Rollback trunk to 3.21.15.

src/platform-openbsd.cc

Index: src/platform-openbsd.cc
diff --git a/src/platform-openbsd.cc b/src/platform-openbsd.cc
index 4f5420ee45c97e5ede7ee0cde34118f1aac7c947..30a484f4b30b83a6fc0c9e281955d0ead0fd405d 100644
--- a/src/platform-openbsd.cc
+++ b/src/platform-openbsd.cc
@@ -231,6 +231,34 @@ void OS::SignalCodeMovingGC() {
 }
 
 
+int OS::StackWalk(Vector<OS::StackFrame> frames) {
+  // backtrace is a glibc extension.
+  int frames_size = frames.length();
+  ScopedVector<void*> addresses(frames_size);
+
+  int frames_count = backtrace(addresses.start(), frames_size);
+
+  char** symbols = backtrace_symbols(addresses.start(), frames_count);
+  if (symbols == NULL) {
+    return kStackWalkError;
+  }
+
+  for (int i = 0; i < frames_count; i++) {
+    frames[i].address = addresses[i];
+    // Format a text representation of the frame based on the information
+    // available.
+    SNPrintF(MutableCStrVector(frames[i].text, kStackWalkMaxTextLen),
+             "%s",
+             symbols[i]);
+    // Make sure line termination is in place.
+    frames[i].text[kStackWalkMaxTextLen - 1] = '\0';
+  }
+
+  free(symbols);
+
+  return frames_count;
+}
+
 
 // Constants used for mmap.
 static const int kMmapFd = -1;