7b22b8da2f
Although I copied dup(2) to create dup3(3), I removed almost all the non-boilerplate, so dup3(3) is copyright me. Reported by: bjk
117 lines
2.7 KiB
Groff
117 lines
2.7 KiB
Groff
.\" Copyright (c) 2013 Jilles Tjoelker
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 16, 2013
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.Dt DUP3 3
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.Os
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.Sh NAME
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.Nm dup3
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.Nd duplicate an existing file descriptor
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In fcntl.h
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.In unistd.h
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.Ft int
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.Fn dup3 "int oldd" "int newd" "int flags"
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.Sh DESCRIPTION
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The
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.Fn dup3
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function
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duplicates an existing object descriptor
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while allowing the value of the new descriptor to be specified.
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.Pp
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The close-on-exec flag on the new file descriptor is determined by the
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.Dv O_CLOEXEC
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bit in
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.Fa flags .
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.Pp
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If
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.Fa oldd
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\*(Ne
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.Fa newd
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and
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.Fa flags
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== 0,
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the behavior is identical to
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.Li dup2(oldd, newd) .
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.Pp
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If
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.Fa oldd
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==
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.Fa newd ,
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then
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.Fn dup3
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fails, unlike
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.Xr dup2 2 .
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.Sh RETURN VALUES
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The value -1 is returned if an error occurs.
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The external variable
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.Va errno
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indicates the cause of the error.
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.Sh ERRORS
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The
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.Fn dup3
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function fails if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa oldd
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argument is not a valid active descriptor or the
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.Fa newd
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argument is negative or exceeds the maximum allowable descriptor number
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.It Bq Er EINVAL
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The
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.Fa oldd
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argument is equal to the
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.Fa newd
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argument.
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.It Bq Er EINVAL
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The
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.Fa flags
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argument has bits set other than
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.Dv O_CLOEXEC .
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.El
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.Sh SEE ALSO
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.Xr accept 2 ,
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.Xr close 2 ,
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.Xr dup2 2 ,
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.Xr fcntl 2 ,
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.Xr getdtablesize 2 ,
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.Xr open 2 ,
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.Xr pipe 2 ,
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.Xr socket 2 ,
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.Xr socketpair 2
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.Sh STANDARDS
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The
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.Fn dup3
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function does not conform to any standard.
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.Sh HISTORY
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The
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.Fn dup3
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function appeared in
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.Fx 10.0 .
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