github.com/jiasir/docker@v1.3.3-0.20170609024000-252e610103e7/opts/env.go (about)

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