localtime_r support on MinGW

Question

I'm working on a Win32 multithread C++ project and I would like to use one of the localtime_* thread-safe alternatives to localtime().

Unfortunately I have to use MinGW compiler, and localtime_s cannot be used outside Microsoft stuff.

The problem is that neither localtime_r is working: the related code snippet is

#include <ctime>

...

string getCurrentTime()
{
    time_t t;
    time(&t);
    struct tm timeinfo;
    //localtime_s(&timeinfo, &t);
    localtime_r(&t, &timeinfo);

    char buf[128]; 
    strftime(buf, 128, "%d-%m-%Y %X", &timeinfo);

    return string(buf);
}

...

This is the compiler output:

error: 'localtime_r' was not declared in this scope

Does MinGW support localtime_r ?

If not, does exist a thread-safe alternative? (excluding boost/QT/etc that I can't use).

---

EDIT: this is the <time.h> provided by my MinGW installation: http://pastebin.com/0CYBfMzg

Solution 1

Does MinGW support localtime_r ?

No.

If not, does exist a thread-safe alternative? (excluding boost/QT/etc that I can't use)

mingw will use the native localtime function on windows, which is thread safe. (But it's not reentrant, so watch out for that).

Solution 2

My quick solution:

#include <time.h>
#if defined(_MSC_VER)
#   define localtime_r(T,Tm) (localtime_s(Tm,T) ? NULL : Tm)
#endif

(Inspired by MinGW code, search for _POSIX_THREAD_SAFE_FUNCTIONS.)

Comments

[Keith4G]

Ooooh that's nifty. I didn't catch that in the documentation. The POSIX versions use static globals instead.

[Simon Kissane]

Actually, MinGW does support localtime_r now, provided you #define _POSIX_THREAD_SAFE_FUNCTIONS before you #include <time.h> – see definitions here: github.com/mirror/mingw-w64/blob/v6.0.0/mingw-w64-headers/cr‌​t/…