#define _GNU_SOURCE
#include "pthread_impl.h"
#include "stdio_impl.h"
#include "libc.h"
#include <sys/mman.h>
#include <string.h>
#include <stddef.h>

void* __mmap(void*, size_t, int, int, int, off_t);
int __munmap(void*, size_t);
int __mprotect(void*, size_t, int);

static void dummy_0() {}
weak_alias(dummy_0, __acquire_ptc);
weak_alias(dummy_0, __release_ptc);
weak_alias(dummy_0, __pthread_tsd_run_dtors);
weak_alias(dummy_0, __do_orphaned_stdio_locks);
weak_alias(dummy_0, __dl_thread_cleanup);

_Noreturn void __pthread_exit(void* result) {
  pthread_t self = __pthread_self();
  sigset_t set;

  self->canceldisable = 1;
  self->cancelasync = 0;
  self->result = result;

  while (self->cancelbuf) {
    void (*f)(void*) = self->cancelbuf->__f;
    void* x = self->cancelbuf->__x;
    self->cancelbuf = self->cancelbuf->__next;
    f(x);
  }

  __pthread_tsd_run_dtors();

  __lock(self->exitlock);

  /* Mark this thread dead before decrementing count */
  __lock(self->killlock);
  self->dead = 1;

  /* Block all signals before decrementing the live thread count.
   * This is important to ensure that dynamically allocated TLS
   * is not under-allocated/over-committed, and possibly for other
   * reasons as well. */
  __block_all_sigs(&set);

  /* Wait to unlock the kill lock, which governs functions like
   * pthread_kill which target a thread id, until signals have
   * been blocked. This precludes observation of the thread id
   * as a live thread (with application code running in it) after
   * the thread was reported dead by ESRCH being returned. */
  __unlock(self->killlock);

  /* It's impossible to determine whether this is "the last thread"
   * until performing the atomic decrement, since multiple threads
   * could exit at the same time. For the last thread, revert the
   * decrement and unblock signals to give the atexit handlers and
   * stdio cleanup code a consistent state. */
  if (a_fetch_add(&libc.threads_minus_1, -1) == 0) {
    libc.threads_minus_1 = 0;
    __restore_sigs(&set);
    exit(0);
  }

  /* Process robust list in userspace to handle non-pshared mutexes
   * and the detached thread case where the robust list head will
   * be invalid when the kernel would process it. */
  __vm_lock();
  volatile void* volatile* rp;
  while ((rp = self->robust_list.head) && rp != &self->robust_list.head) {
    pthread_mutex_t* m =
        (void*)((char*)rp - offsetof(pthread_mutex_t, _m_next));
    int waiters = m->_m_waiters;
    int priv = (m->_m_type & 128) ^ 128;
    self->robust_list.pending = rp;
    self->robust_list.head = *rp;
    int cont = a_swap(&m->_m_lock, self->tid | 0x40000000);
    self->robust_list.pending = 0;
    if (cont < 0 || waiters)
      __wake(&m->_m_lock, 1, priv);
  }
  __vm_unlock();

  __do_orphaned_stdio_locks();
  __dl_thread_cleanup();

  if (self->detached && self->map_base) {
    /* Detached threads must avoid the kernel clear_child_tid
     * feature, since the virtual address will have been
     * unmapped and possibly already reused by a new mapping
     * at the time the kernel would perform the write. In
     * the case of threads that started out detached, the
     * initial clone flags are correct, but if the thread was
     * detached later (== 2), we need to clear it here. */
    if (self->detached == 2)
      __syscall(SYS_set_tid_address, 0);

    /* Robust list will no longer be valid, and was already
     * processed above, so unregister it with the kernel. */
    if (self->robust_list.off)
      __syscall(SYS_set_robust_list, 0, 3 * sizeof(long));

    /* Since __unmapself bypasses the normal munmap code path,
     * explicitly wait for vmlock holders first. */
    __vm_wait();

    /* The following call unmaps the thread's stack mapping
     * and then exits without touching the stack. */
    __unmapself(self->map_base, self->map_size);
  }

  for (;;)
    __syscall(SYS_exit, 0);
}

void __do_cleanup_push(struct __ptcb* cb) {
  struct pthread* self = __pthread_self();
  cb->__next = self->cancelbuf;
  self->cancelbuf = cb;
}

void __do_cleanup_pop(struct __ptcb* cb) {
  __pthread_self()->cancelbuf = cb->__next;
}

static int start(void* p) {
  pthread_t self = p;
  if (self->startlock[0]) {
    __wait(self->startlock, 0, 1, 1);
    if (self->startlock[0]) {
      self->detached = 2;
      pthread_exit(0);
    }
    __restore_sigs(self->sigmask);
  }
  if (self->unblock_cancel)
    __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG / 8);
  __pthread_exit(self->start(self->start_arg));
  return 0;
}

static int start_c11(void* p) {
  pthread_t self = p;
  int (*start)(void*) = (int (*)(void*))self->start;
  __pthread_exit((void*)(uintptr_t)start(self->start_arg));
  return 0;
}

#define ROUND(x) (((x) + PAGE_SIZE - 1) & -PAGE_SIZE)

/* pthread_key_create.c overrides this */
static volatile size_t dummy = 0;
weak_alias(dummy, __pthread_tsd_size);
static void* dummy_tsd[1] = {0};
weak_alias(dummy_tsd, __pthread_tsd_main);

volatile int __block_new_threads = 0;

static FILE* volatile dummy_file = 0;
weak_alias(dummy_file, __stdin_used);
weak_alias(dummy_file, __stdout_used);
weak_alias(dummy_file, __stderr_used);

static void init_file_lock(FILE* f) {
  if (f && f->lock < 0)
    f->lock = 0;
}

void* __copy_tls(unsigned char*);

int __pthread_create(pthread_t* restrict res,
                     const pthread_attr_t* restrict attrp,
                     void* (*entry)(void*),
                     void* restrict arg) {
  int ret, c11 = (attrp == __ATTRP_C11_THREAD);
  size_t size, guard;
  struct pthread *self, *new;
  unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
  unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
                   CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS |
                   CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
  int do_sched = 0;
  pthread_attr_t attr = {0};

  if (!libc.can_do_threads)
    return ENOSYS;
  self = __pthread_self();
  if (!libc.threaded) {
    for (FILE* f = *__ofl_lock(); f; f = f->next)
      init_file_lock(f);
    __ofl_unlock();
    init_file_lock(__stdin_used);
    init_file_lock(__stdout_used);
    init_file_lock(__stderr_used);
    __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG / 8);
    self->tsd = (void**)__pthread_tsd_main;
    libc.threaded = 1;
  }
  if (attrp && !c11)
    attr = *attrp;

  __acquire_ptc();
  if (__block_new_threads)
    __wait(&__block_new_threads, 0, 1, 1);

  if (attr._a_stackaddr) {
    size_t need = libc.tls_size + __pthread_tsd_size;
    size = attr._a_stacksize + DEFAULT_STACK_SIZE;
    stack = (void*)(attr._a_stackaddr & -16);
    stack_limit = (void*)(attr._a_stackaddr - size);
    /* Use application-provided stack for TLS only when
     * it does not take more than ~12% or 2k of the
     * application's stack space. */
    if (need < size / 8 && need < 2048) {
      tsd = stack - __pthread_tsd_size;
      stack = tsd - libc.tls_size;
      memset(stack, 0, need);
    } else {
      size = ROUND(need);
      guard = 0;
    }
  } else {
    guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
    size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize +
                         libc.tls_size + __pthread_tsd_size);
  }

  if (!tsd) {
    if (guard) {
      map = __mmap(0, size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
      if (map == MAP_FAILED)
        goto fail;
      if (__mprotect(map + guard, size - guard, PROT_READ | PROT_WRITE) &&
          errno != ENOSYS) {
        __munmap(map, size);
        goto fail;
      }
    } else {
      map = __mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1,
                   0);
      if (map == MAP_FAILED)
        goto fail;
    }
    tsd = map + size - __pthread_tsd_size;
    if (!stack) {
      stack = tsd - libc.tls_size;
      stack_limit = map + guard;
    }
  }

  new = __copy_tls(tsd - libc.tls_size);
  new->map_base = map;
  new->map_size = size;
  new->stack = stack;
  new->stack_size = stack - stack_limit;
  new->start = entry;
  new->start_arg = arg;
  new->self = new;
  new->tsd = (void*)tsd;
  new->locale = &libc.global_locale;
  if (attr._a_detach) {
    new->detached = 1;
    flags -= CLONE_CHILD_CLEARTID;
  }
  if (attr._a_sched) {
    do_sched = new->startlock[0] = 1;
    __block_app_sigs(new->sigmask);
  }
  new->robust_list.head = &new->robust_list.head;
  new->unblock_cancel = self->cancel;
  new->CANARY = self->CANARY;

  a_inc(&libc.threads_minus_1);
  ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid,
                TP_ADJ(new), &new->tid);

  __release_ptc();

  if (do_sched) {
    __restore_sigs(new->sigmask);
  }

  if (ret < 0) {
    a_dec(&libc.threads_minus_1);
    if (map)
      __munmap(map, size);
    return EAGAIN;
  }

  if (do_sched) {
    ret = __syscall(SYS_sched_setscheduler, new->tid, attr._a_policy,
                    &attr._a_prio);
    a_store(new->startlock, ret < 0 ? 2 : 0);
    __wake(new->startlock, 1, 1);
    if (ret < 0)
      return -ret;
  }

  *res = new;
  return 0;
fail:
  __release_ptc();
  return EAGAIN;
}

weak_alias(__pthread_exit, pthread_exit);
weak_alias(__pthread_create, pthread_create);