cosmopolitan/libc/runtime/cxa_thread_atexit.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/cxaatexit.h"
#include "libc/intrin/strace.h"
#include "libc/intrin/weaken.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/gc.internal.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/tls.h"
#include "third_party/nsync/wait_s.internal.h"

struct Dtor {
  void *fun;
  void *arg;
  struct Dtor *next;
};

static void _pthread_unwind(struct CosmoTib *tib) {
  struct PosixThread *pt;
  struct _pthread_cleanup_buffer *cb;
  pt = (struct PosixThread *)tib->tib_pthread;
  while ((cb = pt->pt_cleanup)) {
    pt->pt_cleanup = cb->__prev;
    cb->__routine(cb->__arg);
  }
}

static void _pthread_unkey(struct CosmoTib *tib) {
  for (int j = 0; j < PTHREAD_DESTRUCTOR_ITERATIONS; ++j) {
    bool gotsome = false;
    for (int i = 0; i < PTHREAD_KEYS_MAX; ++i) {
      void *val;
      pthread_key_dtor dtor;
      if ((dtor = atomic_load_explicit(&_pthread_key_dtor[i],
                                       memory_order_acquire)) &&
          dtor != (pthread_key_dtor)-1 &&
          (val = atomic_exchange_explicit(&tib->tib_keys[i], 0,
                                          memory_order_relaxed))) {
        STRACE("_pthread_unkey(%t, %p)", dtor, val);
        gotsome = true;
        dtor(val);
      }
    }
    if (!gotsome)
      break;
  }
}

static void _pthread_ungarbage(struct CosmoTib *tib) {
  struct Garbages *g;
  while ((g = tib->tib_garbages)) {
    tib->tib_garbages = 0;
    while (g->i--)
      ((void (*)(intptr_t))g->p[g->i].fn)(g->p[g->i].arg);
    if (_weaken(free)) {
      _weaken(free)(g->p);
      _weaken(free)(g);
    }
  }
}

void __cxa_thread_finalize(void) {
  struct Dtor *dtor;
  struct CosmoTib *tib;
  tib = __get_tls();

  // "Any cancellation cleanup handlers that have been pushed and not
  //  yet popped shall be popped in the reverse order that they were
  //  pushed and then executed." ──Quoth POSIX.1-2017
  _pthread_unwind(tib);

  // "After all cancellation cleanup handlers have been executed, if the
  //  thread has any thread-specific data, appropriate destructor
  //  functions shall be called in an unspecified order."
  //                              ──Quoth POSIX.1-2017
  if (tib->tib_nsync)
    _weaken(nsync_waiter_destroy)(tib->tib_nsync);
  _pthread_unkey(tib);

  _pthread_ungarbage(tib);

  while ((dtor = tib->tib_atexit)) {
    STRACE("__cxa_finalize(%t, %p)", dtor->fun, dtor->arg);
    tib->tib_atexit = dtor->next;
    ((void (*)(void *))dtor->fun)(dtor->arg);
    _weaken(free)(dtor);
  }
}

int __cxa_thread_atexit_impl(void *fun, void *arg, void *dso_symbol) {
  struct Dtor *dtor;
  if (!_weaken(malloc))
    return -1;
  if (!(dtor = _weaken(malloc)(sizeof(struct Dtor))))
    return -1;
  struct CosmoTib *tib;
  tib = __get_tls();
  dtor->fun = fun;
  dtor->arg = arg;
  dtor->next = tib->tib_atexit;
  tib->tib_atexit = dtor;
  return 0;
}