--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/unix/signal.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,581 @@
+/* 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 <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifndef SA_RESTART
+# define SA_RESTART 0
+#endif
+
+typedef struct {
+  uv_signal_t* handle;
+  int signum;
+} uv__signal_msg_t;
+
+RB_HEAD(uv__signal_tree_s, uv_signal_s);
+
+
+static int uv__signal_unlock(void);
+static int uv__signal_start(uv_signal_t* handle,
+                            uv_signal_cb signal_cb,
+                            int signum,
+                            int oneshot);
+static void uv__signal_event(uv_loop_t* loop, uv__io_t* w, unsigned int events);
+static int uv__signal_compare(uv_signal_t* w1, uv_signal_t* w2);
+static void uv__signal_stop(uv_signal_t* handle);
+static void uv__signal_unregister_handler(int signum);
+
+
+static uv_once_t uv__signal_global_init_guard = UV_ONCE_INIT;
+static struct uv__signal_tree_s uv__signal_tree =
+    RB_INITIALIZER(uv__signal_tree);
+static int uv__signal_lock_pipefd[2] = { -1, -1 };
+
+RB_GENERATE_STATIC(uv__signal_tree_s,
+                   uv_signal_s, tree_entry,
+                   uv__signal_compare)
+
+static void uv__signal_global_reinit(void);
+
+static void uv__signal_global_init(void) {
+  if (uv__signal_lock_pipefd[0] == -1)
+    /* pthread_atfork can register before and after handlers, one
+     * for each child. This only registers one for the child. That
+     * state is both persistent and cumulative, so if we keep doing
+     * it the handler functions will be called multiple times. Thus
+     * we only want to do it once.
+     */
+    if (pthread_atfork(NULL, NULL, &uv__signal_global_reinit))
+      abort();
+
+  uv__signal_global_reinit();
+}
+
+
+void uv__signal_cleanup(void) {
+  /* We can only use signal-safe functions here.
+   * That includes read/write and close, fortunately.
+   * We do all of this directly here instead of resetting
+   * uv__signal_global_init_guard because
+   * uv__signal_global_once_init is only called from uv_loop_init
+   * and this needs to function in existing loops.
+   */
+  if (uv__signal_lock_pipefd[0] != -1) {
+    uv__close(uv__signal_lock_pipefd[0]);
+    uv__signal_lock_pipefd[0] = -1;
+  }
+
+  if (uv__signal_lock_pipefd[1] != -1) {
+    uv__close(uv__signal_lock_pipefd[1]);
+    uv__signal_lock_pipefd[1] = -1;
+  }
+}
+
+
+static void uv__signal_global_reinit(void) {
+  uv__signal_cleanup();
+
+  if (uv__make_pipe(uv__signal_lock_pipefd, 0))
+    abort();
+
+  if (uv__signal_unlock())
+    abort();
+}
+
+
+void uv__signal_global_once_init(void) {
+  uv_once(&uv__signal_global_init_guard, uv__signal_global_init);
+}
+
+
+static int uv__signal_lock(void) {
+  int r;
+  char data;
+
+  do {
+    r = read(uv__signal_lock_pipefd[0], &data, sizeof data);
+  } while (r < 0 && errno == EINTR);
+
+  return (r < 0) ? -1 : 0;
+}
+
+
+static int uv__signal_unlock(void) {
+  int r;
+  char data = 42;
+
+  do {
+    r = write(uv__signal_lock_pipefd[1], &data, sizeof data);
+  } while (r < 0 && errno == EINTR);
+
+  return (r < 0) ? -1 : 0;
+}
+
+
+static void uv__signal_block_and_lock(sigset_t* saved_sigmask) {
+  sigset_t new_mask;
+
+  if (sigfillset(&new_mask))
+    abort();
+
+  /* to shut up valgrind */
+  sigemptyset(saved_sigmask);
+  if (pthread_sigmask(SIG_SETMASK, &new_mask, saved_sigmask))
+    abort();
+
+  if (uv__signal_lock())
+    abort();
+}
+
+
+static void uv__signal_unlock_and_unblock(sigset_t* saved_sigmask) {
+  if (uv__signal_unlock())
+    abort();
+
+  if (pthread_sigmask(SIG_SETMASK, saved_sigmask, NULL))
+    abort();
+}
+
+
+static uv_signal_t* uv__signal_first_handle(int signum) {
+  /* This function must be called with the signal lock held. */
+  uv_signal_t lookup;
+  uv_signal_t* handle;
+
+  lookup.signum = signum;
+  lookup.flags = 0;
+  lookup.loop = NULL;
+
+  handle = RB_NFIND(uv__signal_tree_s, &uv__signal_tree, &lookup);
+
+  if (handle != NULL && handle->signum == signum)
+    return handle;
+
+  return NULL;
+}
+
+
+static void uv__signal_handler(int signum) {
+  uv__signal_msg_t msg;
+  uv_signal_t* handle;
+  int saved_errno;
+
+  saved_errno = errno;
+  memset(&msg, 0, sizeof msg);
+
+  if (uv__signal_lock()) {
+    errno = saved_errno;
+    return;
+  }
+
+  for (handle = uv__signal_first_handle(signum);
+       handle != NULL && handle->signum == signum;
+       handle = RB_NEXT(uv__signal_tree_s, handle)) {
+    int r;
+
+    msg.signum = signum;
+    msg.handle = handle;
+
+    /* write() should be atomic for small data chunks, so the entire message
+     * should be written at once. In theory the pipe could become full, in
+     * which case the user is out of luck.
+     */
+    do {
+      r = write(handle->loop->signal_pipefd[1], &msg, sizeof msg);
+    } while (r == -1 && errno == EINTR);
+
+    assert(r == sizeof msg ||
+           (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)));
+
+    if (r != -1)
+      handle->caught_signals++;
+  }
+
+  uv__signal_unlock();
+  errno = saved_errno;
+}
+
+
+static int uv__signal_register_handler(int signum, int oneshot) {
+  /* When this function is called, the signal lock must be held. */
+  struct sigaction sa;
+
+  /* XXX use a separate signal stack? */
+  memset(&sa, 0, sizeof(sa));
+  if (sigfillset(&sa.sa_mask))
+    abort();
+  sa.sa_handler = uv__signal_handler;
+  sa.sa_flags = SA_RESTART;
+  if (oneshot)
+    sa.sa_flags |= SA_RESETHAND;
+
+  /* XXX save old action so we can restore it later on? */
+  if (sigaction(signum, &sa, NULL))
+    return UV__ERR(errno);
+
+  return 0;
+}
+
+
+static void uv__signal_unregister_handler(int signum) {
+  /* When this function is called, the signal lock must be held. */
+  struct sigaction sa;
+
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = SIG_DFL;
+
+  /* sigaction can only fail with EINVAL or EFAULT; an attempt to deregister a
+   * signal implies that it was successfully registered earlier, so EINVAL
+   * should never happen.
+   */
+  if (sigaction(signum, &sa, NULL))
+    abort();
+}
+
+
+static int uv__signal_loop_once_init(uv_loop_t* loop) {
+  int* pipefd;
+  int err;
+
+  /* Return if already initialized. */
+  pipefd = loop->signal_pipefd;
+  if (pipefd[0] != -1)
+    return 0;
+
+  err = uv__make_pipe(pipefd, UV_NONBLOCK_PIPE);
+  if (err)
+    return err;
+
+  err = uv__io_init_start(loop, &loop->signal_io_watcher, uv__signal_event,
+                          pipefd[0], POLLIN);
+  if (err) {
+    uv__close(pipefd[0]);
+    uv__close(pipefd[1]);
+    pipefd[0] = -1;
+    pipefd[1] = -1;
+  }
+
+  return err;
+}
+
+
+int uv__signal_loop_fork(uv_loop_t* loop) {
+  struct uv__queue* q;
+
+  if (loop->signal_pipefd[0] == -1)
+    return 0;
+  uv__io_stop(loop, &loop->signal_io_watcher, POLLIN);
+  uv__close(loop->signal_pipefd[0]);
+  uv__close(loop->signal_pipefd[1]);
+  loop->signal_pipefd[0] = -1;
+  loop->signal_pipefd[1] = -1;
+
+  uv__queue_foreach(q, &loop->handle_queue) {
+    uv_handle_t* handle = uv__queue_data(q, uv_handle_t, handle_queue);
+    uv_signal_t* sh;
+
+    if (handle->type != UV_SIGNAL)
+      continue;
+
+    sh = (uv_signal_t*) handle;
+    sh->caught_signals = 0;
+    sh->dispatched_signals = 0;
+  }
+
+  return uv__signal_loop_once_init(loop);
+}
+
+
+void uv__signal_loop_cleanup(uv_loop_t* loop) {
+  struct uv__queue* q;
+
+  /* Stop all the signal watchers that are still attached to this loop. This
+   * ensures that the (shared) signal tree doesn't contain any invalid entries
+   * entries, and that signal handlers are removed when appropriate.
+   * It's safe to use uv__queue_foreach here because the handles and the handle
+   * queue are not modified by uv__signal_stop().
+   */
+  uv__queue_foreach(q, &loop->handle_queue) {
+    uv_handle_t* handle = uv__queue_data(q, uv_handle_t, handle_queue);
+
+    if (handle->type == UV_SIGNAL)
+      uv__signal_stop((uv_signal_t*) handle);
+  }
+
+  if (loop->signal_pipefd[0] != -1) {
+    uv__close(loop->signal_pipefd[0]);
+    loop->signal_pipefd[0] = -1;
+  }
+
+  if (loop->signal_pipefd[1] != -1) {
+    uv__close(loop->signal_pipefd[1]);
+    loop->signal_pipefd[1] = -1;
+  }
+}
+
+
+int uv_signal_init(uv_loop_t* loop, uv_signal_t* handle) {
+  int err;
+
+  err = uv__signal_loop_once_init(loop);
+  if (err)
+    return err;
+
+  uv__handle_init(loop, (uv_handle_t*) handle, UV_SIGNAL);
+  handle->signum = 0;
+  handle->caught_signals = 0;
+  handle->dispatched_signals = 0;
+
+  return 0;
+}
+
+
+void uv__signal_close(uv_signal_t* handle) {
+  uv__signal_stop(handle);
+}
+
+
+int uv_signal_start(uv_signal_t* handle, uv_signal_cb signal_cb, int signum) {
+  return uv__signal_start(handle, signal_cb, signum, 0);
+}
+
+
+int uv_signal_start_oneshot(uv_signal_t* handle,
+                            uv_signal_cb signal_cb,
+                            int signum) {
+  return uv__signal_start(handle, signal_cb, signum, 1);
+}
+
+
+static int uv__signal_start(uv_signal_t* handle,
+                            uv_signal_cb signal_cb,
+                            int signum,
+                            int oneshot) {
+  sigset_t saved_sigmask;
+  int err;
+  uv_signal_t* first_handle;
+
+  assert(!uv__is_closing(handle));
+
+  /* If the user supplies signum == 0, then return an error already. If the
+   * signum is otherwise invalid then uv__signal_register will find out
+   * eventually.
+   */
+  if (signum == 0)
+    return UV_EINVAL;
+
+  /* Short circuit: if the signal watcher is already watching {signum} don't
+   * go through the process of deregistering and registering the handler.
+   * Additionally, this avoids pending signals getting lost in the small
+   * time frame that handle->signum == 0.
+   */
+  if (signum == handle->signum) {
+    handle->signal_cb = signal_cb;
+    return 0;
+  }
+
+  /* If the signal handler was already active, stop it first. */
+  if (handle->signum != 0) {
+    uv__signal_stop(handle);
+  }
+
+  uv__signal_block_and_lock(&saved_sigmask);
+
+  /* If at this point there are no active signal watchers for this signum (in
+   * any of the loops), it's time to try and register a handler for it here.
+   * Also in case there's only one-shot handlers and a regular handler comes in.
+   */
+  first_handle = uv__signal_first_handle(signum);
+  if (first_handle == NULL ||
+      (!oneshot && (first_handle->flags & UV_SIGNAL_ONE_SHOT))) {
+    err = uv__signal_register_handler(signum, oneshot);
+    if (err) {
+      /* Registering the signal handler failed. Must be an invalid signal. */
+      uv__signal_unlock_and_unblock(&saved_sigmask);
+      return err;
+    }
+  }
+
+  handle->signum = signum;
+  if (oneshot)
+    handle->flags |= UV_SIGNAL_ONE_SHOT;
+
+  RB_INSERT(uv__signal_tree_s, &uv__signal_tree, handle);
+
+  uv__signal_unlock_and_unblock(&saved_sigmask);
+
+  handle->signal_cb = signal_cb;
+  uv__handle_start(handle);
+
+  return 0;
+}
+
+
+static void uv__signal_event(uv_loop_t* loop,
+                             uv__io_t* w,
+                             unsigned int events) {
+  uv__signal_msg_t* msg;
+  uv_signal_t* handle;
+  char buf[sizeof(uv__signal_msg_t) * 32];
+  size_t bytes, end, i;
+  int r;
+
+  bytes = 0;
+  end = 0;
+
+  do {
+    r = read(loop->signal_pipefd[0], buf + bytes, sizeof(buf) - bytes);
+
+    if (r == -1 && errno == EINTR)
+      continue;
+
+    if (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
+      /* If there are bytes in the buffer already (which really is extremely
+       * unlikely if possible at all) we can't exit the function here. We'll
+       * spin until more bytes are read instead.
+       */
+      if (bytes > 0)
+        continue;
+
+      /* Otherwise, there was nothing there. */
+      return;
+    }
+
+    /* Other errors really should never happen. */
+    if (r == -1)
+      abort();
+
+    bytes += r;
+
+    /* `end` is rounded down to a multiple of sizeof(uv__signal_msg_t). */
+    end = (bytes / sizeof(uv__signal_msg_t)) * sizeof(uv__signal_msg_t);
+
+    for (i = 0; i < end; i += sizeof(uv__signal_msg_t)) {
+      msg = (uv__signal_msg_t*) (buf + i);
+      handle = msg->handle;
+
+      if (msg->signum == handle->signum) {
+        assert(!(handle->flags & UV_HANDLE_CLOSING));
+        handle->signal_cb(handle, handle->signum);
+      }
+
+      handle->dispatched_signals++;
+
+      if (handle->flags & UV_SIGNAL_ONE_SHOT)
+        uv__signal_stop(handle);
+    }
+
+    bytes -= end;
+
+    /* If there are any "partial" messages left, move them to the start of the
+     * the buffer, and spin. This should not happen.
+     */
+    if (bytes) {
+      memmove(buf, buf + end, bytes);
+      continue;
+    }
+  } while (end == sizeof buf);
+}
+
+
+static int uv__signal_compare(uv_signal_t* w1, uv_signal_t* w2) {
+  int f1;
+  int f2;
+  /* Compare signums first so all watchers with the same signnum end up
+   * adjacent.
+   */
+  if (w1->signum < w2->signum) return -1;
+  if (w1->signum > w2->signum) return 1;
+
+  /* Handlers without UV_SIGNAL_ONE_SHOT set will come first, so if the first
+   * handler returned is a one-shot handler, the rest will be too.
+   */
+  f1 = w1->flags & UV_SIGNAL_ONE_SHOT;
+  f2 = w2->flags & UV_SIGNAL_ONE_SHOT;
+  if (f1 < f2) return -1;
+  if (f1 > f2) return 1;
+
+  /* Sort by loop pointer, so we can easily look up the first item after
+   * { .signum = x, .loop = NULL }.
+   */
+  if (w1->loop < w2->loop) return -1;
+  if (w1->loop > w2->loop) return 1;
+
+  if (w1 < w2) return -1;
+  if (w1 > w2) return 1;
+
+  return 0;
+}
+
+
+int uv_signal_stop(uv_signal_t* handle) {
+  assert(!uv__is_closing(handle));
+  uv__signal_stop(handle);
+  return 0;
+}
+
+
+static void uv__signal_stop(uv_signal_t* handle) {
+  uv_signal_t* removed_handle;
+  sigset_t saved_sigmask;
+  uv_signal_t* first_handle;
+  int rem_oneshot;
+  int first_oneshot;
+  int ret;
+
+  /* If the watcher wasn't started, this is a no-op. */
+  if (handle->signum == 0)
+    return;
+
+  uv__signal_block_and_lock(&saved_sigmask);
+
+  removed_handle = RB_REMOVE(uv__signal_tree_s, &uv__signal_tree, handle);
+  assert(removed_handle == handle);
+  (void) removed_handle;
+
+  /* Check if there are other active signal watchers observing this signal. If
+   * not, unregister the signal handler.
+   */
+  first_handle = uv__signal_first_handle(handle->signum);
+  if (first_handle == NULL) {
+    uv__signal_unregister_handler(handle->signum);
+  } else {
+    rem_oneshot = handle->flags & UV_SIGNAL_ONE_SHOT;
+    first_oneshot = first_handle->flags & UV_SIGNAL_ONE_SHOT;
+    if (first_oneshot && !rem_oneshot) {
+      ret = uv__signal_register_handler(handle->signum, 1);
+      assert(ret == 0);
+      (void)ret;
+    }
+  }
+
+  uv__signal_unlock_and_unblock(&saved_sigmask);
+
+  handle->signum = 0;
+  uv__handle_stop(handle);
+}