PPAPI: Implement PPB_FileMapping on POSIX

ppapi/api/ppb_file_mapping.idl

+/* Copyright (c) 2014 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+/**
+ * This file defines methods for mapping and unmapping files into and out of
+ * memory.
+ */
+
+[generate_thunk]
+
+label Chrome {
+  [channel=dev] M34 = 0.1
+};
+
+/**
+ * The PP_FileMapProtection values indicate the permissions requested for the
+ * file mapping. These should be used in a uint32_t bitfield.
+ */
+[assert_size(4)]
+enum PP_FileMapProtection {
+  /** Requests read access to the mapped address. */
+  PP_FILEMAPPROTECTION_READ = 1u << 0,
+
+  /** Requests write access to the mapped address. */
+  PP_FILEMAPPROTECTION_WRITE = 1u << 1
+};
+
+/**
+ * The PP_FileMapFlags contain flag values for use with Map().
+ */
+[assert_size(4)]
+enum PP_FileMapFlags {
+  /**
+   * Requests a shared mapping. If this flag is set, changes written to the
+   * memory region will be reflected in the underlying file and will thus
+   * eventually be visible to other processes which have opened the file. The
+   * file may not actually be updated until Unmap() is called. This is only
+   * valid if the PPB_FileIO resource was opened with write permission.
+   */
+  PP_FILEMAPFLAG_SHARED = 1u << 0,
+
+  /**
+   * Requests a copy-on-write mapping. If this flag is set, changes are not
+   * written to the underlying file, but only in the memory of the process
+   * (copy-on-write).
+   */
+  PP_FILEMAPFLAG_PRIVATE = 1u << 1,
+
+  /**
+   * Forces Map() to map the file contents at the provided |address|. If Map()
+   * can not comply, Map() will fail.
+   */
+  PP_FILEMAPFLAG_FIXED = 1u << 2
+};
+
+/**
+ *  PPB_FileMapping contains functions for mapping and unmapping files into and
+ *  out of memory.
+ */
+[singleton]
+interface PPB_FileMapping {
+  /**
+   * Map() maps the contents from an offset of the file into memory.
+   *
+   * @param[in] instance A <code>PP_Instance</code> identifying one instance of
+   * a module.
+   * @param[in] file_io A <code>PP_Resource</code> corresponding to a file.
+   * @param[in] length The number of bytes to map.
+   * @param[in] map_protection A bitfield containing values from
+   * <code>PP_FileMapProtection</code>, indicating what memory operations
+   * should be permitted on the mapped region.
+   * @param[in] map_flags A bitfield containing values from
+   * <code>PP_FileMapFlags</code>, providing options for the behavior of Map.
+   * If the region is to be writeable, then exactly one of
+   * <code>PP_FILEMAPFLAG_SHARED</code> or <code>PP_FILEMAPFLAG_PRIVATE</code>
+   * must be set.
+   * @param[in] offset The offset into the file. Must be a multiple of the
+   * Map page size as returned by GetMapPageSize().
+   * @param[inout] address The value of <code>*address</code>, if non-NULL,
+   * will be used as a hint to determine where in memory the file should be
+   * mapped. If the value is NULL, the host operating system will choose
+   * <code>address</code>. Upon Map() completing, <code>*address</code> will
+   * contain the actual memory location at which the file was mapped. If the
+   * plugin provides a non-NULL <code>*address</code>, it must be a multiple of
+   * the map page size as returned by GetMapPageSize().
+   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
+   * completion of Map().
+   *
+   * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   */
+  int32_t Map([in] PP_Instance instance,
+              [in] PP_Resource file_io,
+              [in] int64_t length,
+              [in] uint32_t map_protection,
+              [in] uint32_t map_flags,
+              [in] int64_t offset,
+              [inout] mem_ptr_t address,
+              [in] PP_CompletionCallback callback);
+
+  /**
+   * Unmap() deletes the mapping of the specified address.  The specified
+   * address must have been retrieved with Map().
+   * @param[in] instance A <code>PP_Instance</code> identifying the instance.
+   * @param[in] address The starting address of the address in memory to
+   * be unmapped.
+   * @param[in] length The length of the region to unmap.
+   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
+   * completion of Unmap().
+   *
+   * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   */
+  int32_t Unmap([in] PP_Instance instance,
+                [in] mem_t address,
+                [in] int64_t length,
+                [in] PP_CompletionCallback callback);
+
+  /**
+   * GetMapPageSize() retrieves the size of pages that Map() uses.
+   *
+   * @param[in] instance A <code>PP_Instance</code> identifying the instance.
+   *
+   * @return The size of pages that Map() uses. Returns 0 on failure.
+   */
+  [on_failure=0]
+  int64_t GetMapPageSize(PP_Instance instance);
+};
+