refactor: improve error handling resolver and syscall

acheron.go

@@ -57,17 +57,21 @@ func (a *Acheron) HashString(s string) uint64 {
 
 // GetSyscall returns the Syscall struct for the given function hash.
 func (a *Acheron) GetSyscall(fnHash uint64) (*resolver.Syscall, error) {
-	return a.resolver.GetSyscall(fnHash)
+	if sys := a.resolver.GetSyscall(fnHash); sys == nil {
+		return nil, fmt.Errorf("failed with code: %d", ErrSyscallNotFound)
+	} else {
+		return sys, nil
+	}
 }
 
 // Syscall executes an indirect syscall with the given function hash and arguments. Returns the error code if it fails.
 func (a *Acheron) Syscall(fnHash uint64, args ...uintptr) error {
-	sys, err := a.resolver.GetSyscall(fnHash)
-	if err != nil {
-		return err
-	}
-	if errCode := execIndirectSyscall(sys.SSN, sys.TrampolineAddr, args...); errCode < 0 { // !NT_SUCCESS
-		return fmt.Errorf("syscall failed with error code %d", errCode)
+	if sys := a.resolver.GetSyscall(fnHash); sys == nil {
+		return fmt.Errorf("failed with: %d", ErrSyscallNotFound)
+	} else {
+		if st := execIndirectSyscall(sys.SSN, sys.TrampolineAddr, args...); !NT_SUCCESS(st) {
+			return fmt.Errorf("failed with: %d", st)
+		}
 	}
 	return nil
 }

internal/resolver/resolver.go

@@ -2,5 +2,5 @@ package resolver
 
 type Resolver interface {
 	// GetSyscallSSN returns the syscall SSN.
-	GetSyscall(funcNameHash uint64) (*Syscall, error)
+	GetSyscall(funcNameHash uint64) *Syscall
 }

internal/resolver/rvasort/resolver.go

@@ -1,8 +1,6 @@
 package rvasort
 
 import (
-	"errors"
-	"fmt"
 	"sort"
 
 	"github.com/f1zm0/acheron/internal/resolver"
@@ -51,9 +49,10 @@ func NewResolver(h hashing.HashFunction) (resolver.Resolver, error) {
 	return r, nil
 }
 
-func (r *ssnSortResolver) GetSyscall(fnHash uint64) (*resolver.Syscall, error) {
+// GetSyscall returns the Syscall struct for the given function hash, or nil if not found.
+func (r *ssnSortResolver) GetSyscall(fnHash uint64) *resolver.Syscall {
 	if v, ok := r.syscallStubs[fnHash]; ok {
-		return v, nil
+		return v
 	}
-	return nil, errors.New(fmt.Sprintf("syscall with hash %d not found", fnHash))
+	return nil
 }