dup2.c raw

   1  #include <unistd.h>
   2  #include <errno.h>
   3  #include <fcntl.h>
   4  #include "syscall.h"
   5  
   6  int dup2(int old, int new)
   7  {
   8  	int r;
   9  #ifdef SYS_dup2
  10  	while ((r=__syscall(SYS_dup2, old, new))==-EBUSY);
  11  #else
  12  	if (old==new) {
  13  		r = __syscall(SYS_fcntl, old, F_GETFD);
  14  		if (r >= 0) return old;
  15  	} else {
  16  		while ((r=__syscall(SYS_dup3, old, new, 0))==-EBUSY);
  17  	}
  18  #endif
  19  	return __syscall_ret(r);
  20  }
  21