pkg/timezone: handle TZDIR and local correctly

The special value local must always be higher priority then the TZDIR
env so make sure local is matched before. Without this we joined local
on the TZDIR path which of course does not result in a valid timezone
path.

I will add a regression test in podman.

Fixes: containers/podman#23550

Signed-off-by: Paul Holzinger <[email protected]>

Author: Luap99

pkg/timezone/timezone.go

@@ -23,18 +23,20 @@ func ConfigureContainerTimeZone(timezone, containerRunDir, mountPoint, etcPath,
 	switch {
 	case timezone == "":
 		return "", nil
-	case os.Getenv("TZDIR") != "":
-		// Allow using TZDIR per:
-		// https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzfile.c;h=8a923d0cccc927a106dc3e3c641be310893bab4e;hb=HEAD#l149
-
-		timezonePath = filepath.Join(os.Getenv("TZDIR"), timezone)
 	case timezone == "local":
 		timezonePath, err = filepath.EvalSymlinks("/etc/localtime")
 		if err != nil {
 			return "", fmt.Errorf("finding local timezone for container %s: %w", containerID, err)
 		}
 	default:
-		timezonePath = filepath.Join("/usr/share/zoneinfo", timezone)
+		// Allow using TZDIR per:
+		// https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzfile.c;h=8a923d0cccc927a106dc3e3c641be310893bab4e;hb=HEAD#l149
+		zoneinfo := os.Getenv("TZDIR")
+		if zoneinfo == "" {
+			// default zoneinfo location
+			zoneinfo = "/usr/share/zoneinfo"
+		}
+		timezonePath = filepath.Join(zoneinfo, timezone)
 	}
 
 	etcFd, err := openDirectory(etcPath)