Hello,
I debugged signal processing a bit, and I think that the right solution would
be just to add these signals to the list of known signals. I.e. in
LinuxSignals.cpp:
void
LinuxSignals::Reset()
{
m_signals.clear();
AddSignal (1, "SIGHUP", "HUP", false, true , true , "hangup");
AddSignal (2, "SIGINT", "INT", true , true , true ,
"interrupt");
AddSignal (3, "SIGQUIT", "QUIT", false, true , true , "quit");
AddSignal (4, "SIGILL", "ILL", false, true , true , "illegal
instruction");
AddSignal (5, "SIGTRAP", "TRAP", true , true , true , "trace trap
(not reset when caught)");
AddSignal (6, "SIGABRT", "ABRT", false, true , true , "abort()");
AddSignal (6, "SIGIOT", "IOT", false, true , true , "IOT trap");
AddSignal (7, "SIGBUS", "BUS", false, true , true , "bus
error");
AddSignal (8, "SIGFPE", "FPE", false, true , true , "floating
point exception");
AddSignal (9, "SIGKILL", "KILL", false, true , true , "kill");
AddSignal (10, "SIGUSR1", "USR1", false, true , true , "user
defined signal 1");
AddSignal (11, "SIGSEGV", "SEGV", false, true , true ,
"segmentation violation");
AddSignal (12, "SIGUSR2", "USR2", false, true , true , "user
defined signal 2");
AddSignal (13, "SIGPIPE", "PIPE", false, true , true , "write to
pipe with reading end closed");
AddSignal (14, "SIGALRM", "ALRM", false, false, false, "alarm");
AddSignal (15, "SIGTERM", "TERM", false, true , true ,
"termination requested");
AddSignal (16, "SIGSTKFLT", "STKFLT", false, true , true , "stack
fault");
AddSignal (16, "SIGCLD", "CLD", false, false, true , "same as
SIGCHLD");
AddSignal (17, "SIGCHLD", "CHLD", false, false, true , "child
status has changed");
AddSignal (18, "SIGCONT", "CONT", false, true , true , "process
continue");
AddSignal (19, "SIGSTOP", "STOP", true , true , true , "process
stop");
AddSignal (20, "SIGTSTP", "TSTP", false, true , true , "tty stop");
AddSignal (21, "SIGTTIN", "TTIN", false, true , true , "background
tty read");
AddSignal (22, "SIGTTOU", "TTOU", false, true , true , "background
tty write");
AddSignal (23, "SIGURG", "URG", false, true , true , "urgent
data on socket");
AddSignal (24, "SIGXCPU", "XCPU", false, true , true , "CPU
resource exceeded");
AddSignal (25, "SIGXFSZ", "XFSZ", false, true , true , "file size
limit exceeded");
AddSignal (26, "SIGVTALRM", "VTALRM", false, true , true , "virtual
time alarm");
AddSignal (27, "SIGPROF", "PROF", false, false, false, "profiling
time alarm");
AddSignal (28, "SIGWINCH", "WINCH", false, true , true , "window
size changes");
AddSignal (29, "SIGPOLL", "POLL", false, true , true , "pollable
event");
AddSignal (29, "SIGIO", "IO", false, true , true ,
"input/output ready");
AddSignal (30, "SIGPWR", "PWR", false, true , true , "power
failure");
AddSignal (31, "SIGSYS", "SYS", false, true , true , "invalid
system call");
// Add real-time signals
for (int rtsig = SIGRTMIN + 1; rtsig < SIGRTMAX; ++rtsig)
{
char signame[16];
char sigdescr[64];
::snprintf(signame, sizeof(signame), "SIG%d", rtsig);
::snprintf(sigdescr, sizeof(sigdescr), "Real-time event %d", rtsig);
AddSignal (rtsig, signame, signame, false, true, true, sigdescr);
}
}
Thanks,
Eugene
From: eugen...@hotmail.com
To: lldb-dev@cs.uiuc.edu
Date: Tue, 19 May 2015 10:22:14 -0700
Subject: [lldb-dev] LLDB 3.7 swallows real-time signals
Hi,
I have a simple program that uses real-time signals on Linux Ubuntu 14.04:
$ cat rt.cpp
#include <iostream>
#include <sys/mman.h>
#include <signal.h>
#include <assert.h>
#include <sys/types.h>
#include <unistd.h>
void handler(int sig, siginfo_t* info, void* context)
{
std::cout << "signal " << sig << " received with value " <<
info->si_value.sival_in << "\n";
}
int main()
{
int signo = SIGRTMIN + 1;
if (SIGRTMAX > SIGRTMIN)
{
struct sigaction action;
action.sa_sigaction = handler;
action.sa_flags = SA_SIGINFO;
sigaction(signo, &action, NULL);
for (int i = 0; i < 3; ++i)
{
sigval value;
value.sival_int = i + 10;
sigqueue(getpid(), signo, value);
}
}
else
{
std::cerr << "real-time signals not supported";
}
}
This program works correctly standalone. GDB is capable of intercepting this
signal and continue. LLDB-3.6 that I installed using apt-get does not intercept
the signal but the program still receives it. But LLDB 3.7 that I built from
sources from http://llvm.org/svn/llvm-project/lldb/trunk simply swallows the
signals. I think GDB behavior is the best option, but I could live with 3.6
behavior.
Is this a known problem? Is there a workaround or fix I can apply locally?
Thanks,
Eugene
$ cat rt.cpp
#include <iostream>
#include <sys/mman.h>
#include <signal.h>
#include <assert.h>
#include <sys/types.h>
#include <unistd.h>
void handler(int sig, siginfo_t* info, void* context)
{
std::cout << "signal " << sig << " received with value " <<
info->si_value.sival_in << "\n";
}
int main()
{
int signo = SIGRTMIN + 1;
if (SIGRTMAX > SIGRTMIN)
{
struct sigaction action;
action.sa_sigaction = handler;
action.sa_flags = SA_SIGINFO;
sigaction(signo, &action, NULL);
for (int i = 0; i < 3; ++i)
{
sigval value;
value.sival_int = i + 10;
sigqueue(getpid(), signo, value);
}
}
else
{
std::cerr << "real-time signals are not supported";
}
}
$ ./rt
signal 35 received with value 10
signal 35 received with value 11
signal 35 received with value 12
$ ~/llvm/bin/lldb ./rt
(lldb) target create "./rt"
Current executable set to './rt' (x86_64).
(lldb) pr lau
Process 18697 launched: './rt' (x86_64)
Process 18697 exited with status = 0 (0x00000000)
(lldb) q
$ lldb-3.6 ./rt
(lldb) target create "./rt"
Current executable set to './rt' (x86_64).
(lldb) pr lau
Process 18674 launching
Process 18674 launched: './rt' (x86_64)
signal 35 received with value 10
signal 35 received with value 11
signal 35 received with value 12
Process 18674 exited with status = 0 (0x00000000)
(lldb) q
$ gdb --quiet ./rt
Reading symbols from ./rt...done.
(gdb) r
Starting program: /home/eugene/Z/tmp/rt
Program received signal SIG35, Real-time event 35.
0x00007ffff722cfc4 in __sigqueue (pid=18662, sig=35, val=...) at
../sysdeps/unix/sysv/linux/sigqueue.c:46
46 ../sysdeps/unix/sysv/linux/sigqueue.c: No such file or directory.
(gdb) c
Continuing.
signal 35 received with value 10
Program received signal SIG35, Real-time event 35.
0x00007ffff722cfc4 in __sigqueue (pid=18662, sig=35, val=...) at
../sysdeps/unix/sysv/linux/sigqueue.c:46
46 in ../sysdeps/unix/sysv/linux/sigqueue.c
(gdb) c
Continuing.
signal 35 received with value 11
Program received signal SIG35, Real-time event 35.
0x00007ffff722cfc4 in __sigqueue (pid=18662, sig=35, val=...) at
../sysdeps/unix/sysv/linux/sigqueue.c:46
46 in ../sysdeps/unix/sysv/linux/sigqueue.c
(gdb) c
Continuing.
signal 35 received with value 12
[Inferior 1 (process 18662) exited normally]
(gdb) q
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