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sys_uio.h(0P) POSIX Programmer's Manual sys_uio.h(0P)
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.
sys/uio.h — definitions for vector I/O operations
#include <sys/uio.h>
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.
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>.
None.
limits.h(0p), sys_types.h(0p) The System Interfaces volume of POSIX.1‐2017, read(3p), readv(3p), write(3p), writev(3p)
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 http://www.opengroup.org/unix/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 2017 sys_uio.h(0P)
Pages that refer to this page: sys_socket.h(0p), read(3p), readv(3p), write(3p), writev(3p)