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Cygwin: pipe: Fix race issue regarding handle count. 

- This patch fixes the race issue in the handle counting to detect
  closure of read pipe, which is introduced by commit f79a4611.
  A mutex hdl_cnt_mtx is introduced for this issue.
This commit is contained in:
Takashi Yano 2021-09-16 23:21:57 +09:00 committed by Ken Brown
parent d8614e355d
commit 199482654b
2 changed files with 60 additions and 6 deletions
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1
winsup/cygwin/fhandler.h
View File

@ -1176,6 +1176,7 @@ class fhandler_pipe_fifo: public fhandler_base
protected:
size_t pipe_buf_size;
HANDLE query_hdl;
HANDLE hdl_cnt_mtx;
virtual void release_select_sem (const char *) {};
public:

65
winsup/cygwin/fhandler_pipe.cc
View File

@ -200,7 +200,14 @@ fhandler_pipe::open_setup (int flags)
SECURITY_ATTRIBUTES *sa = sec_none_cloexec (flags);
read_mtx = CreateMutex (sa, FALSE, NULL);
if (!read_mtx)
debug_printf ("CreateMutex failed: %E");
debug_printf ("CreateMutex read_mtx failed: %E");
}
if (!hdl_cnt_mtx)
{
SECURITY_ATTRIBUTES *sa = sec_none_cloexec (flags);
hdl_cnt_mtx = CreateMutex (sa, FALSE, NULL);
if (!hdl_cnt_mtx)
debug_printf ("CreateMutex hdl_cnt_mtx failed: %E");
}
if (get_dev () == FH_PIPEW && !query_hdl)
set_pipe_non_blocking (is_nonblocking ());
@ -390,8 +397,12 @@ fhandler_pipe_fifo::reader_closed ()
{
if (!query_hdl)
return false;
if (hdl_cnt_mtx)
WaitForSingleObject (hdl_cnt_mtx, INFINITE);
int n_reader = get_obj_handle_count (query_hdl);
int n_writer = get_obj_handle_count (get_handle ());
if (hdl_cnt_mtx)
ReleaseMutex (hdl_cnt_mtx);
return n_reader == n_writer;
}
@ -554,11 +565,18 @@ fhandler_pipe::set_close_on_exec (bool val)
set_no_inheritance (select_sem, val);
if (query_hdl)
set_no_inheritance (query_hdl, val);
if (hdl_cnt_mtx)
set_no_inheritance (hdl_cnt_mtx, val);
}
void
fhandler_pipe::fixup_after_fork (HANDLE parent)
{
if (hdl_cnt_mtx)
{
fork_fixup (parent, hdl_cnt_mtx, "hdl_cnt_mtx");
WaitForSingleObject (hdl_cnt_mtx, INFINITE);
}
if (read_mtx)
fork_fixup (parent, read_mtx, "read_mtx");
if (select_sem)
@ -567,6 +585,8 @@ fhandler_pipe::fixup_after_fork (HANDLE parent)
fork_fixup (parent, query_hdl, "query_hdl");
fhandler_base::fixup_after_fork (parent);
if (hdl_cnt_mtx)
ReleaseMutex (hdl_cnt_mtx);
}
int
@ -576,6 +596,8 @@ fhandler_pipe::dup (fhandler_base *child, int flags)
ftp->set_popen_pid (0);
int res = 0;
if (hdl_cnt_mtx)
WaitForSingleObject (hdl_cnt_mtx, INFINITE);
if (fhandler_base::dup (child, flags))
res = -1;
else if (read_mtx &&
@ -589,8 +611,8 @@ fhandler_pipe::dup (fhandler_base *child, int flags)
}
else if (select_sem &&
!DuplicateHandle (GetCurrentProcess (), select_sem,
GetCurrentProcess (), &ftp->select_sem,
0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS))
GetCurrentProcess (), &ftp->select_sem,
0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS))
{
__seterrno ();
ftp->close ();
@ -598,13 +620,24 @@ fhandler_pipe::dup (fhandler_base *child, int flags)
}
else if (query_hdl &&
!DuplicateHandle (GetCurrentProcess (), query_hdl,
GetCurrentProcess (), &ftp->query_hdl,
0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS))
GetCurrentProcess (), &ftp->query_hdl,
0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS))
{
__seterrno ();
ftp->close ();
res = -1;
}
else if (hdl_cnt_mtx &&
!DuplicateHandle (GetCurrentProcess (), hdl_cnt_mtx,
GetCurrentProcess (), &ftp->hdl_cnt_mtx,
0, !(flags & O_CLOEXEC), DUPLICATE_SAME_ACCESS))
{
__seterrno ();
ftp->close ();
res = -1;
}
if (hdl_cnt_mtx)
ReleaseMutex (hdl_cnt_mtx);
debug_printf ("res %d", res);
return res;
@ -620,9 +653,17 @@ fhandler_pipe::close ()
}
if (read_mtx)
CloseHandle (read_mtx);
if (hdl_cnt_mtx)
WaitForSingleObject (hdl_cnt_mtx, INFINITE);
if (query_hdl)
CloseHandle (query_hdl);
return fhandler_base::close ();
int ret = fhandler_base::close ();
if (hdl_cnt_mtx)
{
ReleaseMutex (hdl_cnt_mtx);
CloseHandle (hdl_cnt_mtx);
}
return ret;
}
#define PIPE_INTRO "\\\\.\\pipe\\cygwin-"
@ -834,9 +875,21 @@ fhandler_pipe::create (fhandler_pipe *fhs[2], unsigned psize, int mode)
FILE_READ_DATA, sa->bInheritHandle, 0))
goto err_close_select_sem1;
fhs[0]->hdl_cnt_mtx = CreateMutexW (sa, FALSE, NULL);
if (!fhs[0]->hdl_cnt_mtx)
goto err_close_query_hdl;
if (!DuplicateHandle (GetCurrentProcess (), fhs[0]->hdl_cnt_mtx,
GetCurrentProcess (), &fhs[1]->hdl_cnt_mtx,
0, sa->bInheritHandle, DUPLICATE_SAME_ACCESS))
goto err_close_hdl_cnt_mtx0;
res = 0;
goto out;
err_close_hdl_cnt_mtx0:
CloseHandle (fhs[0]->hdl_cnt_mtx);
err_close_query_hdl:
CloseHandle (fhs[1]->query_hdl);
err_close_select_sem1:
CloseHandle (fhs[1]->select_sem);
err_close_select_sem0: