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/*
* Public domain dup2() lookalike
* by Curtis Jackson @ AT&T Technologies, Burlington, NC
* electronic address: burl!rcj
*
* dup2 performs the following functions:
*
* Check to make sure that fd1 is a valid open file descriptor.
* Check to see if fd2 is already open; if so, close it.
* Duplicate fd1 onto fd2; checking to make sure fd2 is a valid fd.
* Return fd2 if all went well; return BADEXIT otherwise.
*/
#include <fcntl.h>
#define BADEXIT -1
int
dup2(fd1, fd2)
int fd1, fd2;
{
if (fd1 != fd2) {
#ifdef MPW
close (fd2); /* XXX RJW MPW does not implement F_GETFL but it does have dup */
fd2 = dup(fd1);
#else
if (fcntl(fd1, F_GETFL) < 0)
return BADEXIT;
if (fcntl(fd2, F_GETFL) >= 0)
close(fd2);
if (fcntl(fd1, F_DUPFD, fd2) < 0)
return BADEXIT;
#endif
}
return fd2;
}
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