Add 'environment' package

This commit adds a new environment package that manages all calls to the
underlying operating system.

pkg/execx/exec.go

@@ -1,46 +0,0 @@
-// Package execx defines extensions to the "os/exec" package
-package execx
-
-import (
-	"os/exec"
-
-	"github.com/tkw1536/goprogram/stream"
-)
-
-// ExecCommandError is returned by Exec when a command could not be executed.
-// This typically hints that the executable cannot be found, but may have other causes.
-const ExecCommandError = 127
-
-// Exec executes a system command with the specified input/output streams, working directory, and arguments.
-//
-// If the command executes, it's exit code will be returned.
-// If the command can not be executed, returns [ExecCommandError].
-func Exec(io stream.IOStream, workdir string, exe string, argv ...string) int {
-	// setup the command
-	cmd := exec.Command(exe, argv...)
-	cmd.Dir = workdir
-	cmd.Stdin = io.Stdin
-	cmd.Stdout = io.Stdout
-	cmd.Stderr = io.Stderr
-
-	// run it
-	err := cmd.Run()
-
-	// non-zero exit
-	if err, ok := err.(*exec.ExitError); ok {
-		return err.ExitCode()
-	}
-
-	// unknown error
-	if err != nil {
-		return ExecCommandError
-	}
-
-	// everything is fine!
-	return 0
-}
-
-// MustExec is like Exec, except that it returns true if the command exited successfully, and else false.
-func MustExec(io stream.IOStream, workdir string, exe string, argv ...string) bool {
-	return Exec(io, workdir, exe, argv...) == 0
-}

pkg/execx/look.go

@@ -1,15 +0,0 @@
-package execx
-
-import (
-	"os/exec"
-	"path/filepath"
-)
-
-// LookPathAbs is like [exec.LookPath], but always returns an absolute path
-func LookPathAbs(file string) (string, error) {
-	path, err := exec.LookPath(file)
-	if err != nil {
-		return "", err
-	}
-	return filepath.Abs(path)
-}