Plan 9 from Bell Labs’s /usr/web/sources/contrib/anothy/src/lib/djb-ape/unix/fd_copy.c
#include <fcntl.h> #include "fd.h" #include "readwrite.h" int fd_copy(int to,int from) { if (to == from) return 0; if (fcntl(from,F_GETFL,0) == -1) return -1; close(to); if (fcntl(from,F_DUPFD,to) == -1) return -1; return 0; }