Attention AIX developers - factoring out POSIX signal code (JDK-8252324)

[gerard ziemski]

hi all,

I’m hoping I have included the right people in this email, but everyone 
is welcome to provide feedback.

I have a code for JDK-8252324, which factors out the common POSIX signal 
related code out into common file, so that all platforms can benefit 
from fixes that apply to all POSIX platforms (like JDK-82514380)

The preliminary webrev can be found here: 
http://cr.openjdk.java.net/~gziemski/8252324_pre1

I tried to port the changes to AIX myself, but got bogged down by more 
"#ifdef AIX” than I was hoping for (possibly too many differences to 
factor out the code for AIX, but frankly I don't think so), so I stopped 
(though I probably was on the right track) - to me it looks like AIX has 
some extra fixes and differences in the signal code than BSD/Linux.

My question is: given my inability to test on AIX, what can I do to make 
it easier for AIX developers to adopt this fix? I will try porting my 
changes again, but in the meantime if anyone has any pointers or offer 
of other help, I’d appreciate it. I don’t want to straight break AIX 
port unexpectedly.

Reference: https://bugs.openjdk.java.net/browse/JDK-8252324

Some notes about the affected APIs:

--------------------------------------------------------------------------------------------------
The APIs which moved from os/bsd/os_bsd.cpp (similarly for linux) to to 
os/posix/PosixSignals.cpp:

////////////////////////////////////////////////////////////////////////////////
// signal support
void os::Bsd::signal_sets_init()
sigset_t* os::Bsd::unblocked_signals()
sigset_t* os::Bsd::vm_signals()
void os::Bsd::hotspot_sigmask(Thread* thread)
////////////////////////////////////////////////////////////////////////////////
// sun.misc.Signal support
static void UserHandler(int sig, void *siginfo, void *context)
void* os::user_handler()
void* os::signal(int signal_number, void* handler)
void os::signal_raise(int signal_number)
int os::sigexitnum_pd()
static void jdk_misc_signal_init()
void os::signal_notify(int sig)
static int check_pending_signals()
int os::signal_wait()
////////////////////////////////////////////////////////////////////////////////
// suspend/resume support
static void resume_clear_context(OSThread *osthread)
static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, 
ucontext_t* context)
static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context)
static int SR_initialize()
static int sr_notify(OSThread* osthread)
static bool do_suspend(OSThread* osthread)
static void do_resume(OSThread* osthread)
///////////////////////////////////////////////////////////////////////////////////
// signal handling (except suspend/resume)
static void signalHandler(int sig, siginfo_t* info, void* uc)
struct sigaction* os::Bsd::get_chained_signal_action(int sig)
static bool call_chained_handler(struct sigaction *actp, int sig,
                                  siginfo_t *siginfo, void *context)
bool os::Bsd::chained_handler(int sig, siginfo_t* siginfo, void* context)
int os::Bsd::get_our_sigflags(int sig)
void os::Bsd::set_our_sigflags(int sig, int flags)
void os::Bsd::set_signal_handler(int sig, bool set_installed)
void os::Bsd::install_signal_handlers()
static const char* get_signal_handler_name(address handler,
  char* buf, int buflen)
static void print_signal_handler(outputStream* st, int sig,
                                  char* buf, size_t buflen)
void os::run_periodic_checks()
void os::Bsd::check_signal_handler(int sig)

-----------------------------------------------------------------------------
The APIs which moved from os/posix/os_posix.cpp to 
os/posix/PosixSignals.cpp:

const char* os::Posix::get_signal_name(int sig, char* out, size_t outlen)
int os::Posix::get_signal_number(const char* signal_name)
int os::get_signal_number(const char* signal_name)
bool os::Posix::is_valid_signal(int sig)
bool os::Posix::is_sig_ignored(int sig)
const char* os::exception_name(int sig, char* buf, size_t size)
const char* os::Posix::describe_signal_set_short(const sigset_t* set, 
char* buffer, size_t buf_size)
void os::Posix::print_signal_set_short(outputStream* st, const sigset_t* 
set)
const char* os::Posix::describe_sa_flags(int flags, char* buffer, size_t 
size)
oid os::Posix::print_sa_flags(outputStream* st, int flags)
static bool get_signal_code_description(const siginfo_t* si, 
enum_sigcode_desc_t* out)
void os::print_siginfo(outputStream* os, const void* si0)
bool os::signal_thread(Thread* thread, int sig, const char* reason)
int os::Posix::unblock_thread_signal_mask(const sigset_t *set)
address os::Posix::ucontext_get_pc(const ucontext_t* ctx)
void os::Posix::ucontext_set_pc(ucontext_t* ctx, address pc)
struct sigaction* os::Posix::get_preinstalled_handler(int sig)
void os::Posix::save_preinstalled_handler(int sig, struct sigaction& oldAct)



DETAILS:

--------------------------------------------------------
Public APIs which are now internal static PosixSignals::

sigset_t* os::Bsd::vm_signals()
struct sigaction* os::Bsd::get_chained_signal_action(int sig)
int os::Bsd::get_our_sigflags(int sig)
void os::Bsd::set_our_sigflags(int sig, int flags)
void os::Bsd::set_signal_handler(int sig, bool set_installed)
void os::Bsd::check_signal_handler(int sig)
const char* os::Posix::get_signal_name(int sig, char* out, size_t outlen)
bool os::Posix::is_valid_signal(int sig)
const char* os::Posix::describe_signal_set_short(const sigset_t* set, 
char* buffer, size_t buf_size)
void os::Posix::print_signal_set_short(outputStream* st, const sigset_t* 
set)
const char* os::Posix::describe_sa_flags(int flags, char* buffer, size_t 
size)
oid os::Posix::print_sa_flags(outputStream* st, int flags)
static bool get_signal_code_description(const siginfo_t* si, 
enum_sigcode_desc_t* out)
void os::Posix::save_preinstalled_handler(int sig, struct sigaction& oldAct)

------------------------------------------------
Public APIs which moved to public PosixSignals::

void os::Bsd::signal_sets_init()
void os::Bsd::hotspot_sigmask(Thread* thread)
bool os::Bsd::chained_handler(int sig, siginfo_t* siginfo, void* context)
void os::Bsd::install_signal_handlers()
bool os::Posix::is_sig_ignored(int sig)
int os::Posix::unblock_thread_signal_mask(const sigset_t *set)
address os::Posix::ucontext_get_pc(const ucontext_t* ctx)
void os::Posix::ucontext_set_pc(ucontext_t* ctx, address pc)

----------------------------------------------------
Internal APIs which are now public in PosixSignals::

static void jdk_misc_signal_init()
static int SR_initialize()
static bool do_suspend(OSThread* osthread)
static void do_resume(OSThread* osthread)
static void print_signal_handler(outputStream* st, int sig,
                                  char* buf, size_t buflen)

--------------------------
New APIs in PosixSignals::

static bool are_signal_handlers_installed();


cheers