From fa8ef65cd74a560ff7d14d965a3c46a558989e44 Mon Sep 17 00:00:00 2001
From: rakshasa <sundell.software@gmail.com>
Date: Wed, 20 Jul 2011 09:57:29 +0000
Subject: [PATCH] * Added better handling of SIGBUS, including the error type
 and fault address in the dump.

git-svn-id: svn://rakshasa.no/libtorrent/trunk/rtorrent@1247 e378c898-3ddf-0310-93e7-cc216c733640
---
 src/main.cc           | 54 ++++++++++++++++++++++++++++++++++++++++++-
 src/signal_handler.cc | 16 +++++++++++++
 src/signal_handler.h  |  5 ++++
 3 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/src/main.cc b/src/main.cc
index 7f714aea..67b8a7d9 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -44,6 +44,7 @@
 #include <torrent/torrent.h>
 #include <torrent/exceptions.h>
 #include <rak/functional.h>
+#include <rak/error_number.h>
 
 #ifdef USE_EXECINFO
 #include <execinfo.h>
@@ -73,6 +74,7 @@
 #include "thread_main.h"
 #include "thread_worker.h"
 
+void handle_sigbus(int signum, siginfo_t* sa, void* ptr);
 void do_panic(int signum);
 void print_help();
 void initialize_commands();
@@ -178,9 +180,10 @@ main(int argc, char** argv) {
     SignalHandler::set_handler(SIGWINCH, sigc::mem_fun(control->display(), &display::Manager::force_redraw));
     SignalHandler::set_handler(SIGSEGV,  sigc::bind(sigc::ptr_fun(&do_panic), SIGSEGV));
     SignalHandler::set_handler(SIGILL,   sigc::bind(sigc::ptr_fun(&do_panic), SIGILL));
-    SignalHandler::set_handler(SIGBUS,   sigc::bind(sigc::ptr_fun(&do_panic), SIGBUS));
     SignalHandler::set_handler(SIGFPE,   sigc::bind(sigc::ptr_fun(&do_panic), SIGFPE));
 
+    SignalHandler::set_sigaction_handler(SIGBUS, &handle_sigbus);
+
     // SIGUSR1 is used for interrupting polling, forcing that thread
     // to process new non-socket events.
     SignalHandler::set_handler(SIGUSR1,  sigc::ptr_fun(&do_nothing));
@@ -877,6 +880,55 @@ main(int argc, char** argv) {
   return 0;
 }
 
+void
+handle_sigbus(int signum, siginfo_t* sa, void* ptr) {
+  if (signum != SIGBUS)
+    do_panic(signum);
+
+  SignalHandler::set_default(signum);
+  display::Canvas::cleanup();
+
+  // Use printf here instead...
+
+  printf("Caught SIGBUS, dumping stack:\n");
+
+#ifdef USE_EXECINFO
+  void* stackPtrs[20];
+
+  // Print the stack and exit.
+  int stackSize = backtrace(stackPtrs, 20);
+  char** stackStrings = backtrace_symbols(stackPtrs, stackSize);
+
+  for (int i = 0; i < stackSize; ++i)
+    printf("%i %s\n", i, stackStrings[i]);
+
+#else
+  printf("Stack dump not enabled.\n");
+#endif
+  
+  printf("\nError: %s\n", rak::error_number::error_number(sa->si_errno).c_str());
+
+  const char* signal_reason;
+
+  switch (sa->si_code) {
+  case BUS_ADRALN: signal_reason = "Invalid address alignment."; break;
+  case BUS_ADRERR: signal_reason = "Non-existent physical address."; break;
+  case BUS_OBJERR: signal_reason = "Object specific hardware error."; break;
+  default:
+    if (sa->si_code <= 0)
+      signal_reason = "User-generated signal.";
+    else
+      signal_reason = "Unknown.";
+
+    break;
+  };
+
+  printf("Signal code '%i': %s\n", sa->si_code, signal_reason);
+  printf("Fault address: %p.\n", sa->si_addr);
+
+  std::abort();
+}
+
 void
 do_panic(int signum) {
   // Use the default signal handler in the future to avoid infinit
diff --git a/src/signal_handler.cc b/src/signal_handler.cc
index 4b5eb55b..85be25e5 100644
--- a/src/signal_handler.cc
+++ b/src/signal_handler.cc
@@ -36,7 +36,9 @@
 
 #include "config.h"
 
+#include <signal.h>
 #include <stdexcept>
+#include "rak/error_number.h"
 #include "signal_handler.h"
 
 SignalHandler::Slot SignalHandler::m_handlers[HIGHEST_SIGNAL];
@@ -71,6 +73,20 @@ SignalHandler::set_handler(unsigned int signum, Slot slot) {
   m_handlers[signum] = slot;
 }
 
+void
+SignalHandler::set_sigaction_handler(unsigned int signum, handler_slot slot) {
+  if (signum > HIGHEST_SIGNAL)
+    throw std::logic_error("SignalHandler::set_handler(...) received invalid signal value.");
+
+  struct sigaction sa;
+  sa.sa_sigaction = slot;
+  sa.sa_mask = 0;
+  sa.sa_flags = SA_SIGINFO;
+
+  if (sigaction(signum, &sa, NULL) == -1)
+    throw std::logic_error("Could not set sigaction: " + std::string(rak::error_number::current().c_str()));
+}
+
 void
 SignalHandler::caught(int signum) {
   if ((unsigned)signum > HIGHEST_SIGNAL)
diff --git a/src/signal_handler.h b/src/signal_handler.h
index 5c0f4a1c..c6721d16 100644
--- a/src/signal_handler.h
+++ b/src/signal_handler.h
@@ -44,6 +44,9 @@ class SignalHandler {
 public:
   typedef sigc::slot0<void> Slot;
 
+  // typedef void (*handler_slot)(int, siginfo_t *info, ucontext_t *uap);
+  typedef void (*handler_slot)(int, siginfo_t*, void*);
+
 #ifdef NSIG
   static const unsigned int HIGHEST_SIGNAL = NSIG;
 #else
@@ -55,6 +58,8 @@ public:
   static void         set_ignore(unsigned int signum);
   static void         set_handler(unsigned int signum, Slot slot);
 
+  static void         set_sigaction_handler(unsigned int signum, handler_slot slot);
+
   static const char*  as_string(unsigned int signum);
 
 private: