github.com/containerd/nerdctl@v1.7.7/pkg/tarutil/tarutil.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package tarutil
    18  
    19  import (
    20  	"fmt"
    21  	"os"
    22  	"os/exec"
    23  	"strings"
    24  
    25  	"github.com/containerd/log"
    26  )
    27  
    28  // FindTarBinary returns a path to the tar binary and whether it is GNU tar.
    29  func FindTarBinary() (string, bool, error) {
    30  	isGNU := func(exe string) bool {
    31  		v, err := exec.Command(exe, "--version").Output()
    32  		if err != nil {
    33  			log.L.Warnf("Failed to detect whether %q is GNU tar or not", exe)
    34  			return false
    35  		}
    36  		if !strings.Contains(string(v), "GNU tar") {
    37  			log.L.Warnf("%q does not seem GNU tar", exe)
    38  			return false
    39  		}
    40  		return true
    41  	}
    42  	if v := os.Getenv("TAR"); v != "" {
    43  		if exe, err := exec.LookPath(v); err == nil {
    44  			return exe, isGNU(exe), nil
    45  		}
    46  	}
    47  	if exe, err := exec.LookPath("gnutar"); err == nil {
    48  		return exe, true, nil
    49  	}
    50  	if exe, err := exec.LookPath("gtar"); err == nil {
    51  		return exe, true, nil
    52  	}
    53  	if exe, err := exec.LookPath("tar"); err == nil {
    54  		return exe, isGNU(exe), nil
    55  	}
    56  	return "", false, fmt.Errorf("failed to find `tar` binary")
    57  }