Problems creating a get_time() function in C

Question

I have this simple function:

char*
get_time()
{
    char *buffer = malloc(sizeof(char)*10); /* HOW TO FREE IT ? */
    time_t rawtime;
    struct tm * timeinfo;

    time(&rawtime);
    timeinfo = localtime(&rawtime);
    strftime(buffer,10,"%H:%M:%S",timeinfo);

    return buffer;
}

The issue is with strftime() which requires a char* and I can't free(buffer); before returning his content. What could I do?

The macro where I use the function:

#define log_info(msg) printf("%s [INFO ] - %s\n",get_time(), (msg))

Answer 1

Something like this

static char g_buffer[10];                                                      

#define log_info(msg)                               \                          
    do {                                            \                          
    get_time();                                     \                          
    printf("%s [INFO ] - %s\n", g_buffer, (msg));   \                          
    g_buffer[0] = '\0';                             \                          
    } while (0)                                                                

static int get_time()                                                          
{                                                                              
    time_t rawtime;                                                            
    struct tm * timeinfo;                                                      

    time(&rawtime);                                                            
    timeinfo = localtime(&rawtime);                                            
    strftime(g_buffer,sizeof(g_buffer),"%H:%M:%S",timeinfo);                   

    return 0;                                                                  
}                                                                              

int main(void) {                                                               
    log_info("test");                                                          
    return 0;                                                                  
} 

But and don't get the need of a macro, a function will do the job