github.com/lazyboychen7/engine@v17.12.1-ce-rc2+incompatible/opts/env.go (about)

     1  package opts
     2  
     3  import (
     4  	"fmt"
     5  	"os"
     6  	"runtime"
     7  	"strings"
     8  
     9  	"github.com/pkg/errors"
    10  )
    11  
    12  // ValidateEnv validates an environment variable and returns it.
    13  // If no value is specified, it returns the current value using os.Getenv.
    14  //
    15  // As on ParseEnvFile and related to #16585, environment variable names
    16  // are not validate what so ever, it's up to application inside docker
    17  // to validate them or not.
    18  //
    19  // The only validation here is to check if name is empty, per #25099
    20  func ValidateEnv(val string) (string, error) {
    21  	arr := strings.Split(val, "=")
    22  	if arr[0] == "" {
    23  		return "", errors.Errorf("invalid environment variable: %s", val)
    24  	}
    25  	if len(arr) > 1 {
    26  		return val, nil
    27  	}
    28  	if !doesEnvExist(val) {
    29  		return val, nil
    30  	}
    31  	return fmt.Sprintf("%s=%s", val, os.Getenv(val)), nil
    32  }
    33  
    34  func doesEnvExist(name string) bool {
    35  	for _, entry := range os.Environ() {
    36  		parts := strings.SplitN(entry, "=", 2)
    37  		if runtime.GOOS == "windows" {
    38  			// Environment variable are case-insensitive on Windows. PaTh, path and PATH are equivalent.
    39  			if strings.EqualFold(parts[0], name) {
    40  				return true
    41  			}
    42  		}
    43  		if parts[0] == name {
    44  			return true
    45  		}
    46  	}
    47  	return false
    48  }