wepoll.c 66.3 KB
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/*
 * wepoll - epoll for Windows
 * https://github.com/piscisaureus/wepoll
 *
 * Copyright 2012-2018, Bert Belder <bertbelder@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WEPOLL_EXPORT
#define WEPOLL_EXPORT
#endif

#include <stdint.h>

/* clang-format off */

enum EPOLL_EVENTS {
  EPOLLIN      = (int) (1U <<  0),
  EPOLLPRI     = (int) (1U <<  1),
  EPOLLOUT     = (int) (1U <<  2),
  EPOLLERR     = (int) (1U <<  3),
  EPOLLHUP     = (int) (1U <<  4),
  EPOLLRDNORM  = (int) (1U <<  6),
  EPOLLRDBAND  = (int) (1U <<  7),
  EPOLLWRNORM  = (int) (1U <<  8),
  EPOLLWRBAND  = (int) (1U <<  9),
  EPOLLMSG     = (int) (1U << 10), /* Never reported. */
  EPOLLRDHUP   = (int) (1U << 13),
  EPOLLONESHOT = (int) (1U << 31)
};

#define EPOLLIN      (1U <<  0)
#define EPOLLPRI     (1U <<  1)
#define EPOLLOUT     (1U <<  2)
#define EPOLLERR     (1U <<  3)
#define EPOLLHUP     (1U <<  4)
#define EPOLLRDNORM  (1U <<  6)
#define EPOLLRDBAND  (1U <<  7)
#define EPOLLWRNORM  (1U <<  8)
#define EPOLLWRBAND  (1U <<  9)
#define EPOLLMSG     (1U << 10)
#define EPOLLRDHUP   (1U << 13)
#define EPOLLONESHOT (1U << 31)

#define EPOLL_CTL_ADD 1
#define EPOLL_CTL_MOD 2
#define EPOLL_CTL_DEL 3

/* clang-format on */

typedef void* HANDLE;
typedef uintptr_t SOCKET;

typedef union epoll_data {
  void* ptr;
  int fd;
  uint32_t u32;
  uint64_t u64;
  SOCKET sock; /* Windows specific */
  HANDLE hnd;  /* Windows specific */
} epoll_data_t;

struct epoll_event {
  uint32_t events;   /* Epoll events and flags */
  epoll_data_t data; /* User data variable */
};

#ifdef __cplusplus
extern "C" {
#endif

WEPOLL_EXPORT HANDLE epoll_create(int size);
WEPOLL_EXPORT HANDLE epoll_create1(int flags);

WEPOLL_EXPORT int epoll_close(HANDLE ephnd);

WEPOLL_EXPORT int epoll_ctl(HANDLE ephnd,
                            int op,
                            SOCKET sock,
                            struct epoll_event* event);

WEPOLL_EXPORT int epoll_wait(HANDLE ephnd,
                             struct epoll_event* events,
                             int maxevents,
                             int timeout);

#ifdef __cplusplus
} /* extern "C" */
#endif

#include <malloc.h>
#include <stdlib.h>

#define WEPOLL_INTERNAL static
#define WEPOLL_INTERNAL_VAR static

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreserved-id-macro"
#endif

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#ifdef _WIN32_WINNT
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#undef _WIN32_WINNT
#endif

#define _WIN32_WINNT 0x0600

#ifdef __clang__
#pragma clang diagnostic pop
#endif

#ifndef __GNUC__
#pragma warning(push, 1)
#endif

#include <WS2tcpip.h>
#include <WinSock2.h>
#include <Windows.h>

#ifndef __GNUC__
#pragma warning(pop)
#endif

WEPOLL_INTERNAL int nt_global_init(void);

typedef LONG NTSTATUS;
typedef NTSTATUS* PNTSTATUS;

#ifndef NT_SUCCESS
#define NT_SUCCESS(status) (((NTSTATUS)(status)) >= 0)
#endif

#ifndef STATUS_SUCCESS
#define STATUS_SUCCESS ((NTSTATUS) 0x00000000L)
#endif

#ifndef STATUS_PENDING
#define STATUS_PENDING ((NTSTATUS) 0x00000103L)
#endif

#ifndef STATUS_CANCELLED
#define STATUS_CANCELLED ((NTSTATUS) 0xC0000120L)
#endif

typedef struct _IO_STATUS_BLOCK {
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  NTSTATUS Status;
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  ULONG_PTR Information;
} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK;

typedef VOID(NTAPI* PIO_APC_ROUTINE)(PVOID ApcContext,
                                     PIO_STATUS_BLOCK IoStatusBlock,
                                     ULONG Reserved);

typedef struct _LSA_UNICODE_STRING {
  USHORT Length;
  USHORT MaximumLength;
  PWSTR Buffer;
} LSA_UNICODE_STRING, *PLSA_UNICODE_STRING, UNICODE_STRING, *PUNICODE_STRING;

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#define RTL_CONSTANT_STRING(s) \
  { sizeof(s) - sizeof((s)[0]), sizeof(s), s }

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typedef struct _OBJECT_ATTRIBUTES {
  ULONG Length;
  HANDLE RootDirectory;
  PUNICODE_STRING ObjectName;
  ULONG Attributes;
  PVOID SecurityDescriptor;
  PVOID SecurityQualityOfService;
} OBJECT_ATTRIBUTES, *POBJECT_ATTRIBUTES;

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#define RTL_CONSTANT_OBJECT_ATTRIBUTES(ObjectName, Attributes) \
  { sizeof(OBJECT_ATTRIBUTES), NULL, ObjectName, Attributes, NULL, NULL }

#ifndef FILE_OPEN
#define FILE_OPEN 0x00000001UL
#endif

#define NT_NTDLL_IMPORT_LIST(X)                                              \
  X(NTSTATUS,                                                                \
    NTAPI,                                                                   \
    NtCreateFile,                                                            \
    (PHANDLE FileHandle,                                                     \
     ACCESS_MASK DesiredAccess,                                              \
     POBJECT_ATTRIBUTES ObjectAttributes,                                    \
     PIO_STATUS_BLOCK IoStatusBlock,                                         \
     PLARGE_INTEGER AllocationSize,                                          \
     ULONG FileAttributes,                                                   \
     ULONG ShareAccess,                                                      \
     ULONG CreateDisposition,                                                \
     ULONG CreateOptions,                                                    \
     PVOID EaBuffer,                                                         \
     ULONG EaLength))                                                        \
                                                                             \
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  X(NTSTATUS,                                                                \
    NTAPI,                                                                   \
    NtDeviceIoControlFile,                                                   \
    (HANDLE FileHandle,                                                      \
     HANDLE Event,                                                           \
     PIO_APC_ROUTINE ApcRoutine,                                             \
     PVOID ApcContext,                                                       \
     PIO_STATUS_BLOCK IoStatusBlock,                                         \
     ULONG IoControlCode,                                                    \
     PVOID InputBuffer,                                                      \
     ULONG InputBufferLength,                                                \
     PVOID OutputBuffer,                                                     \
     ULONG OutputBufferLength))                                              \
                                                                             \
  X(ULONG, WINAPI, RtlNtStatusToDosError, (NTSTATUS Status))                 \
                                                                             \
  X(NTSTATUS,                                                                \
    NTAPI,                                                                   \
    NtCreateKeyedEvent,                                                      \
    (PHANDLE handle,                                                         \
     ACCESS_MASK access,                                                     \
     POBJECT_ATTRIBUTES attr,                                                \
     ULONG flags))                                                           \
                                                                             \
  X(NTSTATUS,                                                                \
    NTAPI,                                                                   \
    NtWaitForKeyedEvent,                                                     \
    (HANDLE handle, PVOID key, BOOLEAN alertable, PLARGE_INTEGER mstimeout)) \
                                                                             \
  X(NTSTATUS,                                                                \
    NTAPI,                                                                   \
    NtReleaseKeyedEvent,                                                     \
    (HANDLE handle, PVOID key, BOOLEAN alertable, PLARGE_INTEGER mstimeout))

#define X(return_type, attributes, name, parameters) \
  WEPOLL_INTERNAL_VAR return_type(attributes* name) parameters;
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NT_NTDLL_IMPORT_LIST(X)
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#undef X

#include <assert.h>
#include <stddef.h>

#ifndef _SSIZE_T_DEFINED
typedef intptr_t ssize_t;
#endif

#define array_count(a) (sizeof(a) / (sizeof((a)[0])))

/* clang-format off */
#define container_of(ptr, type, member) \
  ((type*) ((uintptr_t) (ptr) - offsetof(type, member)))
/* clang-format on */

#define unused_var(v) ((void) (v))

/* Polyfill `inline` for older versions of msvc (up to Visual Studio 2013) */
#if defined(_MSC_VER) && _MSC_VER < 1900
#define inline __inline
#endif

/* clang-format off */
#define AFD_POLL_RECEIVE           0x0001
#define AFD_POLL_RECEIVE_EXPEDITED 0x0002
#define AFD_POLL_SEND              0x0004
#define AFD_POLL_DISCONNECT        0x0008
#define AFD_POLL_ABORT             0x0010
#define AFD_POLL_LOCAL_CLOSE       0x0020
#define AFD_POLL_ACCEPT            0x0080
#define AFD_POLL_CONNECT_FAIL      0x0100
/* clang-format on */

typedef struct _AFD_POLL_HANDLE_INFO {
  HANDLE Handle;
  ULONG Events;
  NTSTATUS Status;
} AFD_POLL_HANDLE_INFO, *PAFD_POLL_HANDLE_INFO;

typedef struct _AFD_POLL_INFO {
  LARGE_INTEGER Timeout;
  ULONG NumberOfHandles;
  ULONG Exclusive;
  AFD_POLL_HANDLE_INFO Handles[1];
} AFD_POLL_INFO, *PAFD_POLL_INFO;

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WEPOLL_INTERNAL int afd_create_helper_handle(HANDLE iocp,
                                             HANDLE* afd_helper_handle_out);
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WEPOLL_INTERNAL int afd_poll(HANDLE afd_helper_handle,
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                             AFD_POLL_INFO* poll_info,
                             OVERLAPPED* overlapped);

#define return_map_error(value) \
  do {                          \
    err_map_win_error();        \
    return (value);             \
  } while (0)

#define return_set_error(value, error) \
  do {                                 \
    err_set_win_error(error);          \
    return (value);                    \
  } while (0)

WEPOLL_INTERNAL void err_map_win_error(void);
WEPOLL_INTERNAL void err_set_win_error(DWORD error);
WEPOLL_INTERNAL int err_check_handle(HANDLE handle);

WEPOLL_INTERNAL int ws_global_init(void);
WEPOLL_INTERNAL SOCKET ws_get_base_socket(SOCKET socket);

#define IOCTL_AFD_POLL 0x00012024

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static UNICODE_STRING afd__helper_name =
    RTL_CONSTANT_STRING(L"\\Device\\Afd\\Wepoll");
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static OBJECT_ATTRIBUTES afd__helper_attributes =
    RTL_CONSTANT_OBJECT_ATTRIBUTES(&afd__helper_name, 0);
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int afd_create_helper_handle(HANDLE iocp, HANDLE* afd_helper_handle_out) {
  HANDLE afd_helper_handle;
  IO_STATUS_BLOCK iosb;
  NTSTATUS status;
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  /* By opening \Device\Afd without specifying any extended attributes, we'll
   * get a handle that lets us talk to the AFD driver, but that doesn't have an
   * associated endpoint (so it's not a socket). */
  status = NtCreateFile(&afd_helper_handle,
                        SYNCHRONIZE,
                        &afd__helper_attributes,
                        &iosb,
                        NULL,
                        0,
                        FILE_SHARE_READ | FILE_SHARE_WRITE,
                        FILE_OPEN,
                        0,
                        NULL,
                        0);
  if (status != STATUS_SUCCESS)
    return_set_error(-1, RtlNtStatusToDosError(status));
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  if (CreateIoCompletionPort(afd_helper_handle, iocp, 0, 0) == NULL)
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    goto error;

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  if (!SetFileCompletionNotificationModes(afd_helper_handle,
                                          FILE_SKIP_SET_EVENT_ON_HANDLE))
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    goto error;

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  *afd_helper_handle_out = afd_helper_handle;
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  return 0;

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error:
  CloseHandle(afd_helper_handle);
  return_map_error(-1);
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}

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int afd_poll(HANDLE afd_helper_handle,
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             AFD_POLL_INFO* poll_info,
             OVERLAPPED* overlapped) {
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  IO_STATUS_BLOCK* iosb;
  HANDLE event;
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  void* apc_context;
  NTSTATUS status;

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  /* Blocking operation is not supported. */
  assert(overlapped != NULL);
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  iosb = (IO_STATUS_BLOCK*) &overlapped->Internal;
  event = overlapped->hEvent;
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  /* Do what other windows APIs would do: if hEvent has it's lowest bit set,
   * don't post a completion to the completion port. */
  if ((uintptr_t) event & 1) {
    event = (HANDLE)((uintptr_t) event & ~(uintptr_t) 1);
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    apc_context = NULL;
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  } else {
    apc_context = overlapped;
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  }

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  iosb->Status = STATUS_PENDING;
  status = NtDeviceIoControlFile(afd_helper_handle,
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                                 event,
                                 NULL,
                                 apc_context,
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                                 iosb,
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                                 IOCTL_AFD_POLL,
                                 poll_info,
                                 sizeof *poll_info,
                                 poll_info,
                                 sizeof *poll_info);

  if (status == STATUS_SUCCESS)
    return 0;
  else if (status == STATUS_PENDING)
    return_set_error(-1, ERROR_IO_PENDING);
  else
    return_set_error(-1, RtlNtStatusToDosError(status));
}

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WEPOLL_INTERNAL int epoll_global_init(void);
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WEPOLL_INTERNAL int init(void);

#include <stdbool.h>

typedef struct queue_node queue_node_t;

typedef struct queue_node {
  queue_node_t* prev;
  queue_node_t* next;
} queue_node_t;

typedef struct queue {
  queue_node_t head;
} queue_t;

WEPOLL_INTERNAL void queue_init(queue_t* queue);
WEPOLL_INTERNAL void queue_node_init(queue_node_t* node);

WEPOLL_INTERNAL queue_node_t* queue_first(const queue_t* queue);
WEPOLL_INTERNAL queue_node_t* queue_last(const queue_t* queue);

WEPOLL_INTERNAL void queue_prepend(queue_t* queue, queue_node_t* node);
WEPOLL_INTERNAL void queue_append(queue_t* queue, queue_node_t* node);
WEPOLL_INTERNAL void queue_move_first(queue_t* queue, queue_node_t* node);
WEPOLL_INTERNAL void queue_move_last(queue_t* queue, queue_node_t* node);
WEPOLL_INTERNAL void queue_remove(queue_node_t* node);

WEPOLL_INTERNAL bool queue_empty(const queue_t* queue);
WEPOLL_INTERNAL bool queue_enqueued(const queue_node_t* node);

typedef struct port_state port_state_t;
typedef struct poll_group poll_group_t;

WEPOLL_INTERNAL poll_group_t* poll_group_acquire(port_state_t* port);
WEPOLL_INTERNAL void poll_group_release(poll_group_t* poll_group);

WEPOLL_INTERNAL void poll_group_delete(poll_group_t* poll_group);

WEPOLL_INTERNAL poll_group_t* poll_group_from_queue_node(
    queue_node_t* queue_node);
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WEPOLL_INTERNAL HANDLE
    poll_group_get_afd_helper_handle(poll_group_t* poll_group);
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/* N.b.: the tree functions do not set errno or LastError when they fail. Each
 * of the API functions has at most one failure mode. It is up to the caller to
 * set an appropriate error code when necessary. */

typedef struct tree tree_t;
typedef struct tree_node tree_node_t;

typedef struct tree {
  tree_node_t* root;
} tree_t;

typedef struct tree_node {
  tree_node_t* left;
  tree_node_t* right;
  tree_node_t* parent;
  uintptr_t key;
  bool red;
} tree_node_t;

WEPOLL_INTERNAL void tree_init(tree_t* tree);
WEPOLL_INTERNAL void tree_node_init(tree_node_t* node);

WEPOLL_INTERNAL int tree_add(tree_t* tree, tree_node_t* node, uintptr_t key);
WEPOLL_INTERNAL void tree_del(tree_t* tree, tree_node_t* node);

WEPOLL_INTERNAL tree_node_t* tree_find(const tree_t* tree, uintptr_t key);
WEPOLL_INTERNAL tree_node_t* tree_root(const tree_t* tree);

typedef struct port_state port_state_t;
typedef struct sock_state sock_state_t;

WEPOLL_INTERNAL sock_state_t* sock_new(port_state_t* port_state,
                                       SOCKET socket);
WEPOLL_INTERNAL void sock_delete(port_state_t* port_state,
                                 sock_state_t* sock_state);
WEPOLL_INTERNAL void sock_force_delete(port_state_t* port_state,
                                       sock_state_t* sock_state);

WEPOLL_INTERNAL int sock_set_event(port_state_t* port_state,
                                   sock_state_t* sock_state,
                                   const struct epoll_event* ev);

WEPOLL_INTERNAL int sock_update(port_state_t* port_state,
                                sock_state_t* sock_state);
WEPOLL_INTERNAL int sock_feed_event(port_state_t* port_state,
                                    OVERLAPPED* overlapped,
                                    struct epoll_event* ev);

WEPOLL_INTERNAL sock_state_t* sock_state_from_queue_node(
    queue_node_t* queue_node);
WEPOLL_INTERNAL queue_node_t* sock_state_to_queue_node(
    sock_state_t* sock_state);
WEPOLL_INTERNAL sock_state_t* sock_state_from_tree_node(
    tree_node_t* tree_node);
WEPOLL_INTERNAL tree_node_t* sock_state_to_tree_node(sock_state_t* sock_state);

/* The reflock is a special kind of lock that normally prevents a chunk of
 * memory from being freed, but does allow the chunk of memory to eventually be
 * released in a coordinated fashion.
 *
 * Under normal operation, threads increase and decrease the reference count,
 * which are wait-free operations.
 *
 * Exactly once during the reflock's lifecycle, a thread holding a reference to
 * the lock may "destroy" the lock; this operation blocks until all other
 * threads holding a reference to the lock have dereferenced it. After
 * "destroy" returns, the calling thread may assume that no other threads have
 * a reference to the lock.
 *
 * Attemmpting to lock or destroy a lock after reflock_unref_and_destroy() has
 * been called is invalid and results in undefined behavior. Therefore the user
 * should use another lock to guarantee that this can't happen.
 */

typedef struct reflock {
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  volatile long state; /* 32-bit Interlocked APIs operate on `long` values. */
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} reflock_t;

WEPOLL_INTERNAL int reflock_global_init(void);

WEPOLL_INTERNAL void reflock_init(reflock_t* reflock);
WEPOLL_INTERNAL void reflock_ref(reflock_t* reflock);
WEPOLL_INTERNAL void reflock_unref(reflock_t* reflock);
WEPOLL_INTERNAL void reflock_unref_and_destroy(reflock_t* reflock);

typedef struct ts_tree {
  tree_t tree;
  SRWLOCK lock;
} ts_tree_t;

typedef struct ts_tree_node {
  tree_node_t tree_node;
  reflock_t reflock;
} ts_tree_node_t;

WEPOLL_INTERNAL void ts_tree_init(ts_tree_t* rtl);
WEPOLL_INTERNAL void ts_tree_node_init(ts_tree_node_t* node);

WEPOLL_INTERNAL int ts_tree_add(ts_tree_t* ts_tree,
                                ts_tree_node_t* node,
                                uintptr_t key);

WEPOLL_INTERNAL ts_tree_node_t* ts_tree_del_and_ref(ts_tree_t* ts_tree,
                                                    uintptr_t key);
WEPOLL_INTERNAL ts_tree_node_t* ts_tree_find_and_ref(ts_tree_t* ts_tree,
                                                     uintptr_t key);

WEPOLL_INTERNAL void ts_tree_node_unref(ts_tree_node_t* node);
WEPOLL_INTERNAL void ts_tree_node_unref_and_destroy(ts_tree_node_t* node);

typedef struct port_state port_state_t;
typedef struct sock_state sock_state_t;

typedef struct port_state {
  HANDLE iocp;
  tree_t sock_tree;
  queue_t sock_update_queue;
  queue_t sock_deleted_queue;
  queue_t poll_group_queue;
  ts_tree_node_t handle_tree_node;
  CRITICAL_SECTION lock;
  size_t active_poll_count;
} port_state_t;

WEPOLL_INTERNAL port_state_t* port_new(HANDLE* iocp_out);
WEPOLL_INTERNAL int port_close(port_state_t* port_state);
WEPOLL_INTERNAL int port_delete(port_state_t* port_state);

WEPOLL_INTERNAL int port_wait(port_state_t* port_state,
                              struct epoll_event* events,
                              int maxevents,
                              int timeout);

WEPOLL_INTERNAL int port_ctl(port_state_t* port_state,
                             int op,
                             SOCKET sock,
                             struct epoll_event* ev);

WEPOLL_INTERNAL int port_register_socket_handle(port_state_t* port_state,
                                                sock_state_t* sock_state,
                                                SOCKET socket);
WEPOLL_INTERNAL void port_unregister_socket_handle(port_state_t* port_state,
                                                   sock_state_t* sock_state);
WEPOLL_INTERNAL sock_state_t* port_find_socket(port_state_t* port_state,
                                               SOCKET socket);

WEPOLL_INTERNAL void port_request_socket_update(port_state_t* port_state,
                                                sock_state_t* sock_state);
WEPOLL_INTERNAL void port_cancel_socket_update(port_state_t* port_state,
                                               sock_state_t* sock_state);

WEPOLL_INTERNAL void port_add_deleted_socket(port_state_t* port_state,
                                             sock_state_t* sock_state);
WEPOLL_INTERNAL void port_remove_deleted_socket(port_state_t* port_state,
                                                sock_state_t* sock_state);

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static ts_tree_t epoll__handle_tree;
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static inline port_state_t* epoll__handle_tree_node_to_port(
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    ts_tree_node_t* tree_node) {
  return container_of(tree_node, port_state_t, handle_tree_node);
}

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int epoll_global_init(void) {
  ts_tree_init(&epoll__handle_tree);
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  return 0;
}

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static HANDLE epoll__create(void) {
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  port_state_t* port_state;
  HANDLE ephnd;

  if (init() < 0)
    return NULL;

  port_state = port_new(&ephnd);
  if (port_state == NULL)
    return NULL;

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  if (ts_tree_add(&epoll__handle_tree,
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                  &port_state->handle_tree_node,
                  (uintptr_t) ephnd) < 0) {
    /* This should never happen. */
    port_delete(port_state);
    return_set_error(NULL, ERROR_ALREADY_EXISTS);
  }

  return ephnd;
}

HANDLE epoll_create(int size) {
  if (size <= 0)
    return_set_error(NULL, ERROR_INVALID_PARAMETER);

659
  return epoll__create();
660 661 662 663 664 665
}

HANDLE epoll_create1(int flags) {
  if (flags != 0)
    return_set_error(NULL, ERROR_INVALID_PARAMETER);

666
  return epoll__create();
667 668 669 670 671 672 673 674 675
}

int epoll_close(HANDLE ephnd) {
  ts_tree_node_t* tree_node;
  port_state_t* port_state;

  if (init() < 0)
    return -1;

676
  tree_node = ts_tree_del_and_ref(&epoll__handle_tree, (uintptr_t) ephnd);
677 678 679 680 681
  if (tree_node == NULL) {
    err_set_win_error(ERROR_INVALID_PARAMETER);
    goto err;
  }

682
  port_state = epoll__handle_tree_node_to_port(tree_node);
683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701
  port_close(port_state);

  ts_tree_node_unref_and_destroy(tree_node);

  return port_delete(port_state);

err:
  err_check_handle(ephnd);
  return -1;
}

int epoll_ctl(HANDLE ephnd, int op, SOCKET sock, struct epoll_event* ev) {
  ts_tree_node_t* tree_node;
  port_state_t* port_state;
  int r;

  if (init() < 0)
    return -1;

702
  tree_node = ts_tree_find_and_ref(&epoll__handle_tree, (uintptr_t) ephnd);
703 704 705 706 707
  if (tree_node == NULL) {
    err_set_win_error(ERROR_INVALID_PARAMETER);
    goto err;
  }

708
  port_state = epoll__handle_tree_node_to_port(tree_node);
709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739
  r = port_ctl(port_state, op, sock, ev);

  ts_tree_node_unref(tree_node);

  if (r < 0)
    goto err;

  return 0;

err:
  /* On Linux, in the case of epoll_ctl_mod(), EBADF takes priority over other
   * errors. Wepoll mimics this behavior. */
  err_check_handle(ephnd);
  err_check_handle((HANDLE) sock);
  return -1;
}

int epoll_wait(HANDLE ephnd,
               struct epoll_event* events,
               int maxevents,
               int timeout) {
  ts_tree_node_t* tree_node;
  port_state_t* port_state;
  int num_events;

  if (maxevents <= 0)
    return_set_error(-1, ERROR_INVALID_PARAMETER);

  if (init() < 0)
    return -1;

740
  tree_node = ts_tree_find_and_ref(&epoll__handle_tree, (uintptr_t) ephnd);
741 742 743 744 745
  if (tree_node == NULL) {
    err_set_win_error(ERROR_INVALID_PARAMETER);
    goto err;
  }

746
  port_state = epoll__handle_tree_node_to_port(tree_node);
747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865
  num_events = port_wait(port_state, events, maxevents, timeout);

  ts_tree_node_unref(tree_node);

  if (num_events < 0)
    goto err;

  return num_events;

err:
  err_check_handle(ephnd);
  return -1;
}

#include <errno.h>

#define ERR__ERRNO_MAPPINGS(X)               \
  X(ERROR_ACCESS_DENIED, EACCES)             \
  X(ERROR_ALREADY_EXISTS, EEXIST)            \
  X(ERROR_BAD_COMMAND, EACCES)               \
  X(ERROR_BAD_EXE_FORMAT, ENOEXEC)           \
  X(ERROR_BAD_LENGTH, EACCES)                \
  X(ERROR_BAD_NETPATH, ENOENT)               \
  X(ERROR_BAD_NET_NAME, ENOENT)              \
  X(ERROR_BAD_NET_RESP, ENETDOWN)            \
  X(ERROR_BAD_PATHNAME, ENOENT)              \
  X(ERROR_BROKEN_PIPE, EPIPE)                \
  X(ERROR_CANNOT_MAKE, EACCES)               \
  X(ERROR_COMMITMENT_LIMIT, ENOMEM)          \
  X(ERROR_CONNECTION_ABORTED, ECONNABORTED)  \
  X(ERROR_CONNECTION_ACTIVE, EISCONN)        \
  X(ERROR_CONNECTION_REFUSED, ECONNREFUSED)  \
  X(ERROR_CRC, EACCES)                       \
  X(ERROR_DIR_NOT_EMPTY, ENOTEMPTY)          \
  X(ERROR_DISK_FULL, ENOSPC)                 \
  X(ERROR_DUP_NAME, EADDRINUSE)              \
  X(ERROR_FILENAME_EXCED_RANGE, ENOENT)      \
  X(ERROR_FILE_NOT_FOUND, ENOENT)            \
  X(ERROR_GEN_FAILURE, EACCES)               \
  X(ERROR_GRACEFUL_DISCONNECT, EPIPE)        \
  X(ERROR_HOST_DOWN, EHOSTUNREACH)           \
  X(ERROR_HOST_UNREACHABLE, EHOSTUNREACH)    \
  X(ERROR_INSUFFICIENT_BUFFER, EFAULT)       \
  X(ERROR_INVALID_ADDRESS, EADDRNOTAVAIL)    \
  X(ERROR_INVALID_FUNCTION, EINVAL)          \
  X(ERROR_INVALID_HANDLE, EBADF)             \
  X(ERROR_INVALID_NETNAME, EADDRNOTAVAIL)    \
  X(ERROR_INVALID_PARAMETER, EINVAL)         \
  X(ERROR_INVALID_USER_BUFFER, EMSGSIZE)     \
  X(ERROR_IO_PENDING, EINPROGRESS)           \
  X(ERROR_LOCK_VIOLATION, EACCES)            \
  X(ERROR_MORE_DATA, EMSGSIZE)               \
  X(ERROR_NETNAME_DELETED, ECONNABORTED)     \
  X(ERROR_NETWORK_ACCESS_DENIED, EACCES)     \
  X(ERROR_NETWORK_BUSY, ENETDOWN)            \
  X(ERROR_NETWORK_UNREACHABLE, ENETUNREACH)  \
  X(ERROR_NOACCESS, EFAULT)                  \
  X(ERROR_NONPAGED_SYSTEM_RESOURCES, ENOMEM) \
  X(ERROR_NOT_ENOUGH_MEMORY, ENOMEM)         \
  X(ERROR_NOT_ENOUGH_QUOTA, ENOMEM)          \
  X(ERROR_NOT_FOUND, ENOENT)                 \
  X(ERROR_NOT_LOCKED, EACCES)                \
  X(ERROR_NOT_READY, EACCES)                 \
  X(ERROR_NOT_SAME_DEVICE, EXDEV)            \
  X(ERROR_NOT_SUPPORTED, ENOTSUP)            \
  X(ERROR_NO_MORE_FILES, ENOENT)             \
  X(ERROR_NO_SYSTEM_RESOURCES, ENOMEM)       \
  X(ERROR_OPERATION_ABORTED, EINTR)          \
  X(ERROR_OUT_OF_PAPER, EACCES)              \
  X(ERROR_PAGED_SYSTEM_RESOURCES, ENOMEM)    \
  X(ERROR_PAGEFILE_QUOTA, ENOMEM)            \
  X(ERROR_PATH_NOT_FOUND, ENOENT)            \
  X(ERROR_PIPE_NOT_CONNECTED, EPIPE)         \
  X(ERROR_PORT_UNREACHABLE, ECONNRESET)      \
  X(ERROR_PROTOCOL_UNREACHABLE, ENETUNREACH) \
  X(ERROR_REM_NOT_LIST, ECONNREFUSED)        \
  X(ERROR_REQUEST_ABORTED, EINTR)            \
  X(ERROR_REQ_NOT_ACCEP, EWOULDBLOCK)        \
  X(ERROR_SECTOR_NOT_FOUND, EACCES)          \
  X(ERROR_SEM_TIMEOUT, ETIMEDOUT)            \
  X(ERROR_SHARING_VIOLATION, EACCES)         \
  X(ERROR_TOO_MANY_NAMES, ENOMEM)            \
  X(ERROR_TOO_MANY_OPEN_FILES, EMFILE)       \
  X(ERROR_UNEXP_NET_ERR, ECONNABORTED)       \
  X(ERROR_WAIT_NO_CHILDREN, ECHILD)          \
  X(ERROR_WORKING_SET_QUOTA, ENOMEM)         \
  X(ERROR_WRITE_PROTECT, EACCES)             \
  X(ERROR_WRONG_DISK, EACCES)                \
  X(WSAEACCES, EACCES)                       \
  X(WSAEADDRINUSE, EADDRINUSE)               \
  X(WSAEADDRNOTAVAIL, EADDRNOTAVAIL)         \
  X(WSAEAFNOSUPPORT, EAFNOSUPPORT)           \
  X(WSAECONNABORTED, ECONNABORTED)           \
  X(WSAECONNREFUSED, ECONNREFUSED)           \
  X(WSAECONNRESET, ECONNRESET)               \
  X(WSAEDISCON, EPIPE)                       \
  X(WSAEFAULT, EFAULT)                       \
  X(WSAEHOSTDOWN, EHOSTUNREACH)              \
  X(WSAEHOSTUNREACH, EHOSTUNREACH)           \
  X(WSAEINPROGRESS, EBUSY)                   \
  X(WSAEINTR, EINTR)                         \
  X(WSAEINVAL, EINVAL)                       \
  X(WSAEISCONN, EISCONN)                     \
  X(WSAEMSGSIZE, EMSGSIZE)                   \
  X(WSAENETDOWN, ENETDOWN)                   \
  X(WSAENETRESET, EHOSTUNREACH)              \
  X(WSAENETUNREACH, ENETUNREACH)             \
  X(WSAENOBUFS, ENOMEM)                      \
  X(WSAENOTCONN, ENOTCONN)                   \
  X(WSAENOTSOCK, ENOTSOCK)                   \
  X(WSAEOPNOTSUPP, EOPNOTSUPP)               \
  X(WSAEPROCLIM, ENOMEM)                     \
  X(WSAESHUTDOWN, EPIPE)                     \
  X(WSAETIMEDOUT, ETIMEDOUT)                 \
  X(WSAEWOULDBLOCK, EWOULDBLOCK)             \
  X(WSANOTINITIALISED, ENETDOWN)             \
  X(WSASYSNOTREADY, ENETDOWN)                \
  X(WSAVERNOTSUPPORTED, ENOSYS)

866
static errno_t err__map_win_error_to_errno(DWORD error) {
867 868 869 870 871 872 873 874 875 876 877
  switch (error) {
#define X(error_sym, errno_sym) \
  case error_sym:               \
    return errno_sym;
    ERR__ERRNO_MAPPINGS(X)
#undef X
  }
  return EINVAL;
}

void err_map_win_error(void) {
878
  errno = err__map_win_error_to_errno(GetLastError());
879 880 881 882
}

void err_set_win_error(DWORD error) {
  SetLastError(error);
883
  errno = err__map_win_error_to_errno(error);
884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899
}

int err_check_handle(HANDLE handle) {
  DWORD flags;

  /* GetHandleInformation() succeeds when passed INVALID_HANDLE_VALUE, so check
   * for this condition explicitly. */
  if (handle == INVALID_HANDLE_VALUE)
    return_set_error(-1, ERROR_INVALID_HANDLE);

  if (!GetHandleInformation(handle, &flags))
    return_map_error(-1);

  return 0;
}

900 901
static bool init__done = false;
static INIT_ONCE init__once = INIT_ONCE_STATIC_INIT;
902

903
static BOOL CALLBACK init__once_callback(INIT_ONCE* once,
904 905 906 907 908 909 910
                                         void* parameter,
                                         void** context) {
  unused_var(once);
  unused_var(parameter);
  unused_var(context);

  /* N.b. that initialization order matters here. */
911 912
  if (ws_global_init() < 0 || nt_global_init() < 0 ||
      reflock_global_init() < 0 || epoll_global_init() < 0)
913 914
    return FALSE;

915
  init__done = true;
916 917 918 919
  return TRUE;
}

int init(void) {
920 921
  if (!init__done &&
      !InitOnceExecuteOnce(&init__once, init__once_callback, NULL, NULL))
922 923 924 925 926
    return -1; /* LastError and errno aren't touched InitOnceExecuteOnce. */

  return 0;
}

927 928 929 930 931 932 933 934 935 936 937 938
/* Set up a workaround for the following problem:
 *   FARPROC addr = GetProcAddress(...);
 *   MY_FUNC func = (MY_FUNC) addr;          <-- GCC 8 warning/error.
 *   MY_FUNC func = (MY_FUNC) (void*) addr;  <-- MSVC  warning/error.
 * To compile cleanly with either compiler, do casts with this "bridge" type:
 *   MY_FUNC func = (MY_FUNC) (nt__fn_ptr_cast_t) addr; */
#ifdef __GNUC__
typedef void* nt__fn_ptr_cast_t;
#else
typedef FARPROC nt__fn_ptr_cast_t;
#endif

939 940
#define X(return_type, attributes, name, parameters) \
  WEPOLL_INTERNAL return_type(attributes* name) parameters = NULL;
941
NT_NTDLL_IMPORT_LIST(X)
942 943 944 945
#undef X

int nt_global_init(void) {
  HMODULE ntdll;
946
  FARPROC fn_ptr;
947 948 949 950 951

  ntdll = GetModuleHandleW(L"ntdll.dll");
  if (ntdll == NULL)
    return -1;

952 953 954 955 956
#define X(return_type, attributes, name, parameters) \
  fn_ptr = GetProcAddress(ntdll, #name);             \
  if (fn_ptr == NULL)                                \
    return -1;                                       \
  name = (return_type(attributes*) parameters)(nt__fn_ptr_cast_t) fn_ptr;
957
  NT_NTDLL_IMPORT_LIST(X)
958 959 960 961 962 963 964
#undef X

  return 0;
}

#include <string.h>

965
static const size_t POLL_GROUP__MAX_GROUP_SIZE = 32;
966 967 968 969

typedef struct poll_group {
  port_state_t* port_state;
  queue_node_t queue_node;
970
  HANDLE afd_helper_handle;
971 972 973
  size_t group_size;
} poll_group_t;

974
static poll_group_t* poll_group__new(port_state_t* port_state) {
975 976 977 978 979 980 981 982 983
  poll_group_t* poll_group = malloc(sizeof *poll_group);
  if (poll_group == NULL)
    return_set_error(NULL, ERROR_NOT_ENOUGH_MEMORY);

  memset(poll_group, 0, sizeof *poll_group);

  queue_node_init(&poll_group->queue_node);
  poll_group->port_state = port_state;

984 985
  if (afd_create_helper_handle(port_state->iocp,
                               &poll_group->afd_helper_handle) < 0) {
986 987 988 989 990 991 992 993 994 995 996
    free(poll_group);
    return NULL;
  }

  queue_append(&port_state->poll_group_queue, &poll_group->queue_node);

  return poll_group;
}

void poll_group_delete(poll_group_t* poll_group) {
  assert(poll_group->group_size == 0);
997
  CloseHandle(poll_group->afd_helper_handle);
998 999 1000 1001 1002 1003 1004 1005
  queue_remove(&poll_group->queue_node);
  free(poll_group);
}

poll_group_t* poll_group_from_queue_node(queue_node_t* queue_node) {
  return container_of(queue_node, poll_group_t, queue_node);
}

1006 1007
HANDLE poll_group_get_afd_helper_handle(poll_group_t* poll_group) {
  return poll_group->afd_helper_handle;
1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
}

poll_group_t* poll_group_acquire(port_state_t* port_state) {
  queue_t* queue = &port_state->poll_group_queue;
  poll_group_t* poll_group =
      !queue_empty(queue)
          ? container_of(queue_last(queue), poll_group_t, queue_node)
          : NULL;

  if (poll_group == NULL ||
1018 1019
      poll_group->group_size >= POLL_GROUP__MAX_GROUP_SIZE)
    poll_group = poll_group__new(port_state);
1020 1021 1022
  if (poll_group == NULL)
    return NULL;

1023
  if (++poll_group->group_size == POLL_GROUP__MAX_GROUP_SIZE)
1024 1025 1026 1027 1028 1029 1030 1031 1032
    queue_move_first(&port_state->poll_group_queue, &poll_group->queue_node);

  return poll_group;
}

void poll_group_release(poll_group_t* poll_group) {
  port_state_t* port_state = poll_group->port_state;

  poll_group->group_size--;
1033
  assert(poll_group->group_size < POLL_GROUP__MAX_GROUP_SIZE);
1034 1035 1036 1037 1038 1039 1040 1041

  queue_move_last(&port_state->poll_group_queue, &poll_group->queue_node);

  /* Poll groups are currently only freed when the epoll port is closed. */
}

#define PORT__MAX_ON_STACK_COMPLETIONS 256

1042
static port_state_t* port__alloc(void) {
1043 1044 1045 1046 1047 1048 1049
  port_state_t* port_state = malloc(sizeof *port_state);
  if (port_state == NULL)
    return_set_error(NULL, ERROR_NOT_ENOUGH_MEMORY);

  return port_state;
}

1050
static void port__free(port_state_t* port) {
1051 1052 1053 1054
  assert(port != NULL);
  free(port);
}

1055
static HANDLE port__create_iocp(void) {
1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066
  HANDLE iocp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);
  if (iocp == NULL)
    return_map_error(NULL);

  return iocp;
}

port_state_t* port_new(HANDLE* iocp_out) {
  port_state_t* port_state;
  HANDLE iocp;

1067
  port_state = port__alloc();
1068 1069 1070
  if (port_state == NULL)
    goto err1;

1071
  iocp = port__create_iocp();
1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088
  if (iocp == NULL)
    goto err2;

  memset(port_state, 0, sizeof *port_state);

  port_state->iocp = iocp;
  tree_init(&port_state->sock_tree);
  queue_init(&port_state->sock_update_queue);
  queue_init(&port_state->sock_deleted_queue);
  queue_init(&port_state->poll_group_queue);
  ts_tree_node_init(&port_state->handle_tree_node);
  InitializeCriticalSection(&port_state->lock);

  *iocp_out = iocp;
  return port_state;

err2:
1089
  port__free(port_state);
1090 1091 1092 1093
err1:
  return NULL;
}

1094
static int port__close_iocp(port_state_t* port_state) {
1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107
  HANDLE iocp = port_state->iocp;
  port_state->iocp = NULL;

  if (!CloseHandle(iocp))
    return_map_error(-1);

  return 0;
}

int port_close(port_state_t* port_state) {
  int result;

  EnterCriticalSection(&port_state->lock);
1108
  result = port__close_iocp(port_state);
1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139
  LeaveCriticalSection(&port_state->lock);

  return result;
}

int port_delete(port_state_t* port_state) {
  tree_node_t* tree_node;
  queue_node_t* queue_node;

  /* At this point the IOCP port should have been closed. */
  assert(port_state->iocp == NULL);

  while ((tree_node = tree_root(&port_state->sock_tree)) != NULL) {
    sock_state_t* sock_state = sock_state_from_tree_node(tree_node);
    sock_force_delete(port_state, sock_state);
  }

  while ((queue_node = queue_first(&port_state->sock_deleted_queue)) != NULL) {
    sock_state_t* sock_state = sock_state_from_queue_node(queue_node);
    sock_force_delete(port_state, sock_state);
  }

  while ((queue_node = queue_first(&port_state->poll_group_queue)) != NULL) {
    poll_group_t* poll_group = poll_group_from_queue_node(queue_node);
    poll_group_delete(poll_group);
  }

  assert(queue_empty(&port_state->sock_update_queue));

  DeleteCriticalSection(&port_state->lock);

1140
  port__free(port_state);
1141 1142 1143 1144

  return 0;
}

1145
static int port__update_events(port_state_t* port_state) {
1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162
  queue_t* sock_update_queue = &port_state->sock_update_queue;

  /* Walk the queue, submitting new poll requests for every socket that needs
   * it. */
  while (!queue_empty(sock_update_queue)) {
    queue_node_t* queue_node = queue_first(sock_update_queue);
    sock_state_t* sock_state = sock_state_from_queue_node(queue_node);

    if (sock_update(port_state, sock_state) < 0)
      return -1;

    /* sock_update() removes the socket from the update queue. */
  }

  return 0;
}

1163
static void port__update_events_if_polling(port_state_t* port_state) {
1164
  if (port_state->active_poll_count > 0)
1165
    port__update_events(port_state);
1166 1167
}

1168
static int port__feed_events(port_state_t* port_state,
1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184
                             struct epoll_event* epoll_events,
                             OVERLAPPED_ENTRY* iocp_events,
                             DWORD iocp_event_count) {
  int epoll_event_count = 0;
  DWORD i;

  for (i = 0; i < iocp_event_count; i++) {
    OVERLAPPED* overlapped = iocp_events[i].lpOverlapped;
    struct epoll_event* ev = &epoll_events[epoll_event_count];

    epoll_event_count += sock_feed_event(port_state, overlapped, ev);
  }

  return epoll_event_count;
}

1185
static int port__poll(port_state_t* port_state,
1186 1187 1188 1189 1190 1191
                      struct epoll_event* epoll_events,
                      OVERLAPPED_ENTRY* iocp_events,
                      DWORD maxevents,
                      DWORD timeout) {
  DWORD completion_count;

1192
  if (port__update_events(port_state) < 0)
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212
    return -1;

  port_state->active_poll_count++;

  LeaveCriticalSection(&port_state->lock);

  BOOL r = GetQueuedCompletionStatusEx(port_state->iocp,
                                       iocp_events,
                                       maxevents,
                                       &completion_count,
                                       timeout,
                                       FALSE);

  EnterCriticalSection(&port_state->lock);

  port_state->active_poll_count--;

  if (!r)
    return_map_error(-1);

1213
  return port__feed_events(
1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258
      port_state, epoll_events, iocp_events, completion_count);
}

int port_wait(port_state_t* port_state,
              struct epoll_event* events,
              int maxevents,
              int timeout) {
  OVERLAPPED_ENTRY stack_iocp_events[PORT__MAX_ON_STACK_COMPLETIONS];
  OVERLAPPED_ENTRY* iocp_events;
  uint64_t due = 0;
  DWORD gqcs_timeout;
  int result;

  /* Check whether `maxevents` is in range. */
  if (maxevents <= 0)
    return_set_error(-1, ERROR_INVALID_PARAMETER);

  /* Decide whether the IOCP completion list can live on the stack, or allocate
   * memory for it on the heap. */
  if ((size_t) maxevents <= array_count(stack_iocp_events)) {
    iocp_events = stack_iocp_events;
  } else if ((iocp_events =
                  malloc((size_t) maxevents * sizeof *iocp_events)) == NULL) {
    iocp_events = stack_iocp_events;
    maxevents = array_count(stack_iocp_events);
  }

  /* Compute the timeout for GetQueuedCompletionStatus, and the wait end
   * time, if the user specified a timeout other than zero or infinite. */
  if (timeout > 0) {
    due = GetTickCount64() + (uint64_t) timeout;
    gqcs_timeout = (DWORD) timeout;
  } else if (timeout == 0) {
    gqcs_timeout = 0;
  } else {
    gqcs_timeout = INFINITE;
  }

  EnterCriticalSection(&port_state->lock);

  /* Dequeue completion packets until either at least one interesting event
   * has been discovered, or the timeout is reached. */
  for (;;) {
    uint64_t now;

1259
    result = port__poll(
1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279
        port_state, events, iocp_events, (DWORD) maxevents, gqcs_timeout);
    if (result < 0 || result > 0)
      break; /* Result, error, or time-out. */

    if (timeout < 0)
      continue; /* When timeout is negative, never time out. */

    /* Update time. */
    now = GetTickCount64();

    /* Do not allow the due time to be in the past. */
    if (now >= due) {
      SetLastError(WAIT_TIMEOUT);
      break;
    }

    /* Recompute time-out argument for GetQueuedCompletionStatus. */
    gqcs_timeout = (DWORD)(due - now);
  }

1280
  port__update_events_if_polling(port_state);
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294

  LeaveCriticalSection(&port_state->lock);

  if (iocp_events != stack_iocp_events)
    free(iocp_events);

  if (result >= 0)
    return result;
  else if (GetLastError() == WAIT_TIMEOUT)
    return 0;
  else
    return -1;
}

1295
static int port__ctl_add(port_state_t* port_state,
1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306
                         SOCKET sock,
                         struct epoll_event* ev) {
  sock_state_t* sock_state = sock_new(port_state, sock);
  if (sock_state == NULL)
    return -1;

  if (sock_set_event(port_state, sock_state, ev) < 0) {
    sock_delete(port_state, sock_state);
    return -1;
  }

1307
  port__update_events_if_polling(port_state);
1308 1309 1310 1311

  return 0;
}

1312
static int port__ctl_mod(port_state_t* port_state,
1313 1314 1315 1316 1317 1318 1319 1320 1321
                         SOCKET sock,
                         struct epoll_event* ev) {
  sock_state_t* sock_state = port_find_socket(port_state, sock);
  if (sock_state == NULL)
    return -1;

  if (sock_set_event(port_state, sock_state, ev) < 0)
    return -1;

1322
  port__update_events_if_polling(port_state);
1323 1324 1325 1326

  return 0;
}

1327
static int port__ctl_del(port_state_t* port_state, SOCKET sock) {
1328 1329 1330 1331 1332 1333 1334 1335 1336
  sock_state_t* sock_state = port_find_socket(port_state, sock);
  if (sock_state == NULL)
    return -1;

  sock_delete(port_state, sock_state);

  return 0;
}

1337
static int port__ctl_op(port_state_t* port_state,
1338 1339 1340 1341 1342
                        int op,
                        SOCKET sock,
                        struct epoll_event* ev) {
  switch (op) {
    case EPOLL_CTL_ADD:
1343
      return port__ctl_add(port_state, sock, ev);
1344
    case EPOLL_CTL_MOD:
1345
      return port__ctl_mod(port_state, sock, ev);
1346
    case EPOLL_CTL_DEL:
1347
      return port__ctl_del(port_state, sock);
1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359
    default:
      return_set_error(-1, ERROR_INVALID_PARAMETER);
  }
}

int port_ctl(port_state_t* port_state,
             int op,
             SOCKET sock,
             struct epoll_event* ev) {
  int result;

  EnterCriticalSection(&port_state->lock);
1360
  result = port__ctl_op(port_state, op, sock, ev);
1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428
  LeaveCriticalSection(&port_state->lock);

  return result;
}

int port_register_socket_handle(port_state_t* port_state,
                                sock_state_t* sock_state,
                                SOCKET socket) {
  if (tree_add(&port_state->sock_tree,
               sock_state_to_tree_node(sock_state),
               socket) < 0)
    return_set_error(-1, ERROR_ALREADY_EXISTS);
  return 0;
}

void port_unregister_socket_handle(port_state_t* port_state,
                                   sock_state_t* sock_state) {
  tree_del(&port_state->sock_tree, sock_state_to_tree_node(sock_state));
}

sock_state_t* port_find_socket(port_state_t* port_state, SOCKET socket) {
  tree_node_t* tree_node = tree_find(&port_state->sock_tree, socket);
  if (tree_node == NULL)
    return_set_error(NULL, ERROR_NOT_FOUND);
  return sock_state_from_tree_node(tree_node);
}

void port_request_socket_update(port_state_t* port_state,
                                sock_state_t* sock_state) {
  if (queue_enqueued(sock_state_to_queue_node(sock_state)))
    return;
  queue_append(&port_state->sock_update_queue,
               sock_state_to_queue_node(sock_state));
}

void port_cancel_socket_update(port_state_t* port_state,
                               sock_state_t* sock_state) {
  unused_var(port_state);
  if (!queue_enqueued(sock_state_to_queue_node(sock_state)))
    return;
  queue_remove(sock_state_to_queue_node(sock_state));
}

void port_add_deleted_socket(port_state_t* port_state,
                             sock_state_t* sock_state) {
  if (queue_enqueued(sock_state_to_queue_node(sock_state)))
    return;
  queue_append(&port_state->sock_deleted_queue,
               sock_state_to_queue_node(sock_state));
}

void port_remove_deleted_socket(port_state_t* port_state,
                                sock_state_t* sock_state) {
  unused_var(port_state);
  if (!queue_enqueued(sock_state_to_queue_node(sock_state)))
    return;
  queue_remove(sock_state_to_queue_node(sock_state));
}

void queue_init(queue_t* queue) {
  queue_node_init(&queue->head);
}

void queue_node_init(queue_node_t* node) {
  node->prev = node;
  node->next = node;
}

1429
static inline void queue__detach_node(queue_node_t* node) {
1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456
  node->prev->next = node->next;
  node->next->prev = node->prev;
}

queue_node_t* queue_first(const queue_t* queue) {
  return !queue_empty(queue) ? queue->head.next : NULL;
}

queue_node_t* queue_last(const queue_t* queue) {
  return !queue_empty(queue) ? queue->head.prev : NULL;
}

void queue_prepend(queue_t* queue, queue_node_t* node) {
  node->next = queue->head.next;
  node->prev = &queue->head;
  node->next->prev = node;
  queue->head.next = node;
}

void queue_append(queue_t* queue, queue_node_t* node) {
  node->next = &queue->head;
  node->prev = queue->head.prev;
  node->prev->next = node;
  queue->head.prev = node;
}

void queue_move_first(queue_t* queue, queue_node_t* node) {
1457
  queue__detach_node(node);
1458 1459 1460 1461
  queue_prepend(queue, node);
}

void queue_move_last(queue_t* queue, queue_node_t* node) {
1462
  queue__detach_node(node);
1463 1464 1465 1466
  queue_append(queue, node);
}

void queue_remove(queue_node_t* node) {
1467
  queue__detach_node(node);
1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
  queue_node_init(node);
}

bool queue_empty(const queue_t* queue) {
  return !queue_enqueued(&queue->head);
}

bool queue_enqueued(const queue_node_t* node) {
  return node->prev != node;
}

/* clang-format off */
1480 1481 1482 1483 1484
static const long REFLOCK__REF          = (long) 0x00000001;
static const long REFLOCK__REF_MASK     = (long) 0x0fffffff;
static const long REFLOCK__DESTROY      = (long) 0x10000000;
static const long REFLOCK__DESTROY_MASK = (long) 0xf0000000;
static const long REFLOCK__POISON       = (long) 0x300DEAD0;
1485 1486
/* clang-format on */

1487
static HANDLE reflock__keyed_event = NULL;
1488 1489 1490

int reflock_global_init(void) {
  NTSTATUS status =
1491
      NtCreateKeyedEvent(&reflock__keyed_event, ~(ACCESS_MASK) 0, NULL, 0);
1492 1493 1494 1495 1496 1497 1498 1499 1500
  if (status != STATUS_SUCCESS)
    return_set_error(-1, RtlNtStatusToDosError(status));
  return 0;
}

void reflock_init(reflock_t* reflock) {
  reflock->state = 0;
}

1501 1502 1503
static void reflock__signal_event(void* address) {
  NTSTATUS status =
      NtReleaseKeyedEvent(reflock__keyed_event, address, FALSE, NULL);
1504 1505 1506 1507
  if (status != STATUS_SUCCESS)
    abort();
}

1508 1509 1510
static void reflock__await_event(void* address) {
  NTSTATUS status =
      NtWaitForKeyedEvent(reflock__keyed_event, address, FALSE, NULL);
1511 1512 1513 1514 1515
  if (status != STATUS_SUCCESS)
    abort();
}

void reflock_ref(reflock_t* reflock) {
1516
  long state = InterlockedAdd(&reflock->state, REFLOCK__REF);
1517
  unused_var(state);
1518
  assert((state & REFLOCK__DESTROY_MASK) == 0); /* Overflow or destroyed. */
1519 1520 1521
}

void reflock_unref(reflock_t* reflock) {
1522 1523 1524
  long state = InterlockedAdd(&reflock->state, -REFLOCK__REF);
  long ref_count = state & REFLOCK__REF_MASK;
  long destroy = state & REFLOCK__DESTROY_MASK;
1525 1526 1527 1528

  unused_var(ref_count);
  unused_var(destroy);

1529 1530
  if (state == REFLOCK__DESTROY)
    reflock__signal_event(reflock);
1531 1532 1533 1534 1535
  else
    assert(destroy == 0 || ref_count > 0);
}

void reflock_unref_and_destroy(reflock_t* reflock) {
1536 1537 1538
  long state =
      InterlockedAdd(&reflock->state, REFLOCK__DESTROY - REFLOCK__REF);
  long ref_count = state & REFLOCK__REF_MASK;
1539

1540 1541
  assert((state & REFLOCK__DESTROY_MASK) ==
         REFLOCK__DESTROY); /* Underflow or already destroyed. */
1542 1543

  if (ref_count != 0)
1544
    reflock__await_event(reflock);
1545

1546 1547
  state = InterlockedExchange(&reflock->state, REFLOCK__POISON);
  assert(state == REFLOCK__DESTROY);
1548 1549
}

1550
static const uint32_t SOCK__KNOWN_EPOLL_EVENTS =
1551 1552 1553
    EPOLLIN | EPOLLPRI | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM |
    EPOLLRDBAND | EPOLLWRNORM | EPOLLWRBAND | EPOLLMSG | EPOLLRDHUP;

1554 1555 1556 1557 1558
typedef enum sock__poll_status {
  SOCK__POLL_IDLE = 0,
  SOCK__POLL_PENDING,
  SOCK__POLL_CANCELLED
} sock__poll_status_t;
1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569

typedef struct sock_state {
  OVERLAPPED overlapped;
  AFD_POLL_INFO poll_info;
  queue_node_t queue_node;
  tree_node_t tree_node;
  poll_group_t* poll_group;
  SOCKET base_socket;
  epoll_data_t user_data;
  uint32_t user_events;
  uint32_t pending_events;
1570
  sock__poll_status_t poll_status;
1571 1572 1573
  bool delete_pending;
} sock_state_t;

1574
static inline sock_state_t* sock__alloc(void) {
1575 1576 1577 1578 1579 1580
  sock_state_t* sock_state = malloc(sizeof *sock_state);
  if (sock_state == NULL)
    return_set_error(NULL, ERROR_NOT_ENOUGH_MEMORY);
  return sock_state;
}

1581
static inline void sock__free(sock_state_t* sock_state) {
1582 1583 1584
  free(sock_state);
}

1585 1586 1587 1588
static int sock__cancel_poll(sock_state_t* sock_state) {
  HANDLE afd_helper_handle =
      poll_group_get_afd_helper_handle(sock_state->poll_group);
  assert(sock_state->poll_status == SOCK__POLL_PENDING);
1589 1590 1591

  /* CancelIoEx() may fail with ERROR_NOT_FOUND if the overlapped operation has
   * already completed. This is not a problem and we proceed normally. */
1592 1593
  if (!HasOverlappedIoCompleted(&sock_state->overlapped) &&
      !CancelIoEx(afd_helper_handle, &sock_state->overlapped) &&
1594 1595 1596
      GetLastError() != ERROR_NOT_FOUND)
    return_map_error(-1);

1597
  sock_state->poll_status = SOCK__POLL_CANCELLED;
1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617
  sock_state->pending_events = 0;
  return 0;
}

sock_state_t* sock_new(port_state_t* port_state, SOCKET socket) {
  SOCKET base_socket;
  poll_group_t* poll_group;
  sock_state_t* sock_state;

  if (socket == 0 || socket == INVALID_SOCKET)
    return_set_error(NULL, ERROR_INVALID_HANDLE);

  base_socket = ws_get_base_socket(socket);
  if (base_socket == INVALID_SOCKET)
    return NULL;

  poll_group = poll_group_acquire(port_state);
  if (poll_group == NULL)
    return NULL;

1618
  sock_state = sock__alloc();
1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635
  if (sock_state == NULL)
    goto err1;

  memset(sock_state, 0, sizeof *sock_state);

  sock_state->base_socket = base_socket;
  sock_state->poll_group = poll_group;

  tree_node_init(&sock_state->tree_node);
  queue_node_init(&sock_state->queue_node);

  if (port_register_socket_handle(port_state, sock_state, socket) < 0)
    goto err2;

  return sock_state;

err2:
1636
  sock__free(sock_state);
1637 1638 1639 1640 1641 1642
err1:
  poll_group_release(poll_group);

  return NULL;
}

1643
static int sock__delete(port_state_t* port_state,
1644 1645 1646
                        sock_state_t* sock_state,
                        bool force) {
  if (!sock_state->delete_pending) {
1647 1648
    if (sock_state->poll_status == SOCK__POLL_PENDING)
      sock__cancel_poll(sock_state);
1649 1650 1651 1652 1653 1654 1655 1656 1657 1658

    port_cancel_socket_update(port_state, sock_state);
    port_unregister_socket_handle(port_state, sock_state);

    sock_state->delete_pending = true;
  }

  /* If the poll request still needs to complete, the sock_state object can't
   * be free()d yet. `sock_feed_event()` or `port_close()` will take care
   * of this later. */
1659
  if (force || sock_state->poll_status == SOCK__POLL_IDLE) {
1660 1661 1662
    /* Free the sock_state now. */
    port_remove_deleted_socket(port_state, sock_state);
    poll_group_release(sock_state->poll_group);
1663
    sock__free(sock_state);
1664 1665 1666 1667 1668 1669 1670 1671 1672
  } else {
    /* Free the socket later. */
    port_add_deleted_socket(port_state, sock_state);
  }

  return 0;
}

void sock_delete(port_state_t* port_state, sock_state_t* sock_state) {
1673
  sock__delete(port_state, sock_state, false);
1674 1675 1676
}

void sock_force_delete(port_state_t* port_state, sock_state_t* sock_state) {
1677
  sock__delete(port_state, sock_state, true);
1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690
}

int sock_set_event(port_state_t* port_state,
                   sock_state_t* sock_state,
                   const struct epoll_event* ev) {
  /* EPOLLERR and EPOLLHUP are always reported, even when not requested by the
   * caller. However they are disabled after a event has been reported for a
   * socket for which the EPOLLONESHOT flag as set. */
  uint32_t events = ev->events | EPOLLERR | EPOLLHUP;

  sock_state->user_events = events;
  sock_state->user_data = ev->data;

1691
  if ((events & SOCK__KNOWN_EPOLL_EVENTS & ~sock_state->pending_events) != 0)
1692 1693 1694 1695 1696
    port_request_socket_update(port_state, sock_state);

  return 0;
}

1697
static inline DWORD sock__epoll_events_to_afd_events(uint32_t epoll_events) {
1698 1699 1700 1701 1702 1703 1704 1705 1706
  /* Always monitor for AFD_POLL_LOCAL_CLOSE, which is triggered when the
   * socket is closed with closesocket() or CloseHandle(). */
  DWORD afd_events = AFD_POLL_LOCAL_CLOSE;

  if (epoll_events & (EPOLLIN | EPOLLRDNORM))
    afd_events |= AFD_POLL_RECEIVE | AFD_POLL_ACCEPT;
  if (epoll_events & (EPOLLPRI | EPOLLRDBAND))
    afd_events |= AFD_POLL_RECEIVE_EXPEDITED;
  if (epoll_events & (EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND))
1707
    afd_events |= AFD_POLL_SEND;
1708 1709 1710 1711 1712 1713 1714 1715 1716 1717
  if (epoll_events & (EPOLLIN | EPOLLRDNORM | EPOLLRDHUP))
    afd_events |= AFD_POLL_DISCONNECT;
  if (epoll_events & EPOLLHUP)
    afd_events |= AFD_POLL_ABORT;
  if (epoll_events & EPOLLERR)
    afd_events |= AFD_POLL_CONNECT_FAIL;

  return afd_events;
}

1718
static inline uint32_t sock__afd_events_to_epoll_events(DWORD afd_events) {
1719 1720 1721 1722 1723 1724
  uint32_t epoll_events = 0;

  if (afd_events & (AFD_POLL_RECEIVE | AFD_POLL_ACCEPT))
    epoll_events |= EPOLLIN | EPOLLRDNORM;
  if (afd_events & AFD_POLL_RECEIVE_EXPEDITED)
    epoll_events |= EPOLLPRI | EPOLLRDBAND;
1725
  if (afd_events & AFD_POLL_SEND)
1726 1727 1728 1729 1730 1731
    epoll_events |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
  if (afd_events & AFD_POLL_DISCONNECT)
    epoll_events |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
  if (afd_events & AFD_POLL_ABORT)
    epoll_events |= EPOLLHUP;
  if (afd_events & AFD_POLL_CONNECT_FAIL)
1732 1733 1734
    /* Linux reports all these events after connect() has failed. */
    epoll_events |=
        EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLRDNORM | EPOLLWRNORM | EPOLLRDHUP;
1735 1736 1737 1738 1739 1740 1741

  return epoll_events;
}

int sock_update(port_state_t* port_state, sock_state_t* sock_state) {
  assert(!sock_state->delete_pending);

1742 1743
  if ((sock_state->poll_status == SOCK__POLL_PENDING) &&
      (sock_state->user_events & SOCK__KNOWN_EPOLL_EVENTS &
1744 1745 1746 1747 1748 1749
       ~sock_state->pending_events) == 0) {
    /* All the events the user is interested in are already being monitored by
     * the pending poll operation. It might spuriously complete because of an
     * event that we're no longer interested in; when that happens we'll submit
     * a new poll operation with the updated event mask. */

1750
  } else if (sock_state->poll_status == SOCK__POLL_PENDING) {
1751 1752 1753 1754
    /* A poll operation is already pending, but it's not monitoring for all the
     * events that the user is interested in. Therefore, cancel the pending
     * poll operation; when we receive it's completion package, a new poll
     * operation will be submitted with the correct event mask. */
1755
    if (sock__cancel_poll(sock_state) < 0)
1756 1757
      return -1;

1758
  } else if (sock_state->poll_status == SOCK__POLL_CANCELLED) {
1759 1760 1761
    /* The poll operation has already been cancelled, we're still waiting for
     * it to return. For now, there's nothing that needs to be done. */

1762
  } else if (sock_state->poll_status == SOCK__POLL_IDLE) {
1763 1764 1765 1766 1767 1768 1769
    /* No poll operation is pending; start one. */
    sock_state->poll_info.Exclusive = FALSE;
    sock_state->poll_info.NumberOfHandles = 1;
    sock_state->poll_info.Timeout.QuadPart = INT64_MAX;
    sock_state->poll_info.Handles[0].Handle = (HANDLE) sock_state->base_socket;
    sock_state->poll_info.Handles[0].Status = 0;
    sock_state->poll_info.Handles[0].Events =
1770
        sock__epoll_events_to_afd_events(sock_state->user_events);
1771 1772 1773

    memset(&sock_state->overlapped, 0, sizeof sock_state->overlapped);

1774
    if (afd_poll(poll_group_get_afd_helper_handle(sock_state->poll_group),
1775 1776 1777 1778 1779 1780 1781 1782
                 &sock_state->poll_info,
                 &sock_state->overlapped) < 0) {
      switch (GetLastError()) {
        case ERROR_IO_PENDING:
          /* Overlapped poll operation in progress; this is expected. */
          break;
        case ERROR_INVALID_HANDLE:
          /* Socket closed; it'll be dropped from the epoll set. */
1783
          return sock__delete(port_state, sock_state, false);
1784 1785 1786 1787 1788 1789 1790
        default:
          /* Other errors are propagated to the caller. */
          return_map_error(-1);
      }
    }

    /* The poll request was successfully submitted. */
1791
    sock_state->poll_status = SOCK__POLL_PENDING;
1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810
    sock_state->pending_events = sock_state->user_events;

  } else {
    /* Unreachable. */
    assert(false);
  }

  port_cancel_socket_update(port_state, sock_state);
  return 0;
}

int sock_feed_event(port_state_t* port_state,
                    OVERLAPPED* overlapped,
                    struct epoll_event* ev) {
  sock_state_t* sock_state =
      container_of(overlapped, sock_state_t, overlapped);
  AFD_POLL_INFO* poll_info = &sock_state->poll_info;
  uint32_t epoll_events = 0;

1811
  sock_state->poll_status = SOCK__POLL_IDLE;
1812 1813 1814 1815
  sock_state->pending_events = 0;

  if (sock_state->delete_pending) {
    /* Socket has been deleted earlier and can now be freed. */
1816
    return sock__delete(port_state, sock_state, false);
1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829

  } else if ((NTSTATUS) overlapped->Internal == STATUS_CANCELLED) {
    /* The poll request was cancelled by CancelIoEx. */

  } else if (!NT_SUCCESS(overlapped->Internal)) {
    /* The overlapped request itself failed in an unexpected way. */
    epoll_events = EPOLLERR;

  } else if (poll_info->NumberOfHandles < 1) {
    /* This poll operation succeeded but didn't report any socket events. */

  } else if (poll_info->Handles[0].Events & AFD_POLL_LOCAL_CLOSE) {
    /* The poll operation reported that the socket was closed. */
1830
    return sock__delete(port_state, sock_state, false);
1831 1832 1833

  } else {
    /* Events related to our socket were reported. */
1834 1835
    epoll_events =
        sock__afd_events_to_epoll_events(poll_info->Handles[0].Events);
1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893
  }

  /* Requeue the socket so a new poll request will be submitted. */
  port_request_socket_update(port_state, sock_state);

  /* Filter out events that the user didn't ask for. */
  epoll_events &= sock_state->user_events;

  /* Return if there are no epoll events to report. */
  if (epoll_events == 0)
    return 0;

  /* If the the socket has the EPOLLONESHOT flag set, unmonitor all events,
   * even EPOLLERR and EPOLLHUP. But always keep looking for closed sockets. */
  if (sock_state->user_events & EPOLLONESHOT)
    sock_state->user_events = 0;

  ev->data = sock_state->user_data;
  ev->events = epoll_events;
  return 1;
}

queue_node_t* sock_state_to_queue_node(sock_state_t* sock_state) {
  return &sock_state->queue_node;
}

sock_state_t* sock_state_from_tree_node(tree_node_t* tree_node) {
  return container_of(tree_node, sock_state_t, tree_node);
}

tree_node_t* sock_state_to_tree_node(sock_state_t* sock_state) {
  return &sock_state->tree_node;
}

sock_state_t* sock_state_from_queue_node(queue_node_t* queue_node) {
  return container_of(queue_node, sock_state_t, queue_node);
}

void ts_tree_init(ts_tree_t* ts_tree) {
  tree_init(&ts_tree->tree);
  InitializeSRWLock(&ts_tree->lock);
}

void ts_tree_node_init(ts_tree_node_t* node) {
  tree_node_init(&node->tree_node);
  reflock_init(&node->reflock);
}

int ts_tree_add(ts_tree_t* ts_tree, ts_tree_node_t* node, uintptr_t key) {
  int r;

  AcquireSRWLockExclusive(&ts_tree->lock);
  r = tree_add(&ts_tree->tree, &node->tree_node, key);
  ReleaseSRWLockExclusive(&ts_tree->lock);

  return r;
}

1894
static inline ts_tree_node_t* ts_tree__find_node(ts_tree_t* ts_tree,
1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907
                                                 uintptr_t key) {
  tree_node_t* tree_node = tree_find(&ts_tree->tree, key);
  if (tree_node == NULL)
    return NULL;

  return container_of(tree_node, ts_tree_node_t, tree_node);
}

ts_tree_node_t* ts_tree_del_and_ref(ts_tree_t* ts_tree, uintptr_t key) {
  ts_tree_node_t* ts_tree_node;

  AcquireSRWLockExclusive(&ts_tree->lock);

1908
  ts_tree_node = ts_tree__find_node(ts_tree, key);
1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923
  if (ts_tree_node != NULL) {
    tree_del(&ts_tree->tree, &ts_tree_node->tree_node);
    reflock_ref(&ts_tree_node->reflock);
  }

  ReleaseSRWLockExclusive(&ts_tree->lock);

  return ts_tree_node;
}

ts_tree_node_t* ts_tree_find_and_ref(ts_tree_t* ts_tree, uintptr_t key) {
  ts_tree_node_t* ts_tree_node;

  AcquireSRWLockShared(&ts_tree->lock);

1924
  ts_tree_node = ts_tree__find_node(ts_tree, key);
1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
  if (ts_tree_node != NULL)
    reflock_ref(&ts_tree_node->reflock);

  ReleaseSRWLockShared(&ts_tree->lock);

  return ts_tree_node;
}

void ts_tree_node_unref(ts_tree_node_t* node) {
  reflock_unref(&node->reflock);
}

void ts_tree_node_unref_and_destroy(ts_tree_node_t* node) {
  reflock_unref_and_destroy(&node->reflock);
}

void tree_init(tree_t* tree) {
  memset(tree, 0, sizeof *tree);
}

void tree_node_init(tree_node_t* node) {
  memset(node, 0, sizeof *node);
}

#define TREE__ROTATE(cis, trans)   \
  tree_node_t* p = node;           \
  tree_node_t* q = node->trans;    \
  tree_node_t* parent = p->parent; \
                                   \
  if (parent) {                    \
    if (parent->left == p)         \
      parent->left = q;            \
    else                           \
      parent->right = q;           \
  } else {                         \
    tree->root = q;                \
  }                                \
                                   \
  q->parent = parent;              \
  p->parent = q;                   \
  p->trans = q->cis;               \
  if (p->trans)                    \
    p->trans->parent = p;          \
  q->cis = p;

1970
static inline void tree__rotate_left(tree_t* tree, tree_node_t* node) {
1971 1972 1973
  TREE__ROTATE(left, right)
}

1974
static inline void tree__rotate_right(tree_t* tree, tree_node_t* node) {
1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995
  TREE__ROTATE(right, left)
}

#define TREE__INSERT_OR_DESCEND(side) \
  if (parent->side) {                 \
    parent = parent->side;            \
  } else {                            \
    parent->side = node;              \
    break;                            \
  }

#define TREE__FIXUP_AFTER_INSERT(cis, trans) \
  tree_node_t* grandparent = parent->parent; \
  tree_node_t* uncle = grandparent->trans;   \
                                             \
  if (uncle && uncle->red) {                 \
    parent->red = uncle->red = false;        \
    grandparent->red = true;                 \
    node = grandparent;                      \
  } else {                                   \
    if (node == parent->trans) {             \
1996
      tree__rotate_##cis(tree, parent);      \
1997 1998 1999 2000 2001
      node = parent;                         \
      parent = node->parent;                 \
    }                                        \
    parent->red = false;                     \
    grandparent->red = true;                 \
2002
    tree__rotate_##trans(tree, grandparent); \
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045
  }

int tree_add(tree_t* tree, tree_node_t* node, uintptr_t key) {
  tree_node_t* parent;

  parent = tree->root;
  if (parent) {
    for (;;) {
      if (key < parent->key) {
        TREE__INSERT_OR_DESCEND(left)
      } else if (key > parent->key) {
        TREE__INSERT_OR_DESCEND(right)
      } else {
        return -1;
      }
    }
  } else {
    tree->root = node;
  }

  node->key = key;
  node->left = node->right = NULL;
  node->parent = parent;
  node->red = true;

  for (; parent && parent->red; parent = node->parent) {
    if (parent == parent->parent->left) {
      TREE__FIXUP_AFTER_INSERT(left, right)
    } else {
      TREE__FIXUP_AFTER_INSERT(right, left)
    }
  }
  tree->root->red = false;

  return 0;
}

#define TREE__FIXUP_AFTER_REMOVE(cis, trans)       \
  tree_node_t* sibling = parent->trans;            \
                                                   \
  if (sibling->red) {                              \
    sibling->red = false;                          \
    parent->red = true;                            \
2046
    tree__rotate_##cis(tree, parent);              \
2047 2048 2049 2050 2051 2052 2053
    sibling = parent->trans;                       \
  }                                                \
  if ((sibling->left && sibling->left->red) ||     \
      (sibling->right && sibling->right->red)) {   \
    if (!sibling->trans || !sibling->trans->red) { \
      sibling->cis->red = false;                   \
      sibling->red = true;                         \
2054
      tree__rotate_##trans(tree, sibling);         \
2055 2056 2057 2058
      sibling = parent->trans;                     \
    }                                              \
    sibling->red = parent->red;                    \
    parent->red = sibling->trans->red = false;     \
2059
    tree__rotate_##cis(tree, parent);              \
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    node = tree->root;                             \
    break;                                         \
  }                                                \
  sibling->red = true;

void tree_del(tree_t* tree, tree_node_t* node) {
  tree_node_t* parent = node->parent;
  tree_node_t* left = node->left;
  tree_node_t* right = node->right;
  tree_node_t* next;
  bool red;

  if (!left) {
    next = right;
  } else if (!right) {
    next = left;
  } else {
    next = right;
    while (next->left)
      next = next->left;
  }

  if (parent) {
    if (parent->left == node)
      parent->left = next;
    else
      parent->right = next;
  } else {
    tree->root = next;
  }

  if (left && right) {
    red = next->red;
    next->red = node->red;
    next->left = left;
    left->parent = next;
    if (next != right) {
      parent = next->parent;
      next->parent = node->parent;
      node = next->right;
      parent->left = node;
      next->right = right;
      right->parent = next;
    } else {
      next->parent = parent;
      parent = next;
      node = next->right;
    }
  } else {
    red = node->red;
    node = next;
  }

  if (node)
    node->parent = parent;
  if (red)
    return;
  if (node && node->red) {
    node->red = false;
    return;
  }

  do {
    if (node == tree->root)
      break;
    if (node == parent->left) {
      TREE__FIXUP_AFTER_REMOVE(left, right)
    } else {
      TREE__FIXUP_AFTER_REMOVE(right, left)
    }
    node = parent;
    parent = parent->parent;
  } while (!node->red);

  if (node)
    node->red = false;
}

tree_node_t* tree_find(const tree_t* tree, uintptr_t key) {
  tree_node_t* node = tree->root;
  while (node) {
    if (key < node->key)
      node = node->left;
    else if (key > node->key)
      node = node->right;
    else
      return node;
  }
  return NULL;
}

tree_node_t* tree_root(const tree_t* tree) {
  return tree->root;
}

#ifndef SIO_BASE_HANDLE
#define SIO_BASE_HANDLE 0x48000022
#endif

int ws_global_init(void) {
  int r;
  WSADATA wsa_data;

  r = WSAStartup(MAKEWORD(2, 2), &wsa_data);
  if (r != 0)
    return_set_error(-1, (DWORD) r);

  return 0;
}

SOCKET ws_get_base_socket(SOCKET socket) {
  SOCKET base_socket;
  DWORD bytes;

  if (WSAIoctl(socket,
               SIO_BASE_HANDLE,
               NULL,
               0,
               &base_socket,
               sizeof base_socket,
               &bytes,
               NULL,
               NULL) == SOCKET_ERROR)
    return_map_error(INVALID_SOCKET);

  return base_socket;
}