graphene/LibOS/shim/src/shim_parser.c

/* Copyright (C) 2014 Stony Brook University
   This file is part of Graphene Library OS.

   Graphene Library OS is free software: you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public License
   as published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   Graphene Library OS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/*
 * shim_parser.c
 *
 * This file contains codes for parsing system call arguements for debug
 * purpose.
 */

#include <shim_internal.h>
#include <shim_tls.h>
#include <shim_table.h>
#include <shim_thread.h>
#include <shim_utils.h>

#include <pal.h>
#include <pal_error.h>

#include <errno.h>

#include <asm/fcntl.h>
#include <asm/unistd.h>
#include <asm/prctl.h>
#include <asm/mman.h>
#include <asm/ioctls.h>

#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/futex.h>
#include <linux/wait.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/un.h>

static void parse_open_flags    (va_list);
static void parse_open_mode     (va_list);
static void parse_access_mode   (va_list);
static void parse_clone_flags   (va_list);
static void parse_mmap_prot     (va_list);
static void parse_mmap_flags    (va_list);
static void parse_exec_args     (va_list);
static void parse_exec_envp     (va_list);
static void parse_pipe_fds      (va_list);
static void parse_signum        (va_list);
static void parse_sigmask       (va_list);
static void parse_sigprocmask_how (va_list);
static void parse_timespec      (va_list);
static void parse_sockaddr      (va_list);
static void parse_domain        (va_list);
static void parse_socktype      (va_list);
static void parse_futexop       (va_list);
static void parse_ioctlop       (va_list);
static void parse_fcntlop       (va_list);
static void parse_seek          (va_list);
static void parse_at_fdcwd      (va_list);
static void parse_wait_option   (va_list);

struct parser_table {
    int slow;
    int stop;
    void (*parser[6]) (va_list);
} syscall_parser_table[LIBOS_SYSCALL_BOUND] = {
    { .slow = 1, .parser = { NULL } }, /* read */
    { .slow = 1, .parser = { NULL } }, /* write */
    { .slow = 1,                       /* open */
      .parser = { NULL, &parse_open_flags, &parse_open_mode, } },
    { .slow = 0, .parser = { NULL } }, /* close */
    { .slow = 0, .parser = { NULL } }, /* stat */
    { .slow = 0, .parser = { NULL } }, /* fstat */
    { .slow = 0, .parser = { NULL } }, /* lstat */
    { .slow = 1, .parser = { NULL } }, /* poll */
    { .slow = 0, .parser = { NULL, NULL, &parse_seek } }, /* lseek */
    { .slow = 1,                       /* mmap */
      .parser = { NULL, NULL, &parse_mmap_prot, &parse_mmap_flags } },
    { .slow = 1,                       /* mprotect */
      .parser = { NULL, NULL, &parse_mmap_prot } },
    { .slow = 1, .parser = { NULL } }, /* munmap */
    { .slow = 0, .parser = { NULL } }, /* brk */
    { .slow = 0, .parser = { &parse_signum } }, /* rt_sigaction */
    { .slow = 0,                       /* rt_sigprocmask */
      .parser = { &parse_sigprocmask_how, &parse_sigmask, &parse_sigmask } },
    { .slow = 0, .parser = { NULL } }, /* rt_sigreturn */
    { .slow = 1, .parser = { NULL, &parse_ioctlop } }, /* ioctl */
    { .slow = 1, .parser = { NULL } }, /* pread64 */
    { .slow = 0, .parser = { NULL } }, /* pwrite64 */
    { .slow = 1, .parser = { NULL } }, /* readv */
    { .slow = 0, .parser = { NULL } }, /* writev */
    { .slow = 0,                       /* access */
      .parser = { NULL, &parse_access_mode } },
    { .slow = 0,                       /* pipe */
      .parser = { &parse_pipe_fds } },
    { .slow = 0, .parser = { NULL } }, /* select */
    { .slow = 0, .parser = { NULL } }, /* sched_yield */
    { .slow = 0, .parser = { NULL } }, /* mremap */
    { .slow = 0, .parser = { NULL } }, /* msync */
    { .slow = 0, .parser = { NULL } }, /* mincore */
    { .slow = 0, .parser = { NULL } }, /* madvise */
    { .slow = 0, .parser = { NULL } }, /* shmget */
    { .slow = 0, .parser = { NULL } }, /* shmat */
    { .slow = 0, .parser = { NULL } }, /* shmctl */
    { .slow = 0, .parser = { NULL } }, /* dup */
    { .slow = 0, .parser = { NULL } }, /* dup2 */
    { .slow = 1, .parser = { NULL } }, /* pause */
    { .slow = 1,
      .parser = { &parse_timespec } }, /* nanosleep */
    { .slow = 0, .parser = { NULL } }, /* getitimer */
    { .slow = 0, .parser = { NULL } }, /* alarm */
    { .slow = 0, .parser = { NULL } }, /* setitimer */
    { .slow = 0, .parser = { NULL } }, /* getpid */
    { .slow = 0, .parser = { NULL } }, /* sendfile */
    { .slow = 0, .parser = { &parse_domain, &parse_socktype } }, /* socket */

    { .slow = 1, .parser = { NULL, &parse_sockaddr } }, /* connect */
    { .slow = 1, .parser = { NULL } }, /* accept */
    { .slow = 0, .parser = { NULL } }, /* sendto */
    { .slow = 0, .parser = { NULL } }, /* recvfrom */
    { .slow = 0, .parser = { NULL } }, /* sendmsg */
    { .slow = 1, .parser = { NULL } }, /* recvmsg */
    { .slow = 0, .parser = { NULL } }, /* shutdown */
    { .slow = 0, .parser = { NULL } }, /* bind */
    { .slow = 0, .parser = { NULL } }, /* listen */
    { .slow = 0, .parser = { NULL } }, /* getsockname */
    { .slow = 0, .parser = { NULL } }, /* getpeername */
    { .slow = 0, .stop = 3,            /* socketpair */
      .parser = { &parse_domain, &parse_socktype, NULL, &parse_pipe_fds } },
    { .slow = 0, .parser = { NULL } }, /* setsockopt */
    { .slow = 0, .parser = { NULL } }, /* getsockopt */
    { .slow = 1, .parser = { &parse_clone_flags } }, /* clone */
    { .slow = 1, .parser = { NULL } }, /* fork */
    { .slow = 1, .parser = { NULL } }, /* vfork */
    { .slow = 1,                       /* execve */
      .parser = { NULL, &parse_exec_args, &parse_exec_envp, } },
    { .slow = 0, .parser = { NULL } }, /* exit */
    { .slow = 1, .parser = { NULL, NULL,
                             &parse_wait_option,
                             NULL } }, /* wait4 */
    { .slow = 0, .parser = { NULL, &parse_signum, } }, /* kill */
    { .slow = 0, .parser = { NULL } }, /* uname */
    { .slow = 0, .parser = { NULL } }, /* semget */
    { .slow = 1, .parser = { NULL } }, /* semop */
    { .slow = 0, .parser = { NULL } }, /* semctl */
    { .slow = 0, .parser = { NULL } }, /* shmdt */
    { .slow = 1, .parser = { NULL } }, /* msgget */
    { .slow = 1, .parser = { NULL } }, /* msgsnd */
    { .slow = 1, .parser = { NULL } }, /* msgrcv */
    { .slow = 1, .parser = { NULL } }, /* msgctl */
    { .slow = 0, .parser = { NULL, &parse_fcntlop } }, /* fcntl */
    { .slow = 0, .parser = { NULL } }, /* flock */
    { .slow = 0, .parser = { NULL } }, /* fsync */
    { .slow = 0, .parser = { NULL } }, /* fdatasync */
    { .slow = 0, .parser = { NULL } }, /* truncate */
    { .slow = 0, .parser = { NULL } }, /* ftruncate */
    { .slow = 0, .parser = { NULL } }, /* getdents */
    { .slow = 0, .parser = { NULL } }, /* getcwd */
    { .slow = 0, .parser = { NULL } }, /* chdir */
    { .slow = 0, .parser = { NULL } }, /* fchdir */
    { .slow = 0, .parser = { NULL } }, /* rename */
    { .slow = 0, .parser = { NULL } }, /* mkdir */
    { .slow = 0, .parser = { NULL } }, /* rmdir */
    { .slow = 0, .parser = { NULL, &parse_open_mode } }, /* creat */
    { .slow = 0, .parser = { NULL } }, /* link */
    { .slow = 0, .parser = { NULL } }, /* unlink */
    { .slow = 0, .parser = { NULL } }, /* symlink */
    { .slow = 0, .parser = { NULL } }, /* readlink */
    { .slow = 0, .parser = { NULL } }, /* chmod */
    { .slow = 0, .parser = { NULL } }, /* fchmod */
    { .slow = 0, .parser = { NULL } }, /* chown */
    { .slow = 0, .parser = { NULL } }, /* fchown */
    { .slow = 0, .parser = { NULL } }, /* lchown */
    { .slow = 0, .parser = { NULL } }, /* umask */
    { .slow = 0, .parser = { NULL } }, /* gettimeofday */
    { .slow = 0, .parser = { NULL } }, /* getrlimit */
    { .slow = 0, .parser = { NULL } }, /* getrusage */
    { .slow = 0, .parser = { NULL } }, /* sysinfo */
    { .slow = 0, .parser = { NULL } }, /* times */
    { .slow = 0, .parser = { NULL } }, /* ptrace */
    { .slow = 0, .parser = { NULL } }, /* getuid */
    { .slow = 0, .parser = { NULL } }, /* syslog */
    { .slow = 0, .parser = { NULL } }, /* getgid */
    { .slow = 0, .parser = { NULL } }, /* setuid */
    { .slow = 0, .parser = { NULL } }, /* setgid */
    { .slow = 0, .parser = { NULL } }, /* geteuid */
    { .slow = 0, .parser = { NULL } }, /* getegid */
    { .slow = 0, .parser = { NULL } }, /* setpgid */
    { .slow = 0, .parser = { NULL } }, /* getppid */
    { .slow = 0, .parser = { NULL } }, /* getpgrp */
    { .slow = 0, .parser = { NULL } }, /* setsid */
    { .slow = 0, .parser = { NULL } }, /* setreuid */
    { .slow = 0, .parser = { NULL } }, /* setregid */
    { .slow = 0, .parser = { NULL } }, /* getgroups */
    { .slow = 0, .parser = { NULL } }, /* setgroups */
    { .slow = 0, .parser = { NULL } }, /* setresuid */
    { .slow = 0, .parser = { NULL } }, /* getresuid */
    { .slow = 0, .parser = { NULL } }, /* setresgid */
    { .slow = 0, .parser = { NULL } }, /* getresgid */
    { .slow = 0, .parser = { NULL } }, /* getpgid */
    { .slow = 0, .parser = { NULL } }, /* setfsuid */
    { .slow = 0, .parser = { NULL } }, /* setfsgid */
    { .slow = 0, .parser = { NULL } }, /* getsid */
    { .slow = 0, .parser = { NULL } }, /* capget */
    { .slow = 0, .parser = { NULL } }, /* capset */
    { .slow = 0, .parser = { NULL } }, /* rt_sigpending */
    { .slow = 0, .parser = { NULL } }, /* rt_sigtimedwait */
    { .slow = 0, .parser = { NULL } }, /* rt_sigqueueinfo */
    { .slow = 1, .parser = { NULL } }, /* rt_sigsuspend */
    { .slow = 0, .parser = { NULL } }, /* sigaltstack */
    { .slow = 0, .parser = { NULL } }, /* utime */
    { .slow = 0, .parser = { NULL } }, /* mknod */
    { .slow = 0, .parser = { NULL } }, /* uselib */
    { .slow = 0, .parser = { NULL } }, /* personality */
    { .slow = 0, .parser = { NULL } }, /* ustat */
    { .slow = 0, .parser = { NULL } }, /* statfs */
    { .slow = 0, .parser = { NULL } }, /* fstatfs */
    { .slow = 0, .parser = { NULL } }, /* sysfs */
    { .slow = 0, .parser = { NULL } }, /* getpriority */
    { .slow = 0, .parser = { NULL } }, /* setpriority */
    { .slow = 0, .parser = { NULL } }, /* sched_setparam */
    { .slow = 0, .parser = { NULL } }, /* sched_getparam */
    { .slow = 0, .parser = { NULL } }, /* sched_setscheduler */
    { .slow = 0, .parser = { NULL } }, /* sched_getscheduler */
    { .slow = 0, .parser = { NULL } }, /* sched_get_priority_max */
    { .slow = 0, .parser = { NULL } }, /* sched_get_priority_min */
    { .slow = 0, .parser = { NULL } }, /* sched_rr_get_interval */
    { .slow = 0, .parser = { NULL } }, /* mlock */
    { .slow = 0, .parser = { NULL } }, /* munlock */
    { .slow = 0, .parser = { NULL } }, /* mlockall */
    { .slow = 0, .parser = { NULL } }, /* munlockall */
    { .slow = 0, .parser = { NULL } }, /* vhangup */
    { .slow = 0, .parser = { NULL } }, /* modify_ldt */
    { .slow = 0, .parser = { NULL } }, /* pivot_root */
    { .slow = 0, .parser = { NULL } }, /* _sysctl */
    { .slow = 0, .parser = { NULL } }, /* prctl */
    { .slow = 0, .parser = { NULL } }, /* arch_prctl */
    { .slow = 0, .parser = { NULL } }, /* adjtimex */
    { .slow = 0, .parser = { NULL } }, /* setrlimit */
    { .slow = 0, .parser = { NULL } }, /* chroot */
    { .slow = 0, .parser = { NULL } }, /* sync */
    { .slow = 0, .parser = { NULL } }, /* acct */
    { .slow = 0, .parser = { NULL } }, /* settimeofday */
    { .slow = 0, .parser = { NULL } }, /* mount */
    { .slow = 0, .parser = { NULL } }, /* umount2 */
    { .slow = 0, .parser = { NULL } }, /* swapon */
    { .slow = 0, .parser = { NULL } }, /* swapoff */
    { .slow = 0, .parser = { NULL } }, /* reboot */
    { .slow = 0, .parser = { NULL } }, /* sethostname */
    { .slow = 0, .parser = { NULL } }, /* setdomainname */
    { .slow = 0, .parser = { NULL } }, /* iopl */
    { .slow = 0, .parser = { NULL } }, /* ioperm */
    { .slow = 0, .parser = { NULL } }, /* create_module */
    { .slow = 0, .parser = { NULL } }, /* init_module */
    { .slow = 0, .parser = { NULL } }, /* delete_module */
    { .slow = 0, .parser = { NULL } }, /* get_kernel_syms */
    { .slow = 0, .parser = { NULL } }, /* query_module */
    { .slow = 0, .parser = { NULL } }, /* quotactl */
    { .slow = 0, .parser = { NULL } }, /* nfsservctl */
    { .slow = 0, .parser = { NULL } }, /* getpmsg */
    { .slow = 0, .parser = { NULL } }, /* putpmsg */
    { .slow = 0, .parser = { NULL } }, /* afs_syscall */
    { .slow = 0, .parser = { NULL } }, /* tuxcall */
    { .slow = 0, .parser = { NULL } }, /* security */
    { .slow = 0, .parser = { NULL } }, /* gettid */
    { .slow = 0, .parser = { NULL } }, /* readahead */
    { .slow = 0, .parser = { NULL } }, /* setxattr */
    { .slow = 0, .parser = { NULL } }, /* lsetxattr */
    { .slow = 0, .parser = { NULL } }, /* fsetxattr */
    { .slow = 0, .parser = { NULL } }, /* getxattr */
    { .slow = 0, .parser = { NULL } }, /* lgetxattr */
    { .slow = 0, .parser = { NULL } }, /* fgetxattr */
    { .slow = 0, .parser = { NULL } }, /* listxattr */
    { .slow = 0, .parser = { NULL } }, /* llistxattr */
    { .slow = 0, .parser = { NULL } }, /* flistxattr */
    { .slow = 0, .parser = { NULL } }, /* removexattr */
    { .slow = 0, .parser = { NULL } }, /* lremovexattr */
    { .slow = 0, .parser = { NULL } }, /* fremovexattr */
    { .slow = 0, .parser = { NULL, &parse_signum } }, /* tkill */
    { .slow = 0, .parser = { NULL } }, /* time */
    { .slow = 1, .parser = { NULL, &parse_futexop } }, /* futex */
    { .slow = 0, .parser = { NULL } }, /* sched_setaffinity */
    { .slow = 0, .parser = { NULL } }, /* sched_getaffinity */
    { .slow = 0, .parser = { NULL } }, /* set_thread_area */
    { .slow = 0, .parser = { NULL } }, /* io_setup */
    { .slow = 0, .parser = { NULL } }, /* io_destroy */
    { .slow = 0, .parser = { NULL } }, /* io_getevents */
    { .slow = 0, .parser = { NULL } }, /* io_submit */
    { .slow = 0, .parser = { NULL } }, /* io_cancel */
    { .slow = 0, .parser = { NULL } }, /* get_thread_area */
    { .slow = 0, .parser = { NULL } }, /* lookup_dcookie */
    { .slow = 0, .parser = { NULL } }, /* epoll_create */
    { .slow = 0, .parser = { NULL } }, /* epoll_ctl_old */
    { .slow = 0, .parser = { NULL } }, /* epoll_wait_old */
    { .slow = 0, .parser = { NULL } }, /* remap_file_pages */
    { .slow = 0, .parser = { NULL } }, /* getdents64 */
    { .slow = 0, .parser = { NULL } }, /* set_tid_address */
    { .slow = 0, .parser = { NULL } }, /* restart_syscall */
    { .slow = 0, .parser = { NULL } }, /* semtimedop */
    { .slow = 0, .parser = { NULL } }, /* fadvise64 */
    { .slow = 0, .parser = { NULL } }, /* timer_create */
    { .slow = 0, .parser = { NULL } }, /* timer_settime */
    { .slow = 0, .parser = { NULL } }, /* timer_gettime */
    { .slow = 0, .parser = { NULL } }, /* timer_getoverrun */
    { .slow = 0, .parser = { NULL } }, /* timer_delete */
    { .slow = 0, .parser = { NULL } }, /* clock_settime */
    { .slow = 0, .parser = { NULL } }, /* clock_gettime */
    { .slow = 0, .parser = { NULL } }, /* clock_getres */
    { .slow = 0, .parser = { NULL } }, /* clock_nanosleep */
    { .slow = 0, .parser = { NULL } }, /* exit_group */
    { .slow = 1, .parser = { NULL } }, /* epoll_wait */
    { .slow = 0, .parser = { NULL } }, /* epoll_ctl */
    { .slow = 0,
      .parser = { NULL, NULL, &parse_signum } }, /* tgkill */
    { .slow = 0, .parser = { NULL } }, /* utimes */
    { .slow = 0, .parser = { NULL } }, /* vserver */
    { .slow = 0, .parser = { NULL } }, /* mbind */
    { .slow = 0, .parser = { NULL } }, /* set_mempolicy */
    { .slow = 0, .parser = { NULL } }, /* get_mempolicy */
    { .slow = 0, .parser = { NULL } }, /* mq_open */
    { .slow = 0, .parser = { NULL } }, /* mq_unlink */
    { .slow = 0, .parser = { NULL } }, /* mq_timedsend */
    { .slow = 0, .parser = { NULL } }, /* mq_timedreceive */
    { .slow = 0, .parser = { NULL } }, /* mq_notify */
    { .slow = 0, .parser = { NULL } }, /* mq_getsetattr */
    { .slow = 0, .parser = { NULL } }, /* kexec_load */
    { .slow = 1, .parser = { NULL } }, /* waitid */
    { .slow = 0, .parser = { NULL } }, /* add_key */
    { .slow = 0, .parser = { NULL } }, /* request_key */
    { .slow = 0, .parser = { NULL } }, /* keyctl */
    { .slow = 0, .parser = { NULL } }, /* ioprio_set */
    { .slow = 0, .parser = { NULL } }, /* ioprio_get */
    { .slow = 0, .parser = { NULL } }, /* inotify_init */
    { .slow = 0, .parser = { NULL } }, /* inotify_add_watch */
    { .slow = 0, .parser = { NULL } }, /* inotify_rm_watch */
    { .slow = 0, .parser = { NULL } }, /* migrate_pages */
    { .slow = 0, .parser = { &parse_at_fdcwd, NULL,
                             &parse_open_flags,
                             &parse_open_mode } }, /* openat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* mkdirat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* mknodat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* fchownat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* futimesat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* newfstatat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* unlinkat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* renameat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* linkat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* symlinkat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* readlinkat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* fchmodat */
    { .slow = 0, .parser = { &parse_at_fdcwd, } }, /* faccessat */
    { .slow = 0, .parser = { NULL } }, /* pselect6 */
    { .slow = 1, .parser = { NULL } }, /* ppoll */
    { .slow = 0, .parser = { NULL } }, /* unshare */
    { .slow = 0, .parser = { NULL } }, /* set_robust_list */
    { .slow = 0, .parser = { NULL } }, /* get_robust_list */
    { .slow = 0, .parser = { NULL } }, /* splice */
    { .slow = 0, .parser = { NULL } }, /* tee */
    { .slow = 0, .parser = { NULL } }, /* sync_file_range */
    { .slow = 0, .parser = { NULL } }, /* vmsplice */
    { .slow = 0, .parser = { NULL } }, /* move_pages */
    { .slow = 0, .parser = { NULL } }, /* utimensat */
    { .slow = 1, .parser = { NULL } }, /* epoll_pwait */
    { .slow = 0, .parser = { NULL } }, /* signalfd */
    { .slow = 0, .parser = { NULL } }, /* timerfd_create */
    { .slow = 0, .parser = { NULL } }, /* eventfd */
    { .slow = 0, .parser = { NULL } }, /* fallocate */
    { .slow = 0, .parser = { NULL } }, /* timerfd_settime */
    { .slow = 0, .parser = { NULL } }, /* timerfd_gettime */
    { .slow = 1, .parser = { NULL } }, /* accept4 */
    { .slow = 0, .parser = { NULL } }, /* signalfd4 */
    { .slow = 0, .parser = { NULL } }, /* eventfd2 */
    { .slow = 0, .parser = { NULL } }, /* epoll_create1 */
    { .slow = 0, .parser = { NULL } }, /* dup3 */
    { .slow = 0, .parser = { NULL } }, /* pipe2 */
    { .slow = 0, .parser = { NULL } }, /* inotify_init1 */
    { .slow = 0, .parser = { NULL } }, /* preadv */
    { .slow = 0, .parser = { NULL } }, /* pwritev */
    { .slow = 0, .parser = { NULL } }, /* rt_tgsigqueueinfo */
    { .slow = 0, .parser = { NULL } }, /* perf_event_open */
    { .slow = 0, .parser = { NULL } }, /* recvmmsg */

    [LIBOS_SYSCALL_BASE] =  { .slow = 0, .parser = { NULL } },

    { .slow = 1, .parser = { NULL } }, /* checkpoint */
    { .slow = 1, .parser = { NULL } }, /* restore */
    { .slow = 1, .parser = { NULL } }, /* msgpersist */
    { .slow = 1, .parser = { NULL } }, /* benchmark_ipc */
    { .slow = 1, .parser = { NULL } }, /* send_rpc */
    { .slow = 1, .parser = { NULL } }, /* recv_rpc */
};

static inline int is_pointer (const char * type)
{
    return type[strlen(type) - 1] == '*'
           || strcmp_static(type, "long")
           || strcmp_static(type, "unsigned long");
}

#define PRINTF(fmt, ...)                            \
    do {                                            \
        debug_printf(fmt, __VA_ARGS__);             \
    } while (0)
#define PUTS(str)                                   \
    do {                                            \
        debug_puts(str);                            \
    } while (0)
#define PUTCH(ch)                                   \
    do {                                            \
        debug_putch(ch);                            \
    } while (0)
#define VPRINTF(fmt, ap)                            \
    do {                                            \
        debug_vprintf(fmt, ap);                     \
    } while (0)

static inline void parse_string_arg (va_list ap)
{
    va_list ap_test_arg;
    va_copy(ap_test_arg, ap);
    const char* test_arg = va_arg(ap_test_arg, const char*);
    if (!test_user_string(test_arg)) {
        VPRINTF("\"%s\"", ap);
    } else {
        /* invalid memory region, print arg as ptr not string */
        VPRINTF("\"(invalid-addr %p)\"", ap);
    }
    va_end(ap_test_arg);
}

static inline void parse_pointer_arg (va_list ap)
{
    VPRINTF("%p", ap);
}

static inline void parse_integer_arg (va_list ap)
{
    VPRINTF("%d", ap);
}

static inline void parse_syscall_args (va_list ap)
{
    const char * arg_type = va_arg(ap, const char *);

    if (strcmp_static(arg_type, "const char *"))
        parse_string_arg(ap);
    else if (is_pointer(arg_type))
        parse_pointer_arg(ap);
    else
        parse_integer_arg(ap);
}

static inline void skip_syscall_args (va_list ap)
{
    const char * arg_type = va_arg(ap, const char *);

    if (strcmp_static(arg_type, "const char *"))
        va_arg(ap, const char *);
    else if (is_pointer(arg_type))
        va_arg(ap, void *);
    else
        va_arg(ap, int);
}

void sysparser_printf (const char * fmt, ...)
{
    va_list ap;
    va_start(ap, fmt);
    VPRINTF(fmt, ap);
    va_end(ap);
}

void parse_syscall_before (int sysno, const char * name, int nr, ...)
{
    if (!debug_handle)
        return;

    struct parser_table * parser = &syscall_parser_table[sysno];

    if (!parser->slow && !parser->stop)
        return;

    va_list ap;
    va_start(ap, nr);

    PRINTF("---- shim_%s(", name);

    for (int i = 0 ; i < nr ; i++) {
        if (parser->stop && parser->stop == i)
            goto dotdotdot;

        if (i)
            PUTCH(',');

        if (parser->parser[i]) {
            const char * type = va_arg(ap, const char *);
            __UNUSED(type); // type not needed on this path
            (*parser->parser[i])(ap);
        } else
            parse_syscall_args(ap);
    }

    PUTCH(')');
dotdotdot:
    PRINTF(" ... %s\n", name);
    va_end(ap);
}

void parse_syscall_after (int sysno, const char * name, int nr, ...)
{
    if (!debug_handle)
        return;

    struct parser_table * parser = &syscall_parser_table[sysno];

    va_list ap;
    va_start(ap, nr);

    const char * ret_type = va_arg(ap, const char *);

    if (parser->slow || parser->stop)
        PRINTF("---- return from shim_%s(...", name);
    else
        PRINTF("---- shim_%s(", name);

    unsigned long ret_ptr;
    int ret_val;

    if (is_pointer(ret_type))
        ret_ptr = (unsigned long) va_arg(ap, void *);
    else
        ret_val = va_arg(ap, int);

    if (!parser->slow || parser->stop)
        for (int i = 0 ; i < nr ; i++) {
            if (parser->stop && i < parser->stop) {
                skip_syscall_args(ap);
                continue;
            }

            if (i)
                PUTCH(',');

            if (parser->parser[i]) {
                const char * type = va_arg(ap, const char *);
                __UNUSED(type); // type not needed on this path
                (*parser->parser[i])(ap);
            } else
                parse_syscall_args(ap);
        }

    if (is_pointer(ret_type)) {
        if ((uint64_t) ret_ptr < (uint64_t) -4095L)
            PRINTF(") = 0x%08lx\n", ret_ptr);
        else
            PRINTF(") = %ld\n", (long) ret_ptr);
    } else {
        if (ret_val >= 0)
            PRINTF(") = %d\n", ret_val);
        else
            PRINTF(") = %d\n", ret_val);
    }

    va_end (ap);
}

static void parse_open_flags (va_list ap)
{
    int flags = va_arg(ap, int);

    if (flags & O_WRONLY) {
        PUTS("O_WRONLY");
        flags &= ~O_WRONLY;
    } else if (flags & O_RDWR) {
        PUTS("O_RDWR");
        flags &= ~O_RDWR;
    } else
        PUTS("O_RDONLY");

    if (flags & O_APPEND) {
        PUTS("|O_APPEND");
        flags &= ~O_APPEND;
    }
    if (flags & O_CREAT) {
        PUTS("|O_CREAT");
        flags &= ~O_CREAT;
    }
    if (flags & O_TRUNC) {
        PUTS("|O_TRUNC");
        flags &= ~O_TRUNC;
    }
    if (flags & O_EXCL) {
        PUTS("|O_EXCL");
        flags &= ~O_EXCL;
    }

    if (flags)
        PRINTF("|%o", flags);
}

static void parse_open_mode (va_list ap)
{
    VPRINTF("%04o", ap);
}

static void parse_access_mode (va_list ap)
{
    int mode = va_arg(ap, int);

    PUTS("F_OK");

    if (mode) {
        if (mode & R_OK)
            PUTS("|R_OK");
        if (mode & W_OK)
            PUTS("|W_OK");
        if (mode & X_OK)
            PUTS("|X_OK");
    }
}

static void parse_clone_flags (va_list ap)
{
    int flags = va_arg(ap, int);

#define FLG(n) { "CLONE_" #n, CLONE_##n, }
    const struct {
        const char * name; int flag;
    } all_flags[] = {
        FLG(VM), FLG(FS), FLG(FILES), FLG(SIGHAND), FLG(PTRACE), FLG(VFORK),
        FLG(PARENT), FLG(THREAD), FLG(NEWNS), FLG(SYSVSEM), FLG(SETTLS),
        FLG(PARENT_SETTID), FLG(CHILD_CLEARTID), FLG(DETACHED), FLG(UNTRACED),
        FLG(CHILD_SETTID), FLG(NEWUTS), FLG(NEWIPC), FLG(NEWUSER),
        FLG(NEWPID), FLG(NEWNET), FLG(IO),
    };
#undef FLG

    bool printed = false;
    for (size_t i = 0 ; i < sizeof(all_flags) / sizeof(all_flags[0]) ; i++)
        if (flags & all_flags[i].flag) {
            if (printed)
                PUTCH('|');
            else
                printed = true;
            PUTS(all_flags[i].name);
            flags &= ~all_flags[i].flag;
        }

#define CLONE_SIGNAL_MASK 0xff
    int exit_signal = flags & CLONE_SIGNAL_MASK;
    flags &= ~CLONE_SIGNAL_MASK;
    if (exit_signal) {
        if (exit_signal >= 0 && exit_signal <= NUM_KNOWN_SIGS)
            PRINTF("|%s", signal_name(exit_signal));
        else
            PRINTF("|[SIG %d]", exit_signal);
    }

    if (flags)
        PRINTF("|0x%x", flags);
}

static void parse_mmap_prot (va_list ap)
{
    int prot = va_arg(ap, int);
    int nflags = 0;

    if (prot == PROT_NONE) {
        PUTS("PROT_NONE");
        return;
    }

    if (prot & PROT_READ) {
        if (nflags++)
            PUTS("|");
        PUTS("PROT_READ");
    }

    if (prot & PROT_WRITE) {
        if (nflags++)
            PUTS("|");
        PUTS("PROT_WRITE");
    }

    if (prot & PROT_EXEC) {
        if (nflags++)
            PUTS("|");

        PUTS("PROT_EXEC");
    }
}

static void parse_mmap_flags (va_list ap)
{
    int flags = va_arg(ap, int);

    if (flags & MAP_SHARED) {
        PUTS("MAP_SHARED");
        flags &= ~MAP_SHARED;
    }

    if (flags & MAP_PRIVATE) {
        PUTS("MAP_PRIVATE");
        flags &= ~MAP_PRIVATE;
    }

    if (flags & MAP_ANONYMOUS) {
        PUTS("|MAP_ANON");
        flags &= ~MAP_ANONYMOUS;
    }

    if (flags & MAP_FILE) {
        PUTS("|MAP_FILE");
        flags &= ~MAP_FILE;
    }

    if (flags & MAP_FIXED) {
        PUTS("|MAP_FIXED");
        flags &= ~MAP_FIXED;
    }

#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED
    if (flags & MAP_UNINITIALIZED) {
        PUTS("|MAP_UNINITIALIZED");
        flags &= ~MAP_UNINITIALIZED;
    }
#endif

    if (flags)
        PRINTF("|0x%x", flags);
}

static void parse_exec_args (va_list ap)
{
    const char ** args = va_arg(ap, const char **);

    PUTS("[");

    for (; ; args++) {
        if (test_user_memory(args, sizeof(*args), false)) {
            PRINTF("(invalid-argv %p)", args);
            break;
        }
        if (*args == NULL)
            break;
        if (test_user_string(*args)) {
            PRINTF("(invalid-addr %p),", *args);
            continue;
        }
        PUTS(*args);
        PUTS(",");
    }

    PUTS("]");
}

static void parse_exec_envp (va_list ap)
{
    const char ** envp = va_arg(ap, const char **);

    if (!envp) {
        PUTS("NULL");
        return;
    }

    PUTS("[");

    int cnt = 0;
    for (; cnt < 2; cnt++, envp++) {
        if (test_user_memory(envp, sizeof(*envp), false)) {
            PRINTF("(invalid-envp %p)", envp);
            break;
        }
        if (*envp == NULL)
            break;
        if (test_user_string(*envp)) {
            PRINTF("(invalid-addr %p),", *envp);
            continue;
        }
        PUTS(*envp);
        PUTS(",");
    }

    if (cnt > 2)
        PRINTF("(%d more)", cnt);

    PUTS("]");
}

static void parse_pipe_fds (va_list ap)
{
    int * fds = va_arg(ap, int *);

    PRINTF("[%d, %d]", fds[0], fds[1]);
}

#define S(sig) #sig

const char *const siglist[NUM_KNOWN_SIGS + 1] =
    {
        S(SIGUNUSED),
        S(SIGHUP),
        S(SIGINT),
        S(SIGQUIT),
        S(SIGILL),
        S(SIGTRAP),
        S(SIGABRT),
        S(SIGBUS),
        S(SIGFPE),
        S(SIGKILL),
        S(SIGUSR1),
        S(SIGSEGV),
        S(SIGUSR2),
        S(SIGPIPE),
        S(SIGALRM),
        S(SIGTERM),
        S(SIGSTKFLT),
        S(SIGCHLD),
        S(SIGCONT),
        S(SIGSTOP),
        S(SIGTSTP),
        S(SIGTTIN),
        S(SIGTTOU),
        S(SIGURG),
        S(SIGXCPU),
        S(SIGXFSZ),
        S(SIGVTALRM),
        S(SIGPROF),
        S(SIGWINCH),
        S(SIGIO),
        S(SIGPWR),
        S(SIGSYS),
        S(SIGRTMIN),
    };

static void parse_signum (va_list ap)
{
    int signum = va_arg(ap, int);

    if (signum >= 0 && signum <= NUM_KNOWN_SIGS)
        PUTS(signal_name(signum));
    else
        PRINTF("[SIG %d]", signum);
}

static void parse_sigmask (va_list ap)
{
    __sigset_t * sigset = va_arg(ap, __sigset_t *);

    if (!sigset) {
        PUTS("NULL");
        return;
    }

    if (test_user_memory(sigset, sizeof(*sigset), false)) {
        PRINTF("(invalid-addr %p)", sigset);
        return;
    }

    PUTS("[");

    for (size_t signum = 1 ; signum <= sizeof(sigset) * 8 ; signum++)
        if (__sigismember(sigset, signum)) {
            PUTS(signal_name(signum));
            PUTS(",");
        }

    PUTS("]");
}

static void parse_sigprocmask_how (va_list ap)
{
    int how = va_arg(ap, int);

    switch (how) {
        case SIG_BLOCK:
            PUTS("BLOCK");
            break;
        case SIG_UNBLOCK:
            PUTS("UNBLOCK");
            break;
        case SIG_SETMASK:
            PUTS("SETMASK");
            break;
        default:
            PUTS("<unknown>");
            break;
    }
}

static void parse_timespec (va_list ap)
{
    const struct timespec * tv = va_arg(ap, const struct timespec *);

    if (!tv) {
        PUTS("NULL");
        return;
    }

    if (test_user_memory((void*)tv, sizeof(*tv), false)) {
        PRINTF("(invalid-addr %p)", tv);
        return;
    }

    PRINTF("[%ld,%ld]", tv->tv_sec, tv->tv_nsec);
}

static void parse_sockaddr (va_list ap)
{
    const struct sockaddr *addr = va_arg(ap, const struct sockaddr *);

    if (!addr) {
        PUTS("NULL");
        return;
    }

    if (test_user_memory((void*)addr, sizeof(*addr), false)) {
        PRINTF("(invalid-addr %p)", addr);
        return;
    }

    switch (addr->sa_family) {
        case AF_INET: {
            struct sockaddr_in * a = (void *) addr;
            unsigned char * ip = (void *) &a->sin_addr.s_addr;
            PRINTF("{family=INET,ip=%u.%u.%u.%u,port=htons(%u)}",
                   ip[0], ip[1], ip[2], ip[3], __ntohs(a->sin_port));
            break;
        }

        case AF_INET6: {
            struct sockaddr_in6 * a = (void *) addr;
            unsigned short * ip = (void *) &a->sin6_addr.s6_addr;
            PRINTF("{family=INET,ip=[%x:%x:%x:%x:%x:%x:%x:%x],"
                   "port=htons(%u)}",
                   __ntohs(ip[0]), __ntohs(ip[1]),
                   __ntohs(ip[2]), __ntohs(ip[3]),
                   __ntohs(ip[4]), __ntohs(ip[5]),
                   __ntohs(ip[6]), __ntohs(ip[7]),
                   __ntohs(a->sin6_port));
            break;
        }

        case AF_UNIX: {
            struct sockaddr_un * a = (void *) addr;
            PRINTF("{family=UNIX,path=%s}", a->sun_path);
            break;
        }

        default:
            PUTS("UNKNOWN");
            break;
    }
}

static void parse_domain (va_list ap)
{
    int domain = va_arg(ap, int);

#define PF_UNSPEC   0   /* Unspecified.  */
#define PF_INET     2   /* IP protocol family.  */
#define PF_AX25     3   /* Amateur Radio AX.25.  */
#define PF_IPX      4   /* Novell Internet Protocol.  */
#define PF_APPLETALK    5   /* Appletalk DDP.  */
#define PF_ATMPVC   8   /* ATM PVCs.  */
#define PF_X25      9   /* Reserved for X.25 project.  */
#define PF_INET6    10  /* IP version 6.  */
#define PF_NETLINK  16
#define PF_PACKET   17  /* Packet family.  */

    switch (domain) {
        case PF_UNSPEC:
            PUTS("UNSPEC");
            break;
        case PF_UNIX:
            PUTS("UNIX");
            break;
        case PF_INET:
            PUTS("INET");
            break;
        case PF_INET6:
            PUTS("INET6");
            break;
        case PF_IPX:
            PUTS("IPX");
            break;
        case PF_NETLINK:
            PUTS("NETLINK");
            break;
        case PF_X25:
            PUTS("X25");
            break;
        case PF_AX25:
            PUTS("AX25");
            break;
        case PF_ATMPVC:
            PUTS("ATMPVC");
            break;
        case PF_APPLETALK:
            PUTS("APPLETALK");
            break;
        case PF_PACKET:
            PUTS("PACKET");
            break;
        default:
            PUTS("UNKNOWN");
            break;
    }
}

static void parse_socktype (va_list ap)
{
    int socktype = va_arg(ap, int);

    if (socktype & SOCK_NONBLOCK) {
        socktype &= ~SOCK_NONBLOCK;
        PUTS("SOCK_NONBLOCK|");
    }

    if (socktype & SOCK_CLOEXEC) {
        socktype &= ~SOCK_CLOEXEC;
        PUTS("SOCK_CLOEXEC|");
    }

#define SOCK_RAW    3   /* Raw protocol interface.  */
#define SOCK_RDM    4   /* Reliably-delivered messages.  */
#define SOCK_SEQPACKET  5   /* Sequenced, reliable, connection-based, */
#define SOCK_DCCP   6   /* Datagram Congestion Control Protocol.  */
#define SOCK_PACKET 10  /* Linux specific way of getting packets */

    switch (socktype) {
        case SOCK_STREAM:
            PUTS("STREAM");
            break;
        case SOCK_DGRAM:
            PUTS("DGRAM");
            break;
        case SOCK_SEQPACKET:
            PUTS("SEQPACKET");
            break;
        case SOCK_RAW:
            PUTS("RAW");
            break;
        case SOCK_RDM:
            PUTS("RDM");
            break;
        case SOCK_PACKET:
            PUTS("PACKET");
            break;
        default:
            PUTS("UNKNOWN");
            break;
    }
}

static void parse_futexop (va_list ap)
{
    int op = va_arg(ap, int);

#ifdef FUTEX_PRIVATE_FLAG
    if (op & FUTEX_PRIVATE_FLAG) {
        PUTS("FUTEX_PRIVATE|");
        op &= ~FUTEX_PRIVATE_FLAG;
    }
#endif

#ifdef FUTEX_CLOCK_REALTIME
    if (op & FUTEX_CLOCK_REALTIME) {
        PUTS("FUTEX_CLOCK_REALTIME|");
        op &= ~FUTEX_CLOCK_REALTIME;
    }
#endif

    op &= FUTEX_CMD_MASK;

    switch (op) {
        case FUTEX_WAIT:
            PUTS("FUTEX_WAIT");
            break;
        case FUTEX_WAIT_BITSET:
            PUTS("FUTEX_WAIT_BITSET");
            break;
        case FUTEX_WAKE:
            PUTS("FUTEX_WAKE");
            break;
        case FUTEX_WAKE_BITSET:
            PUTS("FUTEX_WAKE_BITSET");
            break;
        case FUTEX_FD:
            PUTS("FUTEX_FD");
            break;
        case FUTEX_REQUEUE:
            PUTS("FUTEX_REQUEUE");
            break;
        case FUTEX_CMP_REQUEUE:
            PUTS("FUTEX_CMP_REQUEUE");
            break;
        case FUTEX_WAKE_OP:
            PUTS("FUTEX_WAKE_OP");
            break;
        default:
            PRINTF("OP %d", op);
            break;
    }
}

static void parse_fcntlop (va_list ap)
{
    int op = va_arg(ap, int);

    switch (op) {
        case F_DUPFD:
            PUTS("F_DUPFD");
            break;
        case F_GETFD:
            PUTS("F_GETFD");
            break;
        case F_SETFD:
            PUTS("F_SETFD");
            break;
        case F_GETFL:
            PUTS("F_GETFL");
            break;
        case F_SETFL:
            PUTS("F_SETFL");
            break;
        case F_GETLK:
            PUTS("F_GETLK");
            break;
        case F_SETLK:
            PUTS("F_SETLK");
            break;
        case F_SETLKW:
            PUTS("F_SETLKW");
            break;
        case F_SETOWN:
            PUTS("F_SETOWN");
            break;
        case F_GETOWN:
            PUTS("F_GETOWN");
            break;
        case F_SETSIG:
            PUTS("F_SETSIG");
            break;
        case F_GETSIG:
            PUTS("F_GETSIG");
            break;
        case F_GETLK64:
            PUTS("F_GETLK64");
            break;
        case F_SETLK64:
            PUTS("F_SETLK64");
            break;
        case F_SETLKW64:
            PUTS("F_SETLKW64");
            break;
        case F_SETOWN_EX:
            PUTS("F_SETOWN_EX");
            break;
        case F_GETOWN_EX:
            PUTS("F_GETOWN_EX");
            break;
        case F_GETOWNER_UIDS:
            PUTS("F_GETOWNER_UIDS");
            break;
        default:
            PRINTF("OP %d", op);
            break;
    }
}

static void parse_ioctlop (va_list ap)
{
    int op = va_arg(ap, int);

    if (op >= TCGETS && op <= TIOCVHANGUP) {
        const char * opnames[] = {
            "TCGETS",       /* 0x5401 */    "TCSETS",       /* 0x5402 */
            "TCSETSW",      /* 0x5403 */    "TCSETSF",      /* 0x5404 */
            "TCGETA",       /* 0x5405 */    "TCSETA",       /* 0x5406 */
            "TCSETAW",      /* 0x5407 */    "TCSETAF",      /* 0x5408 */
            "TCSBRK",       /* 0x5409 */    "TCXONC",       /* 0x540A */
            "TCFLSH",       /* 0x540B */    "TIOCEXCL",     /* 0x540C */
            "TIOCNXCL",     /* 0x540D */    "TIOCSCTTY",    /* 0x540E */
            "TIOCGPGRP",    /* 0x540F */    "TIOCSPGRP",    /* 0x5410 */
            "TIOCOUTQ",     /* 0x5411 */    "TIOCSTI",      /* 0x5412 */
            "TIOCGWINSZ",   /* 0x5413 */    "TIOCSWINSZ",   /* 0x5414 */
            "TIOCMGET",     /* 0x5415 */    "TIOCMBIS",     /* 0x5416 */
            "TIOCMBIC",     /* 0x5417 */    "TIOCMSET",     /* 0x5418 */
            "TIOCGSOFTCAR", /* 0x5419 */    "TIOCSSOFTCAR", /* 0x541A */
            "FIONREAD",     /* 0x541B */    "TIOCLINUX",    /* 0x541C */
            "TIOCCONS",     /* 0x541D */    "TIOCGSERIAL",  /* 0x541E */
            "TIOCSSERIAL",  /* 0x541F */    "TIOCPKT",      /* 0x5420 */
            "FIONBIO",      /* 0x5421 */    "TIOCNOTTY",    /* 0x5422 */
            "TIOCSETD",     /* 0x5423 */    "TIOCGETD",     /* 0x5424 */
            "TCSBRKP",      /* 0x5425 */    "",
            "TIOCSBRK",     /* 0x5427 */    "TIOCCBRK",     /* 0x5428 */
            "TIOCGSID",     /* 0x5429 */    "TCGETS2",      /* 0x542A */
            "TCSETS2",      /* 0x542B */    "TCSETSW2",     /* 0x542C */
            "TCSETSF2",     /* 0x542D */    "TIOCGRS485",   /* 0x542E */
            "TIOCSRS485",   /* 0x542F */    "TIOCGPTN",     /* 0x5430 */
            "TIOCSPTLCK",   /* 0x5431 */    "TCGETX",       /* 0x5432 */
            "TCSETX",       /* 0x5433 */    "TCSETXF",      /* 0x5434 */
            "TCSETXW",      /* 0x5435 */    "TIOCSIG",      /* 0x5436 */
            "TIOCVHANGUP",  /* 0x5437 */
        };
        PUTS(opnames[op - TCGETS]);
        return;
    }

    if (op >= FIONCLEX && op <= TIOCSERSETMULTI) {
        const char * opnames[] = {
            "FIONCLEX",         /* 0x5450 */    "FIOCLEX",          /* 0x5451 */
            "FIOASYNC",         /* 0x5452 */    "TIOCSERCONFIG",    /* 0x5453 */
            "TIOCSERGWILD",     /* 0x5454 */    "TIOCSERSWILD",     /* 0x5455 */
            "TIOCGLCKTRMIOS",   /* 0x5456 */    "TIOCSLCKTRMIOS",   /* 0x5457 */
            "TIOCSERGSTRUCT",   /* 0x5458 */    "TIOCSERGETLSR",    /* 0x5459 */
            "TIOCSERGETMULTI",  /* 0x545A */    "TIOCSERSETMULTI",  /* 0x545B */
        };
        PUTS(opnames[op - FIONCLEX]);
        return;
    }



#define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
#define TIOCGICOUNT	0x545D	/* read serial port __inline__ interrupt counts */


    PRINTF("OP 0x%04x", op);
}

static void parse_seek (va_list ap)
{
    int seek = va_arg(ap, int);

    switch(seek) {
        case SEEK_CUR:
            PUTS("SEEK_CUR");
            break;
        case SEEK_SET:
            PUTS("SEEK_SET");
            break;
        case SEEK_END:
            PUTS("SEEK_END");
            break;
        default:
            PRINTF("%d", seek);
            break;
    }
}

static void parse_at_fdcwd (va_list ap)
{
    int fd = va_arg(ap, int);

    switch(fd) {
        case AT_FDCWD:
            PUTS("AT_FDCWD");
            break;
        default:
            PRINTF("%d", fd);
            break;
    }
}

static void parse_wait_option (va_list ap)
{
    int option = va_arg(ap, int);

    if (option & WNOHANG)
        PUTS("WNOHANG");
}