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* [newlib-cygwin] Cygwin: console: Fix race issue regarding cons_master_thread().
@ 2021-04-20 8:46 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2021-04-20 8:46 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b4fc81edcc25b5c313ab3805dc0bcd015c370e62
commit b4fc81edcc25b5c313ab3805dc0bcd015c370e62
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Mon Apr 19 19:30:45 2021 +0900
Cygwin: console: Fix race issue regarding cons_master_thread().
- With this patch, the race issue regarding starting/stopping
cons_master_thread() introduced by commit ff4440fc is fixed.
Addresses:
https://cygwin.com/pipermail/cygwin/2021-April/248292.html
Diff:
---
winsup/cygwin/fhandler_console.cc | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/winsup/cygwin/fhandler_console.cc b/winsup/cygwin/fhandler_console.cc
index 62ee9e07f..ebe89fc9f 100644
--- a/winsup/cygwin/fhandler_console.cc
+++ b/winsup/cygwin/fhandler_console.cc
@@ -48,6 +48,7 @@ details. */
#define con_is_legacy (shared_console_info && con.is_legacy)
#define CONS_THREAD_SYNC "cygcons.thread_sync"
+static bool NO_COPY master_thread_started = false;
const unsigned fhandler_console::MAX_WRITE_CHARS = 16384;
@@ -184,6 +185,7 @@ cons_master_thread (VOID *arg)
GetCurrentProcess (), &thread_sync_event,
0, FALSE, DUPLICATE_SAME_ACCESS);
SetEvent (thread_sync_event);
+ master_thread_started = true;
/* Do not touch class members after here because the class instance
may have been destroyed. */
fhandler_console::cons_master_thread (&handle_set, ttyp);
@@ -370,6 +372,8 @@ fhandler_console::set_unit ()
}
if (!created && shared_console_info)
{
+ while (con.owner > MAX_PID)
+ Sleep (1);
pinfo p (con.owner);
if (!p)
con.owner = myself->pid;
@@ -1393,14 +1397,16 @@ fhandler_console::close ()
release_output_mutex ();
- if (shared_console_info && con.owner == myself->pid)
+ if (shared_console_info && con.owner == myself->pid
+ && master_thread_started)
{
char name[MAX_PATH];
shared_name (name, CONS_THREAD_SYNC, get_minor ());
thread_sync_event = OpenEvent (MAXIMUM_ALLOWED, FALSE, name);
- con.owner = 0;
+ con.owner = MAX_PID + 1;
WaitForSingleObject (thread_sync_event, INFINITE);
CloseHandle (thread_sync_event);
+ con.owner = 0;
}
CloseHandle (input_mutex);
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