--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/unix/os390.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,1070 @@
+/* Copyright libuv project contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "internal.h"
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <utmpx.h>
+#include <unistd.h>
+#include <sys/ps.h>
+#include <builtins.h>
+#include <termios.h>
+#include <sys/msg.h>
+#include <sys/resource.h>
+#include "zos-base.h"
+#include "zos-sys-info.h"
+#if defined(__clang__)
+#include "csrsic.h"
+#else
+#include "//'SYS1.SAMPLIB(CSRSIC)'"
+#endif
+
+#define CVT_PTR           0x10
+#define PSA_PTR           0x00
+#define CSD_OFFSET        0x294
+
+/*
+    Long-term average CPU service used by this logical partition,
+    in millions of service units per hour. If this value is above
+    the partition's defined capacity, the partition will be capped.
+    It is calculated using the physical CPU adjustment factor
+    (RCTPCPUA) so it may not match other measures of service which
+    are based on the logical CPU adjustment factor. It is available
+    if the hardware supports LPAR cluster.
+*/
+#define RCTLACS_OFFSET    0xC4
+
+/* 32-bit count of alive CPUs. This includes both CPs and IFAs */
+#define CSD_NUMBER_ONLINE_CPUS        0xD4
+
+/* Address of system resources manager (SRM) control table */
+#define CVTOPCTP_OFFSET   0x25C
+
+/* Address of the RCT table */
+#define RMCTRCT_OFFSET    0xE4
+
+/* Address of the rsm control and enumeration area. */
+#define CVTRCEP_OFFSET    0x490
+
+/* Total number of frames currently on all available frame queues. */
+#define RCEAFC_OFFSET     0x088
+
+/* Pointer to the home (current) ASCB. */
+#define PSAAOLD           0x224
+
+/* Pointer to rsm address space block extension. */
+#define ASCBRSME          0x16C
+
+/*
+    NUMBER OF FRAMES CURRENTLY IN USE BY THIS ADDRESS SPACE.
+    It does not include 2G frames.
+*/
+#define RAXFMCT           0x2C
+
+/* Thread Entry constants */
+#define PGTH_CURRENT  1
+#define PGTH_LEN      26
+#define PGTHAPATH     0x20
+#pragma linkage(BPX4GTH, OS)
+#pragma linkage(BPX1GTH, OS)
+
+/* TOD Clock resolution in nanoseconds */
+#define TOD_RES 4.096
+
+typedef unsigned data_area_ptr_assign_type;
+
+typedef union {
+  struct {
+#if defined(_LP64)
+    data_area_ptr_assign_type lower;
+#endif
+    data_area_ptr_assign_type assign;
+  };
+  char* deref;
+} data_area_ptr;
+
+
+void uv_loadavg(double avg[3]) {
+  /* TODO: implement the following */
+  avg[0] = 0;
+  avg[1] = 0;
+  avg[2] = 0;
+}
+
+
+int uv__platform_loop_init(uv_loop_t* loop) {
+  uv__os390_epoll* ep;
+
+  ep = epoll_create1(0);
+  loop->ep = ep;
+  if (ep == NULL)
+    return UV__ERR(errno);
+
+  return 0;
+}
+
+
+void uv__platform_loop_delete(uv_loop_t* loop) {
+  if (loop->ep != NULL) {
+    epoll_queue_close(loop->ep);
+    loop->ep = NULL;
+  }
+}
+
+
+uint64_t uv__hrtime(uv_clocktype_t type) {
+  unsigned long long timestamp;
+  __stckf(&timestamp);
+  /* Convert to nanoseconds */
+  return timestamp / TOD_RES;
+}
+
+
+static int getexe(char* buf, size_t len) {
+  return uv__strscpy(buf, __getargv()[0], len);
+}
+
+
+/*
+ * We could use a static buffer for the path manipulations that we need outside
+ * of the function, but this function could be called by multiple consumers and
+ * we don't want to potentially create a race condition in the use of snprintf.
+ * There is no direct way of getting the exe path in zOS - either through /procfs
+ * or through some libc APIs. The below approach is to parse the argv[0]'s pattern
+ * and use it in conjunction with PATH environment variable to craft one.
+ */
+int uv_exepath(char* buffer, size_t* size) {
+  int res;
+  char args[PATH_MAX];
+  int pid;
+
+  if (buffer == NULL || size == NULL || *size == 0)
+    return UV_EINVAL;
+
+  res = getexe(args, sizeof(args));
+  if (res < 0)
+    return UV_EINVAL;
+
+  return uv__search_path(args, buffer, size);
+}
+
+
+uint64_t uv_get_free_memory(void) {
+  uint64_t freeram;
+
+  data_area_ptr cvt = {0};
+  data_area_ptr rcep = {0};
+  cvt.assign = *(data_area_ptr_assign_type*)(CVT_PTR);
+  rcep.assign = *(data_area_ptr_assign_type*)(cvt.deref + CVTRCEP_OFFSET);
+  freeram = (uint64_t)*((uint32_t*)(rcep.deref + RCEAFC_OFFSET)) * 4096;
+  return freeram;
+}
+
+
+uint64_t uv_get_total_memory(void) {
+  /* Use CVTRLSTG to get the size of actual real storage online at IPL in K. */
+  return (uint64_t)((int)((char *__ptr32 *__ptr32 *)0)[4][214]) * 1024;
+}
+
+
+uint64_t uv_get_constrained_memory(void) {
+  struct rlimit rl;
+
+  /* RLIMIT_MEMLIMIT return value is in megabytes rather than bytes. */
+  if (getrlimit(RLIMIT_MEMLIMIT, &rl) == 0)
+    return rl.rlim_cur * 1024 * 1024;
+
+  return 0; /* There is no memory limit set. */
+}
+
+
+uint64_t uv_get_available_memory(void) {
+  return uv_get_free_memory();
+}
+
+
+int uv_resident_set_memory(size_t* rss) {
+  char* ascb;
+  char* rax;
+  size_t nframes;
+
+  ascb  = *(char* __ptr32 *)(PSA_PTR + PSAAOLD);
+  rax = *(char* __ptr32 *)(ascb + ASCBRSME);
+  nframes = *(unsigned int*)(rax + RAXFMCT);
+
+  *rss = nframes * sysconf(_SC_PAGESIZE);
+  return 0;
+}
+
+
+int uv_uptime(double* uptime) {
+  struct utmpx u ;
+  struct utmpx *v;
+  time64_t t;
+
+  u.ut_type = BOOT_TIME;
+  v = getutxid(&u);
+  if (v == NULL)
+    return -1;
+  *uptime = difftime64(time64(&t), v->ut_tv.tv_sec);
+  return 0;
+}
+
+
+int uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count) {
+  uv_cpu_info_t* cpu_info;
+  int idx;
+  siv1v2 info;
+  data_area_ptr cvt = {0};
+  data_area_ptr csd = {0};
+  data_area_ptr rmctrct = {0};
+  data_area_ptr cvtopctp = {0};
+  int cpu_usage_avg;
+
+  cvt.assign = *(data_area_ptr_assign_type*)(CVT_PTR);
+
+  csd.assign = *((data_area_ptr_assign_type *) (cvt.deref + CSD_OFFSET));
+  cvtopctp.assign = *((data_area_ptr_assign_type *) (cvt.deref + CVTOPCTP_OFFSET));
+  rmctrct.assign = *((data_area_ptr_assign_type *) (cvtopctp.deref + RMCTRCT_OFFSET));
+
+  *count = *((int*) (csd.deref + CSD_NUMBER_ONLINE_CPUS));
+  cpu_usage_avg = *((unsigned short int*) (rmctrct.deref + RCTLACS_OFFSET));
+
+  *cpu_infos = uv__malloc(*count * sizeof(uv_cpu_info_t));
+  if (!*cpu_infos)
+    return UV_ENOMEM;
+
+  cpu_info = *cpu_infos;
+  idx = 0;
+  while (idx < *count) {
+    cpu_info->speed = *(int*)(info.siv1v2si22v1.si22v1cpucapability);
+    cpu_info->model = uv__malloc(ZOSCPU_MODEL_LENGTH + 1);
+    if (cpu_info->model == NULL) {
+      uv_free_cpu_info(*cpu_infos, idx);
+      return UV_ENOMEM; 
+    }
+    __get_cpu_model(cpu_info->model, ZOSCPU_MODEL_LENGTH + 1);
+    cpu_info->cpu_times.user = cpu_usage_avg;
+    /* TODO: implement the following */
+    cpu_info->cpu_times.sys = 0;
+    cpu_info->cpu_times.idle = 0;
+    cpu_info->cpu_times.irq = 0;
+    cpu_info->cpu_times.nice = 0;
+    ++cpu_info;
+    ++idx;
+  }
+
+  return 0;
+}
+
+
+static int uv__interface_addresses_v6(uv_interface_address_t** addresses,
+                                      int* count) {
+  uv_interface_address_t* address;
+  int sockfd;
+  int maxsize;
+  __net_ifconf6header_t ifc;
+  __net_ifconf6entry_t* ifr;
+  __net_ifconf6entry_t* p;
+  unsigned int i;
+  int count_names;
+  unsigned char netmask[16] = {0};
+
+  *count = 0;
+  /* Assume maximum buffer size allowable */
+  maxsize = 16384;
+
+  if (0 > (sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP)))
+    return UV__ERR(errno);
+
+  ifc.__nif6h_buffer = uv__calloc(1, maxsize);
+
+  if (ifc.__nif6h_buffer == NULL) {
+    uv__close(sockfd);
+    return UV_ENOMEM;
+  }
+
+  ifc.__nif6h_version = 1;
+  ifc.__nif6h_buflen = maxsize;
+
+  if (ioctl(sockfd, SIOCGIFCONF6, &ifc) == -1) {
+    /* This will error on a system that does not support IPv6. However, we want
+     * to treat this as there being 0 interfaces so we can continue to get IPv4
+     * interfaces in uv_interface_addresses(). So return 0 instead of the error.
+     */
+    uv__free(ifc.__nif6h_buffer);
+    uv__close(sockfd);
+    errno = 0;
+    return 0;
+  }
+
+  ifr = (__net_ifconf6entry_t*)(ifc.__nif6h_buffer);
+  while ((char*)ifr < (char*)ifc.__nif6h_buffer + ifc.__nif6h_buflen) {
+    p = ifr;
+    ifr = (__net_ifconf6entry_t*)((char*)ifr + ifc.__nif6h_entrylen);
+
+    if (!(p->__nif6e_addr.sin6_family == AF_INET6))
+      continue;
+
+    if (!(p->__nif6e_flags & _NIF6E_FLAGS_ON_LINK_ACTIVE))
+      continue;
+
+    ++(*count);
+  }
+
+  if ((*count) == 0) {
+    uv__free(ifc.__nif6h_buffer);
+    uv__close(sockfd);
+    return 0;
+  }
+
+  /* Alloc the return interface structs */
+  *addresses = uv__calloc(1, *count * sizeof(uv_interface_address_t));
+  if (!(*addresses)) {
+    uv__free(ifc.__nif6h_buffer);
+    uv__close(sockfd);
+    return UV_ENOMEM;
+  }
+  address = *addresses;
+
+  count_names = 0;
+  ifr = (__net_ifconf6entry_t*)(ifc.__nif6h_buffer);
+  while ((char*)ifr < (char*)ifc.__nif6h_buffer + ifc.__nif6h_buflen) {
+    p = ifr;
+    ifr = (__net_ifconf6entry_t*)((char*)ifr + ifc.__nif6h_entrylen);
+
+    if (!(p->__nif6e_addr.sin6_family == AF_INET6))
+      continue;
+
+    if (!(p->__nif6e_flags & _NIF6E_FLAGS_ON_LINK_ACTIVE))
+      continue;
+
+    /* All conditions above must match count loop */
+
+    i = 0;
+    /* Ignore EBCDIC space (0x40) padding in name */
+    while (i < ARRAY_SIZE(p->__nif6e_name) &&
+           p->__nif6e_name[i] != 0x40 &&
+           p->__nif6e_name[i] != 0)
+      ++i;
+    address->name = uv__malloc(i + 1);
+    if (address->name == NULL) {
+      uv_free_interface_addresses(*addresses, count_names);
+      uv__free(ifc.__nif6h_buffer);
+      uv__close(sockfd);
+      return UV_ENOMEM;
+    }
+    memcpy(address->name, p->__nif6e_name, i);
+    address->name[i] = '\0';
+    __e2a_s(address->name);
+    count_names++;
+
+    address->address.address6 = *((struct sockaddr_in6*) &p->__nif6e_addr);
+
+    for (i = 0; i < (p->__nif6e_prefixlen / 8); i++)
+      netmask[i] = 0xFF;
+
+    if (p->__nif6e_prefixlen % 8)
+      netmask[i] = 0xFF << (8 - (p->__nif6e_prefixlen % 8));
+
+    address->netmask.netmask6.sin6_len = p->__nif6e_prefixlen;
+    memcpy(&(address->netmask.netmask6.sin6_addr), netmask, 16);
+    address->netmask.netmask6.sin6_family = AF_INET6;
+
+    address->is_internal = p->__nif6e_flags & _NIF6E_FLAGS_LOOPBACK ? 1 : 0;
+    address++;
+  }
+
+  uv__free(ifc.__nif6h_buffer);
+  uv__close(sockfd);
+  return 0;
+}
+
+
+int uv_interface_addresses(uv_interface_address_t** addresses, int* count) {
+  uv_interface_address_t* address;
+  int sockfd;
+  int maxsize;
+  struct ifconf ifc;
+  struct ifreq flg;
+  struct ifreq* ifr;
+  struct ifreq* p;
+  uv_interface_address_t* addresses_v6;
+  int count_v6;
+  unsigned int i;
+  int rc;
+  int count_names;
+
+  *count = 0;
+  *addresses = NULL;
+
+  /* get the ipv6 addresses first */
+  if ((rc = uv__interface_addresses_v6(&addresses_v6, &count_v6)) != 0)
+    return rc;
+
+  /* now get the ipv4 addresses */
+
+  /* Assume maximum buffer size allowable */
+  maxsize = 16384;
+
+  sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
+  if (0 > sockfd) {
+    if (count_v6)
+      uv_free_interface_addresses(addresses_v6, count_v6);
+    return UV__ERR(errno);
+  }
+
+  ifc.ifc_req = uv__calloc(1, maxsize);
+
+  if (ifc.ifc_req == NULL) {
+    if (count_v6)
+      uv_free_interface_addresses(addresses_v6, count_v6);
+    uv__close(sockfd);
+    return UV_ENOMEM;
+  }
+
+  ifc.ifc_len = maxsize;
+
+  if (ioctl(sockfd, SIOCGIFCONF, &ifc) == -1) {
+    if (count_v6)
+      uv_free_interface_addresses(addresses_v6, count_v6);
+    uv__free(ifc.ifc_req);
+    uv__close(sockfd);
+    return UV__ERR(errno);
+  }
+
+#define MAX(a,b) (((a)>(b))?(a):(b))
+#define ADDR_SIZE(p) MAX((p).sa_len, sizeof(p))
+
+  /* Count all up and running ipv4/ipv6 addresses */
+  ifr = ifc.ifc_req;
+  while ((char*)ifr < (char*)ifc.ifc_req + ifc.ifc_len) {
+    p = ifr;
+    ifr = (struct ifreq*)
+      ((char*)ifr + sizeof(ifr->ifr_name) + ADDR_SIZE(ifr->ifr_addr));
+
+    if (!(p->ifr_addr.sa_family == AF_INET6 ||
+          p->ifr_addr.sa_family == AF_INET))
+      continue;
+
+    memcpy(flg.ifr_name, p->ifr_name, sizeof(flg.ifr_name));
+    if (ioctl(sockfd, SIOCGIFFLAGS, &flg) == -1) {
+      if (count_v6)
+        uv_free_interface_addresses(addresses_v6, count_v6);
+      uv__free(ifc.ifc_req);
+      uv__close(sockfd);
+      return UV__ERR(errno);
+    }
+
+    if (!(flg.ifr_flags & IFF_UP && flg.ifr_flags & IFF_RUNNING))
+      continue;
+
+    (*count)++;
+  }
+
+  if (*count == 0 && count_v6 == 0) {
+    uv__free(ifc.ifc_req);
+    uv__close(sockfd);
+    return 0;
+  }
+
+  /* Alloc the return interface structs */
+  *addresses = uv__calloc(1, (*count + count_v6) *
+                          sizeof(uv_interface_address_t));
+
+  if (!(*addresses)) {
+    if (count_v6)
+      uv_free_interface_addresses(addresses_v6, count_v6);
+    uv__free(ifc.ifc_req);
+    uv__close(sockfd);
+    return UV_ENOMEM;
+  }
+  address = *addresses;
+
+  /* copy over the ipv6 addresses if any are found */
+  if (count_v6) {
+    memcpy(address, addresses_v6, count_v6 * sizeof(uv_interface_address_t));
+    address += count_v6;
+    *count += count_v6;
+    /* free ipv6 addresses, but keep address names */
+    uv__free(addresses_v6);
+  }
+
+  count_names = *count;
+  ifr = ifc.ifc_req;
+  while ((char*)ifr < (char*)ifc.ifc_req + ifc.ifc_len) {
+    p = ifr;
+    ifr = (struct ifreq*)
+      ((char*)ifr + sizeof(ifr->ifr_name) + ADDR_SIZE(ifr->ifr_addr));
+
+    if (!(p->ifr_addr.sa_family == AF_INET6 ||
+          p->ifr_addr.sa_family == AF_INET))
+      continue;
+
+    memcpy(flg.ifr_name, p->ifr_name, sizeof(flg.ifr_name));
+    if (ioctl(sockfd, SIOCGIFFLAGS, &flg) == -1) {
+      uv_free_interface_addresses(*addresses, count_names);
+      uv__free(ifc.ifc_req);
+      uv__close(sockfd);
+      return UV_ENOSYS;
+    }
+
+    if (!(flg.ifr_flags & IFF_UP && flg.ifr_flags & IFF_RUNNING))
+      continue;
+
+    /* All conditions above must match count loop */
+
+    i = 0;
+    /* Ignore EBCDIC space (0x40) padding in name */
+    while (i < ARRAY_SIZE(p->ifr_name) &&
+           p->ifr_name[i] != 0x40 &&
+           p->ifr_name[i] != 0)
+      ++i;
+    address->name = uv__malloc(i + 1);
+    if (address->name == NULL) {
+      uv_free_interface_addresses(*addresses, count_names);
+      uv__free(ifc.ifc_req);
+      uv__close(sockfd);
+      return UV_ENOMEM;
+    }
+    memcpy(address->name, p->ifr_name, i);
+    address->name[i] = '\0';
+    __e2a_s(address->name);
+    count_names++;
+
+    address->address.address4 = *((struct sockaddr_in*) &p->ifr_addr);
+
+    if (ioctl(sockfd, SIOCGIFNETMASK, p) == -1) {
+      uv_free_interface_addresses(*addresses, count_names);
+      uv__free(ifc.ifc_req);
+      uv__close(sockfd);
+      return UV__ERR(errno);
+    }
+
+    address->netmask.netmask4 = *((struct sockaddr_in*) &p->ifr_addr);
+    address->netmask.netmask4.sin_family = AF_INET;
+    address->is_internal = flg.ifr_flags & IFF_LOOPBACK ? 1 : 0;
+    address++;
+  }
+
+#undef ADDR_SIZE
+#undef MAX
+
+  uv__free(ifc.ifc_req);
+  uv__close(sockfd);
+  return 0;
+}
+
+
+void uv_free_interface_addresses(uv_interface_address_t* addresses,
+                                 int count) {
+  int i;
+  for (i = 0; i < count; ++i)
+    uv__free(addresses[i].name);
+  uv__free(addresses);
+}
+
+
+void uv__platform_invalidate_fd(uv_loop_t* loop, int fd) {
+  struct epoll_event* events;
+  struct epoll_event dummy;
+  uintptr_t i;
+  uintptr_t nfds;
+
+  assert(loop->watchers != NULL);
+  assert(fd >= 0);
+
+  events = (struct epoll_event*) loop->watchers[loop->nwatchers];
+  nfds = (uintptr_t) loop->watchers[loop->nwatchers + 1];
+  if (events != NULL)
+    /* Invalidate events with same file descriptor */
+    for (i = 0; i < nfds; i++)
+      if ((int) events[i].fd == fd)
+        events[i].fd = -1;
+
+  /* Remove the file descriptor from the epoll. */
+  if (loop->ep != NULL)
+    epoll_ctl(loop->ep, EPOLL_CTL_DEL, fd, &dummy);
+}
+
+
+int uv__io_check_fd(uv_loop_t* loop, int fd) {
+  struct pollfd p[1];
+  int rv;
+
+  p[0].fd = fd;
+  p[0].events = POLLIN;
+
+  do
+    rv = poll(p, 1, 0);
+  while (rv == -1 && errno == EINTR);
+
+  if (rv == -1)
+    abort();
+
+  if (p[0].revents & POLLNVAL)
+    return -1;
+
+  return 0;
+}
+
+
+int uv_fs_event_init(uv_loop_t* loop, uv_fs_event_t* handle) {
+  uv__handle_init(loop, (uv_handle_t*)handle, UV_FS_EVENT);
+  return 0;
+}
+
+
+static int os390_regfileint(uv_fs_event_t* handle, char* path) {
+  uv__os390_epoll* ep;
+  _RFIS reg_struct;
+  int rc;
+
+  ep = handle->loop->ep;
+  assert(ep->msg_queue != -1);
+
+  reg_struct.__rfis_cmd  = _RFIS_REG;
+  reg_struct.__rfis_qid  = ep->msg_queue;
+  reg_struct.__rfis_type = 1;
+  memcpy(reg_struct.__rfis_utok, &handle, sizeof(handle));
+
+  rc = __w_pioctl(path, _IOCC_REGFILEINT, sizeof(reg_struct), &reg_struct);
+  if (rc != 0)
+    return UV__ERR(errno);
+
+  memcpy(handle->rfis_rftok, reg_struct.__rfis_rftok,
+         sizeof(handle->rfis_rftok));
+
+  return 0;
+}
+
+
+int uv_fs_event_start(uv_fs_event_t* handle, uv_fs_event_cb cb,
+                      const char* filename, unsigned int flags) {
+  char* path;
+  int rc;
+
+  if (uv__is_active(handle))
+    return UV_EINVAL;
+
+  path = uv__strdup(filename);
+  if (path == NULL)
+    return UV_ENOMEM;
+
+  rc = os390_regfileint(handle, path);
+  if (rc != 0) {
+    uv__free(path);
+    return rc;
+  }
+
+  uv__handle_start(handle);
+  handle->path = path;
+  handle->cb = cb;
+
+  return 0;
+}
+
+
+int uv__fs_event_stop(uv_fs_event_t* handle) {
+  uv__os390_epoll* ep;
+  _RFIS reg_struct;
+  int rc;
+
+  if (!uv__is_active(handle))
+    return 0;
+
+  ep = handle->loop->ep;
+  assert(ep->msg_queue != -1);
+
+  reg_struct.__rfis_cmd  = _RFIS_UNREG;
+  reg_struct.__rfis_qid  = ep->msg_queue;
+  reg_struct.__rfis_type = 1;
+  memcpy(reg_struct.__rfis_rftok, handle->rfis_rftok,
+         sizeof(handle->rfis_rftok));
+
+  /*
+   * This call will take "/" as the path argument in case we
+   * don't care to supply the correct path. The system will simply
+   * ignore it.
+   */
+  rc = __w_pioctl("/", _IOCC_REGFILEINT, sizeof(reg_struct), &reg_struct);
+  if (rc != 0 && errno != EALREADY && errno != ENOENT)
+    abort();
+
+  if (handle->path != NULL) {
+    uv__free(handle->path);
+    handle->path = NULL;
+  }
+
+  if (rc != 0 && errno == EALREADY)
+    return -1;
+
+  uv__handle_stop(handle);
+
+  return 0;
+}
+
+
+int uv_fs_event_stop(uv_fs_event_t* handle) {
+  uv__fs_event_stop(handle);
+  return 0;
+}
+
+
+void uv__fs_event_close(uv_fs_event_t* handle) {
+  /*
+   * If we were unable to unregister file interest here, then it is most likely
+   * that there is a pending queued change notification. When this happens, we
+   * don't want to complete the close as it will free the underlying memory for
+   * the handle, causing a use-after-free problem when the event is processed.
+   * We defer the final cleanup until after the event is consumed in
+   * os390_message_queue_handler().
+   */
+  if (uv__fs_event_stop(handle) == 0)
+    uv__make_close_pending((uv_handle_t*) handle);
+}
+
+
+static int os390_message_queue_handler(uv__os390_epoll* ep) {
+  uv_fs_event_t* handle;
+  int msglen;
+  int events;
+  _RFIM msg;
+
+  if (ep->msg_queue == -1)
+    return 0;
+
+  msglen = msgrcv(ep->msg_queue, &msg, sizeof(msg), 0, IPC_NOWAIT);
+
+  if (msglen == -1 && errno == ENOMSG)
+    return 0;
+
+  if (msglen == -1)
+    abort();
+
+  events = 0;
+  if (msg.__rfim_event == _RFIM_ATTR || msg.__rfim_event == _RFIM_WRITE)
+    events = UV_CHANGE;
+  else if (msg.__rfim_event == _RFIM_RENAME || msg.__rfim_event == _RFIM_UNLINK)
+    events = UV_RENAME;
+  else if (msg.__rfim_event == 156)
+    /* TODO(gabylb): zos - this event should not happen, need to investigate.
+     *
+     * This event seems to occur when the watched file is [re]moved, or an
+     * editor (like vim) renames then creates the file on save (for vim, that's
+     * when backupcopy=no|auto).
+     */
+    events = UV_RENAME;
+  else
+    /* Some event that we are not interested in. */
+    return 0;
+
+  /* `__rfim_utok` is treated as text when it should be treated as binary while
+   * running in ASCII mode, resulting in an unwanted autoconversion.
+   */
+  __a2e_l(msg.__rfim_utok, sizeof(msg.__rfim_utok));
+  handle = *(uv_fs_event_t**)(msg.__rfim_utok);
+  assert(handle != NULL);
+
+  assert((handle->flags & UV_HANDLE_CLOSED) == 0);
+  if (uv__is_closing(handle)) {
+    uv__handle_stop(handle);
+    uv__make_close_pending((uv_handle_t*) handle);
+    return 0;
+  } else if (handle->path == NULL) {
+    /* _RFIS_UNREG returned EALREADY. */
+    uv__handle_stop(handle);
+    return 0;
+  }
+
+  /* The file is implicitly unregistered when the change notification is
+   * sent, only one notification is sent per registration. So we need to
+   * re-register interest in a file after each change notification we
+   * receive.
+   */
+  assert(handle->path != NULL);
+  os390_regfileint(handle, handle->path);
+  handle->cb(handle, uv__basename_r(handle->path), events, 0);
+  return 1;
+}
+
+
+void uv__io_poll(uv_loop_t* loop, int timeout) {
+  static const int max_safe_timeout = 1789569;
+  uv__loop_internal_fields_t* lfields;
+  struct epoll_event events[1024];
+  struct epoll_event* pe;
+  struct epoll_event e;
+  uv__os390_epoll* ep;
+  int have_signals;
+  int real_timeout;
+  struct uv__queue* q;
+  uv__io_t* w;
+  uint64_t base;
+  int count;
+  int nfds;
+  int fd;
+  int op;
+  int i;
+  int user_timeout;
+  int reset_timeout;
+
+  if (loop->nfds == 0) {
+    assert(uv__queue_empty(&loop->watcher_queue));
+    return;
+  }
+
+  lfields = uv__get_internal_fields(loop);
+
+  while (!uv__queue_empty(&loop->watcher_queue)) {
+    uv_stream_t* stream;
+
+    q = uv__queue_head(&loop->watcher_queue);
+    uv__queue_remove(q);
+    uv__queue_init(q);
+    w = uv__queue_data(q, uv__io_t, watcher_queue);
+
+    assert(w->pevents != 0);
+    assert(w->fd >= 0);
+
+    stream= container_of(w, uv_stream_t, io_watcher);
+
+    assert(w->fd < (int) loop->nwatchers);
+
+    e.events = w->pevents;
+    e.fd = w->fd;
+
+    if (w->events == 0)
+      op = EPOLL_CTL_ADD;
+    else
+      op = EPOLL_CTL_MOD;
+
+    /* XXX Future optimization: do EPOLL_CTL_MOD lazily if we stop watching
+     * events, skip the syscall and squelch the events after epoll_wait().
+     */
+    if (epoll_ctl(loop->ep, op, w->fd, &e)) {
+      if (errno != EEXIST)
+        abort();
+
+      assert(op == EPOLL_CTL_ADD);
+
+      /* We've reactivated a file descriptor that's been watched before. */
+      if (epoll_ctl(loop->ep, EPOLL_CTL_MOD, w->fd, &e))
+        abort();
+    }
+
+    w->events = w->pevents;
+  }
+
+  assert(timeout >= -1);
+  base = loop->time;
+  count = 48; /* Benchmarks suggest this gives the best throughput. */
+  real_timeout = timeout;
+  int nevents = 0;
+  have_signals = 0;
+
+  if (lfields->flags & UV_METRICS_IDLE_TIME) {
+    reset_timeout = 1;
+    user_timeout = timeout;
+    timeout = 0;
+  } else {
+    reset_timeout = 0;
+  }
+
+  nfds = 0;
+  for (;;) {
+    /* Only need to set the provider_entry_time if timeout != 0. The function
+     * will return early if the loop isn't configured with UV_METRICS_IDLE_TIME.
+     */
+    if (timeout != 0)
+      uv__metrics_set_provider_entry_time(loop);
+
+    if (sizeof(int32_t) == sizeof(long) && timeout >= max_safe_timeout)
+      timeout = max_safe_timeout;
+
+    /* Store the current timeout in a location that's globally accessible so
+     * other locations like uv__work_done() can determine whether the queue
+     * of events in the callback were waiting when poll was called.
+     */
+    lfields->current_timeout = timeout;
+
+    nfds = epoll_wait(loop->ep, events,
+                      ARRAY_SIZE(events), timeout);
+
+    /* Update loop->time unconditionally. It's tempting to skip the update when
+     * timeout == 0 (i.e. non-blocking poll) but there is no guarantee that the
+     * operating system didn't reschedule our process while in the syscall.
+     */
+    base = loop->time;
+    SAVE_ERRNO(uv__update_time(loop));
+    if (nfds == 0) {
+      assert(timeout != -1);
+
+      if (reset_timeout != 0) {
+        timeout = user_timeout;
+        reset_timeout = 0;
+      }
+
+      if (timeout == -1)
+        continue;
+
+      if (timeout == 0)
+        return;
+
+      /* We may have been inside the system call for longer than |timeout|
+       * milliseconds so we need to update the timestamp to avoid drift.
+       */
+      goto update_timeout;
+    }
+
+    if (nfds == -1) {
+
+      if (errno != EINTR)
+        abort();
+
+      if (reset_timeout != 0) {
+        timeout = user_timeout;
+        reset_timeout = 0;
+      }
+
+      if (timeout == -1)
+        continue;
+
+      if (timeout == 0)
+        return;
+
+      /* Interrupted by a signal. Update timeout and poll again. */
+      goto update_timeout;
+    }
+
+
+    assert(loop->watchers != NULL);
+    loop->watchers[loop->nwatchers] = (void*) events;
+    loop->watchers[loop->nwatchers + 1] = (void*) (uintptr_t) nfds;
+    for (i = 0; i < nfds; i++) {
+      pe = events + i;
+      fd = pe->fd;
+
+      /* Skip invalidated events, see uv__platform_invalidate_fd */
+      if (fd == -1)
+        continue;
+
+      ep = loop->ep;
+      if (pe->is_msg) {
+        os390_message_queue_handler(ep);
+        nevents++;
+        continue;
+      }
+
+      assert(fd >= 0);
+      assert((unsigned) fd < loop->nwatchers);
+
+      w = loop->watchers[fd];
+
+      if (w == NULL) {
+        /* File descriptor that we've stopped watching, disarm it.
+         *
+         * Ignore all errors because we may be racing with another thread
+         * when the file descriptor is closed.
+         */
+        epoll_ctl(loop->ep, EPOLL_CTL_DEL, fd, pe);
+        continue;
+      }
+
+      /* Give users only events they're interested in. Prevents spurious
+       * callbacks when previous callback invocation in this loop has stopped
+       * the current watcher. Also, filters out events that users has not
+       * requested us to watch.
+       */
+      pe->events &= w->pevents | POLLERR | POLLHUP;
+
+      if (pe->events == POLLERR || pe->events == POLLHUP)
+        pe->events |= w->pevents & (POLLIN | POLLOUT);
+
+      if (pe->events != 0) {
+        /* Run signal watchers last.  This also affects child process watchers
+         * because those are implemented in terms of signal watchers.
+         */
+        if (w == &loop->signal_io_watcher) {
+          have_signals = 1;
+        } else {
+          uv__metrics_update_idle_time(loop);
+          w->cb(loop, w, pe->events);
+        }
+        nevents++;
+      }
+    }
+
+    uv__metrics_inc_events(loop, nevents);
+    if (reset_timeout != 0) {
+      timeout = user_timeout;
+      reset_timeout = 0;
+      uv__metrics_inc_events_waiting(loop, nevents);
+    }
+
+    if (have_signals != 0) {
+      uv__metrics_update_idle_time(loop);
+      loop->signal_io_watcher.cb(loop, &loop->signal_io_watcher, POLLIN);
+    }
+
+    loop->watchers[loop->nwatchers] = NULL;
+    loop->watchers[loop->nwatchers + 1] = NULL;
+
+    if (have_signals != 0)
+      return;  /* Event loop should cycle now so don't poll again. */
+
+    if (nevents != 0) {
+      if (nfds == ARRAY_SIZE(events) && --count != 0) {
+        /* Poll for more events but don't block this time. */
+        timeout = 0;
+        continue;
+      }
+      return;
+    }
+
+    if (timeout == 0)
+      return;
+
+    if (timeout == -1)
+      continue;
+
+update_timeout:
+    assert(timeout > 0);
+
+    real_timeout -= (loop->time - base);
+    if (real_timeout <= 0)
+      return;
+
+    timeout = real_timeout;
+  }
+}
+
+
+int uv__io_fork(uv_loop_t* loop) {
+  /*
+    Nullify the msg queue but don't close it because
+    it is still being used by the parent.
+  */
+  loop->ep = NULL;
+
+  return uv__platform_loop_init(loop);
+}