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-rw-r--r--gnu/usr.bin/cvs/lib/dup2.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/gnu/usr.bin/cvs/lib/dup2.c b/gnu/usr.bin/cvs/lib/dup2.c
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+++ b/gnu/usr.bin/cvs/lib/dup2.c
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+/*
+ dup2 -- 7th Edition UNIX system call emulation for UNIX System V
+
+ last edit: 11-Feb-1987 D A Gwyn
+*/
+
+#include <errno.h>
+#include <fcntl.h>
+
+extern int close(), fcntl();
+
+int
+dup2( oldfd, newfd )
+ int oldfd; /* already-open file descriptor */
+ int newfd; /* desired duplicate descriptor */
+{
+ register int ret; /* for fcntl() return value */
+ register int save; /* for saving entry errno */
+
+ if ( oldfd == newfd )
+ return oldfd; /* be careful not to close() */
+
+ save = errno; /* save entry errno */
+ (void) close( newfd ); /* in case newfd is open */
+ /* (may have just clobbered the original errno value) */
+
+ ret = fcntl( oldfd, F_DUPFD, newfd ); /* dupe it */
+
+ if ( ret >= 0 )
+ errno = save; /* restore entry errno */
+ else /* fcntl() returned error */
+ if ( errno == EINVAL )
+ errno = EBADF; /* we think of everything */
+
+ return ret; /* return file descriptor */
+}
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