sys_uio.h(0p) — Linux manual page


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.


       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



SEE ALSO         top

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

       The System Interfaces volume of POSIX.1‐2017, read(3p),
       readv(3p), write(3p), writev(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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 .

IEEE/The Open Group               2017                     sys_uio.h(0P)

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