changeset 35464:8652ab4046e4

osutil: add a function to unblock signals Signals could be blocked by something like: #include <unistd.h> #include <signal.h> int main(int argc, char * const argv[]) { sigset_t set; sigfillset(&set); sigprocmask(SIG_BLOCK, &set, NULL); execv("/bin/hg", argv); return 0; } One of the problems is if SIGCHLD is blocked, chgserver would not reap zombie workers since it depends on SIGCHLD handler entirely. While it's the parent process to blame but it seems a good idea to just unblock the signal from hg. FWIW git does that for SIGPIPE already [1]. Unfortunately Python 2 does not reset or provide APIs to change signal masks. Therefore let's add one in osutil. Note: Python 3.3 introduced `signal.pthread_sigmask` which solves the problem. `sigprocmask` is part of POSIX [2] so there is no feature testing in `setup.py`. [1]: https://github.com/git/git/commit/7559a1be8a0afb10df41d25e4cf4c5285a5faef1 [2]: http://pubs.opengroup.org/onlinepubs/7908799/xsh/sigprocmask.html Differential Revision: https://phab.mercurial-scm.org/D1736
author Jun Wu <quark@fb.com>
date Wed, 20 Dec 2017 02:13:35 -0800
parents b520c8f98e1e
children 3a119a423953
files mercurial/cext/osutil.c mercurial/policy.py mercurial/util.py
diffstat 3 files changed, 28 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/cext/osutil.c	Mon Dec 18 21:15:53 2017 +0900
+++ b/mercurial/cext/osutil.c	Wed Dec 20 02:13:35 2017 -0800
@@ -20,6 +20,7 @@
 #include <windows.h>
 #else
 #include <dirent.h>
+#include <signal.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -1111,6 +1112,25 @@
 }
 #endif /* defined(HAVE_LINUX_STATFS) || defined(HAVE_BSD_STATFS) */
 
+static PyObject *unblocksignal(PyObject *self, PyObject *args)
+{
+	int sig = 0;
+	int r;
+	if (!PyArg_ParseTuple(args, "i", &sig))
+		return NULL;
+	sigset_t set;
+	r = sigemptyset(&set);
+	if (r != 0)
+		return PyErr_SetFromErrno(PyExc_OSError);
+	r = sigaddset(&set, sig);
+	if (r != 0)
+		return PyErr_SetFromErrno(PyExc_OSError);
+	r = sigprocmask(SIG_UNBLOCK, &set, NULL);
+	if (r != 0)
+		return PyErr_SetFromErrno(PyExc_OSError);
+	Py_RETURN_NONE;
+}
+
 #endif /* ndef _WIN32 */
 
 static PyObject *listdir(PyObject *self, PyObject *args, PyObject *kwargs)
@@ -1291,6 +1311,8 @@
 	{"getfstype", (PyCFunction)getfstype, METH_VARARGS,
 	 "get filesystem type (best-effort)\n"},
 #endif
+	{"unblocksignal", (PyCFunction)unblocksignal, METH_VARARGS,
+	 "change signal mask to unblock a given signal\n"},
 #endif /* ndef _WIN32 */
 #ifdef __APPLE__
 	{
@@ -1301,7 +1323,7 @@
 	{NULL, NULL}
 };
 
-static const int version = 1;
+static const int version = 2;
 
 #ifdef IS_PY3K
 static struct PyModuleDef osutil_module = {
--- a/mercurial/policy.py	Mon Dec 18 21:15:53 2017 +0900
+++ b/mercurial/policy.py	Wed Dec 20 02:13:35 2017 -0800
@@ -74,7 +74,7 @@
     (r'cext', r'bdiff'): 1,
     (r'cext', r'diffhelpers'): 1,
     (r'cext', r'mpatch'): 1,
-    (r'cext', r'osutil'): 1,
+    (r'cext', r'osutil'): 2,
     (r'cext', r'parsers'): 4,
 }
 
--- a/mercurial/util.py	Mon Dec 18 21:15:53 2017 +0900
+++ b/mercurial/util.py	Wed Dec 20 02:13:35 2017 -0800
@@ -163,6 +163,10 @@
     setprocname = osutil.setprocname
 except AttributeError:
     pass
+try:
+    unblocksignal = osutil.unblocksignal
+except AttributeError:
+    pass
 
 # Python compatibility