win32: add a method to fetch the available pipe data size
This will be used in the next patch to do nonblocking reads from the child
process, like on posix platforms. See that for why os.fstat() is insufficient.
--- a/mercurial/win32.py Tue Apr 07 20:43:04 2015 -0700
+++ b/mercurial/win32.py Tue Apr 07 22:30:25 2015 -0400
@@ -5,7 +5,7 @@
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
-import ctypes, errno, os, subprocess, random
+import ctypes, errno, msvcrt, os, subprocess, random
_kernel32 = ctypes.windll.kernel32
_advapi32 = ctypes.windll.advapi32
@@ -26,6 +26,7 @@
_ERROR_SUCCESS = 0
_ERROR_NO_MORE_FILES = 18
_ERROR_INVALID_PARAMETER = 87
+_ERROR_BROKEN_PIPE = 109
_ERROR_INSUFFICIENT_BUFFER = 122
# WPARAM is defined as UINT_PTR (unsigned type)
@@ -211,6 +212,10 @@
_kernel32.CreateToolhelp32Snapshot.argtypes = [_DWORD, _DWORD]
_kernel32.CreateToolhelp32Snapshot.restype = _BOOL
+_kernel32.PeekNamedPipe.argtypes = [_HANDLE, ctypes.c_void_p, _DWORD,
+ ctypes.c_void_p, ctypes.c_void_p, ctypes.c_void_p]
+_kernel32.PeekNamedPipe.restype = _BOOL
+
_kernel32.Process32First.argtypes = [_HANDLE, ctypes.c_void_p]
_kernel32.Process32First.restype = _BOOL
@@ -260,6 +265,19 @@
res2 = _getfileinfo(path2)
return res1.dwVolumeSerialNumber == res2.dwVolumeSerialNumber
+def peekpipe(pipe):
+ handle = msvcrt.get_osfhandle(pipe.fileno())
+ avail = _DWORD()
+
+ if not _kernel32.PeekNamedPipe(handle, None, 0, None, ctypes.byref(avail),
+ None):
+ err = _kernel32.GetLastError()
+ if err == _ERROR_BROKEN_PIPE:
+ return 0
+ raise ctypes.WinError(err)
+
+ return avail.value
+
def testpid(pid):
'''return True if pid is still running or unable to
determine, False otherwise'''