Re: making sscanf() & sprintf() work

[James Youngman <JYoungman@vggas.com>]

>>>>> "pmi" == Peer Moeller Ilsoe <ilsoe@kom.auc.dk> writes:

  pmi> I want thank everyone who responded to my double <-> string
  pmi> conversion problem. It seems that sscanf() and sprintf() do the
  pmi> job just fine -at least on our unix machines. Now when I try to
  pmi> cross-compile with the newlib 1.8 libraries (libm, libc, and
  pmi> libgcc) the linker goes:

  pmi> makebuf.c:93: undefined reference to `isatty'
  pmi> sbrkr.c:61: undefined reference to `sbrk'
  pmi> fstatr.c:61: undefined reference to `fstat'
  pmi> readr.c:58: undefined reference to `read'
  pmi> lseekr.c:58: undefined reference to `lseek'
  pmi> writer.c:58: undefined reference to `write'
  pmi> closer.c:53: undefined reference to `close'

  pmi> Can anybody tell me weather I have to write these functions
  pmi> myself or are they already implemented somewhere?  Can they be
  pmi> stubbed out if I'm not going to use any kind of std I/O?  What
  pmi> should the functions do if they can't be stubbed out?  I just
  pmi> need a minimal system, which will make the conversion work.

Using the stdio functionality will bring in references to those
components that it relies on -- the underlying OS interface.  You have
to attach it to those functions, or stub them out with something like:-

/* typedef long off_t; */
/* typedef long ptrdiff_t; */

/* Most things return failure.
 */
int isatty(int fd) { return 0; }
int fstat(int fd, struct stat *p) { return -1; }
int read(int fd, void *p, size_t n) { return 0; }
int write(int fd, void *p, size_t n) { return 0; }
off_t lseek(int fd, off_t offset, int whence) { return -1; }

/* close() will succeed for std{in,out,err}
 */
int close(int fd) { return (fd < 3) ? 0 : -1; } 



/* Memory allocation: this you really DO have to write, I think.
 */
void *sbrk(ptrdiff_t increment)
{
#error WRITE ME
}