[c-host] added initial crash handler stub

c-host/src/app.c

@@ -23,6 +23,7 @@ Place, Suite 330, Boston, MA 02111-1307 USA
 #include "common/debug.h"
 #include "common/locking.h"
 #include "common/KVMFR.h"
+#include "common/crash.h"
 
 #include <stdio.h>
 #include <inttypes.h>
@@ -257,6 +258,9 @@ static bool captureRestart()
 
 int app_main()
 {
+  if (!installCrashHandler())
+    DEBUG_WARN("Failed to install the crash handler");
+
   unsigned int shmemSize = os_shmemSize();
   uint8_t    * shmemMap  = NULL;
   int          exitcode  = 0;

common/CMakeLists.txt

@@ -5,9 +5,11 @@ include_directories(
 	${PROJECT_SOURCE_DIR}/include
 )
 
-add_library(lg_common STATIC
-	src/debug.c
-)
+if(WIN32)
+  add_library(lg_common STATIC src/crash.windows.c)
+else()
+  add_library(lg_common STATIC src/crash.linux.c)
+endif()
 
 #target_link_libraries(lg_common
 #)

common/include/common/crash.h

@@ -0,0 +1,22 @@
+/*
+KVMGFX Client - A KVM Client for VGA Passthrough
+Copyright (C) 2017-2019 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include <stdbool.h>
+
+bool installCrashHandler();

common/src/crash.linux.c

@@ -0,0 +1,97 @@
+/*
+KVMGFX Client - A KVM Client for VGA Passthrough
+Copyright (C) 2017-2019 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "common/crash.h"
+#include "common/debug.h"
+
+#include <execinfo.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+/*
+  Large portions of this code comes from @jschmier @ https://stackoverflow.com/a/1925461/637874
+*/
+
+/* This structure mirrors the one found in /usr/include/asm/ucontext.h */
+typedef struct _sig_ucontext
+{
+  unsigned long     uc_flags;
+  struct ucontext   *uc_link;
+  stack_t           uc_stack;
+  struct sigcontext uc_mcontext;
+  sigset_t          uc_sigmask;
+}
+sig_ucontext_t;
+
+static void crit_err_hdlr(int sig_num, siginfo_t * info, void * ucontext)
+{
+  void *             array[50];
+  void *             caller_address;
+  char **            messages;
+  int                size, i;
+  sig_ucontext_t *   uc;
+
+  uc = (sig_ucontext_t *)ucontext;
+
+  /* Get the address at the time the signal was raised */
+  #if defined(__i386__) // gcc specific
+   caller_address = (void *) uc->uc_mcontext.eip; // EIP: x86 specific
+  #elif defined(__x86_64__) // gcc specific
+   caller_address = (void *) uc->uc_mcontext.rip; // RIP: x86_64 specific
+  #else
+  #error Unsupported architecture. // TODO: Add support for other arch.
+  #endif
+
+  DEBUG_ERROR("signal %d (%s), address is %p from %p", sig_num, strsignal(sig_num), info->si_addr, (void *)caller_address);
+
+  size = backtrace(array, 50);
+
+  /* overwrite sigaction with caller's address */
+  array[1] = caller_address;
+
+  messages = backtrace_symbols(array, size);
+
+  /* skip first stack frame (points here) */
+  for (i = 1; i < size && messages != NULL; ++i)
+    DEBUG_ERROR("[bt]: (%d) %s", i, messages[i]);
+
+  free(messages);
+
+  exit(EXIT_FAILURE);
+}
+
+bool installCrashHandler()
+{
+  struct sigaction sigact;
+
+  sigact.sa_sigaction = crit_err_hdlr;
+  sigact.sa_flags = SA_RESTART | SA_SIGINFO;
+
+  if (sigaction(SIGSEGV, &sigact, (struct sigaction *)NULL) != 0)
+  {
+    DEBUG_ERROR("Error setting signal handler for %d (%s)", SIGSEGV, strsignal(SIGSEGV));
+    return false;
+  }
+
+  return true;
+}

common/src/crash.windows.c

@@ -0,0 +1,26 @@
+/*
+KVMGFX Client - A KVM Client for VGA Passthrough
+Copyright (C) 2017-2019 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "common/crash.h"
+
+bool installCrashHandler()
+{
+  //TODO
+  return true;
+}