Memory leak in vsnprintf

[Paul Mattes <paul dot mattes at usa dot net>]

I believe I have found a memory leak in the newlib version of 
vsnprintf().  If it is called with a NULL 'str' parameter and a 0 
'length', it leaks a BUFSIZ-sized buffer.  (Per C99 and SUSv3, calling 
vsnprintf() with a NULL 'str' and 0 'length' is a way to find out how 
big the formatted string would be without actually storing it anywhere.)

Here is an example program:

  #include <stdio.h>
  #include <stdarg.h>

  int
  waste_it(char *fmt, ...)
  {
          int ns;
          va_list a;

          va_start(a, fmt);
          ns = vsnprintf(NULL, 0, fmt, a);
          va_end(a);
          return ns;
  }

  main(int argc, char *argv[])
  {
          int i;
          int n;

          for (i = 0; i < 10000; i++) {
                  n += waste_it("%s foo %d", "hello", 49);
          }
  }

This program will consume quite a lot of memory on Cygwin, which is 
where it was first reported to me.

--
       pdm