Re: [lmi] Suppressing exception stack dumps

[Vadim Zeitlin]

On Mon, 15 Mar 2021 00:27:02 +0100 I wrote:

Me>  IOW I'd like to propose the following patch:
[...untested patch snipped...]

 This morning I'd rather like propose a different patch which has a
non-negligible advantage of not resulting in an immediate crash when
LMI_VERBOSE_EXCEPTIONS environment variable doesn't exist:

---------------------------------- >8 --------------------------------------
diff --git a/unwind.cpp b/unwind.cpp
index 8260cc94a..e4a7d9c8f 100644
--- a/unwind.cpp
+++ b/unwind.cpp
@@ -28,7 +28,8 @@
 #define UNW_LOCAL_ONLY

 #include <cstdio>                       // fprintf()
-#include <cstdlib>                      // free()
+#include <cstdlib>                      // free(), getenv()
+#include <cstring>                      // strcmp()
 #include <cxxabi.h>
 #include <dlfcn.h>
 #include <elfutils/libdwfl.h>
@@ -186,8 +187,12 @@ void print_backtrace()
 extern "C"
 void __cxa_throw(void* thrown_exception, std::type_info* tinfo, void 
(*dest)(void*))
 {
-    identify_exception(thrown_exception, tinfo);
-    print_backtrace();
+    static char const* const env_var = std::getenv("LMI_VERBOSE_EXCEPTIONS");
+    if (env_var && std::strcmp(env_var, "1") == 0)
+        {
+        identify_exception(thrown_exception, tinfo);
+        print_backtrace();
+        }
     original_cxa_throw(thrown_exception, tinfo, dest);
 }

---------------------------------- >8 --------------------------------------

 Sorry for the broken first version,
VZ

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