// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "config_for_unittests.h"
#ifdef HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#include <stdio.h>
#include <stdlib.h>

// On those architectures we can and should test if backtracing with
// ucontext and from signal handler works
#if __GNUC__ && __linux__ && (__x86_64__ || __aarch64__ || __riscv)
#include <signal.h>
#define TEST_UCONTEXT_BITS 1
#endif

#include "base/commandlineflags.h"
#include "base/logging.h"
#include <gperftools/stacktrace.h>
#include "tests/testutil.h"

namespace {

// Obtain a backtrace, verify that the expected callers are present in the
// backtrace, and maybe print the backtrace to stdout.

// The sequence of functions whose return addresses we expect to see in the
// backtrace.
const int BACKTRACE_STEPS = 6;

struct AddressRange {
  const void *start, *end;
};

// Expected function [start,end] range.
AddressRange expected_range[BACKTRACE_STEPS];

#if __GNUC__
// Using GCC extension: address of a label can be taken with '&&label'.
// Start should be a label somewhere before recursive call, end somewhere
// after it.
#define INIT_ADDRESS_RANGE(fn, start_label, end_label, prange)           \
  do {                                                                   \
    (prange)->start = &&start_label;                                     \
    (prange)->end = &&end_label;                                         \
    CHECK_LT((prange)->start, (prange)->end);                            \
  } while (0)
// This macro expands into "unmovable" code (opaque to GCC), and that
// prevents GCC from moving a_label up or down in the code.
// Without it, there is no code following the 'end' label, and GCC
// (4.3.1, 4.4.0) thinks it safe to assign &&end an address that is before
// the recursive call.
#define DECLARE_ADDRESS_LABEL(a_label)                                   \
  a_label: do { __asm__ __volatile__(""); } while (0)
// Gcc 4.4.0 may split function into multiple chunks, and the chunk
// performing recursive call may end up later in the code then the return
// instruction (this actually happens with FDO).
// Adjust function range from __builtin_return_address.
#define ADJUST_ADDRESS_RANGE_FROM_RA(prange)                             \
  do {                                                                   \
    void *ra = __builtin_return_address(0);                              \
    CHECK_LT((prange)->start, ra);                                       \
    if (ra > (prange)->end) {                                            \
      printf("Adjusting range from %p..%p to %p..%p\n",                  \
             (prange)->start, (prange)->end,                             \
             (prange)->start, ra);                                       \
      (prange)->end = ra;                                                \
    }                                                                    \
  } while (0)
#else
// Assume the Check* functions below are not longer than 256 bytes.
#define INIT_ADDRESS_RANGE(fn, start_label, end_label, prange)           \
  do {                                                                   \
    (prange)->start = reinterpret_cast<const void *>(&fn);               \
    (prange)->end = reinterpret_cast<const char *>(&fn) + 256;           \
  } while (0)
#define DECLARE_ADDRESS_LABEL(a_label) do { } while (0)
#define ADJUST_ADDRESS_RANGE_FROM_RA(prange) do { } while (0)
#endif  // __GNUC__


//-----------------------------------------------------------------------//

void CheckRetAddrIsInFunction(void *ret_addr, const AddressRange &range)
{
  CHECK_GE(ret_addr, range.start);
  CHECK_LE(ret_addr, range.end);
}

//-----------------------------------------------------------------------//

#if TEST_UCONTEXT_BITS

struct get_stack_trace_args {
	int *size_ptr;
	void **result;
	int max_depth;
	uintptr_t where;
} gst_args;

static
void SignalHandler(int dummy, siginfo_t *si, void* ucv) {
	auto uc = static_cast<ucontext_t*>(ucv);

#ifdef __riscv
	uc->uc_mcontext.__gregs[REG_PC] = gst_args.where;
#elif __aarch64__
	uc->uc_mcontext.pc = gst_args.where;
#else
	uc->uc_mcontext.gregs[REG_RIP] = gst_args.where;
#endif

	*gst_args.size_ptr = GetStackTraceWithContext(
		gst_args.result,
		gst_args.max_depth,
		2,
		uc);
}

int ATTRIBUTE_NOINLINE CaptureLeafUContext(void **stack, int stack_len) {
  INIT_ADDRESS_RANGE(CheckStackTraceLeaf, start, end, &expected_range[0]);
  DECLARE_ADDRESS_LABEL(start);

  int size;

  printf("Capturing stack trace from signal's ucontext\n");
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sa.sa_sigaction = SignalHandler;
  sa.sa_flags = SA_SIGINFO | SA_RESETHAND;
  int rv = sigaction(SIGSEGV, &sa, nullptr);
  CHECK(rv == 0);

  gst_args.size_ptr = &size;
  gst_args.result = stack;
  gst_args.max_depth = stack_len;
  gst_args.where = reinterpret_cast<uintptr_t>(noopt(&&after));

  // now, "write" to null pointer and trigger sigsegv to run signal
  // handler. It'll then change PC to after, as if we jumped one line
  // below.
  *noopt(reinterpret_cast<void**>(0)) = 0;
  // this is not reached, but gcc gets really odd if we don't actually
  // use computed goto.
  static void* jump_target = &&after;
  goto *noopt(&jump_target);

after:
  printf("Obtained %d stack frames.\n", size);
  CHECK_GE(size, 1);
  CHECK_LE(size, stack_len);

  DECLARE_ADDRESS_LABEL(end);

  return size;
}

#endif  // TEST_UCONTEXT_BITS

int ATTRIBUTE_NOINLINE CaptureLeafPlain(void **stack, int stack_len) {
  INIT_ADDRESS_RANGE(CheckStackTraceLeaf, start, end, &expected_range[0]);
  DECLARE_ADDRESS_LABEL(start);

  int size = GetStackTrace(stack, stack_len, 0);

  printf("Obtained %d stack frames.\n", size);
  CHECK_GE(size, 1);
  CHECK_LE(size, stack_len);

  DECLARE_ADDRESS_LABEL(end);

  return size;
}

void ATTRIBUTE_NOINLINE CheckStackTrace(int);

int (*leaf_capture_fn)(void**, int) = CaptureLeafPlain;

void ATTRIBUTE_NOINLINE CheckStackTraceLeaf(int i) {
  const int STACK_LEN = 20;
  void *stack[STACK_LEN];
  int size;

  ADJUST_ADDRESS_RANGE_FROM_RA(&expected_range[1]);

  size = leaf_capture_fn(stack, STACK_LEN);

#ifdef HAVE_EXECINFO_H
  {
    char **strings = backtrace_symbols(stack, size);
    for (int i = 0; i < size; i++)
      printf("%s %p\n", strings[i], stack[i]);
    printf("CheckStackTrace() addr: %p\n", &CheckStackTrace);
    free(strings);
  }
#endif

  for (int i = 0, j = 0; i < BACKTRACE_STEPS; i++, j++) {
    if (i == 1 && j == 1) {
      // this is expected to be our function for which we don't
      // establish bounds. So skip.
      j++;
    }
    printf("Backtrace %d: expected: %p..%p  actual: %p ... ",
           i, expected_range[i].start, expected_range[i].end, stack[j]);
    fflush(stdout);
    CheckRetAddrIsInFunction(stack[j], expected_range[i]);
    printf("OK\n");
  }
}

//-----------------------------------------------------------------------//

/* Dummy functions to make the backtrace more interesting. */
void ATTRIBUTE_NOINLINE CheckStackTrace4(int i) {
  ADJUST_ADDRESS_RANGE_FROM_RA(&expected_range[2]);
  INIT_ADDRESS_RANGE(CheckStackTrace4, start, end, &expected_range[1]);
  DECLARE_ADDRESS_LABEL(start);
  for (int j = i; j >= 0; j--)
    CheckStackTraceLeaf(j);
  DECLARE_ADDRESS_LABEL(end);
}
void ATTRIBUTE_NOINLINE CheckStackTrace3(int i) {
  ADJUST_ADDRESS_RANGE_FROM_RA(&expected_range[3]);
  INIT_ADDRESS_RANGE(CheckStackTrace3, start, end, &expected_range[2]);
  DECLARE_ADDRESS_LABEL(start);
  for (int j = i; j >= 0; j--)
    CheckStackTrace4(j);
  DECLARE_ADDRESS_LABEL(end);
}
void ATTRIBUTE_NOINLINE CheckStackTrace2(int i) {
  ADJUST_ADDRESS_RANGE_FROM_RA(&expected_range[4]);
  INIT_ADDRESS_RANGE(CheckStackTrace2, start, end, &expected_range[3]);
  DECLARE_ADDRESS_LABEL(start);
  for (int j = i; j >= 0; j--)
    CheckStackTrace3(j);
  DECLARE_ADDRESS_LABEL(end);
}
void ATTRIBUTE_NOINLINE CheckStackTrace1(int i) {
  ADJUST_ADDRESS_RANGE_FROM_RA(&expected_range[5]);
  INIT_ADDRESS_RANGE(CheckStackTrace1, start, end, &expected_range[4]);
  DECLARE_ADDRESS_LABEL(start);
  for (int j = i; j >= 0; j--)
    CheckStackTrace2(j);
  DECLARE_ADDRESS_LABEL(end);
}
void ATTRIBUTE_NOINLINE CheckStackTrace(int i) {
  INIT_ADDRESS_RANGE(CheckStackTrace, start, end, &expected_range[5]);
  DECLARE_ADDRESS_LABEL(start);
  for (int j = i; j >= 0; j--) {
    CheckStackTrace1(j);
  }
  DECLARE_ADDRESS_LABEL(end);
}

}  // namespace
//-----------------------------------------------------------------------//

int main(int argc, char ** argv) {
  CheckStackTrace(0);
  printf("PASS\n");

#if TEST_UCONTEXT_BITS
  leaf_capture_fn = CaptureLeafUContext;
  CheckStackTrace(0);
  printf("PASS\n");
#endif  // TEST_UCONTEXT_BITS

  return 0;
}