signal SIGSEGV, Segmentation fault. __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:65

Question

I have converted my old code:

#define MAX_LOG_MSG 2048

in the *.h file

typedef void (*LogMessageFunction)(char *);

in the *.cpp file

static LogMessageFunction m_MessageFunctions[LastLogCount] = {NULL};

void DebugMsg(const char* fmt, ...)
{
    if (!m_MessageFunctions[DebugLevel]) return;

    char msgBuffer[MAX_LOG_MSG];
    va_list argList;
    va_start(argList, fmt);
    vsnprintf(msgBuffer, MAX_LOG_MSG, fmt, argList);
    va_end(argList);
    
    m_MessageFunctions[DebugLevel](msgBuffer);
}

into a dynamic allocated char*

void DebugMsg(const char* fmt, ...)
{
    if (!m_MessageFunctions[DebugLevel]) return;

    va_list argList;
    va_start(argList, fmt);
    size_t size = vsnprintf(NULL, 0, fmt, argList) + 1;
    va_end(argList);
    char* msgBuffer = new char[size];

    va_start(argList, fmt);
    vsnprintf(msgBuffer, size, fmt, argList);
    va_end(argList);

    m_MessageFunctions[DebugLevel](msgBuffer);
    delete[] msgBuffer;
}

on windows everything works great now.

Thread 1 "ATETests" received signal SIGSEGV, Segmentation fault. __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:65 65 ../sysdeps/x86_64/multiarch/strlen-avx2.S: No such file or directory.

as far as I can see this has something to do with the size of the buffer or the string? Can you help?

Answer 1

I'd make a variadic template out of it instead and use a std::unique_ptr<char[]> for the memory allocation:

#include <memory>

template<class... Args>
void DebugMsg(const char* fmt, Args&&... args)
{
    if (!m_MessageFunctions[DebugLevel]) return;

    int size = std::snprintf(nullptr, 0, fmt, args...) + 1;
    if (size < 1) return; // check for error

    auto msgBuffer = std::make_unique<char[]>(size);

    size = std::snprintf(msgBuffer.get(), size, fmt, args...);
    if (size < 0) return; // probably unnecessary

    m_MessageFunctions[DebugLevel](msgBuffer.get());
}