cmd/hakurei: short identifier from lower half

The upper half is now a nanosecond timestamp. Lower half is still random bytes, so use lower half for short identifier.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/hakurei/command.go

@@ -301,7 +301,7 @@ func buildCommand(ctx context.Context, msg message.Msg, early *earlyHardeningErr
 
 			case 1: // instance
 				name := args[0]
-				config, entry := tryShort(msg, name)
+				config, entry := tryIdentifier(msg, name)
 				if config == nil {
 					config = tryPath(msg, name)
 				}

cmd/hakurei/parse.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/hex"
 	"errors"
 	"io"
 	"log"
@@ -15,6 +16,9 @@ import (
 	"hakurei.app/message"
 )
 
+// tryPath attempts to read [hst.Config] from multiple sources.
+// tryPath reads from [os.Stdin] if name has value "-".
+// Otherwise, name is passed to tryFd, and if that returns nil, name is passed to [os.Open].
 func tryPath(msg message.Msg, name string) (config *hst.Config) {
 	var r io.ReadCloser
 	config = new(hst.Config)
@@ -42,6 +46,7 @@ func tryPath(msg message.Msg, name string) (config *hst.Config) {
 	return
 }
 
+// tryFd returns a [io.ReadCloser] if name represents an integer corresponding to a valid file descriptor.
 func tryFd(msg message.Msg, name string) io.ReadCloser {
 	if v, err := strconv.Atoi(name); err != nil {
 		if !errors.Is(err, strconv.ErrSyntax) {
@@ -61,10 +66,48 @@ func tryFd(msg message.Msg, name string) io.ReadCloser {
 	}
 }
 
-func tryShort(msg message.Msg, name string) (config *hst.Config, entry *hst.State) {
-	likePrefix := false
-	if len(name) <= 32 {
-		likePrefix = true
+// shortLengthMin is the minimum length a short form identifier can have and still be interpreted as an identifier.
+const shortLengthMin = 1 << 3
+
+// shortIdentifier returns an eight character short representation of [hst.ID] from its random bytes.
+func shortIdentifier(id *hst.ID) string {
+	return shortIdentifierString(id.String())
+}
+
+// shortIdentifierString implements shortIdentifier on an arbitrary string.
+func shortIdentifierString(s string) string {
+	return s[len(hst.ID{}) : len(hst.ID{})+shortLengthMin]
+}
+
+// tryIdentifier attempts to match [hst.State] from a [hex] representation of [hst.ID] or a prefix of its lower half.
+func tryIdentifier(msg message.Msg, name string) (config *hst.Config, entry *hst.State) {
+	return tryIdentifierEntries(msg, name, func() map[hst.ID]*hst.State {
+		var sc hst.Paths
+		app.CopyPaths().Copy(&sc, new(app.Hsu).MustID(nil))
+		s := state.NewMulti(msg, sc.RunDirPath.String())
+		if entries, err := state.Join(s); err != nil {
+			msg.GetLogger().Printf("cannot join store: %v", err) // not fatal
+			return nil
+		} else {
+			return entries
+		}
+	})
+}
+
+// tryIdentifierEntries implements tryIdentifier with a custom entries pair getter.
+func tryIdentifierEntries(
+	msg message.Msg,
+	name string,
+	getEntries func() map[hst.ID]*hst.State,
+) (config *hst.Config, entry *hst.State) {
+	const (
+		likeShort = 1 << iota
+		likeFull
+	)
+
+	var likely uintptr
+	if len(name) >= shortLengthMin && len(name) <= len(hst.ID{}) { // half the hex representation
+		// cannot safely decode here due to unknown alignment
 		for _, c := range name {
 			if c >= '0' && c <= '9' {
 				continue
@@ -72,25 +115,27 @@ func tryShort(msg message.Msg, name string) (config *hst.Config, entry *hst.Stat
 			if c >= 'a' && c <= 'f' {
 				continue
 			}
-			likePrefix = false
-			break
+			return
 		}
+		likely |= likeShort
+	} else if len(name) == hex.EncodedLen(len(hst.ID{})) {
+		likely |= likeFull
 	}
 
-	// try to match from state store
-	if likePrefix && len(name) >= 8 {
-		msg.Verbose("argument looks like prefix")
+	if likely == 0 {
+		return
+	}
+	entries := getEntries()
+	if entries == nil {
+		return
+	}
 
-		var sc hst.Paths
-		app.CopyPaths().Copy(&sc, new(app.Hsu).MustID(nil))
-		s := state.NewMulti(msg, sc.RunDirPath.String())
-		if entries, err := state.Join(s); err != nil {
-			log.Printf("cannot join store: %v", err)
-			// drop to fetch from file
-		} else {
+	switch {
+	case likely&likeShort != 0:
+		msg.Verbose("argument looks like short identifier")
 		for id := range entries {
 			v := id.String()
-				if strings.HasPrefix(v, name) {
+			if strings.HasPrefix(v[len(hst.ID{}):], name) {
 				// match, use config from this state entry
 				entry = entries[id]
 				config = entry.Config
@@ -99,8 +144,21 @@ func tryShort(msg message.Msg, name string) (config *hst.Config, entry *hst.Stat
 
 			msg.Verbosef("instance %s skipped", v)
 		}
-		}
-	}
+		return
 
+	case likely&likeFull != 0:
+		var likelyID hst.ID
+		if likelyID.UnmarshalText([]byte(name)) != nil {
 			return
 		}
+		msg.Verbose("argument looks like identifier")
+		if ent, ok := entries[likelyID]; ok {
+			entry = ent
+			config = ent.Config
+		}
+		return
+
+	default:
+		panic("unreachable")
+	}
+}

cmd/hakurei/parse_test.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+
+	"hakurei.app/hst"
+	"hakurei.app/message"
+)
+
+func TestShortIdentifier(t *testing.T) {
+	t.Parallel()
+	id := hst.ID{
+		0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
+		0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10,
+	}
+
+	const want = "fedcba98"
+	if got := shortIdentifier(&id); got != want {
+		t.Errorf("shortIdentifier: %q, want %q", got, want)
+	}
+}
+
+func TestTryIdentifier(t *testing.T) {
+	t.Parallel()
+	msg := message.NewMsg(nil)
+	id := hst.ID{
+		0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
+		0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10,
+	}
+
+	testCases := []struct {
+		name    string
+		s       string
+		entries map[hst.ID]*hst.State
+		want    *hst.State
+	}{
+		{"likely entries fault", "ffffffff", nil, nil},
+
+		{"likely short too short", "ff", nil, nil},
+		{"likely short too long", "fffffffffffffffff", nil, nil},
+		{"likely short invalid lower", "fffffff\x00", nil, nil},
+		{"likely short invalid higher", "0000000\xff", nil, nil},
+		{"short no match", "fedcba98", map[hst.ID]*hst.State{hst.ID{}: nil}, nil},
+		{"short match", "fedcba98", map[hst.ID]*hst.State{
+			hst.ID{}: nil,
+			id: {
+				ID:      id,
+				PID:     0xcafebabe,
+				ShimPID: 0xdeadbeef,
+				Config:  hst.Template(),
+			},
+		}, &hst.State{
+			ID:      id,
+			PID:     0xcafebabe,
+			ShimPID: 0xdeadbeef,
+			Config:  hst.Template(),
+		}},
+		{"short match longer", "fedcba98765", map[hst.ID]*hst.State{
+			hst.ID{}: nil,
+			id: {
+				ID:      id,
+				PID:     0xcafebabe,
+				ShimPID: 0xdeadbeef,
+				Config:  hst.Template(),
+			},
+		}, &hst.State{
+			ID:      id,
+			PID:     0xcafebabe,
+			ShimPID: 0xdeadbeef,
+			Config:  hst.Template(),
+		}},
+
+		{"likely long invalid", "0123456789abcdeffedcba987654321\x00", map[hst.ID]*hst.State{}, nil},
+		{"long no match", "0123456789abcdeffedcba9876543210", map[hst.ID]*hst.State{hst.ID{}: nil}, nil},
+		{"long match", "0123456789abcdeffedcba9876543210", map[hst.ID]*hst.State{
+			hst.ID{}: nil,
+			id: {
+				ID:      id,
+				PID:     0xcafebabe,
+				ShimPID: 0xdeadbeef,
+				Config:  hst.Template(),
+			},
+		}, &hst.State{
+			ID:      id,
+			PID:     0xcafebabe,
+			ShimPID: 0xdeadbeef,
+			Config:  hst.Template(),
+		}},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, got := tryIdentifierEntries(msg, tc.s, func() map[hst.ID]*hst.State { return tc.entries })
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("tryIdentifier: %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}

cmd/hakurei/print.go

@@ -215,7 +215,7 @@ func printPs(output io.Writer, now time.Time, s state.Store, short, flagJSON boo
 			encodeJSON(log.Fatal, output, short, v)
 		} else {
 			for _, e := range exp {
-				mustPrintln(output, e.s[:8])
+				mustPrintln(output, shortIdentifierString(e.s))
 			}
 		}
 		return
@@ -237,12 +237,12 @@ func printPs(output io.Writer, now time.Time, s state.Store, short, flagJSON boo
 			as = strconv.Itoa(e.Config.Identity)
 			id := e.Config.ID
 			if id == "" {
-				id = "app.hakurei." + e.s[:8]
+				id = "app.hakurei." + shortIdentifierString(e.s)
 			}
 			as += " (" + id + ")"
 		}
 		t.Printf("\t%s\t%d\t%s\t%s\n",
-			e.s[:8], e.PID, as, now.Sub(e.Time).Round(time.Second).String())
+			shortIdentifierString(e.s), e.PID, as, now.Sub(e.Time).Round(time.Second).String())
 	}
 }
 

cmd/hakurei/print_test.go

@@ -523,13 +523,13 @@ func TestPrintPs(t *testing.T) {
 		{"state corruption", map[hst.ID]*hst.State{hst.ID{}: testState}, false, false, "    Instance    PID    Application    Uptime\n"},
 
 		{"valid pd", map[hst.ID]*hst.State{testID: {ID: testID, PID: 1 << 8, Config: new(hst.Config), Time: testAppTime}}, false, false, `    Instance    PID    Application                 Uptime
-    8e2c76b0    256    0 (app.hakurei.8e2c76b0)    1h2m32s
+    4cf073bd    256    0 (app.hakurei.4cf073bd)    1h2m32s
 `},
 
 		{"valid", map[hst.ID]*hst.State{testID: testState}, false, false, `    Instance    PID           Application                  Uptime
-    8e2c76b0    3405691582    9 (org.chromium.Chromium)    1h2m32s
+    4cf073bd    3405691582    9 (org.chromium.Chromium)    1h2m32s
 `},
-		{"valid short", map[hst.ID]*hst.State{testID: testState}, true, false, "8e2c76b0\n"},
+		{"valid short", map[hst.ID]*hst.State{testID: testState}, true, false, "4cf073bd\n"},
 		{"valid json", map[hst.ID]*hst.State{testID: testState}, false, true, `{
   "8e2c76b066dabe574cf073bdb46eb5c1": {
     "instance": "8e2c76b066dabe574cf073bdb46eb5c1",