bits/sigset.h.
* login/utmp_file.c, shadow/lckpwdf.c, signal/sigandset.c
* signal/sigisempty.c, stdlib/abort.c, sysdeps/posix/profil.c
* sysdeps/posix/sigignore.c, sysdeps/posix/sigintr.c
* sysdeps/posix/signal.c, sysdeps/posix/sigset.c
* sysdeps/posix/sprofil.c, sysdeps/posix/sysv_signal.c
* sysdeps/unix/sysv/linux/nptl-signals.h:
Include sigsetops.h.
* signal/sigaddset.c, signal/sigandset.c, signal/sigdelset.c
* signal/sigorset.c, stdlib/abort.c, sysdeps/posix/sigignore.c
* sysdeps/posix/signal.c, sysdeps/posix/sigset.c:
__sigaddset, __sigandset, __sigdelset, __sigemptyset, __sigorset
now return no value.
* signal/sigaddset.c, signal/sigdelset.c, signal/sigismem.c
Include <errno.h>, <signal.h>, and <sigsetops.h> instead of
"sigsetops.h".
* signal/sigsetops.c: Explicitly define __sigismember,
__sigaddset, and __sigdelset as compatibility symbols.
* signal/Versions: Correct commentary on __sigpause,
__sigaddset, __sigdelset, __sigismember.
* inet/rcmd.c: Include sigsetops.h. Convert old code using
__sigblock/__sigsetmask to use __sigprocmask and friends.
This patch adds support for the POSIX_SPAWN_SETSID flag.
It was recently accepted by the Austin Group:
http://austingroupbugs.net/view.php?id=1044
Checked on x86_64
Daurnimator <quae@daurnimator.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #21340]
* posix/Makefile (tests): Add tst-posix_spawn-setsid to list of tests.
* posix/spawn.h: define POSIX_SPAWN_SETSID flag.
* posix/spawnattr_setflags.c (ALL_FLAGS): Add POSIX_SPAWN_SETSID to
valid flags.
* posix/tst-posix_spawn-setsid.c: Add test for POSIX_SPAWN_SETSID.
* sysdeps/mach/hurd/spawni.c (__spawni): Implementation of
POSIX_SPAWN_SETSID.
* sysdeps/posix/spawni.c (__spawni): Likewise.
* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Likewise.
* NEWS: Add note about POSIX_SPAWN_SETSID support.
* posix/spawn.h [__USE_GNU]: Define POSIX_SPAWN_USEVFORK.
* posix/spawnattr_setflags.c: Check whether any unknown bit is set
in FLAGS parameter and fail if this is the case.
* sysdeps/posix/spawni.c: Use vfork if POSIX_SPAWN_USEVFORK flag is
set.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
Adhemerval Zanella