PPAPI: Implement PPB_FileMapping on POSIX

ppapi/c/ppb_file_mapping.h

+/* 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.
+ */
+
+/* From ppb_file_mapping.idl modified Wed Jan 22 10:45:15 2014. */
+
+#ifndef PPAPI_C_PPB_FILE_MAPPING_H_
+#define PPAPI_C_PPB_FILE_MAPPING_H_
+
+#include "ppapi/c/pp_completion_callback.h"
+#include "ppapi/c/pp_instance.h"
+#include "ppapi/c/pp_macros.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/pp_stdint.h"
+
+#define PPB_FILEMAPPING_INTERFACE_0_1 "PPB_FileMapping;0.1" /* dev */
+/**
+ * @file
+ * This file defines methods for mapping and unmapping files into and out of
+ * memory.
+ */
+
+
+/**
+ * @addtogroup Enums
+ * @{
+ */
+/**
+ * The PP_FileMapProtection values indicate the permissions requested for the
+ * file mapping. These should be used in a uint32_t bitfield.
+ */
+typedef enum {
+  /** Requests read access to the mapped address. */
+  PP_FILEMAPPROTECTION_READ = 1u << 0,
+  /** Requests write access to the mapped address. */
+  PP_FILEMAPPROTECTION_WRITE = 1u << 1
+} PP_FileMapProtection;
+PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_FileMapProtection, 4);
+
+/**
+ * The PP_FileMapFlags contain flag values for use with Map().
+ */
+typedef enum {
+  /**
+   * 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
+} PP_FileMapFlags;
+PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_FileMapFlags, 4);
+/**
+ * @}
+ */
+
+/**
+ * @addtogroup Interfaces
+ * @{
+ */
+/**
+ *  PPB_FileMapping contains functions for mapping and unmapping files into and
+ *  out of memory.
+ */
+struct PPB_FileMapping_0_1 { /* dev */
+  /**
+   * 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)(PP_Instance instance,
+                 PP_Resource file_io,
+                 int64_t length,
+                 uint32_t map_protection,
+                 uint32_t map_flags,
+                 int64_t offset,
+                 void** address,
+                 struct 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)(PP_Instance instance,
+                   const void* address,
+                   int64_t length,
+                   struct 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.
+   */
+  int64_t (*GetMapPageSize)(PP_Instance instance);
+};
+/**
+ * @}
+ */
+
+#endif  /* PPAPI_C_PPB_FILE_MAPPING_H_ */
+