gh-ost/vendor/github.com/go-sql-driver/mysql/conncheck.go

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// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
//
// Copyright 2019 The Go-MySQL-Driver Authors. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
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// +build linux darwin dragonfly freebsd netbsd openbsd solaris illumos
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package mysql
import (
"errors"
"io"
"net"
"syscall"
)
var errUnexpectedRead = errors.New("unexpected read from socket")
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func connCheck(conn net.Conn) error {
var sysErr error
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sysConn, ok := conn.(syscall.Conn)
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if !ok {
return nil
}
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rawConn, err := sysConn.SyscallConn()
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if err != nil {
return err
}
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err = rawConn.Read(func(fd uintptr) bool {
var buf [1]byte
n, err := syscall.Read(int(fd), buf[:])
switch {
case n == 0 && err == nil:
sysErr = io.EOF
case n > 0:
sysErr = errUnexpectedRead
case err == syscall.EAGAIN || err == syscall.EWOULDBLOCK:
sysErr = nil
default:
sysErr = err
}
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return true
})
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if err != nil {
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return err
}
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return sysErr
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}