2010-01-09 09:18:26 +01:00
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.TH READV 3 "January 6, 2010"
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2010-01-08 14:40:34 +01:00
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.UC 4
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.SH NAME
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readv, writev \- vector-based IO
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.SH SYNOPSIS
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.nf
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.ft B
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#include <sys/uio.h>
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ssize_t readv(int \fIfildes\fP, const struct iovec *\fIiov\fP, int \fIiovcnt\fP);
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ssize_t writev(int \fIfildes\fP, const struct iovec *\fIiov\fP, int \fIiovcnt\fP);
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.fi
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.SH DESCRIPTION
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The \fBreadv\fP and \fBwritev\fP functions allow one to use multiple buffers
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when reading from or writing to files. The \fIfildes\fP parameter specifies the
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file descriptor as with the \fBread\fP and \fBwrite\fP functions. \fIiov\fP
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specifies an array of buffers to be read into or written from. For each element
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of this array, the iov_base member specifies the address of the buffer and
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iov_len specifies its size in bytes. The number of buffers is specified by
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\fIiovcnt\fP. At most IOV_MAX buffers may be specified and their total size may
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not exceed SSIZE_MAX (both constants are defined in limits.h).
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.SH "RETURN VALUE"
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In case of success, the total number of bytes read or written is returned.
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Zero may be returned if no buffers were specified or each buffer has size zero.
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In the case of writev, a return value zero may also indicate an end of file
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condition. If the functions fail, -1 is returned.
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.SH "SEE ALSO"
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read(2), write(2)
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