trusty (7) uio.h.7posix.gz

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NAME
       sys/uio.h - definitions for vector I/O operations


SYNOPSIS
       #include <sys/uio.h>


DESCRIPTION
       The <sys/uio.h> header shall define the iovec structure that includes at least the following members:

              void   *iov_base  Base address of a memory region for input or output.
              size_t  iov_len   The size of the memory pointed to by iov_base.

       The <sys/uio.h> header uses the iovec structure for scatter/gather I/O.

       The ssize_t and size_t types shall be defined as described in <sys/types.h>.

       The following shall be declared as functions and may also be defined as macros. Function prototypes shall
       be provided.

              ssize_t readv(int, const struct iovec *, int);
              ssize_t writev(int, const struct iovec *, int);

       The following sections are informative.


APPLICATION USAGE
       The implementation can put a limit on the number of scatter/gather elements which can be processed in one
       call.  The symbol {IOV_MAX} defined in <limits.h> should always be used to learn about the limits instead
       of assuming a fixed value.


RATIONALE
       Traditionally, the maximum number of scatter/gather elements the system can  process  in  one  call  were
       described  by  the  symbolic  value  {UIO_MAXIOV}.  In IEEE Std 1003.1-2001 this value is replaced by the
       constant {IOV_MAX} which can be found in <limits.h>.


FUTURE DIRECTIONS
       None.


SEE ALSO
       <limits.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001, read(), write()


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc  and  The  Open Group. In the event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .