From 243a041bd0164aa62813ac4ba5a1a02eb2db455b Mon Sep 17 00:00:00 2001 From: Christopher Faylor Date: Sat, 3 Nov 2001 03:32:27 +0000 Subject: * dll_init.h (class dll_list): Reorder functions to avoid compiler "can't inline" warnings. * security.h (class cygsid): Ditto. * sigproc.cc (get_proc_lock): Ditto. * sigproc.h (class sigframe): Ditto. * sync.h (class muto): Ditto. * fhandler.h (fhandler_base::get_guard): Actually MAKE virtual as previously indicated. * pipe.cc (make_pipe): Remove extraneous set_errno. * syscalls.cc (_open): Ditto. * select.cc (peek_pipe): Need to check that there is still something to read from the pipe after acquiring the mutex since another process/thread could have eaten the input before we got to acquiring the lock. (Thanks to Nick Duffek for this inspiration.) --- winsup/cygwin/select.cc | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'winsup/cygwin/select.cc') diff --git a/winsup/cygwin/select.cc b/winsup/cygwin/select.cc index 1ba3ef3d8..78d1aaabe 100644 --- a/winsup/cygwin/select.cc +++ b/winsup/cygwin/select.cc @@ -389,7 +389,7 @@ peek_pipe (select_record *s, int ignra) fhandler_base *fh = s->fh; HANDLE h; - HANDLE guard_mutex = s->fh->get_guard (); + HANDLE guard_mutex = fh->get_guard (); set_handle_or_return_if_not_open (h, s); /* Don't perform complicated tests if we don't need to. */ @@ -438,12 +438,23 @@ peek_pipe (select_record *s, int ignra) select_printf ("%s, PeekNamedPipe failed, %E", fh->get_name ()); n = -1; } - else if (n && guard_mutex - && WaitForSingleObject (guard_mutex, 0) != WAIT_OBJECT_0) + else if (n && guard_mutex) { - select_printf ("%s, couldn't get mutex %p, %E", fh->get_name (), - guard_mutex); - n = 0; + if (WaitForSingleObject (guard_mutex, 0) != WAIT_OBJECT_0) + { + select_printf ("%s, couldn't get mutex %p, %E", fh->get_name (), + guard_mutex); + n = 0; + } + /* Now that we have the mutex, make sure that no one else has snuck + in and grabbed the data that we originally saw. */ + if (!PeekNamedPipe (h, NULL, 0, NULL, (DWORD *) &n, NULL)) + { + select_printf ("%s, PeekNamedPipe failed, %E", fh->get_name ()); + n = -1; + } + if (n <= 0) + ReleaseMutex (guard_mutex); /* Oops. We lost the race. */ } if (n < 0) -- cgit v1.2.3