minio/pkg/utils/execpipe.go
2015-01-20 23:16:24 -08:00

64 lines
1.6 KiB
Go

/*
* Mini Object Storage, (C) 2014 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package utils
import (
"bytes"
"errors"
"io"
"os/exec"
)
// A simple ExecPipe() pipes exec.Cmd together - somewhat similar to how bash pipes "|" behave.
// Each command's standard output is connected to the standard input of the next command
// and the output of the final command is returned
func ExecPipe(cmds ...*exec.Cmd) (pipeLineOutput io.Reader, pipeLineError error) {
// Require at least one command
if len(cmds) < 1 {
return nil, errors.New("Invalid argument")
}
// Collect the output from the command(s)
var output bytes.Buffer
lastIndex := len(cmds) - 1
for i, cmd := range cmds[:lastIndex] {
cmds[i+1].Stdin, _ = cmd.StdoutPipe()
}
// Final ---> output buffer
cmds[lastIndex].Stdout = &output
// Start each command
for _, cmd := range cmds {
if err := cmd.Start(); err != nil {
return &output, err
}
}
// We should Wait() for each command to complete
for _, cmd := range cmds {
if err := cmd.Wait(); err != nil {
return &output, err
}
}
// Return the output
return &output, nil
}