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bpo-42146: Unify cleanup in subprocess_fork_exec() #22970

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Merged
gpshead merged 4 commits into from
Nov 1, 2020
Merged

bpo-42146: Unify cleanup in subprocess_fork_exec() #22970

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89143b4
bpo-42146: Unify cleanup in subprocess_fork_exec()
Oct 25, 2020
551f611
Code defensively: also check for pid == -1
gpshead Oct 31, 2020
72d86c4
PyErr_Print instead of PyErr_Clear on gc.en fail
gpshead Oct 31, 2020
3f333c1
undo my added pid == -1 check, it was wrong
gpshead Nov 1, 2020
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53 changes: 18 additions & 35 deletions Modules/_posixsubprocess.c
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Original file line number Diff line number Diff line change
Expand Up @@ -87,8 +87,8 @@ get_posixsubprocess_state(PyObject *module)

#define _posixsubprocessstate_global get_posixsubprocess_state(PyState_FindModule(&_posixsubprocessmodule))

/* If gc was disabled, call gc.enable(). Return 0 on success. */
static int
/* If gc was disabled, call gc.enable(). Ignore errors. */
static void
_enable_gc(int need_to_reenable_gc, PyObject *gc_module)
{
PyObject *result;
Expand All @@ -98,15 +98,17 @@ _enable_gc(int need_to_reenable_gc, PyObject *gc_module)
PyErr_Fetch(&exctype, &val, &tb);
result = PyObject_CallMethodNoArgs(
gc_module, _posixsubprocessstate_global->enable);
if (result == NULL) {
/* We might have created a child process at this point, we
* we have no good way to handle a failure to reenable GC
* and return information about the child process. */
PyErr_Print();
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gpshead marked this conversation as resolved.
}
Py_XDECREF(result);
if (exctype != NULL) {
PyErr_Restore(exctype, val, tb);
}
if (result == NULL) {
return 1;
}
Py_DECREF(result);
}
return 0;
}


Expand Down Expand Up @@ -774,7 +776,7 @@ subprocess_fork_exec(PyObject* self, PyObject *args)
int child_umask;
PyObject *cwd_obj, *cwd_obj2 = NULL;
const char *cwd;
pid_t pid;
pid_t pid = -1;
int need_to_reenable_gc = 0;
char *const *exec_array, *const *argv = NULL, *const *envp = NULL;
Py_ssize_t arg_num, num_groups = 0;
Expand Down Expand Up @@ -1010,8 +1012,6 @@ subprocess_fork_exec(PyObject* self, PyObject *args)
sigset_t all_sigs;
sigfillset(&all_sigs);
if ((saved_errno = pthread_sigmask(SIG_BLOCK, &all_sigs, &old_sigs))) {
errno = saved_errno;
PyErr_SetFromErrno(PyExc_OSError);
goto cleanup;
}
old_sigmask = &old_sigs;
Expand Down Expand Up @@ -1050,50 +1050,33 @@ subprocess_fork_exec(PyObject* self, PyObject *args)
}
#endif

Py_XDECREF(cwd_obj2);

if (need_after_fork)
PyOS_AfterFork_Parent();
if (envp)
_Py_FreeCharPArray(envp);
if (argv)
_Py_FreeCharPArray(argv);
_Py_FreeCharPArray(exec_array);

/* Reenable gc in the parent process (or if fork failed). */
if (_enable_gc(need_to_reenable_gc, gc_module)) {
pid = -1;
}
PyMem_RawFree(groups);
Py_XDECREF(preexec_fn_args_tuple);
Py_XDECREF(gc_module);

if (pid == -1) {
cleanup:
if (saved_errno != 0) {
errno = saved_errno;
/* We can't call this above as PyOS_AfterFork_Parent() calls back
* into Python code which would see the unreturned error. */
PyErr_SetFromErrno(PyExc_OSError);
return NULL; /* fork() failed. */
}

return PyLong_FromPid(pid);

cleanup:
Py_XDECREF(preexec_fn_args_tuple);
PyMem_RawFree(groups);
Py_XDECREF(cwd_obj2);
if (envp)
_Py_FreeCharPArray(envp);
Py_XDECREF(converted_args);
Py_XDECREF(fast_args);
if (argv)
_Py_FreeCharPArray(argv);
if (exec_array)
_Py_FreeCharPArray(exec_array);

PyMem_RawFree(groups);
Py_XDECREF(converted_args);
Py_XDECREF(fast_args);
Py_XDECREF(preexec_fn_args_tuple);
_enable_gc(need_to_reenable_gc, gc_module);
Py_XDECREF(gc_module);
return NULL;

return pid == -1 ? NULL : PyLong_FromPid(pid);
}


Expand Down