Per https://cygwin.com/pipermail/cygwin-developers/2021-October/012429.html,
we may encounter a crash when starting multiple threads during process
startup (here: fhandler_fifo::fixup_after_{fork,exec}) which in turn
allocate memory via malloc.
The problem is concurrent usage of malloc before the malloc muto has
been initialized.
To fix this issue, convert the muto to a SRWLOCK and make sure it is
statically initalized. Thus, malloc can be called as early as necessary
and malloc_init is only required to check for user space provided malloc.
Note that this requires to implement a __malloc_trylock macro to be
called from fork.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This patch unifies the layout of the clipboard descriptor cygcb_t for
32- and 64-bit Cygwin. It allows correct copy/paste between the two
environments without corruption of user's copied data and without access
violations due to interpreting that data as a size field.
The definitions of CYGWIN_NATIVE and cygcb_t are moved to a new include
file, sys/clipboard.h. The include file is used by fhandler_clipboard.cc
as well as getclip.c and putclip.c in the Cygwin cygutils package.
When copy/pasting between 32- and 64-bit Cygwin environments, both must
be running version 3.3.0 or later for successful operation.
Due to reports on the Cygwin mailing list[1][2], it was uncovered
that a NtOpenDirectoryObject/NtQueryDirectoryObject/NtClose sequence
with NtQueryDirectoryObject iterating over the directory entries,
one entry per invocation, is not running atomically. If new entries
are inserted into the queried directory, other entries may be moved
around and then accidentally show up twice while iterating.
Change (almost) all NtQueryDirectoryObject invocations so that it gets
a really big buffer (64K) and ideally fetches all entries at once.
This appears to work atomically.
"Almost" all, because fhandler_procsys::readdir can't be easily changed.
[1] https://cygwin.com/pipermail/cygwin/2021-July/248998.html
[2] https://cygwin.com/pipermail/cygwin/2021-August/249124.html
Fixes: e9c8cb3193 ("(format_proc_partitions): Revamp loop over existing harddisks by scanning the NT native \Device object directory and looking for Harddisk entries.")
Fixes: a998dd7055 ("Implement advisory file locking.")
Fixes: 3b7cd74bfd ("(winpids::enum_processes): Fetch Cygwin processes from listing of shared cygwin object dir in the native NT namespace.")
Fixes: 0d6f2b0117 ("syscalls.cc (sync_worker): Rewrite using native NT functions.")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Corinna Vinschen
Mark Geisert
Takashi Yano
Ken Brown