The Tor Browser: toolkit/components/osfile/modules/osfile_shared

toolkit/components/osfile/modules/osfile_shared_allthreads.jsm@925c144e1f1f (annotated)

toolkit/components/osfile/modules/osfile_shared_allthreads.jsm

Fri, 16 Jan 2015 18:13:44 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 16 Jan 2015 18:13:44 +0100
branch: TOR_BUG_9701
changeset 14: 925c144e1f1f
permissions: -rw-r--r--

Integrate suggestion from review to improve consistency with existing code.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 /**
  * OS.File utilities used by all threads.
  *
  * This module defines:
  * - logging;
  * - the base constants;
  * - base types and primitives for declaring new types;
  * - primitives for importing C functions;
  * - primitives for dealing with integers, pointers, typed arrays;
  * - the base class OSError;
  * - a few additional utilities.
  */
 // Boilerplate used to be able to import this module both from the main
 // thread and from worker threads.
 if (typeof Components != "undefined") {
   // Global definition of |exports|, to keep everybody happy.
   // In non-main thread, |exports| is provided by the module
   // loader.
   this.exports = {};
   const Cu = Components.utils;
   const Ci = Components.interfaces;
   const Cc = Components.classes;
   Cu.import("resource://gre/modules/Services.jsm", this);
 }
 let EXPORTED_SYMBOLS = [
   "LOG",
   "clone",
   "Config",
   "Constants",
   "Type",
   "HollowStructure",
   "OSError",
   "Library",
   "declareFFI",
   "declareLazy",
   "declareLazyFFI",
   "normalizeToPointer",
   "projectValue",
   "isTypedArray",
   "defineLazyGetter",
   "offsetBy",
   "OS" // Warning: this exported symbol will disappear
 ];
 ////////////////////// Configuration of OS.File
 let Config = {
   /**
    * If |true|, calls to |LOG| are shown. Otherwise, they are hidden.
    *
    * This configuration option is controlled by preference "toolkit.osfile.log".
    */
   DEBUG: false,
   /**
    * TEST
    */
   TEST: false
 };
 exports.Config = Config;
 ////////////////////// OS Constants
 if (typeof Components != "undefined") {
   // On the main thread, OS.Constants is defined by a xpcom
   // component. On other threads, it is available automatically
   Cu.import("resource://gre/modules/ctypes.jsm");
   Cc["@mozilla.org/net/osfileconstantsservice;1"].
     getService(Ci.nsIOSFileConstantsService).init();
 }
 exports.Constants = OS.Constants;
 ///////////////////// Utilities
 // Define a lazy getter for a property
 let defineLazyGetter = function defineLazyGetter(object, name, getter) {
   Object.defineProperty(object, name, {
     configurable: true,
     get: function lazy() {
       delete this[name];
       let value = getter.call(this);
       Object.defineProperty(object, name, {
         value: value
       });
       return value;
     }
   });
 };
 exports.defineLazyGetter = defineLazyGetter;
 ///////////////////// Logging
 /**
  * The default implementation of the logger.
  *
  * The choice of logger can be overridden with Config.TEST.
  */
 let gLogger;
 if (typeof window != "undefined" && window.console && console.log) {
   gLogger = console.log.bind(console, "OS");
 } else {
   gLogger = function(...args) {
     dump("OS " + args.join(" ") + "\n");
   };
 }
 /**
  * Attempt to stringify an argument into something useful for
  * debugging purposes, by using |.toString()| or |JSON.stringify|
  * if available.
  *
  * @param {*} arg An argument to be stringified if possible.
  * @return {string} A stringified version of |arg|.
  */
 let stringifyArg = function stringifyArg(arg) {
   if (typeof arg === "string") {
     return arg;
   }
   if (arg && typeof arg === "object") {
     let argToString = "" + arg;
     /**
      * The only way to detect whether this object has a non-default
      * implementation of |toString| is to check whether it returns
      * '[object Object]'. Unfortunately, we cannot simply compare |arg.toString|
      * and |Object.prototype.toString| as |arg| typically comes from another
      * compartment.
      */
     if (argToString === "[object Object]") {
       return JSON.stringify(arg);
     } else {
       return argToString;
     }
   }
   return arg;
 };
 let LOG = function (...args) {
   if (!Config.DEBUG) {
     // If logging is deactivated, don't log
     return;
   }
   let logFunc = gLogger;
   if (Config.TEST && typeof Components != "undefined") {
     // If _TESTING_LOGGING is set, and if we are on the main thread,
     // redirect logs to Services.console, for testing purposes
     logFunc = function logFunc(...args) {
       let message = ["TEST", "OS"].concat(args).join(" ");
       Services.console.logStringMessage(message + "\n");
     };
   }
   logFunc.apply(null, [stringifyArg(arg) for (arg of args)]);
 };
 exports.LOG = LOG;
 /**
  * Return a shallow clone of the enumerable properties of an object.
  *
  * Utility used whenever normalizing options requires making (shallow)
  * changes to an option object. The copy ensures that we do not modify
  * a client-provided object by accident.
  *
  * Note: to reference and not copy specific fields, provide an optional
  * |refs| argument containing their names.
  *
  * @param {JSON} object Options to be cloned.
  * @param {Array} refs An optional array of field names to be passed by
  * reference instead of copying.
  */
 let clone = function (object, refs = []) {
   let result = {};
   // Make a reference between result[key] and object[key].
   let refer = function refer(result, key, object) {
     Object.defineProperty(result, key, {
       enumerable: true,
       get: function() {
         return object[key];
       },
       set: function(value) {
         object[key] = value;
       }
     });
   };
   for (let k in object) {
     if (refs.indexOf(k) < 0) {
       result[k] = object[k];
     } else {
       refer(result, k, object);
     }
   }
   return result;
 };
 exports.clone = clone;
 ///////////////////// Abstractions above js-ctypes
 /**
  * Abstraction above js-ctypes types.
  *
  * Use values of this type to register FFI functions. In addition to the
  * usual features of js-ctypes, values of this type perform the necessary
  * transformations to ensure that C errors are handled nicely, to connect
  * resources with their finalizer, etc.
  *
  * @param {string} name The name of the type. Must be unique.
  * @param {CType} implementation The js-ctypes implementation of the type.
  *
  * @constructor
  */
 function Type(name, implementation) {
   if (!(typeof name == "string")) {
     throw new TypeError("Type expects as first argument a name, got: "
                         + name);
   }
   if (!(implementation instanceof ctypes.CType)) {
     throw new TypeError("Type expects as second argument a ctypes.CType"+
                         ", got: " + implementation);
   }
   Object.defineProperty(this, "name", { value: name });
   Object.defineProperty(this, "implementation", { value: implementation });
 }
 Type.prototype = {
   /**
    * Serialize a value of |this| |Type| into a format that can
    * be transmitted as a message (not necessarily a string).
    *
    * In the default implementation, the method returns the
    * value unchanged.
    */
   toMsg: function default_toMsg(value) {
     return value;
   },
   /**
    * Deserialize a message to a value of |this| |Type|.
    *
    * In the default implementation, the method returns the
    * message unchanged.
    */
   fromMsg: function default_fromMsg(msg) {
     return msg;
   },
   /**
    * Import a value from C.
    *
    * In this default implementation, return the value
    * unchanged.
    */
   importFromC: function default_importFromC(value) {
     return value;
   },
   /**
    * A pointer/array used to pass data to the foreign function.
    */
   get in_ptr() {
     delete this.in_ptr;
     let ptr_t = new PtrType(
       "[in] " + this.name + "*",
       this.implementation.ptr,
       this);
     Object.defineProperty(this, "in_ptr",
     {
       get: function() {
         return ptr_t;
       }
     });
     return ptr_t;
   },
   /**
    * A pointer/array used to receive data from the foreign function.
    */
   get out_ptr() {
     delete this.out_ptr;
     let ptr_t = new PtrType(
       "[out] " + this.name + "*",
       this.implementation.ptr,
       this);
     Object.defineProperty(this, "out_ptr",
     {
       get: function() {
         return ptr_t;
       }
     });
     return ptr_t;
   },
   /**
    * A pointer/array used to both pass data to the foreign function
    * and receive data from the foreign function.
    *
    * Whenever possible, prefer using |in_ptr| or |out_ptr|, which
    * are generally faster.
    */
   get inout_ptr() {
     delete this.inout_ptr;
     let ptr_t = new PtrType(
       "[inout] " + this.name + "*",
       this.implementation.ptr,
       this);
     Object.defineProperty(this, "inout_ptr",
     {
       get: function() {
         return ptr_t;
       }
     });
     return ptr_t;
   },
   /**
    * Attach a finalizer to a type.
    */
   releaseWith: function releaseWith(finalizer) {
     let parent = this;
     let type = this.withName("[auto " + this.name + ", " + finalizer + "] ");
     type.importFromC = function importFromC(value, operation) {
       return ctypes.CDataFinalizer(
         parent.importFromC(value, operation),
         finalizer);
     };
     return type;
   },
   /**
    * Lazy variant of releaseWith.
    * Attach a finalizer lazily to a type.
    *
    * @param {function} getFinalizer The function that
    * returns finalizer lazily.
    */
   releaseWithLazy: function releaseWithLazy(getFinalizer) {
     let parent = this;
     let type = this.withName("[auto " + this.name + ", (lazy)] ");
     type.importFromC = function importFromC(value, operation) {
       return ctypes.CDataFinalizer(
         parent.importFromC(value, operation),
         getFinalizer());
     };
     return type;
   },
   /**
    * Return an alias to a type with a different name.
    */
   withName: function withName(name) {
     return Object.create(this, {name: {value: name}});
   },
   /**
    * Cast a C value to |this| type.
    *
    * Throw an error if the value cannot be casted.
    */
   cast: function cast(value) {
     return ctypes.cast(value, this.implementation);
   },
   /**
    * Return the number of bytes in a value of |this| type.
    *
    * This may not be defined, e.g. for |void_t|, array types
    * without length, etc.
    */
   get size() {
     return this.implementation.size;
   }
 };
 /**
  * Utility function used to determine whether an object is a typed array
  */
 let isTypedArray = function isTypedArray(obj) {
   return typeof obj == "object"
     && "byteOffset" in obj;
 };
 exports.isTypedArray = isTypedArray;
 /**
  * A |Type| of pointers.
  *
  * @param {string} name The name of this type.
  * @param {CType} implementation The type of this pointer.
  * @param {Type} targetType The target type.
  */
 function PtrType(name, implementation, targetType) {
   Type.call(this, name, implementation);
   if (targetType == null || !targetType instanceof Type) {
     throw new TypeError("targetType must be an instance of Type");
   }
   /**
    * The type of values targeted by this pointer type.
    */
   Object.defineProperty(this, "targetType", {
     value: targetType
   });
 }
 PtrType.prototype = Object.create(Type.prototype);
 /**
  * Convert a value to a pointer.
  *
  * Protocol:
  * - |null| returns |null|
  * - a string returns |{string: value}|
  * - a typed array returns |{ptr: address_of_buffer}|
  * - a C array returns |{ptr: address_of_buffer}|
  * everything else raises an error
  */
 PtrType.prototype.toMsg = function ptr_toMsg(value) {
   if (value == null) {
     return null;
   }
   if (typeof value == "string") {
     return { string: value };
   }
   let normalized;
   if (isTypedArray(value)) { // Typed array
     normalized = Type.uint8_t.in_ptr.implementation(value.buffer);
     if (value.byteOffset != 0) {
       normalized = offsetBy(normalized, value.byteOffset);
     }
   } else if ("addressOfElement" in value) { // C array
     normalized = value.addressOfElement(0);
   } else if ("isNull" in value) { // C pointer
     normalized = value;
   } else {
     throw new TypeError("Value " + value +
       " cannot be converted to a pointer");
   }
   let cast = Type.uintptr_t.cast(normalized);
   return {ptr: cast.value.toString()};
 };
 /**
  * Convert a message back to a pointer.
  */
 PtrType.prototype.fromMsg = function ptr_fromMsg(msg) {
   if (msg == null) {
     return null;
   }
   if ("string" in msg) {
     return msg.string;
   }
   if ("ptr" in msg) {
     let address = ctypes.uintptr_t(msg.ptr);
     return this.cast(address);
   }
   throw new TypeError("Message " + msg.toSource() +
     " does not represent a pointer");
 };
 exports.Type = Type;
 /*
  * Some values are large integers on 64 bit platforms. Unfortunately,
  * in practice, 64 bit integers cannot be manipulated in JS. We
  * therefore project them to regular numbers whenever possible.
  */
 let projectLargeInt = function projectLargeInt(x) {
   let str = x.toString();
   let rv = parseInt(str, 10);
   if (rv.toString() !== str) {
     throw new TypeError("Number " + str + " cannot be projected to a double");
   }
   return rv;
 };
 let projectLargeUInt = function projectLargeUInt(x) {
   return projectLargeInt(x);
 };
 let projectValue = function projectValue(x) {
   if (!(x instanceof ctypes.CData)) {
     return x;
   }
   if (!("value" in x)) { // Sanity check
     throw new TypeError("Number " + x.toSource() + " has no field |value|");
   }
   return x.value;
 };
 function projector(type, signed) {
   LOG("Determining best projection for", type,
     "(size: ", type.size, ")", signed?"signed":"unsigned");
   if (type instanceof Type) {
     type = type.implementation;
   }
   if (!type.size) {
     throw new TypeError("Argument is not a proper C type");
   }
   // Determine if type is projected to Int64/Uint64
   if (type.size == 8           // Usual case
       // The following cases have special treatment in js-ctypes
       // Regardless of their size, the value getter returns
       // a Int64/Uint64
       || type == ctypes.size_t // Special cases
       || type == ctypes.ssize_t
       || type == ctypes.intptr_t
       || type == ctypes.uintptr_t
       || type == ctypes.off_t) {
     if (signed) {
       LOG("Projected as a large signed integer");
       return projectLargeInt;
     } else {
       LOG("Projected as a large unsigned integer");
       return projectLargeUInt;
     }
   }
   LOG("Projected as a regular number");
   return projectValue;
 };
 exports.projectValue = projectValue;
 /**
  * Get the appropriate type for an unsigned int of the given size.
  *
  * This function is useful to define types such as |mode_t| whose
  * actual width depends on the OS/platform.
  *
  * @param {number} size The number of bytes requested.
  */
 Type.uintn_t = function uintn_t(size) {
   switch (size) {
   case 1: return Type.uint8_t;
   case 2: return Type.uint16_t;
   case 4: return Type.uint32_t;
   case 8: return Type.uint64_t;
   default:
     throw new Error("Cannot represent unsigned integers of " + size + " bytes");
   }
 };
 /**
  * Get the appropriate type for an signed int of the given size.
  *
  * This function is useful to define types such as |mode_t| whose
  * actual width depends on the OS/platform.
  *
  * @param {number} size The number of bytes requested.
  */
 Type.intn_t = function intn_t(size) {
   switch (size) {
   case 1: return Type.int8_t;
   case 2: return Type.int16_t;
   case 4: return Type.int32_t;
   case 8: return Type.int64_t;
   default:
     throw new Error("Cannot represent integers of " + size + " bytes");
   }
 };
 /**
  * Actual implementation of common C types.
  */
 /**
  * The void value.
  */
 Type.void_t =
   new Type("void",
            ctypes.void_t);
 /**
  * Shortcut for |void*|.
  */
 Type.voidptr_t =
   new PtrType("void*",
               ctypes.voidptr_t,
               Type.void_t);
 // void* is a special case as we can cast any pointer to/from it
 // so we have to shortcut |in_ptr|/|out_ptr|/|inout_ptr| and
 // ensure that js-ctypes' casting mechanism is invoked directly
 ["in_ptr", "out_ptr", "inout_ptr"].forEach(function(key) {
   Object.defineProperty(Type.void_t, key,
   {
     value: Type.voidptr_t
   });
 });
 /**
  * A Type of integers.
  *
  * @param {string} name The name of this type.
  * @param {CType} implementation The underlying js-ctypes implementation.
  * @param {bool} signed |true| if this is a type of signed integers,
  * |false| otherwise.
  *
  * @constructor
  */
 function IntType(name, implementation, signed) {
   Type.call(this, name, implementation);
   this.importFromC = projector(implementation, signed);
   this.project = this.importFromC;
 };
 IntType.prototype = Object.create(Type.prototype);
 IntType.prototype.toMsg = function toMsg(value) {
   if (typeof value == "number") {
     return value;
   }
   return this.project(value);
 };
 /**
  * A C char (one byte)
  */
 Type.char =
   new Type("char",
            ctypes.char);
 /**
  * A C wide char (two bytes)
  */
 Type.jschar =
   new Type("jschar",
            ctypes.jschar);
  /**
   * Base string types.
   */
 Type.cstring = Type.char.in_ptr.withName("[in] C string");
 Type.wstring = Type.jschar.in_ptr.withName("[in] wide string");
 Type.out_cstring = Type.char.out_ptr.withName("[out] C string");
 Type.out_wstring = Type.jschar.out_ptr.withName("[out] wide string");
 /**
  * A C integer (8-bits).
  */
 Type.int8_t =
   new IntType("int8_t", ctypes.int8_t, true);
 Type.uint8_t =
   new IntType("uint8_t", ctypes.uint8_t, false);
 /**
  * A C integer (16-bits).
  *
  * Also known as WORD under Windows.
  */
 Type.int16_t =
   new IntType("int16_t", ctypes.int16_t, true);
 Type.uint16_t =
   new IntType("uint16_t", ctypes.uint16_t, false);
 /**
  * A C integer (32-bits).
  *
  * Also known as DWORD under Windows.
  */
 Type.int32_t =
   new IntType("int32_t", ctypes.int32_t, true);
 Type.uint32_t =
   new IntType("uint32_t", ctypes.uint32_t, false);
 /**
  * A C integer (64-bits).
  */
 Type.int64_t =
   new IntType("int64_t", ctypes.int64_t, true);
 Type.uint64_t =
   new IntType("uint64_t", ctypes.uint64_t, false);
  /**
  * A C integer
  *
  * Size depends on the platform.
  */
 Type.int = Type.intn_t(ctypes.int.size).
   withName("int");
 Type.unsigned_int = Type.intn_t(ctypes.unsigned_int.size).
   withName("unsigned int");
 /**
  * A C long integer.
  *
  * Size depends on the platform.
  */
 Type.long =
   Type.intn_t(ctypes.long.size).withName("long");
 Type.unsigned_long =
   Type.intn_t(ctypes.unsigned_long.size).withName("unsigned long");
 /**
  * An unsigned integer with the same size as a pointer.
  *
  * Used to cast a pointer to an integer, whenever necessary.
  */
 Type.uintptr_t =
   Type.uintn_t(ctypes.uintptr_t.size).withName("uintptr_t");
 /**
  * A boolean.
  * Implemented as a C integer.
  */
 Type.bool = Type.int.withName("bool");
 Type.bool.importFromC = function projectBool(x) {
   return !!(x.value);
 };
 /**
  * A user identifier.
  *
  * Implemented as a C integer.
  */
 Type.uid_t =
   Type.int.withName("uid_t");
 /**
  * A group identifier.
  *
  * Implemented as a C integer.
  */
 Type.gid_t =
   Type.int.withName("gid_t");
 /**
  * An offset (positive or negative).
  *
  * Implemented as a C integer.
  */
 Type.off_t =
   new IntType("off_t", ctypes.off_t, true);
 /**
  * A size (positive).
  *
  * Implemented as a C size_t.
  */
 Type.size_t =
   new IntType("size_t", ctypes.size_t, false);
 /**
  * An offset (positive or negative).
  * Implemented as a C integer.
  */
 Type.ssize_t =
   new IntType("ssize_t", ctypes.ssize_t, true);
 /**
  * Encoding/decoding strings
  */
 Type.uencoder =
   new Type("uencoder", ctypes.StructType("uencoder"));
 Type.udecoder =
   new Type("udecoder", ctypes.StructType("udecoder"));
 /**
  * Utility class, used to build a |struct| type
  * from a set of field names, types and offsets.
  *
  * @param {string} name The name of the |struct| type.
  * @param {number} size The total size of the |struct| type in bytes.
  */
 function HollowStructure(name, size) {
   if (!name) {
     throw new TypeError("HollowStructure expects a name");
   }
   if (!size || size < 0) {
     throw new TypeError("HollowStructure expects a (positive) size");
   }
   // A mapping from offsets in the struct to name/type pairs
   // (or nothing if no field starts at that offset).
   this.offset_to_field_info = [];
   // The name of the struct
   this.name = name;
   // The size of the struct, in bytes
   this.size = size;
   // The number of paddings inserted so far.
   // Used to give distinct names to padding fields.
   this._paddings = 0;
 }
 HollowStructure.prototype = {
   /**
    * Add a field at a given offset.
    *
    * @param {number} offset The offset at which to insert the field.
    * @param {string} name The name of the field.
    * @param {CType|Type} type The type of the field.
    */
   add_field_at: function add_field_at(offset, name, type) {
     if (offset == null) {
       throw new TypeError("add_field_at requires a non-null offset");
     }
     if (!name) {
       throw new TypeError("add_field_at requires a non-null name");
     }
     if (!type) {
       throw new TypeError("add_field_at requires a non-null type");
     }
     if (type instanceof Type) {
       type = type.implementation;
     }
     if (this.offset_to_field_info[offset]) {
       throw new Error("HollowStructure " + this.name +
                       " already has a field at offset " + offset);
     }
     if (offset + type.size > this.size) {
       throw new Error("HollowStructure " + this.name +
                       " cannot place a value of type " + type +
                       " at offset " + offset +
                       " without exceeding its size of " + this.size);
     }
     let field = {name: name, type:type};
     this.offset_to_field_info[offset] = field;
   },
   /**
    * Create a pseudo-field that will only serve as padding.
    *
    * @param {number} size The number of bytes in the field.
    * @return {Object} An association field-name => field-type,
    * as expected by |ctypes.StructType|.
    */
   _makePaddingField: function makePaddingField(size) {
     let field = ({});
     field["padding_" + this._paddings] =
       ctypes.ArrayType(ctypes.uint8_t, size);
     this._paddings++;
     return field;
   },
   /**
    * Convert this |HollowStructure| into a |Type|.
    */
   getType: function getType() {
     // Contents of the structure, in the format expected
     // by ctypes.StructType.
     let struct = [];
     let i = 0;
     while (i < this.size) {
       let currentField = this.offset_to_field_info[i];
       if (!currentField) {
         // No field was specified at this offset, we need to
         // introduce some padding.
         // Firstly, determine how many bytes of padding
         let padding_length = 1;
         while (i + padding_length < this.size
             && !this.offset_to_field_info[i + padding_length]) {
           ++padding_length;
         }
         // Then add the padding
         struct.push(this._makePaddingField(padding_length));
         // And proceed
         i += padding_length;
       } else {
         // We have a field at this offset.
         // Firstly, ensure that we do not have two overlapping fields
         for (let j = 1; j < currentField.type.size; ++j) {
           let candidateField = this.offset_to_field_info[i + j];
           if (candidateField) {
             throw new Error("Fields " + currentField.name +
               " and " + candidateField.name +
               " overlap at position " + (i + j));
           }
         }
         // Then add the field
         let field = ({});
         field[currentField.name] = currentField.type;
         struct.push(field);
         // And proceed
         i += currentField.type.size;
       }
     }
     let result = new Type(this.name, ctypes.StructType(this.name, struct));
     if (result.implementation.size != this.size) {
       throw new Error("Wrong size for type " + this.name +
           ": expected " + this.size +
           ", found " + result.implementation.size +
           " (" + result.implementation.toSource() + ")");
     }
     return result;
   }
 };
 exports.HollowStructure = HollowStructure;
 /**
  * Representation of a native library.
  *
  * The native library is opened lazily, during the first call to its
  * field |library| or whenever accessing one of the methods imported
  * with declareLazyFFI.
  *
  * @param {string} name A human-readable name for the library. Used
  * for debugging and error reporting.
  * @param {string...} candidates A list of system libraries that may
  * represent this library. Used e.g. to try different library names
  * on distinct operating systems ("libxul", "XUL", etc.).
  *
  * @constructor
  */
 function Library(name, ...candidates) {
   this.name = name;
   this._candidates = candidates;
 };
 Library.prototype = Object.freeze({
   /**
    * The native library as a js-ctypes object.
    *
    * @throws {Error} If none of the candidate libraries could be opened.
    */
   get library() {
     let library;
     delete this.library;
     for (let candidate of this._candidates) {
       try {
         library = ctypes.open(candidate);
         break;
       } catch (ex) {
         LOG("Could not open library", candidate, ex);
       }
     }
     this._candidates = null;
     if (library) {
       Object.defineProperty(this, "library", {
         value: library
       });
       Object.freeze(this);
       return library;
     }
     let error = new Error("Could not open library " + this.name);
     Object.defineProperty(this, "library", {
       get: function() {
         throw error;
       }
     });
     Object.freeze(this);
     throw error;
   },
   /**
    * Declare a function, lazily.
    *
    * @param {object} The object containing the function as a field.
    * @param {string} The name of the field containing the function.
    * @param {string} symbol The name of the function, as defined in the
    * library.
    * @param {ctypes.abi} abi The abi to use, or |null| for default.
    * @param {Type} returnType The type of values returned by the function.
    * @param {...Type} argTypes The type of arguments to the function.
    */
   declareLazyFFI: function(object, field, ...args) {
     let lib = this;
     Object.defineProperty(object, field, {
       get: function() {
         delete this[field];
         let ffi = declareFFI(lib.library, ...args);
         if (ffi) {
           return this[field] = ffi;
         }
         return undefined;
       },
       configurable: true,
       enumerable: true
     });
   },
   /**
    * Define a js-ctypes function lazily using ctypes method declare.
    *
    * @param {object} The object containing the function as a field.
    * @param {string} The name of the field containing the function.
    * @param {string} symbol The name of the function, as defined in the
    * library.
    * @param {ctypes.abi} abi The abi to use, or |null| for default.
    * @param {ctypes.CType} returnType The type of values returned by the function.
    * @param {...ctypes.CType} argTypes The type of arguments to the function.
    */
   declareLazy: function(object, field, ...args) {
     let lib = this;
     Object.defineProperty(object, field, {
       get: function() {
         delete this[field];
         let ffi = lib.library.declare(...args);
         if (ffi) {
           return this[field] = ffi;
         }
         return undefined;
       },
       configurable: true,
       enumerable: true
     });
   },
   toString: function() {
     return "[Library " + this.name + "]";
   }
 });
 exports.Library = Library;
 /**
  * Declare a function through js-ctypes
  *
  * @param {ctypes.library} lib The ctypes library holding the function.
  * @param {string} symbol The name of the function, as defined in the
  * library.
  * @param {ctypes.abi} abi The abi to use, or |null| for default.
  * @param {Type} returnType The type of values returned by the function.
  * @param {...Type} argTypes The type of arguments to the function.
  *
  * @return null if the function could not be defined (generally because
  * it does not exist), or a JavaScript wrapper performing the call to C
  * and any type conversion required.
  */
 let declareFFI = function declareFFI(lib, symbol, abi,
                                      returnType /*, argTypes ...*/) {
   LOG("Attempting to declare FFI ", symbol);
   // We guard agressively, to avoid any late surprise
   if (typeof symbol != "string") {
     throw new TypeError("declareFFI expects as first argument a string");
   }
   abi = abi || ctypes.default_abi;
   if (Object.prototype.toString.call(abi) != "[object CABI]") {
     // Note: This is the only known manner of checking whether an object
     // is an abi.
     throw new TypeError("declareFFI expects as second argument an abi or null");
   }
   if (!returnType.importFromC) {
     throw new TypeError("declareFFI expects as third argument an instance of Type");
   }
   let signature = [symbol, abi];
   let argtypes  = [];
   for (let i = 3; i < arguments.length; ++i) {
     let current = arguments[i];
     if (!current) {
       throw new TypeError("Missing type for argument " + ( i - 3 ) +
                           " of symbol " + symbol);
     }
     if (!current.implementation) {
       throw new TypeError("Missing implementation for argument " + (i - 3)
                           + " of symbol " + symbol
                           + " ( " + current.name + " )" );
     }
     signature.push(current.implementation);
   }
   try {
     let fun = lib.declare.apply(lib, signature);
     let result = function ffi(...args) {
       for (let i = 0; i < args.length; i++) {
         if (typeof args[i] == "undefined") {
           throw new TypeError("Argument " + i + " of " + symbol + " is undefined");
         }
       }
       let result = fun.apply(fun, args);
       return returnType.importFromC(result, symbol);
     };
     LOG("Function", symbol, "declared");
     return result;
   } catch (x) {
     // Note: Not being able to declare a function is normal.
     // Some functions are OS (or OS version)-specific.
     LOG("Could not declare function ", symbol, x);
     return null;
   }
 };
 exports.declareFFI = declareFFI;
 /**
  * Define a lazy getter to a js-ctypes function using declareFFI.
  *
  * @param {object} The object containing the function as a field.
  * @param {string} The name of the field containing the function.
  * @param {ctypes.library} lib The ctypes library holding the function.
  * @param {string} symbol The name of the function, as defined in the
  * library.
  * @param {ctypes.abi} abi The abi to use, or |null| for default.
  * @param {Type} returnType The type of values returned by the function.
  * @param {...Type} argTypes The type of arguments to the function.
  */
 function declareLazyFFI(object, field, ...declareFFIArgs) {
   Object.defineProperty(object, field, {
     get: function() {
       delete this[field];
       let ffi = declareFFI(...declareFFIArgs);
       if (ffi) {
         return this[field] = ffi;
       }
       return undefined;
     },
     configurable: true,
     enumerable: true
   });
 }
 exports.declareLazyFFI = declareLazyFFI;
 /**
  * Define a lazy getter to a js-ctypes function using ctypes method declare.
  *
  * @param {object} The object containing the function as a field.
  * @param {string} The name of the field containing the function.
  * @param {ctypes.library} lib The ctypes library holding the function.
  * @param {string} symbol The name of the function, as defined in the
  * library.
  * @param {ctypes.abi} abi The abi to use, or |null| for default.
  * @param {ctypes.CType} returnType The type of values returned by the function.
  * @param {...ctypes.CType} argTypes The type of arguments to the function.
  */
 function declareLazy(object, field, lib, ...declareArgs) {
   Object.defineProperty(object, field, {
     get: function() {
       delete this[field];
       try {
         let ffi = lib.declare(...declareArgs);
         return this[field] = ffi;
       } catch (ex) {
         // The symbol doesn't exist
         return undefined;
       }
     },
     configurable: true
   });
 }
 exports.declareLazy = declareLazy;
 // A bogus array type used to perform pointer arithmetics
 let gOffsetByType;
 /**
  * Advance a pointer by a number of items.
  *
  * This method implements adding an integer to a pointer in C.
  *
  * Example:
  *   // ptr is a uint16_t*,
  *   offsetBy(ptr, 3)
  *  // returns a uint16_t* with the address ptr + 3 * 2 bytes
  *
  * @param {C pointer} pointer The start pointer.
  * @param {number} length The number of items to advance. Must not be
  * negative.
  *
  * @return {C pointer} |pointer| advanced by |length| items
  */
 let offsetBy =
   function offsetBy(pointer, length) {
     if (length === undefined || length < 0) {
       throw new TypeError("offsetBy expects a positive number");
     }
    if (!("isNull" in pointer)) {
       throw new TypeError("offsetBy expects a pointer");
     }
     if (length == 0) {
       return pointer;
     }
     let type = pointer.constructor;
     let size = type.targetType.size;
     if (size == 0 || size == null) {
       throw new TypeError("offsetBy cannot be applied to a pointer without size");
     }
     let bytes = length * size;
     if (!gOffsetByType || gOffsetByType.size <= bytes) {
       gOffsetByType = ctypes.uint8_t.array(bytes * 2);
     }
     let addr = ctypes.cast(pointer, gOffsetByType.ptr).
       contents.addressOfElement(bytes);
     return ctypes.cast(addr, type);
 };
 exports.offsetBy = offsetBy;
 /**
  * Utility function used to normalize a Typed Array or C
  * pointer into a uint8_t C pointer.
  *
  * Future versions might extend this to other data structures.
  *
  * @param {Typed array | C pointer} candidate The buffer. If
  * a C pointer, it must be non-null.
  * @param {number} bytes The number of bytes that |candidate| should contain.
  * Used for sanity checking if the size of |candidate| can be determined.
  *
  * @return {ptr:{C pointer}, bytes:number} A C pointer of type uint8_t,
  * corresponding to the start of |candidate|.
  */
 function normalizeToPointer(candidate, bytes) {
   if (!candidate) {
     throw new TypeError("Expecting  a Typed Array or a C pointer");
   }
   let ptr;
   if ("isNull" in candidate) {
     if (candidate.isNull()) {
       throw new TypeError("Expecting a non-null pointer");
     }
     ptr = Type.uint8_t.out_ptr.cast(candidate);
     if (bytes == null) {
       throw new TypeError("C pointer missing bytes indication.");
     }
   } else if (isTypedArray(candidate)) {
     // Typed Array
     ptr = Type.uint8_t.out_ptr.implementation(candidate.buffer);
     if (bytes == null) {
       bytes = candidate.byteLength;
     } else if (candidate.byteLength < bytes) {
       throw new TypeError("Buffer is too short. I need at least " +
                          bytes +
                          " bytes but I have only " +
                          candidate.byteLength +
                           "bytes");
     }
   } else {
     throw new TypeError("Expecting  a Typed Array or a C pointer");
   }
   return {ptr: ptr, bytes: bytes};
 };
 exports.normalizeToPointer = normalizeToPointer;
 ///////////////////// OS interactions
 /**
  * An OS error.
  *
  * This class is provided mostly for type-matching. If you need more
  * details about an error, you should use the platform-specific error
  * codes provided by subclasses of |OS.Shared.Error|.
  *
  * @param {string} operation The operation that failed.
  * @param {string=} path The path of the file on which the operation failed,
  * or nothing if there was no file involved in the failure.
  *
  * @constructor
  */
 function OSError(operation, path = "") {
   Error.call(this);
   this.operation = operation;
   this.path = path;
 }
 exports.OSError = OSError;
 ///////////////////// Temporary boilerplate
 // Boilerplate, to simplify the transition to require()
 // Do not rely upon this symbol, it will disappear with
 // bug 883050.
 exports.OS = {
   Constants: exports.Constants,
   Shared: {
     LOG: LOG,
     clone: clone,
     Type: Type,
     HollowStructure: HollowStructure,
     Error: OSError,
     declareFFI: declareFFI,
     projectValue: projectValue,
     isTypedArray: isTypedArray,
     defineLazyGetter: defineLazyGetter,
     offsetBy: offsetBy
   }
 };
 Object.defineProperty(exports.OS.Shared, "DEBUG", {
   get: function() {
     return Config.DEBUG;
   },
   set: function(x) {
     return Config.DEBUG = x;
   }
 });
 Object.defineProperty(exports.OS.Shared, "TEST", {
   get: function() {
     return Config.TEST;
   },
   set: function(x) {
     return Config.TEST = x;
   }
 });
 ///////////////////// Permanent boilerplate
 if (typeof Components != "undefined") {
   this.EXPORTED_SYMBOLS = EXPORTED_SYMBOLS;
   for (let symbol of EXPORTED_SYMBOLS) {
     this[symbol] = exports[symbol];
   }
 }

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toolkit/components/osfile/modules/osfile_shared_allthreads.jsm@925c144e1f1f (annotated)

toolkit/components/osfile/modules/osfile_shared_allthreads.jsm