Move trimCurrentPrefix to tools

Right now, we have a function which can trim the relative path prefix,
but that is only available in the `commands` package.  In the future,
we'll want to use it elsewhere as well, so let's move it somewhere more
accessible.

commands/command_track.go

@@ -74,7 +74,7 @@ func trackCommand(cmd *cobra.Command, args []string) {
 	var writeablePatterns []string
 ArgsLoop:
 	for _, unsanitizedPattern := range args {
-		pattern := trimCurrentPrefix(cleanRootPath(unsanitizedPattern))
+		pattern := tools.TrimCurrentPrefix(cleanRootPath(unsanitizedPattern))
 
 		// Generate the new / changed attrib line for merging
 		var encodedArg string

commands/command_untrack.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/git-lfs/git-lfs/v3/tools"
 	"github.com/git-lfs/git-lfs/v3/tr"
 	"github.com/spf13/cobra"
 )
@@ -57,9 +58,9 @@ func untrackCommand(cmd *cobra.Command, args []string) {
 }
 
 func removePath(path string, args []string) bool {
-	withoutCurrentDir := trimCurrentPrefix(path)
+	withoutCurrentDir := tools.TrimCurrentPrefix(path)
 	for _, t := range args {
-		if withoutCurrentDir == escapeAttrPattern(trimCurrentPrefix(t)) {
+		if withoutCurrentDir == escapeAttrPattern(tools.TrimCurrentPrefix(t)) {
 			return true
 		}
 	}

commands/path.go

@@ -12,24 +12,6 @@ func gitLineEnding(git env) string {
 	}
 }
 
-const (
-	windowsPrefix = `.\`
-	nixPrefix     = `./`
-)
-
-// trimCurrentPrefix removes a leading prefix of "./" or ".\" (referring to the
-// current directory in a platform independent manner).
-//
-// It is useful for callers such as "git lfs track" and "git lfs untrack", that
-// wish to compare filepaths and/or attributes patterns without cleaning across
-// multiple platforms.
-func trimCurrentPrefix(p string) string {
-	if strings.HasPrefix(p, windowsPrefix) {
-		return strings.TrimPrefix(p, windowsPrefix)
-	}
-	return strings.TrimPrefix(p, nixPrefix)
-}
-
 type env interface {
 	Get(string) (string, bool)
 }

tools/filetools.go

@@ -503,3 +503,21 @@ func CanonicalizePath(path string, missingOk bool) (string, error) {
 	}
 	return "", nil
 }
+
+const (
+	windowsPrefix = `.\`
+	nixPrefix     = `./`
+)
+
+// TrimCurrentPrefix removes a leading prefix of "./" or ".\" (referring to the
+// current directory in a platform independent manner).
+//
+// It is useful for callers such as "git lfs track" and "git lfs untrack", that
+// wish to compare filepaths and/or attributes patterns without cleaning across
+// multiple platforms.
+func TrimCurrentPrefix(p string) string {
+	if strings.HasPrefix(p, windowsPrefix) {
+		return strings.TrimPrefix(p, windowsPrefix)
+	}
+	return strings.TrimPrefix(p, nixPrefix)
+}