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| author | Gregory P. Smith <greg@krypto.org> | 2020-10-24 19:07:35 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-10-24 19:07:35 (GMT) |
| commit | be3c3a0e468237430ad7d19a33c60d306199a7f2 (patch) | |
| tree | 63fb8ca636108b358012da9cf8e005e9569a501b | |
| parent | 8cd1dbae32d9303caac3a473d3332f17bc98c921 (diff) | |
| download | cpython-be3c3a0e468237430ad7d19a33c60d306199a7f2.zip cpython-be3c3a0e468237430ad7d19a33c60d306199a7f2.tar.gz cpython-be3c3a0e468237430ad7d19a33c60d306199a7f2.tar.bz2 | |
bpo-35823: Allow setsid() after vfork() on Linux. (GH-22945)
It should just be a syscall updating a couple of fields in the kernel side
process info. Confirming, in glibc is appears to be a shim for the setsid
syscall (based on not finding any code implementing anything special for it)
and in uclibc (*much* easier to read) it is clearly just a setsid syscall shim.
A breadcrumb _suggesting_ that it is not allowed on Darwin/macOS comes from
a commit in emacs: https://lists.gnu.org/archive/html/bug-gnu-emacs/2017-04/msg00297.html
but I don't have a way to verify if that is true or not.
As we are not supporting vfork on macOS today I just left a note in a comment.
| -rw-r--r-- | Modules/_posixsubprocess.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c index b7cba30..8baea31 100644 --- a/Modules/_posixsubprocess.c +++ b/Modules/_posixsubprocess.c @@ -38,6 +38,8 @@ #if defined(__linux__) && defined(HAVE_VFORK) && defined(HAVE_SIGNAL_H) && \ defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) +/* If this is ever expanded to non-Linux platforms, verify what calls are + * allowed after vfork(). Ex: setsid() may be disallowed on macOS? */ # include <signal.h> # define VFORK_USABLE 1 #endif @@ -712,7 +714,6 @@ do_fork_exec(char *const exec_array[], #ifdef VFORK_USABLE if (child_sigmask) { /* These are checked by our caller; verify them in debug builds. */ - assert(!call_setsid); assert(!call_setuid); assert(!call_setgid); assert(!call_setgroups); @@ -997,7 +998,7 @@ subprocess_fork_exec(PyObject* self, PyObject *args) /* Use vfork() only if it's safe. See the comment above child_exec(). */ sigset_t old_sigs; if (preexec_fn == Py_None && - !call_setuid && !call_setgid && !call_setgroups && !call_setsid) { + !call_setuid && !call_setgid && !call_setgroups) { /* Block all signals to ensure that no signal handlers are run in the * child process while it shares memory with us. Note that signals * used internally by C libraries won't be blocked by |