Fixes aof file permission with arbitrary user

core/aof.go

@@ -2,11 +2,8 @@ package core
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"strings"
-
-	"github.com/dicedb/dice/config"
 )
 
 // TODO: Support Expiration
@@ -17,17 +14,3 @@ func dumpKey(fp *os.File, key string, obj *Obj) {
 	tokens := strings.Split(cmd, " ")
 	fp.Write(Encode(tokens, false))
 }
-
-// TODO: To to new and switch
-func DumpAllAOF() {
-	fp, err := os.OpenFile(config.AOFFile, os.O_CREATE|os.O_WRONLY, os.ModeAppend)
-	if err != nil {
-		fmt.Print("error", err)
-		return
-	}
-	log.Println("rewriting AOF file at", config.AOFFile)
-	for k, obj := range store {
-		dumpKey(fp, k, obj)
-	}
-	log.Println("AOF file rewrite complete")
-}

core/aof_darwin.go

@@ -0,0 +1,41 @@
+package core
+
+import (
+	"fmt"
+	"github.com/dicedb/dice/config"
+	"log"
+	"os"
+)
+
+func FileSync(f *os.File) error {
+	_, _, err := syscall.Syscall(syscall.SYS_FCNTL, f.Fd(), syscall.F_FULLFSYNC, 0)
+	if err == 0 {
+		return nil
+	}
+	return err
+}
+
+// TODO: To to new and switch
+func DumpAllAOF() error {
+	fp, err := os.OpenFile(config.AOFFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	/* Note: A close function also returns an error, a plain defer is harmful.
+	A successful close does not guarantee that the data has been successfully saved
+	to disk,as the kernel uses the buffer cache to defer writes or write calls delays the writing
+	to disk to mitigate cost of frequent writes to disk. A more reliable method is to use
+	fsync() or f.Sync() and Close()
+	*/
+	defer func() {
+		if err := fp.Close(); err != nil {
+			fmt.Print("error", err)
+			return
+		}
+	}()
+	log.Println("rewriting AOF file at", config.AOFFile)
+	for k, obj := range store {
+		dumpKey(fp, k, obj)
+	}
+	return FileSync(fp)
+}

core/aof_linux.go

@@ -0,0 +1,33 @@
+package core
+
+import (
+	"fmt"
+	"github.com/dicedb/dice/config"
+	"log"
+	"os"
+)
+
+// TODO: To to new and switch
+func DumpAllAOF() error {
+	fp, err := os.OpenFile(config.AOFFile, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	/* Note: A close function also returns an error, a plain defer is harmful.
+	A successful close does not guarantee that the data has been successfully saved
+	to disk,as the kernel uses the buffer cache to defer writes or write calls delays the writing
+	to disk to mitigate cost of frequent writes to disk. A more reliable method is to use
+	fsync() or f.Sync() and Close()
+	*/
+	defer func() {
+		if err := fp.Close(); err != nil {
+			fmt.Print("error", err)
+			return
+		}
+	}()
+	log.Println("rewriting AOF file at", config.AOFFile)
+	for k, obj := range store {
+		dumpKey(fp, k, obj)
+	}
+	return fp.Sync()
+}

core/eval.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"log"
 	"strconv"
 	"syscall"
 	"time"
@@ -46,7 +47,9 @@ func evalPING(args []string) []byte {
 // evalSET puts a new <key, value> pair in db as in the args
 // args must contain key and value.
 // args can also contain multiple options -
-//	 	EX or ex which will set the expiry time(in secs) for the key
+//
+//	EX or ex which will set the expiry time(in secs) for the key
+//
 // Returns encoded error response if at least a <key, value> pair is not part of args
 // Returns encoded error response if expiry tme value in not integer
 // Returns encoded OK RESP once new entry is added
@@ -116,8 +119,9 @@ func evalGET(args []string) []byte {
 // evalTTL returns Time-to-Live in secs for the queried key in args
 // The key should be the only param in args else returns with an error
 // Returns	RESP encoded time (in secs) remaining for the key to expire
-//			RESP encoded -2 stating key doesn't exist or key is expired
-//			RESP encoded -1 in case no expiration is set on the key
+//
+//	RESP encoded -2 stating key doesn't exist or key is expired
+//	RESP encoded -1 in case no expiration is set on the key
 func evalTTL(args []string) []byte {
 	if len(args) != 1 {
 		return Encode(errors.New("ERR wrong number of arguments for 'ttl' command"), false)
@@ -206,7 +210,13 @@ func evalBGREWRITEAOF(args []string) []byte {
 	newChild, _, _ := syscall.Syscall(syscall.SYS_FORK, 0, 0, 0)
 	if newChild == 0 {
 		//We are inside child process now, so we'll start flushing to disk.
-		DumpAllAOF()
+		err := DumpAllAOF()
+		if err != nil {
+			return Encode(errors.New("ERR AOF failed"), false)
+		} else {
+			log.Println("AOF file rewrite completed")
+		}
+		syscall.Exit(0)
 		return []byte("")
 	} else {
 		//Back to main thread

main.go

@@ -24,6 +24,8 @@ func main() {
 
 	var sigs chan os.Signal = make(chan os.Signal, 1)
 	signal.Notify(sigs, syscall.SIGTERM, syscall.SIGINT)
+	//Need to clean up zombie process as soon as they appear once AOF background thread exits.
+	signal.Ignore(syscall.SIGCHLD)
 	var wg sync.WaitGroup
 	wg.Add(1)