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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
FD "fd";
Flag "flag";
)
var rot13_flag = Flag.Bool("rot13", false, nil, "rot13 the input")
func rot13(b byte) byte {
if 'a' <= b && b <= 'z' {
b = 'a' + ((b - 'a') + 13) % 26;
}
if 'A' <= b && b <= 'Z' {
b = 'A' + ((b - 'A') + 13) % 26
}
return b
}
type Reader interface {
Read(b *[]byte) (ret int64, errno int64);
Name() string;
}
type Rot13 struct {
source Reader;
}
func NewRot13(source Reader) *Rot13 {
r13 := new(Rot13);
r13.source = source;
return r13
}
func (r13 *Rot13) Read(b *[]byte) (ret int64, errno int64) {
r, e := r13.source.Read(b);
for i := int64(0); i < r; i++ {
b[i] = rot13(b[i])
}
return r, e
}
func (r13 *Rot13) Name() string {
return r13.source.Name()
}
// end of Rot13 implementation
func cat(r Reader) {
const NBUF = 512;
var buf [NBUF]byte;
if rot13_flag.BVal() {
r = NewRot13(r)
}
for {
switch nr, er := r.Read(&buf); {
case nr < 0:
print("error reading from ", r.Name(), ": ", er, "\n");
sys.exit(1);
case nr == 0: // EOF
return;
case nr > 0:
nw, ew := FD.Stdout.Write((&buf)[0:nr]);
if nw != nr {
print("error writing from ", r.Name(), ": ", ew, "\n");
}
}
}
}
func main() {
var bug FD.FD;
Flag.Parse(); // Scans the arg list and sets up flags
if Flag.NArg() == 0 {
cat(FD.Stdin);
}
for i := 0; i < Flag.NArg(); i++ {
fd, err := FD.Open(Flag.Arg(i), 0, 0);
if fd == nil {
print("can't open ", Flag.Arg(i), ": error ", err, "\n");
sys.exit(1);
}
cat(fd);
fd.Close();
}
}
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