mirror of https://github.com/mkerrisk/man-pages
72 lines
2.4 KiB
Plaintext
72 lines
2.4 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "<sys/uio.h>" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" <sys/uio.h>
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.SH NAME
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sys/uio.h \- definitions for vector I/O operations
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.SH SYNOPSIS
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.LP
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\fB#include <sys/uio.h> \fP
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.SH DESCRIPTION
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.LP
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The \fI<sys/uio.h>\fP header shall define the \fBiovec\fP structure
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that includes at least the following members:
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.sp
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.RS
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.nf
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\fBvoid *iov_base \fP Base address of a memory region for input or output. \fB
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size_t iov_len \fP The size of the memory pointed to by \fIiov_base.\fP \fB
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\fP
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.fi
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.RE
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.LP
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The \fI<sys/uio.h>\fP header uses the \fBiovec\fP structure for scatter/gather
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I/O.
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.LP
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The \fBssize_t\fP and \fBsize_t\fP types shall be defined as described
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in \fI<sys/types.h>\fP.
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.LP
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The following shall be declared as functions and may also be defined
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as macros. Function prototypes shall be provided.
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.sp
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.RS
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.nf
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\fBssize_t readv(int, const struct iovec *, int);
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ssize_t writev(int, const struct iovec *, int);
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\fP
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.fi
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.RE
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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The implementation can put a limit on the number of scatter/gather
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elements which can be processed in one call. The symbol
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{IOV_MAX} defined in \fI<limits.h>\fP should always be used to learn
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about the
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limits instead of assuming a fixed value.
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.SH RATIONALE
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.LP
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Traditionally, the maximum number of scatter/gather elements the system
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can process in one call were described by the symbolic
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value {UIO_MAXIOV}. In IEEE\ Std\ 1003.1-2001 this value is replaced
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by the constant {IOV_MAX} which can be found in \fI<limits.h>\fP.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fI<limits.h>\fP , \fI<sys/types.h>\fP , the System Interfaces volume
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of IEEE\ Std\ 1003.1-2001, \fIread\fP(), \fIwrite\fP()
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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