--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/unix/process.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,1123 @@
+/* Copyright Joyent, Inc. and other Node 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 <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+
+#if defined(__APPLE__)
+# include <spawn.h>
+# include <paths.h>
+# include <sys/kauth.h>
+# include <sys/types.h>
+# include <sys/sysctl.h>
+# include <dlfcn.h>
+# include <crt_externs.h>
+# include <xlocale.h>
+# define environ (*_NSGetEnviron())
+
+/* macOS 10.14 back does not define this constant */
+# ifndef POSIX_SPAWN_SETSID
+#  define POSIX_SPAWN_SETSID 1024
+# endif
+
+#else
+extern char **environ;
+#endif
+
+#if defined(__linux__) || \
+    defined(__GNU__)
+# include <grp.h>
+#endif
+
+#if defined(__MVS__)
+# include "zos-base.h"
+#endif
+
+#ifdef UV_HAVE_KQUEUE
+#include <sys/event.h>
+#else
+#define UV_USE_SIGCHLD
+#endif
+
+
+#ifdef UV_USE_SIGCHLD
+static void uv__chld(uv_signal_t* handle, int signum) {
+  assert(signum == SIGCHLD);
+  uv__wait_children(handle->loop);
+}
+
+
+int uv__process_init(uv_loop_t* loop) {
+  int err;
+
+  err = uv_signal_init(loop, &loop->child_watcher);
+  if (err)
+    return err;
+  uv__handle_unref(&loop->child_watcher);
+  loop->child_watcher.flags |= UV_HANDLE_INTERNAL;
+  return 0;
+}
+
+
+#else
+int uv__process_init(uv_loop_t* loop) {
+  memset(&loop->child_watcher, 0, sizeof(loop->child_watcher));
+  return 0;
+}
+#endif
+
+
+void uv__wait_children(uv_loop_t* loop) {
+  uv_process_t* process;
+  int exit_status;
+  int term_signal;
+  int status;
+  int options;
+  pid_t pid;
+  struct uv__queue pending;
+  struct uv__queue* q;
+  struct uv__queue* h;
+
+  uv__queue_init(&pending);
+
+  h = &loop->process_handles;
+  q = uv__queue_head(h);
+  while (q != h) {
+    process = uv__queue_data(q, uv_process_t, queue);
+    q = uv__queue_next(q);
+
+#ifndef UV_USE_SIGCHLD
+    if ((process->flags & UV_HANDLE_REAP) == 0)
+      continue;
+    options = 0;
+    process->flags &= ~UV_HANDLE_REAP;
+    loop->nfds--;
+#else
+    options = WNOHANG;
+#endif
+
+    do
+      pid = waitpid(process->pid, &status, options);
+    while (pid == -1 && errno == EINTR);
+
+#ifdef UV_USE_SIGCHLD
+    if (pid == 0) /* Not yet exited */
+      continue;
+#endif
+
+    if (pid == -1) {
+      if (errno != ECHILD)
+        abort();
+      /* The child died, and we missed it. This probably means someone else
+       * stole the waitpid from us. Handle this by not handling it at all. */
+      continue;
+    }
+
+    assert(pid == process->pid);
+    process->status = status;
+    uv__queue_remove(&process->queue);
+    uv__queue_insert_tail(&pending, &process->queue);
+  }
+
+  h = &pending;
+  q = uv__queue_head(h);
+  while (q != h) {
+    process = uv__queue_data(q, uv_process_t, queue);
+    q = uv__queue_next(q);
+
+    uv__queue_remove(&process->queue);
+    uv__queue_init(&process->queue);
+    uv__handle_stop(process);
+
+    if (process->exit_cb == NULL)
+      continue;
+
+    exit_status = 0;
+    if (WIFEXITED(process->status))
+      exit_status = WEXITSTATUS(process->status);
+
+    term_signal = 0;
+    if (WIFSIGNALED(process->status))
+      term_signal = WTERMSIG(process->status);
+
+    process->exit_cb(process, exit_status, term_signal);
+  }
+  assert(uv__queue_empty(&pending));
+}
+
+/*
+ * Used for initializing stdio streams like options.stdin_stream. Returns
+ * zero on success. See also the cleanup section in uv_spawn().
+ */
+#if !(defined(__APPLE__) && (TARGET_OS_TV || TARGET_OS_WATCH))
+/* execvp is marked __WATCHOS_PROHIBITED __TVOS_PROHIBITED, so must be
+ * avoided. Since this isn't called on those targets, the function
+ * doesn't even need to be defined for them.
+ */
+static int uv__process_init_stdio(uv_stdio_container_t* container, int fds[2]) {
+  int mask;
+  int fd;
+  int ret;
+  int size;
+  int i;
+
+  mask = UV_IGNORE | UV_CREATE_PIPE | UV_INHERIT_FD | UV_INHERIT_STREAM;
+  size = 64 * 1024;
+
+  switch (container->flags & mask) {
+  case UV_IGNORE:
+    return 0;
+
+  case UV_CREATE_PIPE:
+    assert(container->data.stream != NULL);
+    if (container->data.stream->type != UV_NAMED_PIPE)
+      return UV_EINVAL;
+    else {
+      ret = uv_socketpair(SOCK_STREAM, 0, fds, 0, 0);
+
+      if (ret == 0)
+        for (i = 0; i < 2; i++) {
+          setsockopt(fds[i], SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));
+          setsockopt(fds[i], SOL_SOCKET, SO_SNDBUF, &size, sizeof(size));
+        }
+    }
+
+    return ret;
+
+  case UV_INHERIT_FD:
+  case UV_INHERIT_STREAM:
+    if (container->flags & UV_INHERIT_FD)
+      fd = container->data.fd;
+    else
+      fd = uv__stream_fd(container->data.stream);
+
+    if (fd == -1)
+      return UV_EINVAL;
+
+    fds[1] = fd;
+    return 0;
+
+  default:
+    assert(0 && "Unexpected flags");
+    return UV_EINVAL;
+  }
+}
+
+
+static int uv__process_open_stream(uv_stdio_container_t* container,
+                                   int pipefds[2]) {
+  int flags;
+  int err;
+
+  if (!(container->flags & UV_CREATE_PIPE) || pipefds[0] < 0)
+    return 0;
+
+  err = uv__close(pipefds[1]);
+  if (err != 0)
+    abort();
+
+  pipefds[1] = -1;
+  uv__nonblock(pipefds[0], 1);
+
+  flags = 0;
+  if (container->flags & UV_WRITABLE_PIPE)
+    flags |= UV_HANDLE_READABLE;
+  if (container->flags & UV_READABLE_PIPE)
+    flags |= UV_HANDLE_WRITABLE;
+
+  return uv__stream_open(container->data.stream, pipefds[0], flags);
+}
+
+
+static void uv__process_close_stream(uv_stdio_container_t* container) {
+  if (!(container->flags & UV_CREATE_PIPE)) return;
+  uv__stream_close(container->data.stream);
+}
+
+
+static void uv__write_int(int fd, int val) {
+  ssize_t n;
+
+  do
+    n = write(fd, &val, sizeof(val));
+  while (n == -1 && errno == EINTR);
+
+  /* The write might have failed (e.g. if the parent process has died),
+   * but we have nothing left but to _exit ourself now too. */
+  _exit(127);
+}
+
+
+static void uv__write_errno(int error_fd) {
+  uv__write_int(error_fd, UV__ERR(errno));
+}
+
+
+static void uv__process_child_init(const uv_process_options_t* options,
+                                   int stdio_count,
+                                   int (*pipes)[2],
+                                   int error_fd) {
+  sigset_t signewset;
+  int close_fd;
+  int use_fd;
+  int fd;
+  int n;
+
+  /* Reset signal disposition first. Use a hard-coded limit because NSIG is not
+   * fixed on Linux: it's either 32, 34 or 64, depending on whether RT signals
+   * are enabled. We are not allowed to touch RT signal handlers, glibc uses
+   * them internally.
+   */
+  for (n = 1; n < 32; n += 1) {
+    if (n == SIGKILL || n == SIGSTOP)
+      continue;  /* Can't be changed. */
+
+#if defined(__HAIKU__)
+    if (n == SIGKILLTHR)
+      continue;  /* Can't be changed. */
+#endif
+
+    if (SIG_ERR != signal(n, SIG_DFL))
+      continue;
+
+    uv__write_errno(error_fd);
+  }
+
+  if (options->flags & UV_PROCESS_DETACHED)
+    setsid();
+
+  /* First duplicate low numbered fds, since it's not safe to duplicate them,
+   * they could get replaced. Example: swapping stdout and stderr; without
+   * this fd 2 (stderr) would be duplicated into fd 1, thus making both
+   * stdout and stderr go to the same fd, which was not the intention. */
+  for (fd = 0; fd < stdio_count; fd++) {
+    use_fd = pipes[fd][1];
+    if (use_fd < 0 || use_fd >= fd)
+      continue;
+#ifdef F_DUPFD_CLOEXEC /* POSIX 2008 */
+    pipes[fd][1] = fcntl(use_fd, F_DUPFD_CLOEXEC, stdio_count);
+#else
+    pipes[fd][1] = fcntl(use_fd, F_DUPFD, stdio_count);
+#endif
+    if (pipes[fd][1] == -1)
+      uv__write_errno(error_fd);
+#ifndef F_DUPFD_CLOEXEC /* POSIX 2008 */
+    n = uv__cloexec(pipes[fd][1], 1);
+    if (n)
+      uv__write_int(error_fd, n);
+#endif
+  }
+
+  for (fd = 0; fd < stdio_count; fd++) {
+    close_fd = -1;
+    use_fd = pipes[fd][1];
+
+    if (use_fd < 0) {
+      if (fd >= 3)
+        continue;
+      else {
+        /* Redirect stdin, stdout and stderr to /dev/null even if UV_IGNORE is
+         * set. */
+        uv__close_nocheckstdio(fd); /* Free up fd, if it happens to be open. */
+        use_fd = open("/dev/null", fd == 0 ? O_RDONLY : O_RDWR);
+        close_fd = use_fd;
+
+        if (use_fd < 0)
+          uv__write_errno(error_fd);
+      }
+    }
+
+    if (fd == use_fd) {
+      if (close_fd == -1) {
+        n = uv__cloexec(use_fd, 0);
+        if (n)
+          uv__write_int(error_fd, n);
+      }
+    }
+    else {
+      fd = dup2(use_fd, fd);
+    }
+
+    if (fd == -1)
+      uv__write_errno(error_fd);
+
+    if (fd <= 2 && close_fd == -1)
+      uv__nonblock_fcntl(fd, 0);
+
+    if (close_fd >= stdio_count)
+      uv__close(close_fd);
+  }
+
+  if (options->cwd != NULL && chdir(options->cwd))
+    uv__write_errno(error_fd);
+
+  if (options->flags & (UV_PROCESS_SETUID | UV_PROCESS_SETGID)) {
+    /* When dropping privileges from root, the `setgroups` call will
+     * remove any extraneous groups. If we don't call this, then
+     * even though our uid has dropped, we may still have groups
+     * that enable us to do super-user things. This will fail if we
+     * aren't root, so don't bother checking the return value, this
+     * is just done as an optimistic privilege dropping function.
+     */
+    SAVE_ERRNO(setgroups(0, NULL));
+  }
+
+  if ((options->flags & UV_PROCESS_SETGID) && setgid(options->gid))
+    uv__write_errno(error_fd);
+
+  if ((options->flags & UV_PROCESS_SETUID) && setuid(options->uid))
+    uv__write_errno(error_fd);
+
+  if (options->env != NULL)
+    environ = options->env;
+
+  /* Reset signal mask just before exec. */
+  sigemptyset(&signewset);
+  if (sigprocmask(SIG_SETMASK, &signewset, NULL) != 0)
+    abort();
+
+#ifdef __MVS__
+  execvpe(options->file, options->args, environ);
+#else
+  execvp(options->file, options->args);
+#endif
+
+  uv__write_errno(error_fd);
+}
+
+
+#if defined(__APPLE__)
+typedef struct uv__posix_spawn_fncs_tag {
+  struct {
+    int (*addchdir_np)(const posix_spawn_file_actions_t *, const char *);
+  } file_actions;
+} uv__posix_spawn_fncs_t;
+
+
+static uv_once_t posix_spawn_init_once = UV_ONCE_INIT;
+static uv__posix_spawn_fncs_t posix_spawn_fncs;
+static int posix_spawn_can_use_setsid;
+
+
+static void uv__spawn_init_posix_spawn_fncs(void) {
+  /* Try to locate all non-portable functions at runtime */
+  posix_spawn_fncs.file_actions.addchdir_np =
+    dlsym(RTLD_DEFAULT, "posix_spawn_file_actions_addchdir_np");
+}
+
+
+static void uv__spawn_init_can_use_setsid(void) {
+  int which[] = {CTL_KERN, KERN_OSRELEASE};
+  unsigned major;
+  unsigned minor;
+  unsigned patch;
+  char buf[256];
+  size_t len;
+
+  len = sizeof(buf);
+  if (sysctl(which, ARRAY_SIZE(which), buf, &len, NULL, 0))
+    return;
+
+  /* NULL specifies to use LC_C_LOCALE */
+  if (3 != sscanf_l(buf, NULL, "%u.%u.%u", &major, &minor, &patch))
+    return;
+
+  posix_spawn_can_use_setsid = (major >= 19);  /* macOS Catalina */
+}
+
+
+static void uv__spawn_init_posix_spawn(void) {
+  /* Init handles to all potentially non-defined functions */
+  uv__spawn_init_posix_spawn_fncs();
+
+  /* Init feature detection for POSIX_SPAWN_SETSID flag */
+  uv__spawn_init_can_use_setsid();
+}
+
+
+static int uv__spawn_set_posix_spawn_attrs(
+    posix_spawnattr_t* attrs,
+    const uv__posix_spawn_fncs_t* posix_spawn_fncs,
+    const uv_process_options_t* options) {
+  int err;
+  unsigned int flags;
+  sigset_t signal_set;
+
+  err = posix_spawnattr_init(attrs);
+  if (err != 0) {
+    /* If initialization fails, no need to de-init, just return */
+    return err;
+  }
+
+  if (options->flags & (UV_PROCESS_SETUID | UV_PROCESS_SETGID)) {
+    /* kauth_cred_issuser currently requires exactly uid == 0 for these
+     * posixspawn_attrs (set_groups_np, setuid_np, setgid_np), which deviates
+     * from the normal specification of setuid (which also uses euid), and they
+     * are also undocumented syscalls, so we do not use them. */
+    err = ENOSYS;
+    goto error;
+  }
+
+  /* Set flags for spawn behavior
+   * 1) POSIX_SPAWN_CLOEXEC_DEFAULT: (Apple Extension) All descriptors in the
+   *    parent will be treated as if they had been created with O_CLOEXEC. The
+   *    only fds that will be passed on to the child are those manipulated by
+   *    the file actions
+   * 2) POSIX_SPAWN_SETSIGDEF: Signals mentioned in spawn-sigdefault in the
+   *    spawn attributes will be reset to behave as their default
+   * 3) POSIX_SPAWN_SETSIGMASK: Signal mask will be set to the value of
+   *    spawn-sigmask in attributes
+   * 4) POSIX_SPAWN_SETSID: Make the process a new session leader if a detached
+   *    session was requested. */
+  flags = POSIX_SPAWN_CLOEXEC_DEFAULT |
+          POSIX_SPAWN_SETSIGDEF |
+          POSIX_SPAWN_SETSIGMASK;
+  if (options->flags & UV_PROCESS_DETACHED) {
+    /* If running on a version of macOS where this flag is not supported,
+     * revert back to the fork/exec flow. Otherwise posix_spawn will
+     * silently ignore the flag. */
+    if (!posix_spawn_can_use_setsid) {
+      err = ENOSYS;
+      goto error;
+    }
+
+    flags |= POSIX_SPAWN_SETSID;
+  }
+  err = posix_spawnattr_setflags(attrs, flags);
+  if (err != 0)
+    goto error;
+
+  /* Reset all signal the child to their default behavior */
+  sigfillset(&signal_set);
+  err = posix_spawnattr_setsigdefault(attrs, &signal_set);
+  if (err != 0)
+    goto error;
+
+  /* Reset the signal mask for all signals */
+  sigemptyset(&signal_set);
+  err = posix_spawnattr_setsigmask(attrs, &signal_set);
+  if (err != 0)
+    goto error;
+
+  return err;
+
+error:
+  (void) posix_spawnattr_destroy(attrs);
+  return err;
+}
+
+
+static int uv__spawn_set_posix_spawn_file_actions(
+    posix_spawn_file_actions_t* actions,
+    const uv__posix_spawn_fncs_t* posix_spawn_fncs,
+    const uv_process_options_t* options,
+    int stdio_count,
+    int (*pipes)[2]) {
+  int fd;
+  int fd2;
+  int use_fd;
+  int err;
+
+  err = posix_spawn_file_actions_init(actions);
+  if (err != 0) {
+    /* If initialization fails, no need to de-init, just return */
+    return err;
+  }
+
+  /* Set the current working directory if requested */
+  if (options->cwd != NULL) {
+    if (posix_spawn_fncs->file_actions.addchdir_np == NULL) {
+      err = ENOSYS;
+      goto error;
+    }
+
+    err = posix_spawn_fncs->file_actions.addchdir_np(actions, options->cwd);
+    if (err != 0)
+      goto error;
+  }
+
+  /* Do not return ENOSYS after this point, as we may mutate pipes. */
+
+  /* First duplicate low numbered fds, since it's not safe to duplicate them,
+   * they could get replaced. Example: swapping stdout and stderr; without
+   * this fd 2 (stderr) would be duplicated into fd 1, thus making both
+   * stdout and stderr go to the same fd, which was not the intention. */
+  for (fd = 0; fd < stdio_count; fd++) {
+    use_fd = pipes[fd][1];
+    if (use_fd < 0 || use_fd >= fd)
+      continue;
+    use_fd = stdio_count;
+    for (fd2 = 0; fd2 < stdio_count; fd2++) {
+      /* If we were not setting POSIX_SPAWN_CLOEXEC_DEFAULT, we would need to
+       * also consider whether fcntl(fd, F_GETFD) returned without the
+       * FD_CLOEXEC flag set. */
+      if (pipes[fd2][1] == use_fd) {
+        use_fd++;
+        fd2 = 0;
+      }
+    }
+    err = posix_spawn_file_actions_adddup2(
+      actions,
+      pipes[fd][1],
+      use_fd);
+    assert(err != ENOSYS);
+    if (err != 0)
+      goto error;
+    pipes[fd][1] = use_fd;
+  }
+
+  /* Second, move the descriptors into their respective places */
+  for (fd = 0; fd < stdio_count; fd++) {
+    use_fd = pipes[fd][1];
+    if (use_fd < 0) {
+      if (fd >= 3)
+        continue;
+      else {
+        /* If ignored, redirect to (or from) /dev/null, */
+        err = posix_spawn_file_actions_addopen(
+          actions,
+          fd,
+          "/dev/null",
+          fd == 0 ? O_RDONLY : O_RDWR,
+          0);
+        assert(err != ENOSYS);
+        if (err != 0)
+          goto error;
+        continue;
+      }
+    }
+
+    if (fd == use_fd)
+        err = posix_spawn_file_actions_addinherit_np(actions, fd);
+    else
+        err = posix_spawn_file_actions_adddup2(actions, use_fd, fd);
+    assert(err != ENOSYS);
+    if (err != 0)
+      goto error;
+
+    /* Make sure the fd is marked as non-blocking (state shared between child
+     * and parent). */
+    uv__nonblock_fcntl(use_fd, 0);
+  }
+
+  /* Finally, close all the superfluous descriptors */
+  for (fd = 0; fd < stdio_count; fd++) {
+    use_fd = pipes[fd][1];
+    if (use_fd < stdio_count)
+      continue;
+
+    /* Check if we already closed this. */
+    for (fd2 = 0; fd2 < fd; fd2++) {
+      if (pipes[fd2][1] == use_fd)
+          break;
+    }
+    if (fd2 < fd)
+      continue;
+
+    err = posix_spawn_file_actions_addclose(actions, use_fd);
+    assert(err != ENOSYS);
+    if (err != 0)
+      goto error;
+  }
+
+  return 0;
+
+error:
+  (void) posix_spawn_file_actions_destroy(actions);
+  return err;
+}
+
+char* uv__spawn_find_path_in_env(char** env) {
+  char** env_iterator;
+  const char path_var[] = "PATH=";
+
+  /* Look for an environment variable called PATH in the
+   * provided env array, and return its value if found */
+  for (env_iterator = env; *env_iterator != NULL; env_iterator++) {
+    if (strncmp(*env_iterator, path_var, sizeof(path_var) - 1) == 0) {
+      /* Found "PATH=" at the beginning of the string */
+      return *env_iterator + sizeof(path_var) - 1;
+    }
+  }
+
+  return NULL;
+}
+
+
+static int uv__spawn_resolve_and_spawn(const uv_process_options_t* options,
+                                       posix_spawnattr_t* attrs,
+                                       posix_spawn_file_actions_t* actions,
+                                       pid_t* pid) {
+  const char *p;
+  const char *z;
+  const char *path;
+  size_t l;
+  size_t k;
+  int err;
+  int seen_eacces;
+
+  path = NULL;
+  err = -1;
+  seen_eacces = 0;
+
+  /* Short circuit for erroneous case */
+  if (options->file == NULL)
+    return ENOENT;
+
+  /* The environment for the child process is that of the parent unless overridden
+   * by options->env */
+  char** env = environ;
+  if (options->env != NULL)
+    env = options->env;
+
+  /* If options->file contains a slash, posix_spawn/posix_spawnp should behave
+   * the same, and do not involve PATH resolution at all. The libc
+   * `posix_spawnp` provided by Apple is buggy (since 10.15), so we now emulate it
+   * here, per https://github.com/libuv/libuv/pull/3583. */
+  if (strchr(options->file, '/') != NULL) {
+    do
+      err = posix_spawn(pid, options->file, actions, attrs, options->args, env);
+    while (err == EINTR);
+    return err;
+  }
+
+  /* Look for the definition of PATH in the provided env */
+  path = uv__spawn_find_path_in_env(env);
+
+  /* The following resolution logic (execvpe emulation) is copied from
+   * https://git.musl-libc.org/cgit/musl/tree/src/process/execvp.c
+   * and adapted to work for our specific usage */
+
+  /* If no path was provided in env, use the default value
+   * to look for the executable */
+  if (path == NULL)
+    path = _PATH_DEFPATH;
+
+  k = strnlen(options->file, NAME_MAX + 1);
+  if (k > NAME_MAX)
+    return ENAMETOOLONG;
+
+  l = strnlen(path, PATH_MAX - 1) + 1;
+
+  for (p = path;; p = z) {
+    /* Compose the new process file from the entry in the PATH
+     * environment variable and the actual file name */
+    char b[PATH_MAX + NAME_MAX];
+    z = strchr(p, ':');
+    if (!z)
+      z = p + strlen(p);
+    if ((size_t)(z - p) >= l) {
+      if (!*z++)
+        break;
+
+      continue;
+    }
+    memcpy(b, p, z - p);
+    b[z - p] = '/';
+    memcpy(b + (z - p) + (z > p), options->file, k + 1);
+
+    /* Try to spawn the new process file. If it fails with ENOENT, the
+     * new process file is not in this PATH entry, continue with the next
+     * PATH entry. */
+    do
+      err = posix_spawn(pid, b, actions, attrs, options->args, env);
+    while (err == EINTR);
+
+    switch (err) {
+    case EACCES:
+      seen_eacces = 1;
+      break; /* continue search */
+    case ENOENT:
+    case ENOTDIR:
+      break; /* continue search */
+    default:
+      return err;
+    }
+
+    if (!*z++)
+      break;
+  }
+
+  if (seen_eacces)
+    return EACCES;
+  return err;
+}
+
+
+static int uv__spawn_and_init_child_posix_spawn(
+    const uv_process_options_t* options,
+    int stdio_count,
+    int (*pipes)[2],
+    pid_t* pid,
+    const uv__posix_spawn_fncs_t* posix_spawn_fncs) {
+  int err;
+  posix_spawnattr_t attrs;
+  posix_spawn_file_actions_t actions;
+
+  err = uv__spawn_set_posix_spawn_attrs(&attrs, posix_spawn_fncs, options);
+  if (err != 0)
+    goto error;
+
+  /* This may mutate pipes. */
+  err = uv__spawn_set_posix_spawn_file_actions(&actions,
+                                               posix_spawn_fncs,
+                                               options,
+                                               stdio_count,
+                                               pipes);
+  if (err != 0) {
+    (void) posix_spawnattr_destroy(&attrs);
+    goto error;
+  }
+
+  /* Try to spawn options->file resolving in the provided environment
+   * if any */
+  err = uv__spawn_resolve_and_spawn(options, &attrs, &actions, pid);
+  assert(err != ENOSYS);
+
+  /* Destroy the actions/attributes */
+  (void) posix_spawn_file_actions_destroy(&actions);
+  (void) posix_spawnattr_destroy(&attrs);
+
+error:
+  /* In an error situation, the attributes and file actions are
+   * already destroyed, only the happy path requires cleanup */
+  return UV__ERR(err);
+}
+#endif
+
+static int uv__spawn_and_init_child_fork(const uv_process_options_t* options,
+                                         int stdio_count,
+                                         int (*pipes)[2],
+                                         int error_fd,
+                                         pid_t* pid) {
+  sigset_t signewset;
+  sigset_t sigoldset;
+
+  /* Start the child with most signals blocked, to avoid any issues before we
+   * can reset them, but allow program failures to exit (and not hang). */
+  sigfillset(&signewset);
+  sigdelset(&signewset, SIGKILL);
+  sigdelset(&signewset, SIGSTOP);
+  sigdelset(&signewset, SIGTRAP);
+  sigdelset(&signewset, SIGSEGV);
+  sigdelset(&signewset, SIGBUS);
+  sigdelset(&signewset, SIGILL);
+  sigdelset(&signewset, SIGSYS);
+  sigdelset(&signewset, SIGABRT);
+  if (pthread_sigmask(SIG_BLOCK, &signewset, &sigoldset) != 0)
+    abort();
+
+  *pid = fork();
+
+  if (*pid == 0) {
+    /* Fork succeeded, in the child process */
+    uv__process_child_init(options, stdio_count, pipes, error_fd);
+    abort();
+  }
+
+  if (pthread_sigmask(SIG_SETMASK, &sigoldset, NULL) != 0)
+    abort();
+
+  if (*pid == -1)
+    /* Failed to fork */
+    return UV__ERR(errno);
+
+  /* Fork succeeded, in the parent process */
+  return 0;
+}
+
+static int uv__spawn_and_init_child(
+    uv_loop_t* loop,
+    const uv_process_options_t* options,
+    int stdio_count,
+    int (*pipes)[2],
+    pid_t* pid) {
+  int signal_pipe[2] = { -1, -1 };
+  int status;
+  int err;
+  int exec_errorno;
+  ssize_t r;
+
+#if defined(__APPLE__)
+  uv_once(&posix_spawn_init_once, uv__spawn_init_posix_spawn);
+
+  /* Special child process spawn case for macOS Big Sur (11.0) onwards
+   *
+   * Big Sur introduced a significant performance degradation on a call to
+   * fork/exec when the process has many pages mmaped in with MAP_JIT, like, say
+   * a javascript interpreter. Electron-based applications, for example,
+   * are impacted; though the magnitude of the impact depends on how much the
+   * app relies on subprocesses.
+   *
+   * On macOS, though, posix_spawn is implemented in a way that does not
+   * exhibit the problem. This block implements the forking and preparation
+   * logic with posix_spawn and its related primitives. It also takes advantage of
+   * the macOS extension POSIX_SPAWN_CLOEXEC_DEFAULT that makes impossible to
+   * leak descriptors to the child process. */
+  err = uv__spawn_and_init_child_posix_spawn(options,
+                                             stdio_count,
+                                             pipes,
+                                             pid,
+                                             &posix_spawn_fncs);
+
+  /* The posix_spawn flow will return UV_ENOSYS if any of the posix_spawn_x_np
+   * non-standard functions is both _needed_ and _undefined_. In those cases,
+   * default back to the fork/execve strategy. For all other errors, just fail. */
+  if (err != UV_ENOSYS)
+    return err;
+
+#endif
+
+  /* This pipe is used by the parent to wait until
+   * the child has called `execve()`. We need this
+   * to avoid the following race condition:
+   *
+   *    if ((pid = fork()) > 0) {
+   *      kill(pid, SIGTERM);
+   *    }
+   *    else if (pid == 0) {
+   *      execve("/bin/cat", argp, envp);
+   *    }
+   *
+   * The parent sends a signal immediately after forking.
+   * Since the child may not have called `execve()` yet,
+   * there is no telling what process receives the signal,
+   * our fork or /bin/cat.
+   *
+   * To avoid ambiguity, we create a pipe with both ends
+   * marked close-on-exec. Then, after the call to `fork()`,
+   * the parent polls the read end until it EOFs or errors with EPIPE.
+   */
+  err = uv__make_pipe(signal_pipe, 0);
+  if (err)
+    return err;
+
+  /* Acquire write lock to prevent opening new fds in worker threads */
+  uv_rwlock_wrlock(&loop->cloexec_lock);
+
+  err = uv__spawn_and_init_child_fork(options, stdio_count, pipes, signal_pipe[1], pid);
+
+  /* Release lock in parent process */
+  uv_rwlock_wrunlock(&loop->cloexec_lock);
+
+  uv__close(signal_pipe[1]);
+
+  if (err == 0) {
+    do
+      r = read(signal_pipe[0], &exec_errorno, sizeof(exec_errorno));
+    while (r == -1 && errno == EINTR);
+
+    if (r == 0)
+      ; /* okay, EOF */
+    else if (r == sizeof(exec_errorno)) {
+      do
+        err = waitpid(*pid, &status, 0); /* okay, read errorno */
+      while (err == -1 && errno == EINTR);
+      assert(err == *pid);
+      err = exec_errorno;
+    } else if (r == -1 && errno == EPIPE) {
+      /* Something unknown happened to our child before spawn */
+      do
+        err = waitpid(*pid, &status, 0); /* okay, got EPIPE */
+      while (err == -1 && errno == EINTR);
+      assert(err == *pid);
+      err = UV_EPIPE;
+    } else
+      abort();
+  }
+
+  uv__close_nocheckstdio(signal_pipe[0]);
+
+  return err;
+}
+#endif /* ISN'T TARGET_OS_TV || TARGET_OS_WATCH */
+
+int uv_spawn(uv_loop_t* loop,
+             uv_process_t* process,
+             const uv_process_options_t* options) {
+#if defined(__APPLE__) && (TARGET_OS_TV || TARGET_OS_WATCH)
+  /* fork is marked __WATCHOS_PROHIBITED __TVOS_PROHIBITED. */
+  return UV_ENOSYS;
+#else
+  int pipes_storage[8][2];
+  int (*pipes)[2];
+  int stdio_count;
+  pid_t pid;
+  int err;
+  int exec_errorno;
+  int i;
+
+  assert(options->file != NULL);
+  assert(!(options->flags & ~(UV_PROCESS_DETACHED |
+                              UV_PROCESS_SETGID |
+                              UV_PROCESS_SETUID |
+                              UV_PROCESS_WINDOWS_FILE_PATH_EXACT_NAME |
+                              UV_PROCESS_WINDOWS_HIDE |
+                              UV_PROCESS_WINDOWS_HIDE_CONSOLE |
+                              UV_PROCESS_WINDOWS_HIDE_GUI |
+                              UV_PROCESS_WINDOWS_VERBATIM_ARGUMENTS)));
+
+  uv__handle_init(loop, (uv_handle_t*)process, UV_PROCESS);
+  uv__queue_init(&process->queue);
+  process->status = 0;
+
+  stdio_count = options->stdio_count;
+  if (stdio_count < 3)
+    stdio_count = 3;
+
+  err = UV_ENOMEM;
+  pipes = pipes_storage;
+  if (stdio_count > (int) ARRAY_SIZE(pipes_storage))
+    pipes = uv__malloc(stdio_count * sizeof(*pipes));
+
+  if (pipes == NULL)
+    goto error;
+
+  for (i = 0; i < stdio_count; i++) {
+    pipes[i][0] = -1;
+    pipes[i][1] = -1;
+  }
+
+  for (i = 0; i < options->stdio_count; i++) {
+    err = uv__process_init_stdio(options->stdio + i, pipes[i]);
+    if (err)
+      goto error;
+  }
+
+#ifdef UV_USE_SIGCHLD
+  uv_signal_start(&loop->child_watcher, uv__chld, SIGCHLD);
+#endif
+
+  /* Spawn the child */
+  exec_errorno = uv__spawn_and_init_child(loop, options, stdio_count, pipes, &pid);
+
+#if 0
+  /* This runs into a nodejs issue (it expects initialized streams, even if the
+   * exec failed).
+   * See https://github.com/libuv/libuv/pull/3107#issuecomment-782482608 */
+  if (exec_errorno != 0)
+      goto error;
+#endif
+
+  /* Activate this handle if exec() happened successfully, even if we later
+   * fail to open a stdio handle. This ensures we can eventually reap the child
+   * with waitpid. */
+  if (exec_errorno == 0) {
+#ifndef UV_USE_SIGCHLD
+    struct kevent event;
+    EV_SET(&event, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT, NOTE_EXIT, 0, 0);
+    if (kevent(loop->backend_fd, &event, 1, NULL, 0, NULL)) {
+      if (errno != ESRCH)
+        abort();
+      /* Process already exited. Call waitpid on the next loop iteration. */
+      process->flags |= UV_HANDLE_REAP;
+      loop->flags |= UV_LOOP_REAP_CHILDREN;
+    }
+    /* This prevents uv__io_poll() from bailing out prematurely, being unaware
+     * that we added an event here for it to react to. We will decrement this
+     * again after the waitpid call succeeds. */
+    loop->nfds++;
+#endif
+
+    process->pid = pid;
+    process->exit_cb = options->exit_cb;
+    uv__queue_insert_tail(&loop->process_handles, &process->queue);
+    uv__handle_start(process);
+  }
+
+  for (i = 0; i < options->stdio_count; i++) {
+    err = uv__process_open_stream(options->stdio + i, pipes[i]);
+    if (err == 0)
+      continue;
+
+    while (i--)
+      uv__process_close_stream(options->stdio + i);
+
+    goto error;
+  }
+
+  if (pipes != pipes_storage)
+    uv__free(pipes);
+
+  return exec_errorno;
+
+error:
+  if (pipes != NULL) {
+    for (i = 0; i < stdio_count; i++) {
+      if (i < options->stdio_count)
+        if (options->stdio[i].flags & (UV_INHERIT_FD | UV_INHERIT_STREAM))
+          continue;
+      if (pipes[i][0] != -1)
+        uv__close_nocheckstdio(pipes[i][0]);
+      if (pipes[i][1] != -1)
+        uv__close_nocheckstdio(pipes[i][1]);
+    }
+
+    if (pipes != pipes_storage)
+      uv__free(pipes);
+  }
+
+  return err;
+#endif
+}
+
+
+int uv_process_kill(uv_process_t* process, int signum) {
+  return uv_kill(process->pid, signum);
+}
+
+
+int uv_kill(int pid, int signum) {
+  if (kill(pid, signum)) {
+#if defined(__MVS__)
+    /* EPERM is returned if the process is a zombie. */
+    siginfo_t infop;
+    if (errno == EPERM &&
+        waitid(P_PID, pid, &infop, WNOHANG | WNOWAIT | WEXITED) == 0)
+      return 0;
+#endif
+    return UV__ERR(errno);
+  } else
+    return 0;
+}
+
+
+void uv__process_close(uv_process_t* handle) {
+  uv__queue_remove(&handle->queue);
+  uv__handle_stop(handle);
+#ifdef UV_USE_SIGCHLD
+  if (uv__queue_empty(&handle->loop->process_handles))
+    uv_signal_stop(&handle->loop->child_watcher);
+#endif
+}