[shellutils] Remove racy file lock

acquire_lock is racy on Unix (TOCTOU) and broken on Windows (lock file
is removed instantly since ProcInfo always raises NoSuchProcess on this
OS).

2 files changed, 3 insertions, 97 deletions

diff --git a/logilab/common/shellutils.py b/logilab/common/shellutils.py
index 4e68956..b4abbf1 100644
--- a/logilab/common/shellutils.py
+++ b/logilab/common/shellutils.py
@@ -44,15 +44,6 @@ from logilab.common import STD_BLACKLIST, _handle_blacklist
 from logilab.common.compat import str_to_bytes
 from logilab.common.deprecation import deprecated
 
-try:
-    from logilab.common.proc import ProcInfo, NoSuchProcess
-except ImportError:
-    # windows platform
-    class NoSuchProcess(Exception): pass
-
-    def ProcInfo(pid):
-        raise NoSuchProcess()
-
 
 class tempdir(object):
 
@@ -245,53 +236,6 @@ class Execute:
 Execute = deprecated('Use subprocess.Popen instead')(Execute)
 
 
-def acquire_lock(lock_file, max_try=10, delay=10, max_delay=3600):
-    """Acquire a lock represented by a file on the file system
-
-    If the process written in lock file doesn't exist anymore, we remove the
-    lock file immediately
-    If age of the lock_file is greater than max_delay, then we raise a UserWarning
-    """
-    count = abs(max_try)
-    while count:
-        try:
-            fd = os.open(lock_file, os.O_EXCL | os.O_RDWR | os.O_CREAT)
-            os.write(fd, str_to_bytes(str(os.getpid())) )
-            os.close(fd)
-            return True
-        except OSError as e:
-            if e.errno == errno.EEXIST:
-                try:
-                    fd = open(lock_file, "r")
-                    pid = int(fd.readline())
-                    pi = ProcInfo(pid)
-                    age = (time.time() - os.stat(lock_file)[stat.ST_MTIME])
-                    if age / max_delay > 1 :
-                        raise UserWarning("Command '%s' (pid %s) has locked the "
-                                          "file '%s' for %s minutes"
-                                          % (pi.name(), pid, lock_file, age/60))
-                except UserWarning:
-                    raise
-                except NoSuchProcess:
-                    os.remove(lock_file)
-                except Exception:
-                    # The try block is not essential. can be skipped.
-                    # Note: ProcInfo object is only available for linux
-                    # process information are not accessible...
-                    # or lock_file is no more present...
-                    pass
-            else:
-                raise
-            count -= 1
-            time.sleep(delay)
-    else:
-        raise Exception('Unable to acquire %s' % lock_file)
-
-def release_lock(lock_file):
-    """Release a lock represented by a file on the file system."""
-    os.remove(lock_file)
-
-
 class ProgressBar(object):
     """A simple text progression bar."""
 
diff --git a/test/unittest_shellutils.py b/test/unittest_shellutils.py
index 16ee63e..9342ae9 100644
--- a/test/unittest_shellutils.py
+++ b/test/unittest_shellutils.py
@@ -26,13 +26,13 @@ from six.moves import range
 from logilab.common.testlib import TestCase, unittest_main
 
 from logilab.common.shellutils import (globfind, find, ProgressBar,
-                                       acquire_lock, release_lock,
                                        RawInput)
-from logilab.common.compat import str_to_bytes, StringIO
-from logilab.common.proc import NoSuchProcess
+from logilab.common.compat import StringIO
+
 
 DATA_DIR = join(dirname(abspath(__file__)), 'data', 'find_test')
 
+
 class FindTC(TestCase):
     def test_include(self):
         files = set(find(DATA_DIR, '.py'))
@@ -170,44 +170,6 @@ class ProgressBarTC(TestCase):
             self.assertEqual(pgb_stream.getvalue(), expected_stream.getvalue())
 
 
-class AcquireLockTC(TestCase):
-
-    def setUp(self):
-        self.tmpdir = tempfile.mkdtemp()
-        self.lock = join(self.tmpdir, 'LOCK')
-
-    def tearDown(self):
-        shutil.rmtree(self.tmpdir)
-
-    def test_acquire_normal(self):
-        self.assertTrue(acquire_lock(self.lock, 1, 1))
-        self.assertTrue(os.path.exists(self.lock))
-        release_lock(self.lock)
-        self.assertFalse(os.path.exists(self.lock))
-
-    def test_no_possible_acquire(self):
-        self.assertRaises(Exception, acquire_lock, self.lock, 0)
-
-    def test_wrong_process(self):
-        fd = os.open(self.lock, os.O_EXCL | os.O_RDWR | os.O_CREAT)
-        os.write(fd, str_to_bytes('1111111111'))
-        os.close(fd)
-        self.assertTrue(os.path.exists(self.lock))
-        self.assertRaises(Exception, acquire_lock, self.lock, 1, 1)
-
-    def test_wrong_process_and_continue(self):
-        fd = os.open(self.lock, os.O_EXCL | os.O_RDWR | os.O_CREAT)
-        os.write(fd, str_to_bytes('1111111111'))
-        os.close(fd)
-        self.assertTrue(os.path.exists(self.lock))
-        self.assertTrue(acquire_lock(self.lock))
-
-    def test_locked_for_one_hour(self):
-        self.assertTrue(acquire_lock(self.lock))
-        touch = datetime.datetime.fromtimestamp(time.time() - 3601).strftime("%m%d%H%M")
-        os.system("touch -t %s %s" % (touch, self.lock))
-        self.assertRaises(UserWarning, acquire_lock, self.lock, max_try=2, delay=1)
-
 class RawInputTC(TestCase):
 
     def auto_input(self, *args):