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+/*
+ * dup2.C -- A dup2 emulation.
+ */
+
+/*
+ * $Id: dup2.C,v 3.0.1.1 1994/01/24 13:58:37 ram Exp $
+ *
+ * Copyright (c) 1991-1993, Raphael Manfredi
+ *
+ * You may redistribute only under the terms of the Artistic Licence,
+ * as specified in the README file that comes with the distribution.
+ * You may reuse parts of this distribution only within the terms of
+ * that same Artistic Licence; a copy of which may be found at the root
+ * of the source tree for dist 3.0.
+ *
+ * Original Author: Larry Wall <lwall@netlabs.com>
+ *
+ * $Log: dup2.C,v $
+ * Revision 3.0.1.1 1994/01/24 13:58:37 ram
+ * patch16: created
+ *
+ */
+
+#include "config.h"
+
+#ifdef I_FCNTL
+#include <fcntl.h>
+#endif
+
+#include "confmagic.h" /* Remove if not metaconfig -M */
+
+#ifndef HAS_DUP2
+/*
+ * dup2
+ *
+ * This routine duplicates file descriptor 'old' into 'new'. After the
+ * operation, both 'new' and 'old' refer to the same file 'old' was referring
+ * to in the first place.
+ *
+ * Returns 0 if OK, -1 on failure with errno being set to indicate the error.
+ *
+ */
+V_FUNC(int dup2, (old, new),
+ int old /* Opened file descriptor */ NXT_ARG
+ int new /* File descriptor we'd like to get */)
+{
+#ifdef HAS_FCNTL
+#ifdef F_DUPFD
+#define USE_FNCTL
+#endif
+#endif
+
+#ifdef USE_FCNTL
+ if (old == new)
+ return 0;
+
+ close(new);
+ return fcntl(old, F_DUPFD, new);
+#else
+ int fd_used[256]; /* Fixed stack used to record dup'ed files */
+ int fd_top = 0; /* Top in the fixed stack */
+ int fd; /* Currently dup'ed file descriptor */
+
+ if (old == new)
+ return 0;
+
+ close(new); /* Ensure one free slot */
+ while ((fd = dup(old)) != new) /* Until dup'ed file matches */
+ fd_used[fd_top++] = fd; /* Remember we have to close it later */
+
+ while (fd_top > 0) /* Close all useless dup'ed slots */
+ close(fd_used[--fd_top]);
+
+ return 0;
+#endif
+}
+#endif
+