+ if (flag) {
+ int ret = __syscall(SYS_faccessat2, fd, filename, amode, flag);
+ if (ret != -ENOSYS) return __syscall_ret(ret);
+ }
+
+ if (flag & ~AT_EACCESS)
+ return __syscall_ret(-EINVAL);
+
+ if (!flag || (getuid()==geteuid() && getgid()==getegid()))
+ return syscall(SYS_faccessat, fd, filename, amode);
+
+ char stack[1024];
+ sigset_t set;
+ pid_t pid;
+ int status;
+ int ret, p[2];
+
+ if (pipe2(p, O_CLOEXEC)) return __syscall_ret(-EBUSY);
+ struct ctx c = { .fd = fd, .filename = filename, .amode = amode, .p = p[1] };
+
+ __block_all_sigs(&set);
+
+ pid = __clone(checker, stack+sizeof stack, 0, &c);
+ __syscall(SYS_close, p[1]);
+
+ if (pid<0 || __syscall(SYS_read, p[0], &ret, sizeof ret) != sizeof(ret))
+ ret = -EBUSY;
+ __syscall(SYS_close, p[0]);
+ __syscall(SYS_wait4, pid, &status, __WCLONE, 0);
+
+ __restore_sigs(&set);
+
+ return __syscall_ret(ret);