Fix system calls returning errno values instead of setting errno.

kernel/descriptor.cpp

@@ -608,7 +608,7 @@ int Descriptor::utimens(ioctx_t* ctx, const struct timespec* user_times)
 		return -1;
 	if ( !valid_utimens_timespec(times[0]) ||
 	     !valid_utimens_timespec(times[1]) )
-		return errno = EINVAL;
+		return errno = EINVAL, -1;
 	// TODO: Regardless of dflags, check if the user/group can utimens.
 	return vnode->utimens(ctx, times);
 }

kernel/io.cpp

@@ -282,7 +282,7 @@ int sys_ftruncate(int fd, off_t length)
 int sys_fstatat(int dirfd, const char* path, struct stat* st, int flags)
 {
 	if ( flags & ~(AT_SYMLINK_NOFOLLOW) )
-		return errno = EINVAL;
+		return errno = EINVAL, -1;
 	char* pathcopy = GetStringFromUser(path);
 	if ( !pathcopy )
 		return -1;
@@ -319,7 +319,7 @@ int sys_fstatvfs(int fd, struct statvfs* stvfs)
 int sys_fstatvfsat(int dirfd, const char* path, struct statvfs* stvfs, int flags)
 {
 	if ( flags & ~(AT_SYMLINK_NOFOLLOW) )
-		return errno = EINVAL;
+		return errno = EINVAL, -1;
 	char* pathcopy = GetStringFromUser(path);
 	if ( !pathcopy )
 		return -1;

kernel/net/tcp.cpp

@@ -2016,7 +2016,7 @@ ssize_t TCPSocket::send_unlocked(ioctx_t* ctx,
 			if ( sockerr )
 				return errno = sockerr, -1;
 			if ( ctx->dflags & O_NONBLOCK )
-				return errno = EWOULDBLOCK;
+				return errno = EWOULDBLOCK, -1;
 			if ( !kthread_cond_wait_signal(&transmit_cond, &tcp_lock) )
 				return errno = EINTR, -1;
 		}

kernel/signal.cpp

@@ -114,7 +114,7 @@ int sys_sigaction(int signum,
                   struct sigaction* user_oldact)
 {
 	if ( signum < 0 || signum == 0 /* null signal */ || SIG_MAX_NUM <= signum )
-		return errno = EINVAL;
+		return errno = EINVAL, -1;
 
 	Process* process = CurrentProcess();
 	ScopedLock lock(&process->signal_lock);

kernel/tty.cpp

@@ -760,7 +760,7 @@ int TTY::tcflow(ioctx_t* /*ctx*/, int action)
 	case TCOON: break; // TODO: Resume suspended output.
 	case TCIOFF: break; // TODO: Transmit STOP character.
 	case TCION: break; // TODO: Transmit START character.
-	default: return errno = EINVAL -1;
+	default: return errno = EINVAL, -1;
 	}
 	return 0;
 }