go-vise

commit 7ea16f9137b46ff746f6ba40d3afc7b305d98f87
parent 5769abf3366f78392dd9ad59607fde3bfe3e63b3
Author: lash <dev@holbrook.no>
Date:   Sun, 22 Sep 2024 16:21:36 +0100

Add read only modifier to database

Diffstat:
M
db/gdbm/gdbm.go
 | 
36
+++++++++++++++++++++++++++++++-----
M
engine/db.go
 | 
2
+-
M
state/state.go
 | 
6
+++++-

3 files changed, 37 insertions(+), 7 deletions(-)
diff --git a/db/gdbm/gdbm.go b/db/gdbm/gdbm.go
@@ -3,6 +3,7 @@ package gdbm
 import (
 	"context"
 	"errors"
+	"fmt"
 	"os"
 
 	gdbm "github.com/graygnuorg/go-gdbm"
@@ -14,6 +15,7 @@ import (
 type gdbmDb struct {
 	*db.DbBase
 	conn *gdbm.Database
+	readOnly bool
 	prefix uint8
 }
 
@@ -25,6 +27,18 @@ func NewGdbmDb() *gdbmDb {
 	return db
 }
 
+// WithReadOnly sets database as read only.
+//
+// There may exist more than one instance of read-only
+// databases to the same file at the same time.
+// However, only one single write database.
+//
+// Readonly cannot be set when creating a new database.
+func(gdb *gdbmDb) WithReadOnly() *gdbmDb {
+	gdb.readOnly = true
+	return gdb
+}
+
 // String implements the string interface.
 func(gdb *gdbmDb) String() string {
 	fn, err := gdb.conn.FileName()
@@ -41,18 +55,30 @@ func(gdb *gdbmDb) Connect(ctx context.Context, connStr string) error {
 		return nil
 	}
 	var db *gdbm.Database
+	cfg := gdbm.DatabaseConfig{
+		FileName: connStr,
+		Flags: gdbm.OF_NOLOCK | gdbm.OF_PREREAD,
+		FileMode: 0600,
+	}
+
 	_, err := os.Stat(connStr)
 	if err != nil {
 		if !errors.Is(err.(*os.PathError).Unwrap(), os.ErrNotExist) {
-			return err
+			return fmt.Errorf("db path lookup err: %v", err)
 		}
-		db, err = gdbm.Open(connStr, gdbm.ModeWrcreat)
+		if gdb.readOnly {
+			return fmt.Errorf("cannot open new database readonly")
+		}
+		cfg.Mode = gdbm.ModeReader | gdbm.ModeWrcreat
 	} else {
-		db, err = gdbm.Open(connStr, gdbm.ModeWriter | gdbm.ModeReader)
+		cfg.Mode = gdbm.ModeReader
+		if !gdb.readOnly {
+			cfg.Mode |= gdbm.ModeWriter
+		}
 	}
-
+	db, err = gdbm.OpenConfig(cfg)
 	if err != nil {
-		return err
+		return fmt.Errorf("db open err: %v", err)
 	}
 	logg.DebugCtxf(ctx, "gdbm connected", "connstr", connStr)
 	gdb.conn = db
diff --git a/engine/db.go b/engine/db.go
@@ -244,7 +244,7 @@ func(en *DefaultEngine) ensurePersist() error {
 	} else {
 		en.ca = cac
 	}
-	logg.Tracef("set persister", "st", st, "cac", cac)
+	logg.Tracef("set persister", "st", st, "cac", cac, "session", en.cfg.SessionId)
 	en.pe = en.pe.WithContent(st, cac)
 	err := en.pe.Load(en.cfg.SessionId)
 	if err != nil {
diff --git a/state/state.go b/state/state.go
@@ -7,6 +7,10 @@ import (
 	"git.defalsify.org/vise.git/lang"
 )
 
+const (
+	INPUT_LIMIT = 255
+)
+
 var (
 	IndexError = fmt.Errorf("already at first index")
 	MaxLevel = 128
@@ -347,7 +351,7 @@ func(st *State) GetInput() ([]byte, error) {
 // SetInput is used to record the latest client input.
 func(st *State) SetInput(input []byte) error {
 	l := len(input)
-	if l > 255 {
+	if l > INPUT_LIMIT {
 		return fmt.Errorf("input size %v too large (limit %v)", l, 255)
 	}
 	st.input = input