common: improve documentation comments (#16701)

This commit adds many comments and removes unused code.
It also removes the EmptyHash function, which had some uses
but was silly.

1 files changed, 4 insertions, 2 deletions

diff --git a/common/path.go b/common/path.go
index bd8da86e7..69820cfe5 100644
--- a/common/path.go
+++ b/common/path.go
@@ -30,6 +30,7 @@ func MakeName(name, version string) string {
 	return fmt.Sprintf("%s/v%s/%s/%s", name, version, runtime.GOOS, runtime.Version())
 }
 
+// FileExist checks if a file exists at filePath.
 func FileExist(filePath string) bool {
 	_, err := os.Stat(filePath)
 	if err != nil && os.IsNotExist(err) {
@@ -39,9 +40,10 @@ func FileExist(filePath string) bool {
 	return true
 }
 
-func AbsolutePath(Datadir string, filename string) string {
+// AbsolutePath returns datadir + filename, or filename if it is absolute.
+func AbsolutePath(datadir string, filename string) string {
 	if filepath.IsAbs(filename) {
 		return filename
 	}
-	return filepath.Join(Datadir, filename)
+	return filepath.Join(datadir, filename)
 }