集成专有静态库后混淆问题：PN4/N2/N3/N4开头无法解析符号的来源与原因咨询

Those Weird PN4/... Strings: What They Are, Where They Come From, and Why Demanglers Choke on Them #

Great question—those cryptic PN4/... strings you’re spotting with strings are partial, leftover fragments of Itanium C++ ABI mangled symbols, but with critical missing pieces that make them unparseable by standard demanglers. Let’s break this down:

1. What Exactly Are These Strings?

First, let’s decode the prefixes using the Itanium C++ mangling rules (the standard for GCC, Clang, and most non-MSVC compilers):

• P: Stands for pointer — this fragment refers to a pointer type.
• N: Marks a nested name specifier (like a namespace or nested class). The number right after N (e.g., 4 in N4something_namespace) is the length of the identifier that follows (so 4 maps to something_namespace).

The problem? These are only partial mangled symbols. A full valid mangled type would end with an E (the closing marker for nested names), and follow strict syntax. Your examples cut off mid-structure, so they’re not complete enough for demanglers to process.

2. Where Do These Fragments Come From?

They’re almost certainly leftover metadata that strip doesn’t touch, even when it removes the symbol table. The most common sources are:

• RTTI (Run-Time Type Information): If your code (or the libBla.a static library) uses typeid or dynamic_cast, the compiler generates RTTI data that includes mangled type names. This data lives in read-only data sections (like .rodata), not the symbol table, so strip leaves it untouched.
• Template Instantiation Metadata: Your BlaObserver looks like a template class. When templates are instantiated, the compiler emits extra metadata about the instantiated types. Even after stripping symbols, these partial mangled names can linger in data sections.
• Incomplete Stripping: The strip tool only targets symbol tables (.symtab and .dynsym). It doesn’t scan and remove arbitrary strings from data segments—so any mangled names embedded in other runtime data structures will stay behind.

3. Why Can’t the C++ Demangler Parse Them?

Demanglers rely on the full, well-formed structure of Itanium mangled symbols. Your fragments fail for two key reasons:

• They’re Truncated/Incomplete: A valid mangled type needs a proper closing marker (usually E) and a complete hierarchy of types. Your examples cut off mid-nested type definition, so the demangler can’t resolve the full structure.
• No Root Marker: Full mangled symbols start with a root indicator (like _Z for functions/objects, or a standalone N for nested types). Your fragments start with P (pointer) attached to an N (nested name), but lack the full context the demangler needs to unpack the rest.

Quick Fixes to Remove These Fragments

If you need to eliminate these strings entirely (to meet the obfuscation requirements), try these steps:

• Disable RTTI: Compile your code with -fno-rtti (GCC/Clang) or equivalent. This turns off RTTI generation, which removes most of these type name strings. Just make sure your code (and libBla.a) doesn’t depend on typeid or dynamic_cast.
• Aggressive Stripping: Use the linker’s -s flag (instead of running strip post-link) to remove all symbol tables and debugging info more thoroughly.
• Clean Data Sections: Use objcopy to remove specific read-only sections that might contain these strings. For example:

  objcopy --remove-section .rodata.str.1.1 libsomething.so libsomething-clean.so
  

  Note: Test this carefully—removing the wrong section can break your library.

内容的提问来源于stack exchange，提问作者nayana