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.TH io_fd_canwrite 3
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.SH NAME
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io_fd_canwrite \- prepare descriptor for io_wait
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.SH SYNTAX
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.B #include <libowfat/io.h>
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int \fBio_fd\fP(int64 fd);
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int \fBio_fd_canwrite\fP(int64 fd);
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.SH DESCRIPTION
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io_fd_canwrite is just like io_fd, except that it assumes the descriptor
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is writable, which may save a syscall or two. This assumption is true
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in most cases, because the kernel buffers writes. Noteworthy cases in
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which you need to use io_fd instead of io_fd_canwrite are unconnected
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sockets, i.e. when you queued a non-blocking connect() and want to ask
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for writability to get notified when it went through.
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It is OK to call this function on a descriptor that io_fd() has already
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been called on.
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.SH "RETURN VALUE"
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io_fd_canwrite returns 1 on success, 0 on error.
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.SH "SEE ALSO"
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io_wait(3), io_wantread(3), io_canread(3), io_eagain(3), io_nonblock(3), io_fd(3)
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