xdg: add functions to deal with user home paths

These are intended to replace the following deprecated libraries:

	github.com/kyoh86/xdg
	github.com/mitchellh/go-homedir

The feature set should be roughly equivalent with some tweaks to make
our life easier in aerc.

Signed-off-by: Robin Jarry <robin@jarry.cc>
Reviewed-by: Moritz Poldrack <moritz@poldrack.dev>

1 files changed, 47 insertions, 0 deletions

diff --git a/lib/xdg/home.go b/lib/xdg/home.go
new file mode 100644
index 00000000..3471e5e2
--- /dev/null
+++ b/lib/xdg/home.go
@@ -0,0 +1,47 @@
+package xdg
+
+import (
+	"os"
+	"os/user"
+	"path"
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/log"
+)
+
+// assign to a local var to allow mocking in unit tests
+var currentUser = user.Current
+
+// Get the current user home directory (first from the $HOME env var and
+// fallback on calling getpwuid_r() from libc if $HOME is unset).
+func HomeDir() string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		u, e := currentUser()
+		if e == nil {
+			home = u.HomeDir
+		} else {
+			log.Errorf("HomeDir: %s (while handling %s)", e, err)
+		}
+	}
+	return home
+}
+
+// Replace ~ with the current user's home dir
+func ExpandHome(fragments ...string) string {
+	home := HomeDir()
+	res := path.Join(fragments...)
+	if strings.HasPrefix(res, "~/") || res == "~" {
+		res = home + strings.TrimPrefix(res, "~")
+	}
+	return res
+}
+
+// Replace $HOME with ~ (inverse function of ExpandHome)
+func TildeHome(path string) string {
+	home := HomeDir()
+	if strings.HasPrefix(path, home+"/") || path == home {
+		path = "~" + strings.TrimPrefix(path, home)
+	}
+	return path
+}