// readConsole reads utf16 characters from console File,
// encodes them into utf8 and stores them in buffer b.
// It returns the number of utf8 bytes read and an error, if any.
func (f *File) readConsole(b []byte) (n int, err error) {
if len(b) == 0 {
return 0, nil
}
if len(f.readbuf) == 0 {
// get more input data from os
wchars := make([]uint16, len(b))
var p *uint16
if len(b) > 0 {
p = &wchars[0]
}
var nw uint32
err := syscall.ReadConsole(f.fd, p, uint32(len(wchars)), &nw, nil)
if err != nil {
return 0, err
}
f.readbuf = utf16.Decode(wchars[:nw])
}
for i, r := range f.readbuf {
if utf8.RuneLen(r) > len(b) {
f.readbuf = f.readbuf[i:]
return n, nil
}
nr := utf8.EncodeRune(b, r)
b = b[nr:]
n += nr
}
f.readbuf = nil
return n, nil
}
// readConsole reads utf16 characters from console File,
// encodes them into utf8 and stores them in buffer b.
// It returns the number of utf8 bytes read and an error, if any.
func (f *File) readConsole(b []byte) (n int, err error) {
if len(b) == 0 {
return 0, nil
}
if len(f.readbuf) == 0 {
// syscall.ReadConsole seems to fail, if given large buffer.
// So limit the buffer to 16000 characters.
numBytes := len(b)
if numBytes > 16000 {
numBytes = 16000
}
// get more input data from os
wchars := make([]uint16, numBytes)
var p *uint16
if len(b) > 0 {
p = &wchars[0]
}
var nw uint32
err := syscall.ReadConsole(f.fd, p, uint32(len(wchars)), &nw, nil)
if err != nil {
return 0, err
}
f.readbuf = utf16.Decode(wchars[:nw])
}
for i, r := range f.readbuf {
if utf8.RuneLen(r) > len(b) {
f.readbuf = f.readbuf[i:]
return n, nil
}
nr := utf8.EncodeRune(b, r)
b = b[nr:]
n += nr
}
f.readbuf = nil
return n, nil
}