#include <stdio.h>
#include <time.h>
#include <string.h>

int main()
{
    const char* logfile = "zandronum-crash.log";
    time_t timestamp;
    char newLogfile[256];

    time( &timestamp );
    char* bufferEnd = newLogfile + sizeof newLogfile;
    strncpy( newLogfile, logfile, sizeof newLogfile );

    // Find the dot in the string and append the formatted time. If the dot is not found, append
    // the date at the end of the string.
    char* appendPoint = strrchr( newLogfile, '.' );

    if ( appendPoint == NULL )
        appendPoint = newLogfile + strlen (newLogfile);

    strftime( appendPoint, bufferEnd - appendPoint, "-%m_%d_%Y-%H_%M_%S.log", localtime( &timestamp ) );
    logfile = newLogfile;

    printf ("%s\n", logfile);
}