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Annotated edit history of readv(2) version 2, including all changes. View license author blame.
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1 perry 1 !!NAME
2 PerryLorier 2 readv, writev - read or write a vector
1 perry 3
4 !!SYNOPSIS
2 PerryLorier 5 __#include <sys/uio.h>__
1 perry 6
2 PerryLorier 7 __int readv(int__ ''fd''__, const struct iovec *__ ''vector''__, int__ ''count''__);__
1 perry 8
2 PerryLorier 9 __int writev(int__ ''fd''__, const struct iovec *__ ''vector''__, int__ ''count''__);__
1 perry 10
2 PerryLorier 11 __struct iovec {__
12 ptr_t__ ''iov_base''__;__ /* Starting address. */__
13 size_t__ ''iov_len''__;__ /* Length in bytes. */__
14 __};__
1 perry 15
16 !!DESCRIPTION
2 PerryLorier 17 readv(2) reads data from file descriptor ''fd'', and puts the result in the buffers described by ''vector''. The number of buffers is specified by ''count''. The
18 buffers are filled in the order specified. Operates just like __read__ except that data is put in ''vector'' instead of a contiguous buffer.
1 perry 19
2 PerryLorier 20 __writev__ writes data to file descriptor ''fd'', and from the buffers described by ''vector''. The number of buffers is specified by ''count''. The buffers are used
21 in the order specified. Operates just like __write__ except that data is taken from ''vector'' instead of a contiguous buffer.
1 perry 22
23 !!RETURN VALUE
2 PerryLorier 24 On success __readv__ returns the number of bytes read. On success __writev__ returns the number of bytes written. On error, -1 is returned, and ''errno'' is set appropriately.
1 perry 25
26 !!ERRORS
2 PerryLorier 27 ;[EINVAL]: An invalid argument was given. For instance ''count'' might be greater than __MAX_IOVEC__, or zero. ''fd'' could also be attached to an object which is unsuitable for reading (for __readv__) or writing (for __writev__).
28 ;[EFAULT]: vector'' or some of the ''iov_base'' pointers points to memory that is not properly allocated.
29 ;[EBADF]: The file descriptor ''fd'' is not valid.
30 ;[EINTR]: The call was interrupted by a signal before any data was read/written.
31 ;[EAGAIN]: Non-blocking I/O has been selected using __O_NONBLOCK__ and no data was immediately available for reading. (Or the file descriptor ''fd'' is for an object that is locked.)
32 ;[EISDIR]: ''fd'' refers to a directory.
33 ;[EOPNOTSUP]: ''fd'' refers to a socket or device that does not support reading/writing.
34 ;[ENOMEM]: Insufficient kernel memory was available.
1 perry 35
2 PerryLorier 36 Other errors may occur, depending on the object connected to ''fd''.
1 perry 37
38 !!CONFORMING TO
2 PerryLorier 39 4.4BSD (the __readv__ and __writev__ functions first appeared in BSD 4.2), Unix98. Linux libc5 uses __size_t__ as the type of the ''count'' parameter, which is logical
40 but non-standard.
1 perry 41
42 !!SEE ALSO
2 PerryLorier 43 read(2), write(2), fprintf(3), fscanf(3)
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