Merge pull request #50 from LandonTClipp/relative_to

Wrap sentinel error in RelativeTo

Author: LandonTClipp

errors.go

@@ -12,6 +12,8 @@ var (
 	ErrInvalidAlgorithm = fmt.Errorf("invalid algorithm specified")
 	// ErrLstatNotPossible specifies that the filesystem does not support lstat-ing
 	ErrLstatNotPossible = fmt.Errorf("lstat is not possible")
+	// ErrRelativeTo indicates that we could not make one path relative to another
+	ErrRelativeTo = fmt.Errorf("failed to make path relative to other")
 	// ErrStopWalk indicates to the Walk function that the walk should be aborted
 	ErrStopWalk = fmt.Errorf("stop filesystem walk")
 )

path.go

@@ -433,7 +433,7 @@ func (p *Path) RelativeTo(other *Path) (*Path, error) {
 	var relativeBase int
 	for idx, part := range otherParts {
 		if idx >= len(thisParts) || thisParts[idx] != part {
-			return p, fmt.Errorf("%s does not start with %s", thisPathNormalized, otherPathNormalized)
+			return p, fmt.Errorf("%s does not start with %s: %w", thisPathNormalized, otherPathNormalized, ErrRelativeTo)
 		}
 		relativeBase = idx
 	}