mirror of https://github.com/docker/cli.git
103 lines
3.6 KiB
Go
103 lines
3.6 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package execabs is a drop-in replacement for os/exec
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// that requires PATH lookups to find absolute paths.
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// That is, execabs.Command("cmd") runs the same PATH lookup
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// as exec.Command("cmd"), but if the result is a path
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// which is relative, the Run and Start methods will report
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// an error instead of running the executable.
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//
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// See https://blog.golang.org/path-security for more information
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// about when it may be necessary or appropriate to use this package.
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package execabs
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import (
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"context"
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"fmt"
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"os/exec"
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"path/filepath"
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"reflect"
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"unsafe"
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)
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// ErrNotFound is the error resulting if a path search failed to find an executable file.
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// It is an alias for exec.ErrNotFound.
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var ErrNotFound = exec.ErrNotFound
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// Cmd represents an external command being prepared or run.
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// It is an alias for exec.Cmd.
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type Cmd = exec.Cmd
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// Error is returned by LookPath when it fails to classify a file as an executable.
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// It is an alias for exec.Error.
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type Error = exec.Error
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// An ExitError reports an unsuccessful exit by a command.
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// It is an alias for exec.ExitError.
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type ExitError = exec.ExitError
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func relError(file, path string) error {
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return fmt.Errorf("%s resolves to executable in current directory (.%c%s)", file, filepath.Separator, path)
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}
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// LookPath searches for an executable named file in the directories
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// named by the PATH environment variable. If file contains a slash,
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// it is tried directly and the PATH is not consulted. The result will be
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// an absolute path.
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//
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// LookPath differs from exec.LookPath in its handling of PATH lookups,
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// which are used for file names without slashes. If exec.LookPath's
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// PATH lookup would have returned an executable from the current directory,
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// LookPath instead returns an error.
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func LookPath(file string) (string, error) {
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path, err := exec.LookPath(file)
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if err != nil && !isGo119ErrDot(err) {
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return "", err
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}
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if filepath.Base(file) == file && !filepath.IsAbs(path) {
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return "", relError(file, path)
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}
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return path, nil
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}
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func fixCmd(name string, cmd *exec.Cmd) {
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if filepath.Base(name) == name && !filepath.IsAbs(cmd.Path) {
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// exec.Command was called with a bare binary name and
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// exec.LookPath returned a path which is not absolute.
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// Set cmd.lookPathErr and clear cmd.Path so that it
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// cannot be run.
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lookPathErr := (*error)(unsafe.Pointer(reflect.ValueOf(cmd).Elem().FieldByName("lookPathErr").Addr().Pointer()))
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if *lookPathErr == nil {
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*lookPathErr = relError(name, cmd.Path)
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}
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cmd.Path = ""
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}
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}
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// CommandContext is like Command but includes a context.
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//
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// The provided context is used to kill the process (by calling os.Process.Kill)
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// if the context becomes done before the command completes on its own.
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func CommandContext(ctx context.Context, name string, arg ...string) *exec.Cmd {
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cmd := exec.CommandContext(ctx, name, arg...)
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fixCmd(name, cmd)
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return cmd
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}
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// Command returns the Cmd struct to execute the named program with the given arguments.
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// See exec.Command for most details.
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//
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// Command differs from exec.Command in its handling of PATH lookups,
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// which are used when the program name contains no slashes.
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// If exec.Command would have returned an exec.Cmd configured to run an
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// executable from the current directory, Command instead
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// returns an exec.Cmd that will return an error from Start or Run.
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func Command(name string, arg ...string) *exec.Cmd {
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cmd := exec.Command(name, arg...)
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fixCmd(name, cmd)
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return cmd
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}
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