This is necessary in order to be consistent with the following comment
in the definition of _Unwind_RaiseException() in the GCC source file
libgcc/unwind-seh.c:
The exception handler installed in crt0 will continue any GCC
exception that reaches there (and isn't marked non-continuable).
Previously we failed to do this and, as a consequence, the C++ runtime
didn't call std::terminate after an unhandled exception.
This fixes the problem reported here:
https://cygwin.com/pipermail/cygwin/2019-October/242795.htmlhttps://sourceware.org/pipermail/cygwin/2020-August/245897.html
This patch has been inspired by the Linux kernel patch
294f69e662d1 compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use
written by Joe Perches <joe AT perches DOT com> based on an idea from
Dan Carpenter <dan DOT carpenter AT oracle DOT com>. The following text
is from the original log message:
Reserve the pseudo keyword 'fallthrough' for the ability to convert the
various case block /* fallthrough */ style comments to appear to be an
actual reserved word with the same gcc case block missing fallthrough
warning capability.
All switch/case blocks now should end in one of:
break;
fallthrough;
goto <label>;
return [expression];
continue;
In C mode, GCC supports the __fallthrough__ attribute since 7.1,
the same time the warning and the comment parsing were introduced.
Cygwin-only: add an explicit -Wimplicit-fallthrough=5 to the build
flags.
NSIG is a deprecated symbol only visible under MISC visibility.
_NSIG is used widely instead, and on most systems NSIG is
defined in terms of _NSIG.
Follow suit: Change NSIG to _NSIG throughout and change visiblity
of NSIG to be defined only in __MISC_VISIBLE case.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Rather than waiting for signalfd_select_wait in a thread, which is racy,
create a global event "my_pendingsigs_evt" which is set and reset by
wait_sig depending only on the fact if blocked signals are pending or not.
This in turn allows to WFMO on this event in select as soon as signalfds
are present in the read descriptor set. Select's peek and verify
will then check if one of the present signalfds is affected.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
On sigwaitinfo or reading from a signalfd, signal processing sets up
signal handling via sigdelayed even if the handler address is NULL.
This doesn't have any impact on sigwaitinfo scenarios (or at least, I
wasn't able to come up with a reproducer) but it breaks signalfd
scenarios, where eventually a call to call_signal_handler from
sigdelayed will try to call the NULL function.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
In case SA_SIGINFO flag is given, the signal handler may change
the context and the application is supposed to pick up from the
changed context. So far we don't do that, so the context given
to the signal handler is basically read-only, unless the signal
handler calls setcontext or swapcontext.
For a start, restore the thread's signal mask from the uc_sigmask
value of the context given to the signal handler.
If that's feasible for Cygwin, we restore the entire context from
the context changed by the signal handler in a followup patch.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- Rename files timer.* to posix_timer.*.
- Reimplement using an OS timer rather than a handcrafted wait loop.
- Use a Slim R/W Lock for synchronization.
- Drop timer chaining. It doesn't server a purpose since all timers
are local only.
- Rename ttstart to itimer_tracker to better reflect its purpose.
It's not the anchor for a timer chain anymore anyway.
- Drop fixup_timers_after_fork. Everything is process-local, nothing
gets inherited.
- Rename timer_tracker::disarm_event to disarm_overrun_event for
better readability.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Allow the signal thread to recognize we're called in consequence of
select on a signalfd. If the signal is part of the wait mask, don't
call any signal handler and don't remove the signal from the queue,
so a subsequent read (or sigwaitinfo/sigtimedwait) still gets the
signal. Instead, just signal the event object at
_cygtls::signalfd_select_wait for the thread running select.
The addition of signalfd_select_wait to _cygtls unearthed the alignment
problem of the context member again. To make sure this doesn't get lost,
improve the related comment in the header file so that this (hopefully)
doesn't get lost (again).
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This new function returns the name of the calling thread; works for both
cygthreads and pthreads. All calls to cygthread::name(/*void*/) replaced
by calls to mythreadname(/*void*/).
The third argument of RtlLookupFunctionEntry actually is documented as
_Inout_opt_ for both x64 and ARM, although generic doc says _Out_ only.
* exceptions.cc (__unwind_single_frame): Initialize hist variable.
GDB since commit 24cdb46e [1] can report and use these names.
Add utility function SetThreadName(), which sends a thread name to the
debugger.
Use that:
- to set the default thread name for main thread and newly created pthreads.
- in pthread_setname_np() for user thread names.
- for helper thread names in cygthread::create()
- for helper threads which are created directly with CreateThread.
Note that there can still be anonymous threads, created by system or
injected DLLs.
[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=24cdb46e9f0a694b4fbc11085e094857f08c0419
Bump GPLv2+ to GPLv3+ for some files, clarify BSD 2-clause.
Everything else stays under GPLv3+.
New Linking Exception exempts resulting executables from LGPLv3 section 4.
Add CONTRIBUTORS file to keep track of licensing.
Remove 'Copyright Red Hat Inc' comments.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Don't use u_char, u_short, u_int or u_long in Cygwin, unless it refers
to the Winsock types. Use u_intN_t in BSD-based sources, unsigned char
where strings are concerned, uintN_t otherwise. Also:
* net.cc: Fix comment, we're not using u_long anymore.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
GCC 5 switched from C89 to C11 by default. This implies a change from
GNU to C99 inline by default, which have very different meanings of
extern inline vs. static inline:
https://gcc.gnu.org/onlinedocs/gcc/Inline.html
Marking these as gnu_inline retains the previous behaviour.
winsup/cygwin/
* exceptions.cc (exception::handle): Change debugging to int to fix
an always-true boolean comparison warning.
* include/cygwin/config.h (__getreent): Mark gnu_inline.
* winbase.h (ilockcmpexch, ilockcmpexch64): Ditto.
Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>
* cygtls.h (_cygtls::wait_signal_arrived): Renamed from
set_signal_arrived.
(_cygtls::set_signal_arrived): New function signalling signal_arrived.
(_cygtls::reset_signal_arrived): Don't reset will_wait_for_signal.
(_cygtls::unwait_signal_arrived): New function only resetting
will_wait_for_signal.
(class wait_signal_arrived): Rename from set_signal_arrived.
Accommodate name change throughout Cygwin.
(wait_signal_arrived::~wait_signal_arrived): Call
_cygtls::unwait_signal_arrived. Add comment.
* cygserver_ipc.h (ipc_set_proc_info): Fetch signal_arrived handle
via call to _cygtls::get_signal_arrived.
* exceptions.cc (_cygtls::interrupt_setup): Signal signal_arrived via
call to _cygtls::set_signal_arrived.
(_cygtls::handle_SIGCONT): Ditto.
* fhandler_socket.cc (fhandler_socket::wait_for_events): Generate
WSAEVENT array prior to entering wait loop. Add cancel event object
if available. Remove calls to pthread_testcancel and just call
pthread::static_cancel_self if the cancel event object is signalled.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
glibc's tst-makecontext2 testcase uncovered a bug in
__cont_link_context. If the function misses to reserve
shadow space for the calls to setcontext/cygwin_exit,
both functions could overwrite memory beyond the stack
configured in uc_stack.
* exceptions.cc (__cont_link_context): x86_64: align stack and reserve
shadow space for subsequent function calls, otherwise suffer potential
buffer overflow.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* dcrt0.cc (initial_env): Reduce size of local path buffers to
PATH_MAX. Allocate debugger_command from process heap.
(init_windows_system_directory): Very early initialize new global
variable global_progname.
* dll_init.cc (dll_list::alloc): Make path buffer static. Explain why.
(dll_list::populate_deps): Use tmp_pathbuf for local path buffer.
* exceptions.cc (debugger_command): Convert to PWCHAR.
(error_start_init): Allocate debugger_command and fill with wide char
strings. Only allocate if NULL.
(try_to_debug): Just check if debugger_command is a NULL pointer to
return. Drop conversion from char to WCHAR and drop local variable
dbg_cmd.
* globals.cc (global_progname): New global variable to store Windows
application path.
* pinfo.cc (pinfo_basic::pinfo_basic): Just copy progname over from
global_progname.
(pinfo::status_exit): Let path_conv create the POSIX path to
avoid local buffer.
* pseudo_reloc.cc (__report_error): Utilize global_progname, drop local
buffer.
* smallprint.cc (__small_vsprintf): Just utilize global_progname for
%P format specifier.
(__small_vswprintf): Ditto.
* strace.cc (PROTECT): Change to reflect x being a pointer. Reformat.
(CHECK): Ditto. Reformat.
(strace::activate): Utilize global_progname, drop local buffer.
Fix formatting.
(strace::vsprntf): Reduce size of local progname buffer to NAME_MAX.
Copy and, if necessary, convert only the last path component to
progname.
(strace_buf_guard): New muto.
(buf): New static pointer.
(strace::vprntf): Use buf under strace_buf_guard lock only. Allocate
buffer space for buf on Windows heap.
* wow64.cc (wow64_respawn_process): Utilize global_progname, drop
local path buffer.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (__unwind_single_frame): Define empty macro on i686.
(_cygtls::call_signal_handler): Try to make sure signal context makes
sense in case we're generating context here. Add comment to explain.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (__unwind_single_frame): Move up in file to be
accessible from other places. Move comment to getcontext.
(stack_info::walk): Call __unwind_single_frame in 64 bit case. Fix
preceeding comment.
(myfault_altstack_handler): Call __unwind_single_frame.
(getcontext): Give comment from __unwind_single_frame a new home.
(swapcontext): Fix comment.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
x86_64 only:
* cygtls.cc (san::leave): Restore _my_tls.andreas.
* cygtls.h (class san): Add _clemente as in 32 bit case. Add ret and
frame members.
(san::san): Handle _my_tls.andreas as on 32 bit. Take parameter and
write it to new member ret. Store current stack pointer in frame.
(san::~san): New destructor to restore _my_tls.andreas.
(__try): Use __l_except address as parameter to san::san.
* dcrt0.cc (dll_crt0_0): Add myfault_altstack_handler as vectored
continuation handler.
* exception.h (myfault_altstack_handler): Declare.
* exceptions.cc (myfault_altstack_handler): New function. Explain what
it's good for.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* autoload.cc (SetThreadStackGuarantee): Import.
* cygtls.h (struct _cygtls): Replace thread_context with a ucontext_t
called context.
* exceptions.cc (exception::handle): Exit from process via signal_exit
in case sig_send returns from handling a stack overflow SIGSEGV.
Explain why.
(dumpstack_overflow_wrapper): Thread wrapper to create a stackdump
from another thread.
(signal_exit): Fix argument list to reflect three-arg signal handler.
In case we have to create a stackdump for a stack overflow condition,
do so from a separate thread. Explain why.
(sigpacket::process): Don't run signal_exit on alternate stack.
(altstack_wrapper): Wrapper function to do stack correction when
calling the signal handler on an alternate stack to handle a stack
overflow. Make sure to have lots of comments.
(_cygtls::call_signal_handler): Drop local context variable to reduce
stack pressure. Use this->context instead. Change inline assembler
to call altstack_wrapper.
(_cygtls::signal_debugger): Accommodate aforementioned change to
struct _cygtls.
* tlsoffset.h: Regenerate.
* tlsoffset64.h: Regenerate.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (_cygtls::call_signal_handler): Drop manipulating
thread's ss_flags here. It's not safe against longjmp.
* signal.cc (sigaltstack): Check if we're running on the alternate
stack and set ss_flags returned in oss to SS_ONSTACK.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (_cygtls::call_signal_handler): Drop pushing a register
on the original stack, it confuses GCC. Rearrange the assembler code
so that $rax/$eax is not used by GCC to prepare an argument value.
Use $rax/$eax without saving. Drop clearing $rbp/$epb.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (_cygtls::call_signal_handler): Drop subtracting 16
bytes from the alternate stack, it's not necessary. Safe all clobbered
registers. Safe one on the orignal stack, the others on the alternate
stack on both platforms.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Ken Brown
Corinna Vinschen
Mark Geisert
Takashi Yano
Michael Haubenwallner
Jon Turney
Yaakov Selkowitz