backtrace-lite.c

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// -*-Mode: C++;-*- // technically C99

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//***************************************************************************
// system include files
//***************************************************************************

#include <stdbool.h>

#include <sys/types.h>
#include <ucontext.h>


//***************************************************************************
// local include files
//***************************************************************************

#include "unwind.h"

#include "backtrace.h"
#include "epoch.h"
#include "monitor.h"
#include "sample_event.h"

#include <messages/messages.h>

//***************************************************************************
// 
//***************************************************************************


#if (HPC_UNW_LITE)
static int 
hpcrun_backtrace_lite(void** buffer, int size, ucontext_t* context)
{
  // special trivial case: size == 0 (N.B.: permit size < 0)
  if (size <= 0) {
    return 0;
  }

  // INVARIANT: 'size' > 0; 'buffer' is non-empty; 'context' is non-NULL
  if ( !(size > 0 && buffer && context) ) {
    return -1; // error
  }

  hpcrun_unw_init();

  hpcrun_unw_cursor_t cursor;
  hpcrun_unw_init_cursor(&cursor, context);

  int my_size = 0;
  while (my_size < size) {
    int ret;

    void *ip = 0;
    ret = hpcrun_unw_get_ip_reg(&cursor, &ip);
    if (ret < 0) { /* ignore error */ }

    buffer[my_size] = ip; // my_size < size
    my_size++;

    ret = hpcrun_unw_step(&cursor);
    if (ret <= 0) {
      // N.B. (ret < 0) indicates an unwind error, which we ignore
      break;
    }
  }
  
  return my_size;
}
#endif


#if (HPC_UNW_LITE)
static int
test_backtrace_lite(ucontext_t* context)
{
  const int bufsz = 100;

  void* buffer[bufsz];
  int sz = hpcrun_backtrace_lite(buffer, bufsz, context);

  for (int i = 0; i < sz; ++i) {
    TMSG(UNW, "backtrace_lite: pc=%p", buffer[i]);
  }

  return sz;
}
#endif


//***************************************************************************
// 
//***************************************************************************