1 files changed, 66 insertions, 1 deletions
diff --git a/python/skytools/fileutil.py b/python/skytools/fileutil.py
index fd657fd4..c6fcefdd 100644
--- a/python/skytools/fileutil.py
+++ b/python/skytools/fileutil.py
@@ -2,7 +2,7 @@
 
 import os
 
-__all__ = ['write_atomic']
+__all__ = ['write_atomic', 'signal_pidfile']
 
 def write_atomic(fn, data, bakext=None, mode='b'):
     """Write file with rename."""
@@ -35,3 +35,68 @@ def write_atomic(fn, data, bakext=None, mode='b'):
     # atomically replace file
     os.rename(fn2, fn)
 
+def signal_pidfile(pidfile, sig):
+    """Send a signal to process whose ID is located in pidfile.
+
+    Read only first line of pidfile to support multiline
+    pidfiles like postmaster.pid.
+
+    Returns True is successful, False if pidfile does not exist
+    or process itself is dead.  Any other errors will passed
+    as exceptions."""
+
+    ln = ''
+    try:
+        f = open(pidfile, 'r')
+        ln = f.readline().strip()
+        f.close()
+        pid = int(ln)
+        if sig == 0 and sys.platform == 'win32':
+            return win32_detect_pid(pid)
+        os.kill(pid, sig)
+        return True
+    except IOError, ex:
+        if ex.errno != errno.ENOENT:
+            raise
+    except OSError, ex:
+        if ex.errno != errno.ESRCH:
+            raise
+    except ValueError, ex:
+        # this leaves slight race when someone is just creating the file,
+        # but more common case is old empty file.
+        if not ln:
+            return False
+        raise ValueError('Corrupt pidfile: %s' % pidfile)
+    return False
+
+def win32_detect_pid(pid):
+    """Process detection for win32."""
+
+    # avoid pywin32 dependecy, use ctypes instead
+    import ctypes
+
+    # win32 constants
+    PROCESS_QUERY_INFORMATION = 1024
+    STILL_ACTIVE = 259
+    ERROR_INVALID_PARAMETER = 87
+    ERROR_ACCESS_DENIED = 5
+
+    # Load kernel32.dll
+    k = ctypes.windll.kernel32
+    OpenProcess = k.OpenProcess
+    OpenProcess.restype = ctypes.c_void_p
+
+    # query pid exit code
+    h = OpenProcess(PROCESS_QUERY_INFORMATION, 0, pid)
+    if h == None:
+        err = k.GetLastError()
+        if err == ERROR_INVALID_PARAMETER:
+            return False
+        if err == ERROR_ACCESS_DENIED:
+            return True
+        raise OSError(errno.EFAULT, "Unknown win32error: " + str(err))
+    code = ctypes.c_int()
+    k.GetExitCodeProcess(h, ctypes.byref(code))
+    k.CloseHandle(h)
+    return code.value == STILL_ACTIVE
+