github.com/jlmucb/cloudproxy@v0.0.0-20170830161738-b5aa0b619bc4/go/util/fdmessagestream.go (about)

     1  // Copyright (c) 2014, Kevin Walsh.  All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package util
    16  
    17  import (
    18  	"errors"
    19  	"fmt"
    20  	"net"
    21  	"os"
    22  	"strings"
    23  )
    24  
    25  // DeserializeFileMessageStream takes a string description of the form
    26  // "tao::FileMessageChannel(X)" and returns a MessageStream that uses file
    27  // X to communicate.
    28  func DeserializeFileMessageStream(s string) (*MessageStream, error) {
    29  	r := strings.TrimPrefix(s, "tao::FileMessageChannel(")
    30  	if r == s {
    31  		return nil, errors.New("unrecognized channel spec " + s)
    32  	}
    33  	filename := strings.TrimSuffix(r, ")")
    34  	if filename == r {
    35  		return nil, errors.New("unrecognized channel spec " + s)
    36  	}
    37  
    38  	rw, err := os.OpenFile(filename, os.O_RDWR, 0700)
    39  	if err != nil {
    40  		return nil, err
    41  	}
    42  	return NewMessageStream(rw), nil
    43  }
    44  
    45  // DeserializeFDMessageStream takes a string description of the form
    46  // "tao::FDMessageStream(X, Y)" and returns a MessageStream that uses file
    47  // descriptor X as the reader and file descriptor Y as the writer.
    48  func DeserializeFDMessageStream(s string) (*MessageStream, error) {
    49  	var readfd, writefd uintptr
    50  	_, err := fmt.Sscanf(s, "tao::FDMessageChannel(%d, %d)", &readfd, &writefd)
    51  	if err != nil {
    52  		return nil, errors.New("unrecognized channel spec " + s)
    53  	}
    54  	if readfd == writefd {
    55  		rw := os.NewFile(readfd, "read/write pipe")
    56  		return NewMessageStream(rw), nil
    57  	}
    58  	r := os.NewFile(readfd, "read pipe")
    59  	w := os.NewFile(writefd, "write pipe")
    60  	rw := NewPairReadWriteCloser(r, w)
    61  	return NewMessageStream(rw), nil
    62  }
    63  
    64  // DeserializeUnixSocketMessageStream takes a string filename and returns a
    65  // MessageStream that is based on the Unix socket for this file.
    66  func DeserializeUnixSocketMessageStream(f string) (*MessageStream, error) {
    67  	conn, err := net.Dial("unix", f)
    68  	if err != nil {
    69  		return nil, err
    70  	}
    71  
    72  	return NewMessageStream(conn), nil
    73  }