UNIX: prevent sending signals to PID 0

3 files changed, 13 insertions, 4 deletions

diff --git a/HISTORY.rst b/HISTORY.rst
index 9b86c6e8..18aa047c 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -11,6 +11,9 @@ Bug tracker at https://github.com/giampaolo/psutil/issues
   < 3.4.
 - #636: [Linux] *connections functions may swallow errors and return an
   incomplete list of connnections.
+- #637: [UNIX] raise exception if trying to send signal to Process PID 0 as it
+  will affect os.getpid()'s process group instead of PID 0.
+
 
 3.0.0 - 2015-06-13
 ==================
diff --git a/psutil/__init__.py b/psutil/__init__.py
index 16314476..7d47a14f 100644
--- a/psutil/__init__.py
+++ b/psutil/__init__.py
@@ -1007,10 +1007,12 @@ class Process(object):
 
     if _POSIX:
         def _send_signal(self, sig):
-            # XXX: according to "man 2 kill" PID 0 has a special
-            # meaning as it refers to <<every process in the process
-            # group of the calling process>>, so should we prevent
-            # it here?
+            if self.pid == 0:
+                # see "man 2 kill"
+                raise ValueError(
+                    "preventing sending signal to process with PID 0 as it "
+                    "will affect every process in the process group of the "
+                    "calling process (os.getpid()) instead of PID 0")
             try:
                 os.kill(self.pid, sig)
             except OSError as err:
diff --git a/test/test_psutil.py b/test/test_psutil.py
index a7213f4f..31655b72 100644
--- a/test/test_psutil.py
+++ b/test/test_psutil.py
@@ -2233,6 +2233,10 @@ class TestProcess(unittest.TestCase):
             except psutil.AccessDenied:
                 pass
 
+            self.assertRaisesRegexp(
+                ValueError, "preventing sending signal to process with PID 0",
+                p.send_signal(signal.SIGTERM))
+
         self.assertIn(p.ppid(), (0, 1))
         # self.assertEqual(p.exe(), "")
         p.cmdline()