在Linux和Unix系统中进行线程安全的I/O操作

 /************************************************************* * The Sio (Signal-safe I/O) package - simple reentrant output
    
  * functions that are safe for signal handlers.
    
  *************************************************************/
    
  
    
 /* Private sio functions */
    
  
    
 /* $begin sioprivate */
    
 /* sio_reverse - Reverse a string (from K&R) */
    
 static void sio_reverse(char s[])
    
 {
    
     int c, i, j;
    
  
    
     for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
    
     c = s[i];
    
     s[i] = s[j];
    
     s[j] = c;