Add backtrace on errors

Change-Id: Id2ce3a62d97fd4148d661b34f7507d7a4bec4fba
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

diff --git a/src/sig-monitor.c b/src/sig-monitor.c
index aaffaed..fdaf8c0 100644 (file)
--- a/src/sig-monitor.c
+++ b/src/sig-monitor.c
@@ -24,6 +24,7 @@
 #include <time.h>
 #include <unistd.h>
 #include <sys/syscall.h>
+#include <execinfo.h>
 
 #include "sig-monitor.h"
 #include "verbose.h"
@@ -37,6 +38,26 @@ static _Thread_local sigjmp_buf *error_handler;
 static _Thread_local int thread_timer_set;
 static _Thread_local timer_t thread_timerid;
 
+/*
+ * Dumps the current stack
+ */
+static void dumpstack(int crop)
+{
+       int idx, count;
+       void *addresses[1000];
+       char **locations;
+
+       count = backtrace(addresses, sizeof addresses / sizeof *addresses);
+       locations = backtrace_symbols(addresses, count);
+       if (locations == NULL)
+               ERROR("can't get the backtrace (returned %d addresses)", count);
+       else {
+               for (idx = crop; idx < count; idx++)
+                       ERROR("[BACKTRACE %d/%d] %s", idx - crop + 1, count - crop, locations[idx]);
+               free(locations);
+       }
+}
+
 /*
  * Creates a timer for the current thread
  *
@@ -118,6 +139,10 @@ static void on_signal_error(int signum)
        sigset_t sigset;
 
        ERROR("ALERT! signal %d received: %s", signum, strsignal(signum));
+       if (error_handler == NULL && signum == SIG_FOR_TIMER)
+               return;
+
+       dumpstack(3);
 
        // unlock signal to allow a new signal to come
        if (error_handler != NULL) {
@@ -126,8 +151,6 @@ static void on_signal_error(int signum)
                sigprocmask(SIG_UNBLOCK, &sigset, 0);
                longjmp(*error_handler, signum);
        }
-       if (signum == SIG_FOR_TIMER)
-               return;
        ERROR("Unmonitored signal %d received: %s", signum, strsignal(signum));
        exit(2);
 }