Improved ResolveEnvVar and add support of tilde (~/...)

[src/xds/xds-server.git] / lib / common / filepath.go

diff --git a/lib/common/filepath.go b/lib/common/filepath.go
index 603c2a2..42ef82f 100644 (file)
--- a/lib/common/filepath.go
+++ b/lib/common/filepath.go
@@ -1,6 +1,13 @@
 package common
 
-import "os"
+import (
+       "fmt"
+       "os"
+       "os/user"
+       "path"
+       "path/filepath"
+       "regexp"
+)
 
 // Exists returns whether the given file or directory exists or not
 func Exists(path string) bool {
@@ -13,3 +20,35 @@ func Exists(path string) bool {
        }
        return true
 }
+
+// ResolveEnvVar Resolved environment variable regarding the syntax ${MYVAR}
+// or $MYVAR following by a slash or a backslash
+func ResolveEnvVar(s string) (string, error) {
+
+       // Resolved tilde : ~/
+       if s[:2] == "~/" {
+               if usr, err := user.Current(); err == nil {
+                       s = filepath.Join(usr.HomeDir, s[2:])
+               }
+       }
+
+       // Resolved ${MYVAR}
+       re := regexp.MustCompile("\\${([^}]+)}")
+       vars := re.FindAllStringSubmatch(s, -1)
+       res := s
+       for _, v := range vars {
+               val := os.Getenv(v[1])
+               if val == "" {
+                       return res, fmt.Errorf("ERROR: %s env variable not defined", v[1])
+               }
+
+               rer := regexp.MustCompile("\\${" + v[1] + "}")
+               res = rer.ReplaceAllString(res, val)
+       }
+
+       // Resolved $MYVAR following by a slash (or a backslash for Windows)
+       // TODO
+       //re := regexp.MustCompile("\\$([^\\/])+/")
+
+       return path.Clean(res), nil
+}