int backtrace (void **array, int size)
{
struct layout *current;
void *__unbounded top_frame;
void *__unbounded top_stack;
int cnt = 0;
top_frame = FIRST_FRAME_POINTER;
top_stack = CURRENT_STACK_FRAME;
/* We skip the call to this function, it makes no sense to record it. */
current = BOUNDED_1 ((struct layout *) top_frame);
while (cnt < size)
{
if ((void *) current INNER_THAN top_stack
|| !((void *) current INNER_THAN stack_end))
/* This means the address is out of range. Note that for the
toplevel we see a frame pointer with value NULL which clearly is
out of range. */
break;
array[cnt++] = current->return_address;
current = ADVANCE_STACK_FRAME (current->next);
}
return cnt;
}
/* This function is called when a segmentation fault is caught. The system
is in an instable state now. This means especially that malloc() might
not work anymore. */
static void
catch_segfault (int signal, SIGCONTEXT ctx)
{
struct layout *current;
void *__unbounded top_frame;
void *__unbounded top_stack;
int fd;
void **arr;
size_t cnt;
struct sigaction sa;
/* This is the name of the file we are writing to. If none is given
or we cannot write to this file write to stderr. */
fd = 2;
if (fname != NULL)
{
fd = open (fname, O_TRUNC | O_WRONLY | O_CREAT, 0666);
if (fd == -1)
fd = 2;
}
WRITE_STRING ("*** ");
write_strsignal (fd, signal);
WRITE_STRING ("\n");
#ifdef REGISTER_DUMP
REGISTER_DUMP;
#endif
WRITE_STRING ("\nBacktrace:\n");
top_frame = GET_FRAME (ctx);
top_stack = GET_STACK (ctx);
/* First count how many entries we'll have. */
cnt = 1;
current = BOUNDED_1 ((struct layout *) top_frame);
while (!((void *) current INNER_THAN top_stack
|| !((void *) current INNER_THAN __libc_stack_end)))
{
++cnt;
current = ADVANCE_STACK_FRAME (current->next);
}
arr = alloca (cnt * sizeof (void *));
/* First handle the program counter from the structure. */
arr[0] = GET_PC (ctx);
current = BOUNDED_1 ((struct layout *) top_frame);
cnt = 1;
while (!((void *) current INNER_THAN top_stack
|| !((void *) current INNER_THAN __libc_stack_end)))
{
arr[cnt++] = current->return_address;
current = ADVANCE_STACK_FRAME (current->next);
}
/* If the last return address was NULL, assume that it doesn't count. */
if (arr[cnt-1] == NULL)
cnt--;
/* Now generate nicely formatted output. */
__backtrace_symbols_fd (arr, cnt, fd);
/* Pass on the signal (so that a core file is produced). */
sa.sa_handler = SIG_DFL;
sigemptyset (&sa.sa_mask);
sa.sa_flags = 0;
sigaction (signal, &sa, NULL);
raise (signal);
}
