41 lines
948 B
C
41 lines
948 B
C
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/*
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dup2 -- 7th Edition UNIX system call emulation for UNIX System V
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last edit: 11-Feb-1987 D A Gwyn
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <errno.h>
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#include <fcntl.h>
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extern int close(), fcntl();
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int
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dup2( oldfd, newfd )
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int oldfd; /* already-open file descriptor */
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int newfd; /* desired duplicate descriptor */
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{
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register int ret; /* for fcntl() return value */
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register int save; /* for saving entry errno */
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if ( oldfd == newfd )
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return oldfd; /* be careful not to close() */
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save = errno; /* save entry errno */
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(void) close( newfd ); /* in case newfd is open */
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/* (may have just clobbered the original errno value) */
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ret = fcntl( oldfd, F_DUPFD, newfd ); /* dupe it */
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if ( ret >= 0 )
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errno = save; /* restore entry errno */
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else /* fcntl() returned error */
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if ( errno == EINVAL )
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errno = EBADF; /* we think of everything */
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return ret; /* return file descriptor */
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}
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