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package auth
import (
"bytes"
"encoding/json"
"fmt"
"os/exec"
"path/filepath"
"github.com/hashicorp/terraform/svchost"
)
type helperProgramCredentialsSource struct {
executable string
args []string
}
// HelperProgramCredentialsSource returns a CredentialsSource that runs the
// given program with the given arguments in order to obtain credentials.
//
// The given executable path must be an absolute path; it is the caller's
// responsibility to validate and process a relative path or other input
// provided by an end-user. If the given path is not absolute, this
// function will panic.
//
// When credentials are requested, the program will be run in a child process
// with the given arguments along with two additional arguments added to the
// end of the list: the literal string "get", followed by the requested
// hostname in ASCII compatibility form (punycode form).
func HelperProgramCredentialsSource(executable string, args ...string) CredentialsSource {
if !filepath.IsAbs(executable) {
panic("NewCredentialsSourceHelperProgram requires absolute path to executable")
}
fullArgs := make([]string, len(args)+1)
fullArgs[0] = executable
copy(fullArgs[1:], args)
return &helperProgramCredentialsSource{
executable: executable,
args: fullArgs,
}
}
func (s *helperProgramCredentialsSource) ForHost(host svchost.Hostname) (HostCredentials, error) {
args := make([]string, len(s.args), len(s.args)+2)
copy(args, s.args)
args = append(args, "get")
args = append(args, string(host))
outBuf := bytes.Buffer{}
errBuf := bytes.Buffer{}
cmd := exec.Cmd{
Path: s.executable,
Args: args,
Stdin: nil,
Stdout: &outBuf,
Stderr: &errBuf,
}
err := cmd.Run()
if _, isExitErr := err.(*exec.ExitError); isExitErr {
errText := errBuf.String()
if errText == "" {
// Shouldn't happen for a well-behaved helper program
return nil, fmt.Errorf("error in %s, but it produced no error message", s.executable)
}
return nil, fmt.Errorf("error in %s: %s", s.executable, errText)
} else if err != nil {
return nil, fmt.Errorf("failed to run %s: %s", s.executable, err)
}
var m map[string]interface{}
err = json.Unmarshal(outBuf.Bytes(), &m)
if err != nil {
return nil, fmt.Errorf("malformed output from %s: %s", s.executable, err)
}
return HostCredentialsFromMap(m), nil
}
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