1/*
2 * Public domain dup2() lookalike
3 * by Curtis Jackson @ AT&T Technologies, Burlington, NC
4 * electronic address:  burl!rcj
5 *
6 * dup2 performs the following functions:
7 *
8 * Check to make sure that fd1 is a valid open file descriptor.
9 * Check to see if fd2 is already open; if so, close it.
10 * Duplicate fd1 onto fd2; checking to make sure fd2 is a valid fd.
11 * Return fd2 if all went well; return BADEXIT otherwise.
12 */
13
14#include "ruby/config.h"
15
16#if defined(HAVE_FCNTL)
17# include <fcntl.h>
18#endif
19
20#if !defined(HAVE_FCNTL) || !defined(F_DUPFD)
21# include <errno.h>
22#endif
23
24#define BADEXIT -1
25
26int
27dup2(int fd1, int fd2)
28{
29#if defined(HAVE_FCNTL) && defined(F_DUPFD)
30	if (fd1 != fd2) {
31#ifdef F_GETFL
32		if (fcntl(fd1, F_GETFL) < 0)
33			return BADEXIT;
34		if (fcntl(fd2, F_GETFL) >= 0)
35			close(fd2);
36#else
37		close(fd2);
38#endif
39		if (fcntl(fd1, F_DUPFD, fd2) < 0)
40			return BADEXIT;
41	}
42	return fd2;
43#else
44	extern int errno;
45	int i, fd, fds[256];
46
47	if (fd1 == fd2) return 0;
48	close(fd2);
49	for (i=0; i<256; i++) {
50		fd = fds[i] = dup(fd1);
51		if (fd == fd2) break;
52	}
53	while (i) {
54	    	close(fds[i--]);
55	}
56	if (fd == fd2) return 0;
57	errno = EMFILE;
58	return BADEXIT;
59#endif
60}
61