github.com/docker/docker@v299999999.0.0-20200612211812-aaf470eca7b5+incompatible/pkg/system/path.go (about)

     1  package system // import "github.com/docker/docker/pkg/system"
     2  
     3  import (
     4  	"fmt"
     5  	"path/filepath"
     6  	"runtime"
     7  	"strings"
     8  )
     9  
    10  const defaultUnixPathEnv = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
    11  
    12  // DefaultPathEnv is unix style list of directories to search for
    13  // executables. Each directory is separated from the next by a colon
    14  // ':' character .
    15  func DefaultPathEnv(os string) string {
    16  	if runtime.GOOS == "windows" {
    17  		if os != runtime.GOOS {
    18  			return defaultUnixPathEnv
    19  		}
    20  		// Deliberately empty on Windows containers on Windows as the default path will be set by
    21  		// the container. Docker has no context of what the default path should be.
    22  		return ""
    23  	}
    24  	return defaultUnixPathEnv
    25  
    26  }
    27  
    28  // PathVerifier defines the subset of a PathDriver that CheckSystemDriveAndRemoveDriveLetter
    29  // actually uses in order to avoid system depending on containerd/continuity.
    30  type PathVerifier interface {
    31  	IsAbs(string) bool
    32  }
    33  
    34  // CheckSystemDriveAndRemoveDriveLetter verifies that a path, if it includes a drive letter,
    35  // is the system drive.
    36  // On Linux: this is a no-op.
    37  // On Windows: this does the following>
    38  // CheckSystemDriveAndRemoveDriveLetter verifies and manipulates a Windows path.
    39  // This is used, for example, when validating a user provided path in docker cp.
    40  // If a drive letter is supplied, it must be the system drive. The drive letter
    41  // is always removed. Also, it translates it to OS semantics (IOW / to \). We
    42  // need the path in this syntax so that it can ultimately be concatenated with
    43  // a Windows long-path which doesn't support drive-letters. Examples:
    44  // C:			--> Fail
    45  // C:\			--> \
    46  // a			--> a
    47  // /a			--> \a
    48  // d:\			--> Fail
    49  func CheckSystemDriveAndRemoveDriveLetter(path string, driver PathVerifier) (string, error) {
    50  	if runtime.GOOS != "windows" || LCOWSupported() {
    51  		return path, nil
    52  	}
    53  
    54  	if len(path) == 2 && string(path[1]) == ":" {
    55  		return "", fmt.Errorf("No relative path specified in %q", path)
    56  	}
    57  	if !driver.IsAbs(path) || len(path) < 2 {
    58  		return filepath.FromSlash(path), nil
    59  	}
    60  	if string(path[1]) == ":" && !strings.EqualFold(string(path[0]), "c") {
    61  		return "", fmt.Errorf("The specified path is not on the system drive (C:)")
    62  	}
    63  	return filepath.FromSlash(path[2:]), nil
    64  }