PROLOG | NAME | SYNOPSIS | DESCRIPTION | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

sys_uio.h(0P)             POSIX Programmer's Manual            sys_uio.h(0P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       sys/uio.h — definitions for vector I/O operations

SYNOPSIS         top

       #include <sys/uio.h>

DESCRIPTION         top

       The <sys/uio.h> header shall define the iovec structure, which shall
       include 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 <sys/uio.h> header shall define the ssize_t and size_t types 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         top

       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         top

       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         top

       None.

SEE ALSO         top

       limits.h(0p), sys_types.h(0p)

       The System Interfaces volume of POSIX.1‐2008, read(3p), readv(3p),
       write(3p), writev(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                       sys_uio.h(0P)

Pages that refer to this page: sys_socket.h(0p)read(3p)readv(3p)write(3p)writev(3p)