minix/lib/libc/sys/dup2.c

   1 #include <sys/cdefs.h>
   2 #include "namespace.h"
   3 #include <lib.h>
   4
   5 #include <fcntl.h>
   6 #include <unistd.h>
   7
   8 int dup2(fd, fd2)
   9 int fd, fd2;
  10 {
  11 /* The behavior of dup2 is defined by POSIX in 6.2.1.2 as almost, but not
  12  * quite the same as fcntl.
  13  */
  14
  15   if (fd2 < 0 || fd2 > OPEN_MAX) {
  16         errno = EBADF;
  17         return(-1);
  18   }
  19
  20   /* Check to see if fildes is valid. */
  21   if (fcntl(fd, F_GETFL) < 0) {
  22         /* 'fd' is not valid. */
  23         return(-1);
  24   } else {
  25         /* 'fd' is valid. */
  26         if (fd == fd2) return(fd2);
  27         close(fd2);
  28         return(fcntl(fd, F_DUPFD, fd2));
  29   }
  30 }