Android native c++ get back trace (stacktrace)

backtrace.cpp

#include <tinyformat.h>
#include <unwind.h>
#include <cxxabi.h>
#include <dlfcn.h>

struct android_backtrace_state {
    void **current;
    void **end;
};

_Unwind_Reason_Code android_unwind_callback(struct _Unwind_Context *context, void *arg) {
    auto *state = (android_backtrace_state *) arg;
    uintptr_t pc = _Unwind_GetIP(context);
    if (pc) {
        if (state->current == state->end) {
            return _URC_END_OF_STACK;
        } else {
            *state->current++ = reinterpret_cast<void *>(pc);
        }
    }
    return _URC_NO_REASON;
}

std::string getBacktrace(int skip, int max) {
    std::stringstream ss;
    void *buffer[max];
    android_backtrace_state state{};
    state.current = buffer;
    state.end = buffer + max;
    _Unwind_Backtrace(android_unwind_callback, &state);
    int count = (int) (state.current - buffer);

    for (int idx = skip; idx < count; idx++) {
        const void *addr = buffer[idx];
        const char *symbol = "";

        Dl_info info;
        if (dladdr(addr, &info) && info.dli_sname) {
            symbol = info.dli_sname;
        }
        int status = 0;
        char *demangled = abi::__cxa_demangle(symbol, nullptr, nullptr, &status);

        ss << tfm::format("\n    #%02d: %lx %s", idx - skip, addr, status == 0 ? demangled : symbol);
        if (nullptr != demangled) free(demangled);
    }
    return ss.str();
}