From f2679262acfb576f72d464e999cdac0950f92afc Mon Sep 17 00:00:00 2001
From: Mikhail Borisov <borisov.mikhail@gmail.com>
Date: Tue, 26 May 2020 21:44:01 +0300
Subject: [PATCH] Avoid calling demangler for non-C++ symbols on Linux

Bogus demangler warnings should be suppressed on both Mac and Linux
platforms, so there is no reason to keep this filter behind __APPLE__ gate.

Bug: chromium:1062556
Change-Id: Idf28db0b527c3cd6dd91510fcf7d9040aaa64694
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/2210684
Reviewed-by: Mark Mentovai <mark@chromium.org>
---
 src/common/language.cc | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/common/language.cc b/src/common/language.cc
index d26e5638..440d4de1 100644
--- a/src/common/language.cc
+++ b/src/common/language.cc
@@ -79,17 +79,12 @@ class CPPLanguage: public Language {
     demangled->clear();
     return kDontDemangle;
 #else
-#if defined(__APPLE__)
-    // Mac C++ symbols can have up to 4 underscores, followed by a "Z".
-    // Non-C++ symbols are not coded that way, but may have leading underscores.
     // Attempting to demangle non-C++ symbols with the C++ demangler would print
     // warnings and fail, so return kDontDemangle for these.
-    size_t i = mangled.find_first_not_of('_');
-    if (i == 0 || i == string::npos || i > 4 || mangled[i] != 'Z') {
+    if (!IsMangledName(mangled)) {
       demangled->clear();
       return kDontDemangle;
     }
-#endif
 
     int status;
     char* demangled_c =
@@ -109,6 +104,21 @@ class CPPLanguage: public Language {
     }
 
     return result;
+#endif
+  }
+
+ private:
+  static bool IsMangledName(const string &name) {
+    // NOTE: For proper cross-compilation support, this should depend on target
+    // binary's platform, not current build platform.
+#if defined(__APPLE__)
+    // Mac C++ symbols can have up to 4 underscores, followed by a "Z".
+    // Non-C++ symbols are not coded that way, but may have leading underscores.
+    size_t i = name.find_first_not_of('_');
+    return i > 0 && i != string::npos && i <= 4 && name[i] == 'Z';
+#else
+    // Linux C++ symbols always start with "_Z".
+    return name.size() > 2 && name[0] == '_' && name[1] == 'Z';
 #endif
   }
 };