Rollback trunk to 3.21.15.

src/platform-posix.h

Index: src/platform-posix.h
diff --git a/src/platform-posix.h b/src/platform-posix.h
index e0fbc0ceb6797f9bce6342b159f9f1458f3e5aa9..6b73387cd790d3bad65d0cd16b3832bc33d6c2f3 100644
--- a/src/platform-posix.h
+++ b/src/platform-posix.h
@@ -39,6 +39,7 @@ namespace v8 {
 namespace internal {
 
 // Used by platform implementation files during OS::DumpBacktrace()
+// and OS::StackWalk().
 template<int (*backtrace)(void**, int),
          char** (*backtrace_symbols)(void* const*, int)>
 struct POSIXBacktraceHelper {
@@ -72,6 +73,32 @@ struct POSIXBacktraceHelper {
     fflush(stderr);
     free(symbols);
   }
+
+  static int StackWalk(Vector<OS::StackFrame> frames) {
+    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 OS::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.
+      OS::SNPrintF(MutableCStrVector(frames[i].text, OS::kStackWalkMaxTextLen),
+                   "%s", symbols[i]);
+      // Make sure line termination is in place.
+      frames[i].text[OS::kStackWalkMaxTextLen - 1] = '\0';
+    }
+
+    free(symbols);
+
+    return frames_count;
+  }
 };
 
 } }  // namespace v8::internal