From fb5d894cac96ebc82bd03941c04d8657127d6c70 Mon Sep 17 00:00:00 2001 From: "Gregory P. Smith" Date: Thu, 13 Sep 2018 03:59:45 -0700 Subject: [PATCH] bpo-34658: Fix rare prexec_fn fork failure error. bpo-34658: Fix a rare interpreter unhandled exception state SystemError only seen when using subprocess with a preexec_fn while an after_parent handler has been registered with os.register_at_fork and the fork system call fails. --- .../2018-09-13-03-59-43.bpo-34658.ykZ-ia.rst | 3 +++ Modules/_posixsubprocess.c | 20 ++++++++++++------- 2 files changed, 16 insertions(+), 7 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2018-09-13-03-59-43.bpo-34658.ykZ-ia.rst diff --git a/Misc/NEWS.d/next/Library/2018-09-13-03-59-43.bpo-34658.ykZ-ia.rst b/Misc/NEWS.d/next/Library/2018-09-13-03-59-43.bpo-34658.ykZ-ia.rst new file mode 100644 index 00000000000000..35375a088300cc --- /dev/null +++ b/Misc/NEWS.d/next/Library/2018-09-13-03-59-43.bpo-34658.ykZ-ia.rst @@ -0,0 +1,3 @@ +Fix a rare interpreter unhandled exception state SystemError only seen when +using subprocess with a preexec_fn while an after_parent handler has been +registered with os.register_at_fork and the fork system call fails. diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c index aeb10f9ecfe47c..dd69b9eb1ff6c9 100644 --- a/Modules/_posixsubprocess.c +++ b/Modules/_posixsubprocess.c @@ -564,6 +564,7 @@ subprocess_fork_exec(PyObject* self, PyObject *args) char *const *exec_array, *const *argv = NULL, *const *envp = NULL; Py_ssize_t arg_num; int need_after_fork = 0; + int saved_errno = 0; if (!PyArg_ParseTuple( args, "OOpO!OOiiiiiiiiiiO:fork_exec", @@ -700,14 +701,14 @@ subprocess_fork_exec(PyObject* self, PyObject *args) _exit(255); return NULL; /* Dead code to avoid a potential compiler warning. */ } - Py_XDECREF(cwd_obj2); - + /* Parent (original) process */ if (pid == -1) { - /* Capture the errno exception before errno can be clobbered. */ - PyErr_SetFromErrno(PyExc_OSError); + /* Capture errno for the exception. */ + saved_errno = errno; } - /* Parent process */ + Py_XDECREF(cwd_obj2); + if (need_after_fork) PyOS_AfterFork_Parent(); if (envp) @@ -723,8 +724,13 @@ subprocess_fork_exec(PyObject* self, PyObject *args) Py_XDECREF(preexec_fn_args_tuple); Py_XDECREF(gc_module); - if (pid == -1) - return NULL; /* fork() failed. Exception set earlier. */ + if (pid == -1) { + 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); pFad - Phonifier reborn

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