diff --git a/libc/include/android/fdsan.h b/libc/include/android/fdsan.h
new file mode 100644
index 0000000..908619e
--- /dev/null
+++ b/libc/include/android/fdsan.h
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ * 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.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/*
+ * Error checking for close(2).
+ *
+ * Mishandling of file descriptor ownership is a common source of errors that
+ * can be extremely difficult to diagnose. Mistakes like the following can
+ * result in seemingly 'impossible' failures showing up on other threads that
+ * happened to try to open a file descriptor between the buggy code's close and
+ * fclose:
+ *
+ *     int print(int fd) {
+ *         int rc;
+ *         char buf[128];
+ *         while ((rc = read(fd, buf, sizeof(buf))) > 0) {
+ *             printf("%.*s", rc);
+ *         }
+ *         close(fd);
+ *     }
+ *
+ *     int bug() {
+ *         FILE* f = fopen("foo", "r");
+ *         print(fileno(f));
+ *         fclose(f);
+ *     }
+ *
+ * To make it easier to find this class of bugs, bionic provides a method to
+ * require that file descriptors are closed by their owners. File descriptors
+ * can be associated with tags with which they must be closed. This allows
+ * objects that conceptually own an fd (FILE*, unique_fd, etc.) to use their
+ * own address at the tag, to enforce that closure of the fd must come as a
+ * result of their own destruction (fclose, ~unique_fd, etc.)
+ *
+ * By default, a file descriptor's tag is 0, and close(fd) is equivalent to
+ * closing fd with the tag 0.
+ */
+
+/*
+ * For improved diagnostics, the type of a file descriptors owner can be
+ * encoded in the most significant byte of the owner tag. Values of 0 and 0xff
+ * are ignored, which allows for raw pointers to be used as owner tags without
+ * modification.
+ */
+enum android_fdsan_owner_type {
+  /*
+   * Generic Java or native owners.
+   *
+   * Generic Java objects always use 255 as their type, using identityHashCode
+   * as the value of the tag, leaving bits 33-56 unset. Native pointers are sign
+   * extended from 48-bits of virtual address space, and so can have the MSB
+   * set to 255 as well. Use the value of bits 49-56 to distinguish between
+   * these cases.
+   */
+  ANDROID_FDSAN_OWNER_TYPE_GENERIC_00 = 0,
+  ANDROID_FDSAN_OWNER_TYPE_GENERIC_FF = 255,
+
+  /* FILE* */
+  ANDROID_FDSAN_OWNER_TYPE_FILE = 1,
+
+  /* DIR* */
+  ANDROID_FDSAN_OWNER_TYPE_DIR = 2,
+
+  /* android::base::unique_fd */
+  ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD = 3,
+
+  /* java.io.FileInputStream */
+  ANDROID_FDSAN_OWNER_TYPE_FILEINPUTSTREAM = 251,
+
+  /* java.io.FileOutputStream */
+  ANDROID_FDSAN_OWNER_TYPE_FILEOUTPUTSTREAM = 252,
+
+  /* java.io.RandomAccessFile */
+  ANDROID_FDSAN_OWNER_TYPE_RANDOMACCESSFILE = 253,
+
+  /* android.os.ParcelFileDescriptor */
+  ANDROID_FDSAN_OWNER_TYPE_PARCELFILEDESCRIPTOR = 254,
+};
+
+/*
+ * Create an owner tag with the specified type and least significant 56 bits of tag.
+ */
+uint64_t android_fdsan_create_owner_tag(enum android_fdsan_owner_type type, uint64_t tag) __INTRODUCED_IN_FUTURE;
+
+/*
+ * Exchange a file descriptor's tag.
+ *
+ * Logs and aborts if the fd's tag does not match expected_tag.
+ */
+void android_fdsan_exchange_owner_tag(int fd, uint64_t expected_tag, uint64_t new_tag) __INTRODUCED_IN_FUTURE;
+
+/*
+ * Close a file descriptor with a tag, and resets the tag to 0.
+ *
+ * Logs and aborts if the tag is incorrect.
+ */
+int android_fdsan_close_with_tag(int fd, uint64_t tag) __INTRODUCED_IN_FUTURE;
+
+enum android_fdsan_error_level {
+  // No errors.
+  ANDROID_FDSAN_ERROR_LEVEL_DISABLED,
+
+  // Warn once(ish) on error, and then downgrade to ANDROID_FDSAN_ERROR_LEVEL_DISABLED.
+  ANDROID_FDSAN_ERROR_LEVEL_WARN_ONCE,
+
+  // Warn always on error.
+  ANDROID_FDSAN_ERROR_LEVEL_WARN_ALWAYS,
+
+  // Abort on error.
+  ANDROID_FDSAN_ERROR_LEVEL_FATAL,
+};
+
+/*
+ * Get the error level.
+ */
+enum android_fdsan_error_level android_fdsan_get_error_level() __INTRODUCED_IN_FUTURE;
+
+/*
+ * Set the error level and return the previous state.
+ *
+ * Error checking is automatically disabled in the child of a fork, to maintain
+ * compatibility with code that forks, blindly closes FDs, and then execs.
+ *
+ * In cases such as the zygote, where the child has no intention of calling
+ * exec, call this function to reenable fdsan checks.
+ *
+ * This function is not thread-safe and does not synchronize with checks of the
+ * value, and so should probably only be called in single-threaded contexts
+ * (e.g. postfork).
+ */
+enum android_fdsan_error_level android_fdsan_set_error_level(enum android_fdsan_error_level new_level) __INTRODUCED_IN_FUTURE;
+
+__END_DECLS