--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/win/fs-fd-hash-inl.h	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,200 @@
+/* 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.
+ */
+
+#ifndef UV_WIN_FS_FD_HASH_INL_H_
+#define UV_WIN_FS_FD_HASH_INL_H_
+
+#include "uv.h"
+#include "internal.h"
+
+/* Files are only inserted in uv__fd_hash when the UV_FS_O_FILEMAP flag is
+ * specified. Thus, when uv__fd_hash_get returns true, the file mapping in the
+ * info structure should be used for read/write operations.
+ *
+ * If the file is empty, the mapping field will be set to
+ * INVALID_HANDLE_VALUE. This is not an issue since the file mapping needs to
+ * be created anyway when the file size changes.
+ *
+ * Since file descriptors are sequential integers, the modulo operator is used
+ * as hashing function. For each bucket, a single linked list of arrays is
+ * kept to minimize allocations. A statically allocated memory buffer is kept
+ * for the first array in each bucket. */
+
+
+#define UV__FD_HASH_SIZE 256
+#define UV__FD_HASH_GROUP_SIZE 16
+
+struct uv__fd_info_s {
+  int flags;
+  BOOLEAN is_directory;
+  HANDLE mapping;
+  LARGE_INTEGER size;
+  LARGE_INTEGER current_pos;
+};
+
+struct uv__fd_hash_entry_s {
+  uv_file fd;
+  struct uv__fd_info_s info;
+};
+
+struct uv__fd_hash_entry_group_s {
+  struct uv__fd_hash_entry_s entries[UV__FD_HASH_GROUP_SIZE];
+  struct uv__fd_hash_entry_group_s* next;
+};
+
+struct uv__fd_hash_bucket_s {
+  size_t size;
+  struct uv__fd_hash_entry_group_s* data;
+};
+
+
+static uv_mutex_t uv__fd_hash_mutex;
+
+static struct uv__fd_hash_entry_group_s
+  uv__fd_hash_entry_initial[UV__FD_HASH_SIZE * UV__FD_HASH_GROUP_SIZE];
+static struct uv__fd_hash_bucket_s uv__fd_hash[UV__FD_HASH_SIZE];
+
+
+INLINE static void uv__fd_hash_init(void) {
+  size_t i;
+  int err;
+
+  err = uv_mutex_init(&uv__fd_hash_mutex);
+  if (err) {
+    uv_fatal_error(err, "uv_mutex_init");
+  }
+
+  for (i = 0; i < ARRAY_SIZE(uv__fd_hash); ++i) {
+    uv__fd_hash[i].size = 0;
+    uv__fd_hash[i].data =
+        uv__fd_hash_entry_initial + i * UV__FD_HASH_GROUP_SIZE;
+  }
+}
+
+#define FIND_COMMON_VARIABLES                                                \
+  unsigned i;                                                                \
+  unsigned bucket = fd % ARRAY_SIZE(uv__fd_hash);                            \
+  struct uv__fd_hash_entry_s* entry_ptr = NULL;                              \
+  struct uv__fd_hash_entry_group_s* group_ptr;                               \
+  struct uv__fd_hash_bucket_s* bucket_ptr = &uv__fd_hash[bucket];
+
+#define FIND_IN_GROUP_PTR(group_size)                                        \
+  do {                                                                       \
+    for (i = 0; i < group_size; ++i) {                                       \
+      if (group_ptr->entries[i].fd == fd) {                                  \
+        entry_ptr = &group_ptr->entries[i];                                  \
+        break;                                                               \
+      }                                                                      \
+    }                                                                        \
+  } while (0)
+
+#define FIND_IN_BUCKET_PTR()                                                 \
+  do {                                                                       \
+    size_t first_group_size = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;     \
+    if (bucket_ptr->size != 0 && first_group_size == 0)                      \
+      first_group_size = UV__FD_HASH_GROUP_SIZE;                             \
+    group_ptr = bucket_ptr->data;                                            \
+    FIND_IN_GROUP_PTR(first_group_size);                                     \
+    for (group_ptr = group_ptr->next;                                        \
+         group_ptr != NULL && entry_ptr == NULL;                             \
+         group_ptr = group_ptr->next)                                        \
+      FIND_IN_GROUP_PTR(UV__FD_HASH_GROUP_SIZE);                             \
+  } while (0)
+
+INLINE static int uv__fd_hash_get(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr != NULL) {
+    *info = entry_ptr->info;
+  }
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+  return entry_ptr != NULL;
+}
+
+INLINE static void uv__fd_hash_add(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr == NULL) {
+    i = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;
+
+    if (bucket_ptr->size != 0 && i == 0) {
+      struct uv__fd_hash_entry_group_s* new_group_ptr =
+        uv__malloc(sizeof(*new_group_ptr));
+      if (new_group_ptr == NULL) {
+        uv_fatal_error(ERROR_OUTOFMEMORY, "uv__malloc");
+      }
+      new_group_ptr->next = bucket_ptr->data;
+      bucket_ptr->data = new_group_ptr;
+    }
+
+    bucket_ptr->size += 1;
+    entry_ptr = &bucket_ptr->data->entries[i];
+    entry_ptr->fd = fd;
+  }
+
+  entry_ptr->info = *info;
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+}
+
+INLINE static int uv__fd_hash_remove(int fd, struct uv__fd_info_s* info) {
+  FIND_COMMON_VARIABLES
+
+  uv_mutex_lock(&uv__fd_hash_mutex);
+
+  FIND_IN_BUCKET_PTR();
+
+  if (entry_ptr != NULL) {
+    *info = entry_ptr->info;
+
+    bucket_ptr->size -= 1;
+
+    i = bucket_ptr->size % UV__FD_HASH_GROUP_SIZE;
+    if (entry_ptr != &bucket_ptr->data->entries[i]) {
+      *entry_ptr = bucket_ptr->data->entries[i];
+    }
+
+    if (bucket_ptr->size != 0 &&
+        bucket_ptr->size % UV__FD_HASH_GROUP_SIZE == 0) {
+      struct uv__fd_hash_entry_group_s* old_group_ptr = bucket_ptr->data;
+      bucket_ptr->data = old_group_ptr->next;
+      uv__free(old_group_ptr);
+    }
+  }
+
+  uv_mutex_unlock(&uv__fd_hash_mutex);
+  return entry_ptr != NULL;
+}
+
+#undef FIND_COMMON_VARIABLES
+#undef FIND_IN_GROUP_PTR
+#undef FIND_IN_BUCKET_PTR
+
+#endif /* UV_WIN_FS_FD_HASH_INL_H_ */