lib/libc/sys-minix/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 #ifdef __weak_alias
   9 __weak_alias(dup2, _dup2)
  10 #endif
  11
  12 int dup2(fd, fd2)
  13 int fd, fd2;
  14 {
  15 /* The behavior of dup2 is defined by POSIX in 6.2.1.2 as almost, but not
  16  * quite the same as fcntl.
  17  */
  18
  19   if (fd2 < 0 || fd2 > OPEN_MAX) {
  20         errno = EBADF;
  21         return(-1);
  22   }
  23
  24   /* Check to see if fildes is valid. */
  25   if (fcntl(fd, F_GETFL) < 0) {
  26         /* 'fd' is not valid. */
  27         return(-1);
  28   } else {
  29         /* 'fd' is valid. */
  30         if (fd == fd2) return(fd2);
  31         close(fd2);
  32         return(fcntl(fd, F_DUPFD, fd2));
  33   }
  34 }