1sys_uio.h(0P) POSIX Programmer's Manual sys_uio.h(0P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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13 sys/uio.h — definitions for vector I/O operations
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16 #include <sys/uio.h>
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19 The <sys/uio.h> header shall define the iovec structure, which shall
20 include at least the following members:
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22 void *iov_base Base address of a memory region for input or output.
23 size_t iov_len The size of the memory pointed to by iov_base.
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25 The <sys/uio.h> header uses the iovec structure for scatter/gather I/O.
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27 The <sys/uio.h> header shall define the ssize_t and size_t types as
28 described in <sys/types.h>.
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30 The following shall be declared as functions and may also be defined as
31 macros. Function prototypes shall be provided.
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33 ssize_t readv(int, const struct iovec *, int);
34 ssize_t writev(int, const struct iovec *, int);
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36 The following sections are informative.
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39 The implementation can put a limit on the number of scatter/gather ele‐
40 ments which can be processed in one call. The symbol {IOV_MAX} defined
41 in <limits.h> should always be used to learn about the limits instead
42 of assuming a fixed value.
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45 Traditionally, the maximum number of scatter/gather elements the system
46 can process in one call were described by the symbolic value {UIO_MAX‐
47 IOV}. In IEEE Std 1003.1‐2001 this value is replaced by the constant
48 {IOV_MAX} which can be found in <limits.h>.
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51 None.
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54 <limits.h>, <sys_types.h>
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56 The System Interfaces volume of POSIX.1‐2008, read(), readv(), write(),
57 writev()
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60 Portions of this text are reprinted and reproduced in electronic form
61 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
62 -- Portable Operating System Interface (POSIX), The Open Group Base
63 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
64 cal and Electronics Engineers, Inc and The Open Group. (This is
65 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
66 event of any discrepancy between this version and the original IEEE and
67 The Open Group Standard, the original IEEE and The Open Group Standard
68 is the referee document. The original Standard can be obtained online
69 at http://www.unix.org/online.html .
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71 Any typographical or formatting errors that appear in this page are
72 most likely to have been introduced during the conversion of the source
73 files to man page format. To report such errors, see https://www.ker‐
74 nel.org/doc/man-pages/reporting_bugs.html .
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78IEEE/The Open Group 2013 sys_uio.h(0P)