WIP

dlext.odin

@@ -0,0 +1,161 @@
+//+build android
+package android
+
+foreign import android "system:android"
+
+/**
+ * \file
+ * Advanced dynamic library opening support. Most users will want to use
+ * the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
+ * functionality in `<dlfcn.h>` instead.
+ */
+
+/** Bitfield definitions for `android_dlextinfo::flags`. */
+DLextFlagsBits :: enum u64 {
+  /**
+   * When set, the `reserved_addr` and `reserved_size` fields must point to an
+   * already-reserved region of address space which will be used to load the
+   * library if it fits.
+   *
+   * If the reserved region is not large enough, loading will fail.
+   */
+  RESERVED_ADDRESS      = 0,
+
+  /**
+   * Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
+   * the linker will choose an available address instead.
+   */
+  RESERVED_ADDRESS_HINT = 1,
+
+  /**
+   * When set, write the GNU RELRO section of the mapped library to `relro_fd`
+   * after relocation has been performed, to allow it to be reused by another
+   * process loading the same library at the same address. This implies
+   * `ANDROID_DLEXT_USE_RELRO`.
+   *
+   * This is mainly useful for the system WebView implementation.
+   */
+  WRITE_RELRO           = 2,
+
+  /**
+   * When set, compare the GNU RELRO section of the mapped library to `relro_fd`
+   * after relocation has been performed, and replace any relocated pages that
+   * are identical with a version mapped from the file.
+   *
+   * This is mainly useful for the system WebView implementation.
+   */
+  USE_RELRO             = 3,
+
+  /**
+   * Use `library_fd` instead of opening the file by name.
+   * The filename parameter is still used to identify the library.
+   */
+  USE_LIBRARY_FD        = 4,
+
+  /**
+   * If opening a library using `library_fd` read it starting at `library_fd_offset`.
+   * This is mainly useful for loading a library stored within another file (such as uncompressed
+   * inside a ZIP archive).
+   * This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
+   */
+  USE_LIBRARY_FD_OFFSET    = 5,
+
+  /**
+   * When set, do not use `stat(2)` to check if the library has already been loaded.
+   *
+   * This flag allows forced loading of the library in the case when for some
+   * reason multiple ELF files share the same filename (because the already-loaded
+   * library has been removed and overwritten, for example).
+   *
+   * Note that if the library has the same `DT_SONAME` as an old one and some other
+   * library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
+   * dependencies.
+   */
+  FORCE_LOAD = 6,
+
+  // Historically we had two other options for ART.
+  // They were last available in Android P.
+  // Reuse these bits last!
+  // ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80
+  // ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100
+
+  /**
+   * This flag used to load library in a different namespace. The namespace is
+   * specified in `library_namespace`.
+   *
+   * This flag is for internal use only (since there is no NDK API for namespaces).
+   */
+  USE_NAMESPACE = 9,
+
+  /**
+   * Instructs dlopen to apply `ANDROID_DLEXT_RESERVED_ADDRESS`,
+   * `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`, `ANDROID_DLEXT_WRITE_RELRO` and
+   * `ANDROID_DLEXT_USE_RELRO` to any libraries loaded as dependencies of the
+   * main library as well.
+   *
+   * This means that if the main library depends on one or more not-already-loaded libraries, they
+   * will be loaded consecutively into the region starting at `reserved_addr`, and `reserved_size`
+   * must be large enough to contain all of the libraries. The libraries will be loaded in the
+   * deterministic order constructed from the DT_NEEDED entries, rather than the more secure random
+   * order used by default.
+   *
+   * Each library's GNU RELRO sections will be written out to `relro_fd` in the same order they were
+   * loaded. This will mean that the resulting file is dependent on which of the libraries were
+   * already loaded, as only the newly loaded libraries will be included, not any already-loaded
+   * dependencies. The caller should ensure that the set of libraries newly loaded is consistent
+   * for this to be effective.
+   *
+   * This is mainly useful for the system WebView implementation.
+   */
+  RESERVED_ADDRESS_RECURSIVE = 10,
+}
+
+DLextFlags :: bit_set[DLextFlagsBits; u64]
+
+AllDLextFlags :: DLextFlags{
+	.RESERVED_ADDRESS,
+	.RESERVED_ADDRESS_HINT,
+	.WRITE_RELRO,
+	.USE_RELRO,
+	.USE_LIBRARY_FD,
+	.USE_LIBRARY_FD_OFFSET,
+	.FORCE_LOAD,
+	.USE_NAMESPACE,
+	.RESERVED_ADDRESS_RECURSIVE
+}
+
+android_namespace_t :: struct{}
+
+/** Used to pass Android-specific arguments to `android_dlopen_ext`. */
+android_dlextinfo :: struct {
+  /** A bitmask of `ANDROID_DLEXT_` enum values. */
+  flags: DLextFlags,
+
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
+  reserved_addr: rawptr,
+  /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
+  reserved_size: uint,
+
+  /** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
+  relro_fd: i32,
+
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
+  library_fd: i32,
+  /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
+  library_fd_offset: off64_t,
+
+  /** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
+  library_namespace: ^android_namespace_t,
+}
+
+foreign android {
+	/**
+	 * Opens the given library. The `__filename` and `__flags` arguments are
+	 * the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
+	 * with the Android-specific flags supplied via the `flags` member of `__info`.
+	 *
+	 * Available since API level 21.
+	 */
+	android_dlopen_ext :: proc(__filename: cstring, __flags: i32, __info: ^android_dlextinfo) -> rawptr ---
+}
+